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Diatom Biodiversity and Distribution on Wetwalls inGreat Smoky Mountains National ParkAuthor(s) Rex L Lowe Paula C Furey Jennifer A Ress and JeffreyR JohansenSource Southeastern Naturalist 6(sp2)135-152 2007Published By Eagle Hill InstituteDOI httpdxdoiorg1016561528-7092(2007)6[135DBADOW]20CO2URL httpwwwbiooneorgdoifull1016561528-70922820072965B1353ADBADOW5D20CO3B2

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1Department of Biological Sciences Bowling Green State University Bowling Green OH 43402 2Department of Biology John Carroll University University Heights OH 44118 Corresponding author - lowebgsuedu

Diatom Biodiversity and Distribution on Wetwalls in Great Smoky Mountains National Park

Rex L Lowe1 Paula C Furey1 Jennifer A Ress1 and Jeffrey R Johansen2

Abstract - Diatoms and other algae were collected and identifi ed from subaerial habitats (wetwalls) in Great Smoky Mountains National Park as part of a larger bio-diversity survey of the Park Algal collections were made across a range of moisture gradients and bedrock mineralogies with pH ranging from 38 to 77 None of the communities collected were entirely submerged in water but were often associated with moist bryophytes cyanobacterial mats and dripping groundwater seeps Some of the collections were from cliff faces wetted only periodically To date 41 diatom genera and over 223 species have been identifi ed from these habitats Several of these genera are widely distributed across aquatic habitats however several of the genera are ldquosubaerial specialistsrdquo and possess morphological features such as re-duced size reduced external openings in the cell wall or additional external siliceous membranes that allow them to survive in relatively dry habitats Widely distributed species with high fi delity to subaerial habitats occur in the genera Achnanthes Cymbopleura Decussata Diadesmis Luticola Melosira Microcostatus Nupela Psammothidium and Orthoseira Many of the species constitute new Park records national records or are new to science

Introduction

In 1997 an ambitious research agenda was initiated to inventory all species within Great Smoky Mountains National Park (GSMNP) The GSMNP All Taxa Biodiversity Inventory (ATBI) includes all species from prokaryotes to vertebrates and higher plants (Pederson 1999 Sharkey 2001) GSMNP resides at a climatic transition from the northern temperate zone to the southern temperate zone and has a complex geology with a diversity of bedrock chemistry at different elevations and strong moisture gradients from high to low elevations GSMNP represents the largest contiguous preserve east of the Mississippi River and contains a great diversity of freshwater algal habitats including mountain and lowland streams of fi rst through third order (Wallace et al 1992) lowland wetlands and ponds perched bogs and a large reservoir (Fontana Lake) on the southern border Five hundred and eighty four records of algal taxa were documented from the park in 2004 (Johansen et al 2004) although many more have been discovered since that report (Johansen and Lowe in press Olsen 2004 Potapova et al 2003)

135

The Great Smoky Mountains National Park All Taxa Biodiversity Inventory A Search for Species in Our Own Backyard

2007 Southeastern Naturalist Special Issue 1135ndash152

Southeastern Naturalist136 Special Issue 1

The focus habitats of the research reported in this manuscript are subaer-ial wetwalls Wetwalls are exposed vertical or sloping rock faces that vary in moisture availability but are not submerged Moisture may be primarily from the atmosphere (rain and fog) or from groundwater seeps GSMNP contains hundreds of vertical wetwalls with varying bedrock chemistry and levels of moisture Stream cuts road cuts landslides and waterfall spray zones in GSMNP have resulted in an abundance of wetwall habitats We anticipated that wetwalls would provide habitat for many species of algae that are uncommon or absent from streams lakes and wetlands Because of periodic exposure to drying many obligate aquatic algal taxa do not occupy these habitats In previous investigations (Gomez et al 2003) we found wetwalls to support many species of ldquosoftrdquo algae that are infrequently re-ported Because wetwalls are more insular than streams with no upstream source of algal immigrants we expected the fl ora of wetwalls to strongly refl ect local environmental conditions In addition we expected wetwalls to be a refuge for species that might be vulnerable to competition by invasive algal species since wetwalls are less likely to receive species introductions from fi shermen or other stream users The wetwall algal study by Gomez et al (2003) was restricted to ldquosoftrdquo or non-diatom algae One hundred and eighteen algal species were reported from the study and 108 of these were new GSMNP records The objective of the present study was to investigate the diatom fl ora of GSMNP wetwalls We anticipated that diatom distribution on wetwalls would be correlated with bedrock mineralogy chemistry (including pH) wetwall elevation and the presence or absence of ldquomoisture-facilitating algae such as Nostoc that have the capacity to hold water in extra cellular polysaccharides or bryophytes that provide shelter from desiccation

Methods

Study area GSMNP comprises over 2072 km2 (800 square miles) in the Southern Appalachian Mountains on the border between North Carolina and Ten-nessee bridging the northern and southern temperate zones Forested with elevations that range from 267 m to 2025 m rolling mountains dominate the park The unique northeast to southwest orientation of the mountains large tracts of deciduous old-growth and contiguous forests and protection as a national park in addition to having remained unglaciated for over a million years have all contributed to a rich and abundant fauna and fl ora For ex-ample the park has over 100 species of native trees and a high diversity of lungless salamanders The geology of GSMNP is varied and the 25 general categories of bedrock types are comprised of rocks with a complex deposi-tional stratigraphic metamorphic and structural history (Southworth et al 2005)

RL Lowe PC Furey JA Ress and JR Johansen 1372007

Wetwall sampling and analysis The subaerial diatom fl ora was examined from wetwall samples from collecting expeditions to the GSMNP from 2001 to 2005 In May and August 2001 SR Gomez collected subaerial algal samples throughout the park (Gomez et al 2003) In July 2004 samples were collected by Na-tional Park Service (NPS) personnel along with the Appalachian Highlands Learning Center interns Collecting expeditions to GSMNP by the Bowling Green State University (BGSU) and John Carroll University (JCU) research groups occurred on fi ve separate occasions 15ndash18 October 2003 15ndash20 May 2004 11ndash14 July 2004 22ndash23 October 2004 and 15 Mayndash11 August 2005 Sites were generally collected only once and seasonal variability was not assessed although we expect it to be relatively invariable in these sub-aerial communities since there is little opportunity for diatom emigration in contrast to stream periphyton communities Algae were collected from drippy rock faces using forceps pipettes and a knife and by squeezing bryophytes A total of 49 subaerial habitats from 11 different bedrock types were sampled from elevations ranging from 363 to 1841 m (Appendix 1) Bedrock types were selected to represent all the common types that cover the majority of the park (from a total of 25 general bedrock units Southworth et al 2005) Collection locations were geo-referenced (Garmin GPS Unit) where global positioning system (GPS) signals were available (Coordinate datum NAD27 UTM zone 17S) The pH of each site was measured using EMD colorphast pH-indicator strips (range 25 to 10 pH units sensitivity of 02 to 03 pH units) in order to provide a rough estimate of differences in the acidity of sampling locations Samples collected by SR Gomez were pre-served in 2 buffered formaldehyde the remaining samples were preserved in a minimum of 2 glutaraldehyde Diatoms were cleaned in boiling nitric acid and air dried onto cover glasses Permanent diatom mounts for light microscope (LM) analysis were made using Naphraxreg mounting medium Permanent diatom slides will be made for future reference at BGSU and will also be deposited in the GSMNP Science Center the diatom herbaria at the California Academy of Science (CAS) and the Academy of Natural Sciences of Philadelphia (ANSP) Slides were analyzed with an Olympus BX51 Photomicroscope with high-resolution DIC optics A minimum of 200 diatom frustules was counted from each sample Digital images were recorded with a monochromatic camera (Spotreg) attached to the microscope and a computer Diatoms were identifi ed to the lowest taxonomic level possible using standard references References consisted of Krammer and Lange-Bertalot (1986) Krammer and Lange-Bertalot (1988) Krammer and Lange-Bertalot (1991a) Kram-mer and Lange-Bertalot (1991b) Patrick and Reimer (1966) Johansen and Sray (1998) Potapova et al (2003) and Werum and Lange-Bertalot (2004) Cover glasses mounted on specimen stubs and sputter-coated with 10 nm goldpalladium alloy were analyzed on a high-resolution Hitachi S-2700 scanning electron microscope (SEM)

Southeastern Naturalist138 Special Issue 1

Relative abundance of diatoms at each site calculated both at the species and genus levels were normalized with an arcsine transformation (arcsine of the square root Sokal and Rohlf 1995) Ordination of sites was fi rst conducted based on a reduced species list using non-metric multidimension-al scaling (MDS) of Bray Curtis similarities Diatom taxa that occurred at a minimum of three sites were included in the MDS analysis in order to ensure suffi cient data for ordination thus reducing the total number of taxa from 223 to 98 A high stress value for the MDS output indicated that additional analyses should be conducted to confi rm the MDS ordination Therefore the clustering of sites based on species- or genera-level similarity for both a reduced and complete taxa list was examined using a dendrogram of group-average linking of Bray Curtis similarities The cluster analysis using the complete species list is presented in this study because the overall patterns were similar between the two methods and the use of the complete spe-cies list provided a more inclusive picture of the wetwall communities and information on some of the unique wetwall sites Elevation pH latitude longitude watershed and microhabitat type (epiphytic [bryophyte associ-ated] or epilithic) were used as factors for examining clustering patterns Statistical tests were performed with Primer 5 version 529 (PrimerndashE Ltd 2002) Unique communities of algae were identifi ed as those sets of sites with either gt85 relative abundance of a single taxon or lt10 similarity with other sets of sites based on the cluster analysis Clusters were further subdivided into ten subclusters based on a similarity cutoff of 15 Com-mon wetwall taxa were selected based on species and genera that were found at gt3 overall relative abundance (calculated with all sites considered to-gether) or present at gt20 of the sites

Results

Site pH ranged from 38ndash55 with the exception of three unique sites that had pH between 72ndash77 Acidic areas were generally found at the higher elevation sites The three sites with pH gt 7 were all found in the Whiteoak Sink area of the GSMNP Forty-one genera and 223 species were identifi ed from the wetwall sites Nineteen wetwall genera were commonly present across all sites (Table 1) Achnanthes Diadesmis Eunotia Navicula Nupela and Pinnularia were present at gt50 of the sites and Chamaepinnularia Encyonema Frustulia Gomphonema and Nitzschia at gt20 of the sites (Table 1) Of these genera Diadesmis (15) and Eunotia (21) also had high overall relative abundance across sites (Table 1) Within these genera 23 wetwall species were consid-ered notable either because they had a higher mean relative abundance or were frequently present at sites Nitzschia hantzschiana Rabenhorst (58) Eunotia praerupta v bigibba (Kuumltzing) Grunow (55) Cymbopleura rupic-ola (Grunow) Krammer (57) and Navicula keeleyi Patrick (96) had the highest overall relative abundances (Table 1) Diadesmis contenta v biceps (Grunow) Hamilton Diadesmis contenta (Grunow) DG Mann Diadesmis

RL Lowe PC Furey JA Ress and JR Johansen 1392007

perpusilla (Kuumltzing) DG Mann Navicula keeleyi Achnanthes subrostrata v appalachiana Camburn and Lowe Navicula angusta Grunow Nitzschia hantzschiana and Nupela neglecta Ponader Lowe and Potapova were pres-ent at over 35 of the sites (Table 1) Four site-groups ([A] [B] [C D E] and [F G H I J J

1 J

2] were identifi ed by the 2-D MDS ordination (Fig 1 stress

Table 1 Table of common species based on overall relative abundance (all sites considered together) or taxa frequently present across sites Species were selected if overall abundance was gt3 or the taxa were present at gt20 of the sites

Mean relative of sites Taxon abundance where present

Achnanthes subrostrata v appalachiana 39 388Achnanthidium exiguum 05 225Chamaepinnularia spp 05 408Cymbopleura rupicola 57 61Decussata placenta 07 245Diadesmis contenta 16 469Diadesmis contenta v biceps 20 388Diatoma mesodon 29 204Encyonema minutum 14 246Eunotia exigua 26 347Eunotia nymanniana 04 245Eunotia praerupta v bigibba 55 204Frustulia crassinervia 08 204Frustulia krammeri 29 265Gomphonema parvulum 05 204Meridion circulare 07 306Microcostatus krasskei 34 327Navicula angusta 18 449Navicula keeleyi 96 592Nitzschia hantzschiana 58 388Nupela spp 28 510Pinularia spp 39 519Planothidium lanceolatum 26 286Psammothidium marginulatum 23 225

Navicula keeleyi to be transferred to Diadesmis in a subsequent manuscript

Figure 1 Two-dimen-sional non-metric mul-tidimensional scaling (MDS) ordination for the 49 wetwall sites based on the Bray-Cur-tis similarities on arc sine root transformed relative abundance data for species present at gt 3 sites MDS stress = 016 Codes (A through J J1 and J2) represent grops of sites identifi ed in the cluster analysis for all species data (see Fig 2) Four general site-groups were identifi ed (A) (B) (C D E) and (F G H I J J1 J2)

Southeastern Naturalist140 Special Issue 1

value 016) Due to the high stress value these patterns were also examined with a cluster analysis both for the reduced taxa list and for all taxa Similar patterns were observed for both cluster analyses Therefore the dendrogram with all taxa considered is shown since it provides the most information on diatom community composition across sites (Fig 2) The four sitendashgroups identifi ed by the MDS ordination also clustered with less than a 10 site similarity threshold (Fig 2) At lt15 similarity 10 site-groups or clusters were identifi ed (Fig 2) With notable exceptions all sites clustered at lt50 similarity which suggests that the diatom community composition was quite variable at the different wetwall sites The two sites forming cluster A (CR-J1C and NDT-V1A) were strongly dominated by Pinnularia subcapitata v hilseana (Janisch ex Rabenhorst) Muumlller with Eunotia cf glacialis Meister also being very abundant at CR-J1C (Fig 2 Table 2) The sites forming cluster B were dominated by

Table 2 Sites where community composition was comprised of one taxon ge 85 relative abun-dance = sites identifi ed as unique in the dendrogram

Site code Species Relative abundance

ACT-15 Eunotia praerupta v bigibba 955CDR-J5E Eunotia cf fallax 920CR-CAT1C Nitzschia hantzshciana 970CR-J1C Pinnularia subcapitata v hilseana 950NG-J9A Tetracyclus rupestris 850WS-4A Cymbopleura rupicola 995WSF-6C Cymbopleura rupicola 995

Figure 2 Dendrogram of the 49 seep-wall sites using group-average clustering from Bray Curtis similarities on arc sine root transformed relative abundances of the all species A lt10 (dashedndashdot line) and lt15 (dotted line) similarity threshold are identifi ed The unique sites and locations separated at a lt15 (dotted line) similarity threshold are indicated by AndashJ below the xndashaxis

RL Lowe PC Furey JA Ress and JR Johansen 1412007

Cymbopleura rupicola with relative abundances of 995 at site WS-4A and WSF-6C and 82 at WSF-6B (Fig 2 Table 2) Cymbopleura rupicola was only present at these three alkaline sites Cluster C site LF-5A was comprised mainly of Frustulia crassinervia (Breacutebisson ex W Smith) Lange-Bertalot and Frustulia krammeri Lange-Bertalot and Metzeltin (Fig 2 Table 2) The two sites forming cluster D included RC-PF6F which was characterized by Eunotia exigua (Breacutebisson ex Kuumltzing) Rabenhorst and Eunotia sp12 with relative abundances at 675 and 225 respectively and LCR-7B which was primarily composed of Psammothidium margi-nulatum (Grunow) Bukhtiyarova and Round and secondarily of Eunotia exigua with relative abundances of 75 and 205 respectively Psam-mothidium marginulatum was found in only fi ve other communities in low relative abundance (Fig 2) Cluster E included six sites that were generally dominated by Eunotia taxa especially Eunotia praerupta v bigibba and Eunotia cf fallax A Cleve (Fig 2 Table 2) Cluster F site TCT-2B was also dominated by Eunotia taxa (Fig 2) The two sites in Cluster G were dominated by different taxa but Diatoma mesodon Kuumltzing and Fragilari-aforma virescens (Ralfs) Williams and Round were present at both Cluster H site NG-J9A was dominated by a single taxon Tetracyclus rupestris (Braun) Grunow that was absent from all other sites (Fig 2 Table 2) The three sites forming Cluster I (LRR-2 LRT-PF1 and CR-CAT1C) all had Nitzschia hantzschiana as a common taxon at 165 79 and 97 relative abundances respectively (Fig 2 Table 2) Cluster J was the largest cluster of sites and overall these sites were highly variable in their taxonomic composition Cluster J1 tended to be comprised of Diadesmis taxa (includ-ing Navicula keeleyi yet to be transferred to Diadesmis) and sites at Cluster J2 were dominated by Microcostatus krasskei (Hustedt) Johansen and Sray (Fig 2) Within all the clusters (AndashJ) seven communities were characterized as unique based on a relative abundance of ge85 of one taxon (Table 2) Within the MDS ordination factor codes and bubble plots of pH geology elevation latitude longitude and watershed were examined to explore the site-clustering patterns in response to the environmental variables and to examine taxon-specifi c clustering with environmental variables (plots not shown) However no patterns were observed for any of the environmental variables alone or considered with a specifi c taxon (with the exception of Cymbopleura rupestris which was found at the three sites with the highest pH)

Discussion

Two hundred and twenty-three diatom species and varieties within 41 genera were recorded from the wetwall communities in GSMNP (see Figs 3ndash35 for illustrations of some of the more common taxa ) These communi-ties were dominated by several taxa that are common in subaerial habitats Many species in the genus Diadesmis for example have been reported from numerous wetwall studies (Dayner and Johansen 1991 Johansen et al 1983a Lowe and Collins 1973 McMillim and Rushforth 1985) Wetwall

Southeastern Naturalist142 Special Issue 1

Figures 3ndash22 Common taxa denoted in Table 1 ldquordquo signifi es taxa denoted in Table 2 3) Achnanthes subrostrata v appalachiana raphe valve 4) Achnanthes subrostrata v appalachiana rapheless valve 5) Achnanthidium exiguum raphe valve 6) Ach-nanthidium exiguum (Grun) Czarnezki rapheless valve 7) Diatoma mesodon 8) Diatoma mesodon girdle view 9) Chamaepinnularia mediocris (Krasske) Lange-Bertalot 10) Diadesmis contenta 11) Diadesmis contenta v biceps 12) Navicula keeleyi 13) Diadesmis perpusilla 14) Gomphonema cf parvulum Kuumltz 15) Pin-nularia subcapitata v hilseana 16) Decussata placenta (Ehr) Lange-Bertalot amp Mezeltin 17) Cymbopleura rupicola 18) Eunotia praerupta v bigibba 19) Euno-tia nymanianna Grun 20) Eunotia cf fallax 21) Eunotia exigua 22) Encyonema minutum (Hilse ex Rabh) DG Mann

RL Lowe PC Furey JA Ress and JR Johansen 1432007

diatoms must withstand a greater range of environmental variables than aquatic species (Patrick 1977) Unlike truly aquatic habitats subaerial envi-

Figures 23ndash35 Common taxa denoted in Table 1 ldquordquo signifi es taxa denoted in Table 2 23) Frustulia krammeri 24) Frustulia crassinervia 25) Meridion circulare (Grev) Ag 26) Navicula angusta 27) Nitzschia hantzschiana 28) Microcostatus krasskei 29) Nupela sp 30) Planothidium lanceolatum raphe valve 31) Planothid-ium lanceolatum (Breacuteb ex Kuumltz) Round amp Bukhtiyarova rapheless valve 32) Psammothidium marginulatum raphe valve 33) Psammothidium marginulatum rapheless valve 34) Tetracyclus rupestris 35) Tetracyclus rupestris girdle view

Southeastern Naturalist144 Special Issue 1

ronments are moist but can periodically become dry for long periods Also because these diatoms often live in a fi lm of water they do not experience the thermal stability that aquatic taxa experience Wetwall diatoms may also experience more intense ultraviolet radiation than aquatic forms that are more protected by water (Johansen 1999) Many wetwall diatoms have a reduced number of areolae or possess areolae that are occluded with a siliceous lamina (eg species of Nupela Diadesmis Chamaepinnularia and Eunotia Figs 36ndash39) These morpho-logical features may be adaptations to reduce water loss in periodically dry habitats Some common taxa without obviously reduced external openings such as Decussata Luticola Microcostatus and Nitzschia (Figs 40ndash43) are also typical of diatom communities in subaerial habitats Diatom community structure on the wetwall habitats observed in this study was diverse and highly variable Higher pH appeared to be an im-portant variable separating the three Whiteoak Sink samples from the more acidic sites throughout the park However we anticipated that diatom com-munities from habitats with similar bedrock mineralogy and pH would be very similar and this pattern was not usually the case with the acidic wetwalls Even diatom collections from the same acidic wetwall separated by a few centimeters were often very dissimilar In retrospect this is less surprising since the microscale patchiness of algal communities in streams is common We expect that subtle differences in shading and moisture probably play a large role in determining diatom community structure Diatom communities that are only a few cm apart can occupy very dif-ferent microhabitats as rock faces possess subtle differences in surface morphology that influence exposure of the community to sunlight and dry-ing These subtle differences can also regulate the distribution of sympatric patches of non-diatom algae and bryophytes that are also likely to play a role in diatom distribution Several of the wetwalls supported macroscopic growths of algae rich in extracellular water-retaining polysaccharides that can provide a moist environment for diatoms during otherwise dry peri-ods These kinds of habitats seemed favorable to Nitzschia hantzschiana for example Macroscopic growths of Nostoc Stigonema Mesotaenium and several coccoid cyanobacteria were common but highly patchy on the wetwalls which might also reflect patchy environmental variables or the history of chance colonization by propogules We did not examine potential top-down impacts of grazers in these communities but noted the presence of protozoa and occasional dipteran larvae Grazers may be selec-tive in consumption of algae (Gresens and Lowe 1994) The cluster analysis (Fig 2) illustrates the dissimilarity among diatom communities and again probably indicates that parameters that we did not measure are generating these differences However we did identify several notable assemblages that were lt15 similar to the rest of the as-semblages sampled

RL Lowe PC Furey JA Ress and JR Johansen 1452007

The two assemblages in cluster A were largely separated by dominant populations of Pinnularia subcapitata v hilseana and Eunotia cf gla-cialis These two diatoms have been reported from subaerial and acid habitats from both Europe and North America (Beyens 1989 Dixit et al 1999) Both collections in this cluster were from drippy bryophytes similar to the report of Beyens (1989) which may indicate that this is a preferred habitat of Pinnularia subcapitata v hilseana Eunotia is also common on mosses The three collections from wetwalls in Whiteoak Sinks (cluster B) were the only samples that we collected from limestone-dominated alkaline bed-rock Cymbopleura rupicola dominated these communities and was found nowhere else This taxon has been reported from similar alkaline subaerial habitats (Klemenčič 2002) Its disjunct distribution on wetwalls in the GSMNP may indicate its strong habitat specifi city Cluster C is represented by a single collection from a bryophyte-covered rock of Thunderhead Sandstone in a spray zone of Laurel Falls Waterfall spray zones are wetted for longer periods than many of the wetwall habitats and also have a continuous source of diatom immigrants and this may in part account for its uniqueness The assemblage was dominated by two spe-cies of Frustulia

Figures 36ndash39 Species of diatoms showing reduced external openings 36) Nupela sp 37) Diadesmis perpusilla (Kuumltz) DG Mann 38) Eunotia sp 39) Chamaepin-nulari soehrensis (Krasske) Lange-Bertalot (scale bar = 4 μm)

Southeastern Naturalist146 Special Issue 1

Cluster D was another small cluster of only two collections (Thunderhead Sandstone near a waterfall at Ramsay Cascade and Metcalf Phyllite on Lau-rel Creek Road) These two communities were only 23 similar to each other but lt15 similar to the remainder of the assemblages (Fig 2) These two assemblages were related by their relatively dense populations of Euno-tia exigua a cosmopolitan acidophilic species (Lowe 1974) Cluster E with six collections was separated from the other sites largely by species of Eunotia Although these six collections are less than 15 simi-lar to the rest of the assemblages they are not closely related to each other (Fig 2) Cluster F contained a single unique assemblage dominated by Eunotia diodon Ehrenberg and Eunotia rhomboidea Hustedt This was the only collection in this analysis that came from a soil seep and may reflect pe-culiar aspects of this unique environment Surveys of diatom soil flora are few but an extensive study by Lund (1945) illustrates the richness of the flora GSMNP with diverse soil types should hold a large number of soil diatom species We hope to pursue the algal soil flora of GSMNP in suc-ceeding years Cluster G consisted of two assemblages collected from disjunct sites (Thunderhead Sandstone seep and Logarm Quartzite dripwall) Both collection sites had the same pH however (50) The sites were relatively

Figures 40ndash43 Common wetwall diatom species without obviously reduced external openings 40) Decussata placenta 41) Luticola sp 42) Microcostatus krasskei 43) Nitzschia hantzschiana (scale bar = 5μm)

RL Lowe PC Furey JA Ress and JR Johansen 1472007

dissimilar to each other (Fig 2) but were distinct from the remainder of the assemblages primarily due to large populations of Diatoma mesodon and Fragilariaforma virescens Although Diatoma mesodon is often found in a large variety of habitats Fragilariaforma virescens is typically restricted to acidic or low alkalinity habitats (Camburn and Charles 2000) Cluster H is defi ned by Tetracyclus rupestris which occurred only in this single collection and accounted for 85 of the diatoms in this assemblage This is a unique community and is signifi cant in that Tetracyclus rupestris is seldom reported from the North American fl ora The collection site was a drippy Anakeesta bedrock formation at 1500 m elevation Anakeesta pro-vides an acidic environment and is often high in aluminum although we did not measure that element in this study Cluster I is composed of three assemblages each with Nitzschia hantzschiana as a common taxon This diatom is one of the most common subaerial species of the genus Nitzschia and has been reported from many different studies of subaerial algae (Dayner and Johansen 1991 Johansen et al 1983a Lund 1945) The three samples in this cluster are all from drippy wetwalls along road cuts All three of these samples contained conspicuous quantities of green algae or cyanobacteria Such algae might facilitate the presence of Nitzschia which is highly motile and would be capable of mov-ing through the algal matrix The remaining 28 collections all cluster together (J) but within this large cluster several subndashclusters can be identifi ed driven by assemblages with large populations of Diadesmis species and by Microcostatus krasskei These taxa have strong fi delity to subaerial habitats and are generally not seen in abundance in aquatic habitats In addition to the challenges of working with the vertical nature of wetwalls the highly variable and heterogeneous nature of the algal com-munities along with some of the variations in microhabitat discussed above highlights the need to consider both spatial scale and sampling strategy when designing wetwall studies or biodiversity surveys For ex-ample to minimize the effects of microhabitat variation artificial wetwall substrates may be helpful in elucidating the impact of microscale habitat features on algal community structure or several wetwall areas may need to be sampled in order to adequately characterize the diversity of an area or to track changes in algal assemblages over time or in response to en-vironmental changes Additionally the range of values covered for pH for the majority of our sites (pH 38ndash55) was narrow and future studies should include a broader range of pH especially across the intermediate values not examined in this study (pH 55ndash72) Similarly elevation and geology gave no apparent environmental signal in the diatom composition although these influences may have been masked by microscale variability or small sample size and future studies may require more intensive sam-pling experimental work or finer-scale bedrock determination

Southeastern Naturalist148 Special Issue 1

Conclusions

We described the diatom fl ora from several wetwalls throughout GSMNP Some of the species from this research appear to be new species and will be described and published elsewhere Aside from these new taxa many of the diatoms have been reported from other wetwall studies and have been noted as typical subaerial species Although we found little correlation with bedrock mineralogy chemistry including pH and wetwall elevation we did observe highly variable and very diverse diatom community structure among the wetwall habitats We found unique diatom communities along with wetwall-specifi c diatom taxa that appeared to have special adaptations to these subaerial habitats In order to better understand these understud-ied communities future research should explore these subaerial habitat adaptations such as presence of additional external siliceous membranes or interactions with soft algal communities Additionally further research is needed to understand the complexities of these unique algal communi-ties and habitats including examination of factors that may have a more dominant role in shaping wetwall community structure such as moisture gradients and sources infl uences of microscale variability substrate type and shading or the role of ultraviolet radiation We feel that it is particularly important to examine these communities at an appropriate scale Habitat variables and community structure could vary over millimeter distances on wetwalls and the small and spatially unique nature of these microhabitats should be taken into consideration in the experimental design and sampling in future wetwall studies

Acknowledgments

This research was supported by the National Science Foundation (DEB 0315979) and grants from Discover Life In America We are also very grateful for support and facilitation from the National Park Service Jeanie Hilton and volunteers from Dis-cover Life In America and the Appalachian Highlands Learning Center interns This manuscript was greatly improved thanks to detailed reviews by Marina Potapova Peter Siver and one anonymous reviewer

Literature Cited

Beyens L 1989 Moss-dwelling diatom assemblages from Edgeoslashya (Svalbard) Polar Biology 9423ndash430

Camburn KE and DF Charles 2000 Diatoms of Low-alkalinity Lakes in the Northeastern United States Academy of Natural Sciences of Philadelphia Spe-cial Publication 18 Philadelphia PA 152 pp

Dayner DM and JR Johansen 1991 Observations on the algal fl ora of Seneca Caverns Seneca County Ohio Ohio Journal of Science 91118ndash121

Dixit SS JP Smol DF Charles RM Hughes SG Paulsen and GB Collins 1999 Assessing water quality changes in the lakes of the northeastern United States using sediment diatoms Canadian Journal of Fisheries and Aquatic Sci-ences 56(1)131ndash152

RL Lowe PC Furey JA Ress and JR Johansen 1492007

Gomez S 2002 Epilithic aerial algae of Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 78 pp

Gomez SR JR Johansen and RL Lowe 2003 Epilithic aerial algae of Great Smoky Mountains National Park Biologia Bratislava 58603ndash615

Gresens SE and RL Lowe 1994 Periphyton patch preference in grazing chiron-omid larvae Journal of the North American Benthological Society 1389ndash99

Johansen JR 1999 Diatoms of aerial habitats Pp 264ndash273 In EF Stoermer and JP Smol (Eds) The Diatoms Applications for the Environmental and Earth Sciences Cambridge University Press Cambridge UK

Johansen JR and RL Lowe In press Draparnaldia appalachiana sp Nov (Chaetophoraceae Chlorophyceae) from the Great Smoky Mountains National Park

Johansen JR and JC Sray 1998 Microcostatus Gen Nov a new aerophilic dia-tom genus based on Navicula Krasskei Hustedt Diatom Research 1393ndash101

Johansen JR RL Lowe SR Gomez JP Kociolek and SA Makosky 2004 New algal species records for the Great Smoky Mountains National Park USA with an annotated checklist of all reported algal species for the park Algological Studies 11117ndash44

Johansen JR SR Rushforth and JD Brotherson 1983a The algal fl ora of Navajo National Monument Arizona USA Nova Hedwigia 38501ndash553

Johansen JR SR Rushforth R Orbendorfer N Fungladda and J Grimes 1983b The algal fl ora of selected wet walls in Zion National Park Utah USA Nova Hedwigia 38765ndash808

Klemencic AK 2002 Kopenske alge na bentonskem zidu kamniten zidu apnen-casti skali in deblu lipe (Tilia platyphyllos) v Sloveniji Natura Sloveniae 421ndash30

Krammer K and H Lange-Bertalot 1986 Bacillariophyceae 1 Teil Navicula-ceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasser fl ora von Mitteleuropa Band 21 Gustav Fischer Verlag Stuttgart New York 876 pp

Krammer K and H Lange-Bertalot 1988 Bacillariophyceae 2 Teil Bacilla-riaceae Epithemiaceae Surirellaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 22 VEB Gustav Fischer Verlag Jena Germany 596 pp

Krammer K and H Lange-Bertalot 1991a Bacillariophyceae 3 Teil Centrales Fragilariaceae Eunotiaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 23 Gustav Fischer Verlag Stuttgart Jena Germany 576 pp

Krammer K and H Lange-Bertalot 1991b Bacillariophyceae 4 Teil Achnantha-ceae Kritische Ergaumlnzungen zu Navicula (Lineolatae) und Gomphonema Gesamtliteraturverzeichnis Teil 1-4 in Ettl H Gaumlrtner G Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 24 Gustav Fischer Verlag Stuttgart Jena Germany 437 pp

Lowe RL 1974 Environmental requirements and pollution tolerance of freshwater diatoms Environmental Protection Agency Washington DC PA-6704-74-007 340 pp

Lowe RL and GB Collins 1973 An aerophilous diatom community from Hocking Co Ohio Transactions of the American Microscopical Society 92492ndash496

Southeastern Naturalist150 Special Issue 1

Lund JWG 1945 Observations on soil algae I The ecology size and taxonomy of British soil diatoms The New Phytologist 4456ndash110

McMillim M and SR Rushforth 1985 The diatom fl ora of a steam vent of Kilauea Crater Island of Hawaii Pacifi c Science 39294ndash301

Olsen CE 2004 The algal fl ora of selected seeps and waterfalls in the Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 106 pp

Patrick R 1977 Ecology of freshwater diatoms-diatom communities Pp 133ndash191 In D Werner (Ed) The Biology of Diatoms Blackwell Scientifi c Publications London UK

Patrick R and CW Reimer 1966 The diatoms of the United States V1 Mono-graph Academy of Natural Science Philadelphia 13(1)1ndash688

Potapova MG KC Ponader RL Lowe TA Clason and LA Bahls 2003 Small-celled Nupela species from USA rivers Diatom Research 18293ndash306

Pederson D 1999 Scientists are trying to identify every living thing in the Smokies National Park Newsweek November 22 1999

Sharkey MJ 2001 The all taxa biological inventory of the Great Smoky Mountains National Park Florida Entomologist 84556ndash564

Sokal RR and FJ Rohlf 1995 Biometry 3rd Edition WH Freeman New York NY 468 pp

Southworth S A Schultz and D Denenny 2005 Generalized geological map of Bedrock Lithologies and surfi cial deposits in the Great Smoky Mountains National Park Region Tennessee and North Carolina US Geological Survey Resten VA Open-File Report 2004-1410

Wallace BJ J Webster and RL Lowe 1992 High-gradient streams of the Ap-palachians Pp 133ndash191 In CT Hackney SM Adams and WA Martin (Eds) Biodiversity of the Southeastern United StatesAquatic Communities John Wiley and Sons Inc Hoboken NJ USA pp 133-191

Werum M and H Lange-Bertalot 2004 Diatoms in springs and elsewhere under the infl uence of hydrogeology and anthropogenic impacts Iconographia Diato-mologica 131ndash480

RL Lowe PC Furey JA Ress and JR Johansen 1512007

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Southeastern Naturalist136 Special Issue 1

The focus habitats of the research reported in this manuscript are subaer-ial wetwalls Wetwalls are exposed vertical or sloping rock faces that vary in moisture availability but are not submerged Moisture may be primarily from the atmosphere (rain and fog) or from groundwater seeps GSMNP contains hundreds of vertical wetwalls with varying bedrock chemistry and levels of moisture Stream cuts road cuts landslides and waterfall spray zones in GSMNP have resulted in an abundance of wetwall habitats We anticipated that wetwalls would provide habitat for many species of algae that are uncommon or absent from streams lakes and wetlands Because of periodic exposure to drying many obligate aquatic algal taxa do not occupy these habitats In previous investigations (Gomez et al 2003) we found wetwalls to support many species of ldquosoftrdquo algae that are infrequently re-ported Because wetwalls are more insular than streams with no upstream source of algal immigrants we expected the fl ora of wetwalls to strongly refl ect local environmental conditions In addition we expected wetwalls to be a refuge for species that might be vulnerable to competition by invasive algal species since wetwalls are less likely to receive species introductions from fi shermen or other stream users The wetwall algal study by Gomez et al (2003) was restricted to ldquosoftrdquo or non-diatom algae One hundred and eighteen algal species were reported from the study and 108 of these were new GSMNP records The objective of the present study was to investigate the diatom fl ora of GSMNP wetwalls We anticipated that diatom distribution on wetwalls would be correlated with bedrock mineralogy chemistry (including pH) wetwall elevation and the presence or absence of ldquomoisture-facilitating algae such as Nostoc that have the capacity to hold water in extra cellular polysaccharides or bryophytes that provide shelter from desiccation

Methods

Study area GSMNP comprises over 2072 km2 (800 square miles) in the Southern Appalachian Mountains on the border between North Carolina and Ten-nessee bridging the northern and southern temperate zones Forested with elevations that range from 267 m to 2025 m rolling mountains dominate the park The unique northeast to southwest orientation of the mountains large tracts of deciduous old-growth and contiguous forests and protection as a national park in addition to having remained unglaciated for over a million years have all contributed to a rich and abundant fauna and fl ora For ex-ample the park has over 100 species of native trees and a high diversity of lungless salamanders The geology of GSMNP is varied and the 25 general categories of bedrock types are comprised of rocks with a complex deposi-tional stratigraphic metamorphic and structural history (Southworth et al 2005)

RL Lowe PC Furey JA Ress and JR Johansen 1372007

Wetwall sampling and analysis The subaerial diatom fl ora was examined from wetwall samples from collecting expeditions to the GSMNP from 2001 to 2005 In May and August 2001 SR Gomez collected subaerial algal samples throughout the park (Gomez et al 2003) In July 2004 samples were collected by Na-tional Park Service (NPS) personnel along with the Appalachian Highlands Learning Center interns Collecting expeditions to GSMNP by the Bowling Green State University (BGSU) and John Carroll University (JCU) research groups occurred on fi ve separate occasions 15ndash18 October 2003 15ndash20 May 2004 11ndash14 July 2004 22ndash23 October 2004 and 15 Mayndash11 August 2005 Sites were generally collected only once and seasonal variability was not assessed although we expect it to be relatively invariable in these sub-aerial communities since there is little opportunity for diatom emigration in contrast to stream periphyton communities Algae were collected from drippy rock faces using forceps pipettes and a knife and by squeezing bryophytes A total of 49 subaerial habitats from 11 different bedrock types were sampled from elevations ranging from 363 to 1841 m (Appendix 1) Bedrock types were selected to represent all the common types that cover the majority of the park (from a total of 25 general bedrock units Southworth et al 2005) Collection locations were geo-referenced (Garmin GPS Unit) where global positioning system (GPS) signals were available (Coordinate datum NAD27 UTM zone 17S) The pH of each site was measured using EMD colorphast pH-indicator strips (range 25 to 10 pH units sensitivity of 02 to 03 pH units) in order to provide a rough estimate of differences in the acidity of sampling locations Samples collected by SR Gomez were pre-served in 2 buffered formaldehyde the remaining samples were preserved in a minimum of 2 glutaraldehyde Diatoms were cleaned in boiling nitric acid and air dried onto cover glasses Permanent diatom mounts for light microscope (LM) analysis were made using Naphraxreg mounting medium Permanent diatom slides will be made for future reference at BGSU and will also be deposited in the GSMNP Science Center the diatom herbaria at the California Academy of Science (CAS) and the Academy of Natural Sciences of Philadelphia (ANSP) Slides were analyzed with an Olympus BX51 Photomicroscope with high-resolution DIC optics A minimum of 200 diatom frustules was counted from each sample Digital images were recorded with a monochromatic camera (Spotreg) attached to the microscope and a computer Diatoms were identifi ed to the lowest taxonomic level possible using standard references References consisted of Krammer and Lange-Bertalot (1986) Krammer and Lange-Bertalot (1988) Krammer and Lange-Bertalot (1991a) Kram-mer and Lange-Bertalot (1991b) Patrick and Reimer (1966) Johansen and Sray (1998) Potapova et al (2003) and Werum and Lange-Bertalot (2004) Cover glasses mounted on specimen stubs and sputter-coated with 10 nm goldpalladium alloy were analyzed on a high-resolution Hitachi S-2700 scanning electron microscope (SEM)

Southeastern Naturalist138 Special Issue 1

Relative abundance of diatoms at each site calculated both at the species and genus levels were normalized with an arcsine transformation (arcsine of the square root Sokal and Rohlf 1995) Ordination of sites was fi rst conducted based on a reduced species list using non-metric multidimension-al scaling (MDS) of Bray Curtis similarities Diatom taxa that occurred at a minimum of three sites were included in the MDS analysis in order to ensure suffi cient data for ordination thus reducing the total number of taxa from 223 to 98 A high stress value for the MDS output indicated that additional analyses should be conducted to confi rm the MDS ordination Therefore the clustering of sites based on species- or genera-level similarity for both a reduced and complete taxa list was examined using a dendrogram of group-average linking of Bray Curtis similarities The cluster analysis using the complete species list is presented in this study because the overall patterns were similar between the two methods and the use of the complete spe-cies list provided a more inclusive picture of the wetwall communities and information on some of the unique wetwall sites Elevation pH latitude longitude watershed and microhabitat type (epiphytic [bryophyte associ-ated] or epilithic) were used as factors for examining clustering patterns Statistical tests were performed with Primer 5 version 529 (PrimerndashE Ltd 2002) Unique communities of algae were identifi ed as those sets of sites with either gt85 relative abundance of a single taxon or lt10 similarity with other sets of sites based on the cluster analysis Clusters were further subdivided into ten subclusters based on a similarity cutoff of 15 Com-mon wetwall taxa were selected based on species and genera that were found at gt3 overall relative abundance (calculated with all sites considered to-gether) or present at gt20 of the sites

Results

Site pH ranged from 38ndash55 with the exception of three unique sites that had pH between 72ndash77 Acidic areas were generally found at the higher elevation sites The three sites with pH gt 7 were all found in the Whiteoak Sink area of the GSMNP Forty-one genera and 223 species were identifi ed from the wetwall sites Nineteen wetwall genera were commonly present across all sites (Table 1) Achnanthes Diadesmis Eunotia Navicula Nupela and Pinnularia were present at gt50 of the sites and Chamaepinnularia Encyonema Frustulia Gomphonema and Nitzschia at gt20 of the sites (Table 1) Of these genera Diadesmis (15) and Eunotia (21) also had high overall relative abundance across sites (Table 1) Within these genera 23 wetwall species were consid-ered notable either because they had a higher mean relative abundance or were frequently present at sites Nitzschia hantzschiana Rabenhorst (58) Eunotia praerupta v bigibba (Kuumltzing) Grunow (55) Cymbopleura rupic-ola (Grunow) Krammer (57) and Navicula keeleyi Patrick (96) had the highest overall relative abundances (Table 1) Diadesmis contenta v biceps (Grunow) Hamilton Diadesmis contenta (Grunow) DG Mann Diadesmis

RL Lowe PC Furey JA Ress and JR Johansen 1392007

perpusilla (Kuumltzing) DG Mann Navicula keeleyi Achnanthes subrostrata v appalachiana Camburn and Lowe Navicula angusta Grunow Nitzschia hantzschiana and Nupela neglecta Ponader Lowe and Potapova were pres-ent at over 35 of the sites (Table 1) Four site-groups ([A] [B] [C D E] and [F G H I J J

1 J

2] were identifi ed by the 2-D MDS ordination (Fig 1 stress

Table 1 Table of common species based on overall relative abundance (all sites considered together) or taxa frequently present across sites Species were selected if overall abundance was gt3 or the taxa were present at gt20 of the sites

Mean relative of sites Taxon abundance where present

Achnanthes subrostrata v appalachiana 39 388Achnanthidium exiguum 05 225Chamaepinnularia spp 05 408Cymbopleura rupicola 57 61Decussata placenta 07 245Diadesmis contenta 16 469Diadesmis contenta v biceps 20 388Diatoma mesodon 29 204Encyonema minutum 14 246Eunotia exigua 26 347Eunotia nymanniana 04 245Eunotia praerupta v bigibba 55 204Frustulia crassinervia 08 204Frustulia krammeri 29 265Gomphonema parvulum 05 204Meridion circulare 07 306Microcostatus krasskei 34 327Navicula angusta 18 449Navicula keeleyi 96 592Nitzschia hantzschiana 58 388Nupela spp 28 510Pinularia spp 39 519Planothidium lanceolatum 26 286Psammothidium marginulatum 23 225

Navicula keeleyi to be transferred to Diadesmis in a subsequent manuscript

Figure 1 Two-dimen-sional non-metric mul-tidimensional scaling (MDS) ordination for the 49 wetwall sites based on the Bray-Cur-tis similarities on arc sine root transformed relative abundance data for species present at gt 3 sites MDS stress = 016 Codes (A through J J1 and J2) represent grops of sites identifi ed in the cluster analysis for all species data (see Fig 2) Four general site-groups were identifi ed (A) (B) (C D E) and (F G H I J J1 J2)

Southeastern Naturalist140 Special Issue 1

value 016) Due to the high stress value these patterns were also examined with a cluster analysis both for the reduced taxa list and for all taxa Similar patterns were observed for both cluster analyses Therefore the dendrogram with all taxa considered is shown since it provides the most information on diatom community composition across sites (Fig 2) The four sitendashgroups identifi ed by the MDS ordination also clustered with less than a 10 site similarity threshold (Fig 2) At lt15 similarity 10 site-groups or clusters were identifi ed (Fig 2) With notable exceptions all sites clustered at lt50 similarity which suggests that the diatom community composition was quite variable at the different wetwall sites The two sites forming cluster A (CR-J1C and NDT-V1A) were strongly dominated by Pinnularia subcapitata v hilseana (Janisch ex Rabenhorst) Muumlller with Eunotia cf glacialis Meister also being very abundant at CR-J1C (Fig 2 Table 2) The sites forming cluster B were dominated by

Table 2 Sites where community composition was comprised of one taxon ge 85 relative abun-dance = sites identifi ed as unique in the dendrogram

Site code Species Relative abundance

ACT-15 Eunotia praerupta v bigibba 955CDR-J5E Eunotia cf fallax 920CR-CAT1C Nitzschia hantzshciana 970CR-J1C Pinnularia subcapitata v hilseana 950NG-J9A Tetracyclus rupestris 850WS-4A Cymbopleura rupicola 995WSF-6C Cymbopleura rupicola 995

Figure 2 Dendrogram of the 49 seep-wall sites using group-average clustering from Bray Curtis similarities on arc sine root transformed relative abundances of the all species A lt10 (dashedndashdot line) and lt15 (dotted line) similarity threshold are identifi ed The unique sites and locations separated at a lt15 (dotted line) similarity threshold are indicated by AndashJ below the xndashaxis

RL Lowe PC Furey JA Ress and JR Johansen 1412007

Cymbopleura rupicola with relative abundances of 995 at site WS-4A and WSF-6C and 82 at WSF-6B (Fig 2 Table 2) Cymbopleura rupicola was only present at these three alkaline sites Cluster C site LF-5A was comprised mainly of Frustulia crassinervia (Breacutebisson ex W Smith) Lange-Bertalot and Frustulia krammeri Lange-Bertalot and Metzeltin (Fig 2 Table 2) The two sites forming cluster D included RC-PF6F which was characterized by Eunotia exigua (Breacutebisson ex Kuumltzing) Rabenhorst and Eunotia sp12 with relative abundances at 675 and 225 respectively and LCR-7B which was primarily composed of Psammothidium margi-nulatum (Grunow) Bukhtiyarova and Round and secondarily of Eunotia exigua with relative abundances of 75 and 205 respectively Psam-mothidium marginulatum was found in only fi ve other communities in low relative abundance (Fig 2) Cluster E included six sites that were generally dominated by Eunotia taxa especially Eunotia praerupta v bigibba and Eunotia cf fallax A Cleve (Fig 2 Table 2) Cluster F site TCT-2B was also dominated by Eunotia taxa (Fig 2) The two sites in Cluster G were dominated by different taxa but Diatoma mesodon Kuumltzing and Fragilari-aforma virescens (Ralfs) Williams and Round were present at both Cluster H site NG-J9A was dominated by a single taxon Tetracyclus rupestris (Braun) Grunow that was absent from all other sites (Fig 2 Table 2) The three sites forming Cluster I (LRR-2 LRT-PF1 and CR-CAT1C) all had Nitzschia hantzschiana as a common taxon at 165 79 and 97 relative abundances respectively (Fig 2 Table 2) Cluster J was the largest cluster of sites and overall these sites were highly variable in their taxonomic composition Cluster J1 tended to be comprised of Diadesmis taxa (includ-ing Navicula keeleyi yet to be transferred to Diadesmis) and sites at Cluster J2 were dominated by Microcostatus krasskei (Hustedt) Johansen and Sray (Fig 2) Within all the clusters (AndashJ) seven communities were characterized as unique based on a relative abundance of ge85 of one taxon (Table 2) Within the MDS ordination factor codes and bubble plots of pH geology elevation latitude longitude and watershed were examined to explore the site-clustering patterns in response to the environmental variables and to examine taxon-specifi c clustering with environmental variables (plots not shown) However no patterns were observed for any of the environmental variables alone or considered with a specifi c taxon (with the exception of Cymbopleura rupestris which was found at the three sites with the highest pH)

Discussion

Two hundred and twenty-three diatom species and varieties within 41 genera were recorded from the wetwall communities in GSMNP (see Figs 3ndash35 for illustrations of some of the more common taxa ) These communi-ties were dominated by several taxa that are common in subaerial habitats Many species in the genus Diadesmis for example have been reported from numerous wetwall studies (Dayner and Johansen 1991 Johansen et al 1983a Lowe and Collins 1973 McMillim and Rushforth 1985) Wetwall

Southeastern Naturalist142 Special Issue 1

Figures 3ndash22 Common taxa denoted in Table 1 ldquordquo signifi es taxa denoted in Table 2 3) Achnanthes subrostrata v appalachiana raphe valve 4) Achnanthes subrostrata v appalachiana rapheless valve 5) Achnanthidium exiguum raphe valve 6) Ach-nanthidium exiguum (Grun) Czarnezki rapheless valve 7) Diatoma mesodon 8) Diatoma mesodon girdle view 9) Chamaepinnularia mediocris (Krasske) Lange-Bertalot 10) Diadesmis contenta 11) Diadesmis contenta v biceps 12) Navicula keeleyi 13) Diadesmis perpusilla 14) Gomphonema cf parvulum Kuumltz 15) Pin-nularia subcapitata v hilseana 16) Decussata placenta (Ehr) Lange-Bertalot amp Mezeltin 17) Cymbopleura rupicola 18) Eunotia praerupta v bigibba 19) Euno-tia nymanianna Grun 20) Eunotia cf fallax 21) Eunotia exigua 22) Encyonema minutum (Hilse ex Rabh) DG Mann

RL Lowe PC Furey JA Ress and JR Johansen 1432007

diatoms must withstand a greater range of environmental variables than aquatic species (Patrick 1977) Unlike truly aquatic habitats subaerial envi-

Figures 23ndash35 Common taxa denoted in Table 1 ldquordquo signifi es taxa denoted in Table 2 23) Frustulia krammeri 24) Frustulia crassinervia 25) Meridion circulare (Grev) Ag 26) Navicula angusta 27) Nitzschia hantzschiana 28) Microcostatus krasskei 29) Nupela sp 30) Planothidium lanceolatum raphe valve 31) Planothid-ium lanceolatum (Breacuteb ex Kuumltz) Round amp Bukhtiyarova rapheless valve 32) Psammothidium marginulatum raphe valve 33) Psammothidium marginulatum rapheless valve 34) Tetracyclus rupestris 35) Tetracyclus rupestris girdle view

Southeastern Naturalist144 Special Issue 1

ronments are moist but can periodically become dry for long periods Also because these diatoms often live in a fi lm of water they do not experience the thermal stability that aquatic taxa experience Wetwall diatoms may also experience more intense ultraviolet radiation than aquatic forms that are more protected by water (Johansen 1999) Many wetwall diatoms have a reduced number of areolae or possess areolae that are occluded with a siliceous lamina (eg species of Nupela Diadesmis Chamaepinnularia and Eunotia Figs 36ndash39) These morpho-logical features may be adaptations to reduce water loss in periodically dry habitats Some common taxa without obviously reduced external openings such as Decussata Luticola Microcostatus and Nitzschia (Figs 40ndash43) are also typical of diatom communities in subaerial habitats Diatom community structure on the wetwall habitats observed in this study was diverse and highly variable Higher pH appeared to be an im-portant variable separating the three Whiteoak Sink samples from the more acidic sites throughout the park However we anticipated that diatom com-munities from habitats with similar bedrock mineralogy and pH would be very similar and this pattern was not usually the case with the acidic wetwalls Even diatom collections from the same acidic wetwall separated by a few centimeters were often very dissimilar In retrospect this is less surprising since the microscale patchiness of algal communities in streams is common We expect that subtle differences in shading and moisture probably play a large role in determining diatom community structure Diatom communities that are only a few cm apart can occupy very dif-ferent microhabitats as rock faces possess subtle differences in surface morphology that influence exposure of the community to sunlight and dry-ing These subtle differences can also regulate the distribution of sympatric patches of non-diatom algae and bryophytes that are also likely to play a role in diatom distribution Several of the wetwalls supported macroscopic growths of algae rich in extracellular water-retaining polysaccharides that can provide a moist environment for diatoms during otherwise dry peri-ods These kinds of habitats seemed favorable to Nitzschia hantzschiana for example Macroscopic growths of Nostoc Stigonema Mesotaenium and several coccoid cyanobacteria were common but highly patchy on the wetwalls which might also reflect patchy environmental variables or the history of chance colonization by propogules We did not examine potential top-down impacts of grazers in these communities but noted the presence of protozoa and occasional dipteran larvae Grazers may be selec-tive in consumption of algae (Gresens and Lowe 1994) The cluster analysis (Fig 2) illustrates the dissimilarity among diatom communities and again probably indicates that parameters that we did not measure are generating these differences However we did identify several notable assemblages that were lt15 similar to the rest of the as-semblages sampled

RL Lowe PC Furey JA Ress and JR Johansen 1452007

The two assemblages in cluster A were largely separated by dominant populations of Pinnularia subcapitata v hilseana and Eunotia cf gla-cialis These two diatoms have been reported from subaerial and acid habitats from both Europe and North America (Beyens 1989 Dixit et al 1999) Both collections in this cluster were from drippy bryophytes similar to the report of Beyens (1989) which may indicate that this is a preferred habitat of Pinnularia subcapitata v hilseana Eunotia is also common on mosses The three collections from wetwalls in Whiteoak Sinks (cluster B) were the only samples that we collected from limestone-dominated alkaline bed-rock Cymbopleura rupicola dominated these communities and was found nowhere else This taxon has been reported from similar alkaline subaerial habitats (Klemenčič 2002) Its disjunct distribution on wetwalls in the GSMNP may indicate its strong habitat specifi city Cluster C is represented by a single collection from a bryophyte-covered rock of Thunderhead Sandstone in a spray zone of Laurel Falls Waterfall spray zones are wetted for longer periods than many of the wetwall habitats and also have a continuous source of diatom immigrants and this may in part account for its uniqueness The assemblage was dominated by two spe-cies of Frustulia

Figures 36ndash39 Species of diatoms showing reduced external openings 36) Nupela sp 37) Diadesmis perpusilla (Kuumltz) DG Mann 38) Eunotia sp 39) Chamaepin-nulari soehrensis (Krasske) Lange-Bertalot (scale bar = 4 μm)

Southeastern Naturalist146 Special Issue 1

Cluster D was another small cluster of only two collections (Thunderhead Sandstone near a waterfall at Ramsay Cascade and Metcalf Phyllite on Lau-rel Creek Road) These two communities were only 23 similar to each other but lt15 similar to the remainder of the assemblages (Fig 2) These two assemblages were related by their relatively dense populations of Euno-tia exigua a cosmopolitan acidophilic species (Lowe 1974) Cluster E with six collections was separated from the other sites largely by species of Eunotia Although these six collections are less than 15 simi-lar to the rest of the assemblages they are not closely related to each other (Fig 2) Cluster F contained a single unique assemblage dominated by Eunotia diodon Ehrenberg and Eunotia rhomboidea Hustedt This was the only collection in this analysis that came from a soil seep and may reflect pe-culiar aspects of this unique environment Surveys of diatom soil flora are few but an extensive study by Lund (1945) illustrates the richness of the flora GSMNP with diverse soil types should hold a large number of soil diatom species We hope to pursue the algal soil flora of GSMNP in suc-ceeding years Cluster G consisted of two assemblages collected from disjunct sites (Thunderhead Sandstone seep and Logarm Quartzite dripwall) Both collection sites had the same pH however (50) The sites were relatively

Figures 40ndash43 Common wetwall diatom species without obviously reduced external openings 40) Decussata placenta 41) Luticola sp 42) Microcostatus krasskei 43) Nitzschia hantzschiana (scale bar = 5μm)

RL Lowe PC Furey JA Ress and JR Johansen 1472007

dissimilar to each other (Fig 2) but were distinct from the remainder of the assemblages primarily due to large populations of Diatoma mesodon and Fragilariaforma virescens Although Diatoma mesodon is often found in a large variety of habitats Fragilariaforma virescens is typically restricted to acidic or low alkalinity habitats (Camburn and Charles 2000) Cluster H is defi ned by Tetracyclus rupestris which occurred only in this single collection and accounted for 85 of the diatoms in this assemblage This is a unique community and is signifi cant in that Tetracyclus rupestris is seldom reported from the North American fl ora The collection site was a drippy Anakeesta bedrock formation at 1500 m elevation Anakeesta pro-vides an acidic environment and is often high in aluminum although we did not measure that element in this study Cluster I is composed of three assemblages each with Nitzschia hantzschiana as a common taxon This diatom is one of the most common subaerial species of the genus Nitzschia and has been reported from many different studies of subaerial algae (Dayner and Johansen 1991 Johansen et al 1983a Lund 1945) The three samples in this cluster are all from drippy wetwalls along road cuts All three of these samples contained conspicuous quantities of green algae or cyanobacteria Such algae might facilitate the presence of Nitzschia which is highly motile and would be capable of mov-ing through the algal matrix The remaining 28 collections all cluster together (J) but within this large cluster several subndashclusters can be identifi ed driven by assemblages with large populations of Diadesmis species and by Microcostatus krasskei These taxa have strong fi delity to subaerial habitats and are generally not seen in abundance in aquatic habitats In addition to the challenges of working with the vertical nature of wetwalls the highly variable and heterogeneous nature of the algal com-munities along with some of the variations in microhabitat discussed above highlights the need to consider both spatial scale and sampling strategy when designing wetwall studies or biodiversity surveys For ex-ample to minimize the effects of microhabitat variation artificial wetwall substrates may be helpful in elucidating the impact of microscale habitat features on algal community structure or several wetwall areas may need to be sampled in order to adequately characterize the diversity of an area or to track changes in algal assemblages over time or in response to en-vironmental changes Additionally the range of values covered for pH for the majority of our sites (pH 38ndash55) was narrow and future studies should include a broader range of pH especially across the intermediate values not examined in this study (pH 55ndash72) Similarly elevation and geology gave no apparent environmental signal in the diatom composition although these influences may have been masked by microscale variability or small sample size and future studies may require more intensive sam-pling experimental work or finer-scale bedrock determination

Southeastern Naturalist148 Special Issue 1

Conclusions

We described the diatom fl ora from several wetwalls throughout GSMNP Some of the species from this research appear to be new species and will be described and published elsewhere Aside from these new taxa many of the diatoms have been reported from other wetwall studies and have been noted as typical subaerial species Although we found little correlation with bedrock mineralogy chemistry including pH and wetwall elevation we did observe highly variable and very diverse diatom community structure among the wetwall habitats We found unique diatom communities along with wetwall-specifi c diatom taxa that appeared to have special adaptations to these subaerial habitats In order to better understand these understud-ied communities future research should explore these subaerial habitat adaptations such as presence of additional external siliceous membranes or interactions with soft algal communities Additionally further research is needed to understand the complexities of these unique algal communi-ties and habitats including examination of factors that may have a more dominant role in shaping wetwall community structure such as moisture gradients and sources infl uences of microscale variability substrate type and shading or the role of ultraviolet radiation We feel that it is particularly important to examine these communities at an appropriate scale Habitat variables and community structure could vary over millimeter distances on wetwalls and the small and spatially unique nature of these microhabitats should be taken into consideration in the experimental design and sampling in future wetwall studies

Acknowledgments

This research was supported by the National Science Foundation (DEB 0315979) and grants from Discover Life In America We are also very grateful for support and facilitation from the National Park Service Jeanie Hilton and volunteers from Dis-cover Life In America and the Appalachian Highlands Learning Center interns This manuscript was greatly improved thanks to detailed reviews by Marina Potapova Peter Siver and one anonymous reviewer

Literature Cited

Beyens L 1989 Moss-dwelling diatom assemblages from Edgeoslashya (Svalbard) Polar Biology 9423ndash430

Camburn KE and DF Charles 2000 Diatoms of Low-alkalinity Lakes in the Northeastern United States Academy of Natural Sciences of Philadelphia Spe-cial Publication 18 Philadelphia PA 152 pp

Dayner DM and JR Johansen 1991 Observations on the algal fl ora of Seneca Caverns Seneca County Ohio Ohio Journal of Science 91118ndash121

Dixit SS JP Smol DF Charles RM Hughes SG Paulsen and GB Collins 1999 Assessing water quality changes in the lakes of the northeastern United States using sediment diatoms Canadian Journal of Fisheries and Aquatic Sci-ences 56(1)131ndash152

RL Lowe PC Furey JA Ress and JR Johansen 1492007

Gomez S 2002 Epilithic aerial algae of Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 78 pp

Gomez SR JR Johansen and RL Lowe 2003 Epilithic aerial algae of Great Smoky Mountains National Park Biologia Bratislava 58603ndash615

Gresens SE and RL Lowe 1994 Periphyton patch preference in grazing chiron-omid larvae Journal of the North American Benthological Society 1389ndash99

Johansen JR 1999 Diatoms of aerial habitats Pp 264ndash273 In EF Stoermer and JP Smol (Eds) The Diatoms Applications for the Environmental and Earth Sciences Cambridge University Press Cambridge UK

Johansen JR and RL Lowe In press Draparnaldia appalachiana sp Nov (Chaetophoraceae Chlorophyceae) from the Great Smoky Mountains National Park

Johansen JR and JC Sray 1998 Microcostatus Gen Nov a new aerophilic dia-tom genus based on Navicula Krasskei Hustedt Diatom Research 1393ndash101

Johansen JR RL Lowe SR Gomez JP Kociolek and SA Makosky 2004 New algal species records for the Great Smoky Mountains National Park USA with an annotated checklist of all reported algal species for the park Algological Studies 11117ndash44

Johansen JR SR Rushforth and JD Brotherson 1983a The algal fl ora of Navajo National Monument Arizona USA Nova Hedwigia 38501ndash553

Johansen JR SR Rushforth R Orbendorfer N Fungladda and J Grimes 1983b The algal fl ora of selected wet walls in Zion National Park Utah USA Nova Hedwigia 38765ndash808

Klemencic AK 2002 Kopenske alge na bentonskem zidu kamniten zidu apnen-casti skali in deblu lipe (Tilia platyphyllos) v Sloveniji Natura Sloveniae 421ndash30

Krammer K and H Lange-Bertalot 1986 Bacillariophyceae 1 Teil Navicula-ceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasser fl ora von Mitteleuropa Band 21 Gustav Fischer Verlag Stuttgart New York 876 pp

Krammer K and H Lange-Bertalot 1988 Bacillariophyceae 2 Teil Bacilla-riaceae Epithemiaceae Surirellaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 22 VEB Gustav Fischer Verlag Jena Germany 596 pp

Krammer K and H Lange-Bertalot 1991a Bacillariophyceae 3 Teil Centrales Fragilariaceae Eunotiaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 23 Gustav Fischer Verlag Stuttgart Jena Germany 576 pp

Krammer K and H Lange-Bertalot 1991b Bacillariophyceae 4 Teil Achnantha-ceae Kritische Ergaumlnzungen zu Navicula (Lineolatae) und Gomphonema Gesamtliteraturverzeichnis Teil 1-4 in Ettl H Gaumlrtner G Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 24 Gustav Fischer Verlag Stuttgart Jena Germany 437 pp

Lowe RL 1974 Environmental requirements and pollution tolerance of freshwater diatoms Environmental Protection Agency Washington DC PA-6704-74-007 340 pp

Lowe RL and GB Collins 1973 An aerophilous diatom community from Hocking Co Ohio Transactions of the American Microscopical Society 92492ndash496

Southeastern Naturalist150 Special Issue 1

Lund JWG 1945 Observations on soil algae I The ecology size and taxonomy of British soil diatoms The New Phytologist 4456ndash110

McMillim M and SR Rushforth 1985 The diatom fl ora of a steam vent of Kilauea Crater Island of Hawaii Pacifi c Science 39294ndash301

Olsen CE 2004 The algal fl ora of selected seeps and waterfalls in the Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 106 pp

Patrick R 1977 Ecology of freshwater diatoms-diatom communities Pp 133ndash191 In D Werner (Ed) The Biology of Diatoms Blackwell Scientifi c Publications London UK

Patrick R and CW Reimer 1966 The diatoms of the United States V1 Mono-graph Academy of Natural Science Philadelphia 13(1)1ndash688

Potapova MG KC Ponader RL Lowe TA Clason and LA Bahls 2003 Small-celled Nupela species from USA rivers Diatom Research 18293ndash306

Pederson D 1999 Scientists are trying to identify every living thing in the Smokies National Park Newsweek November 22 1999

Sharkey MJ 2001 The all taxa biological inventory of the Great Smoky Mountains National Park Florida Entomologist 84556ndash564

Sokal RR and FJ Rohlf 1995 Biometry 3rd Edition WH Freeman New York NY 468 pp

Southworth S A Schultz and D Denenny 2005 Generalized geological map of Bedrock Lithologies and surfi cial deposits in the Great Smoky Mountains National Park Region Tennessee and North Carolina US Geological Survey Resten VA Open-File Report 2004-1410

Wallace BJ J Webster and RL Lowe 1992 High-gradient streams of the Ap-palachians Pp 133ndash191 In CT Hackney SM Adams and WA Martin (Eds) Biodiversity of the Southeastern United StatesAquatic Communities John Wiley and Sons Inc Hoboken NJ USA pp 133-191

Werum M and H Lange-Bertalot 2004 Diatoms in springs and elsewhere under the infl uence of hydrogeology and anthropogenic impacts Iconographia Diato-mologica 131ndash480

RL Lowe PC Furey JA Ress and JR Johansen 1512007

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Southeastern Naturalist152 Special Issue 1C

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RL Lowe PC Furey JA Ress and JR Johansen 1372007

Wetwall sampling and analysis The subaerial diatom fl ora was examined from wetwall samples from collecting expeditions to the GSMNP from 2001 to 2005 In May and August 2001 SR Gomez collected subaerial algal samples throughout the park (Gomez et al 2003) In July 2004 samples were collected by Na-tional Park Service (NPS) personnel along with the Appalachian Highlands Learning Center interns Collecting expeditions to GSMNP by the Bowling Green State University (BGSU) and John Carroll University (JCU) research groups occurred on fi ve separate occasions 15ndash18 October 2003 15ndash20 May 2004 11ndash14 July 2004 22ndash23 October 2004 and 15 Mayndash11 August 2005 Sites were generally collected only once and seasonal variability was not assessed although we expect it to be relatively invariable in these sub-aerial communities since there is little opportunity for diatom emigration in contrast to stream periphyton communities Algae were collected from drippy rock faces using forceps pipettes and a knife and by squeezing bryophytes A total of 49 subaerial habitats from 11 different bedrock types were sampled from elevations ranging from 363 to 1841 m (Appendix 1) Bedrock types were selected to represent all the common types that cover the majority of the park (from a total of 25 general bedrock units Southworth et al 2005) Collection locations were geo-referenced (Garmin GPS Unit) where global positioning system (GPS) signals were available (Coordinate datum NAD27 UTM zone 17S) The pH of each site was measured using EMD colorphast pH-indicator strips (range 25 to 10 pH units sensitivity of 02 to 03 pH units) in order to provide a rough estimate of differences in the acidity of sampling locations Samples collected by SR Gomez were pre-served in 2 buffered formaldehyde the remaining samples were preserved in a minimum of 2 glutaraldehyde Diatoms were cleaned in boiling nitric acid and air dried onto cover glasses Permanent diatom mounts for light microscope (LM) analysis were made using Naphraxreg mounting medium Permanent diatom slides will be made for future reference at BGSU and will also be deposited in the GSMNP Science Center the diatom herbaria at the California Academy of Science (CAS) and the Academy of Natural Sciences of Philadelphia (ANSP) Slides were analyzed with an Olympus BX51 Photomicroscope with high-resolution DIC optics A minimum of 200 diatom frustules was counted from each sample Digital images were recorded with a monochromatic camera (Spotreg) attached to the microscope and a computer Diatoms were identifi ed to the lowest taxonomic level possible using standard references References consisted of Krammer and Lange-Bertalot (1986) Krammer and Lange-Bertalot (1988) Krammer and Lange-Bertalot (1991a) Kram-mer and Lange-Bertalot (1991b) Patrick and Reimer (1966) Johansen and Sray (1998) Potapova et al (2003) and Werum and Lange-Bertalot (2004) Cover glasses mounted on specimen stubs and sputter-coated with 10 nm goldpalladium alloy were analyzed on a high-resolution Hitachi S-2700 scanning electron microscope (SEM)

Southeastern Naturalist138 Special Issue 1

Relative abundance of diatoms at each site calculated both at the species and genus levels were normalized with an arcsine transformation (arcsine of the square root Sokal and Rohlf 1995) Ordination of sites was fi rst conducted based on a reduced species list using non-metric multidimension-al scaling (MDS) of Bray Curtis similarities Diatom taxa that occurred at a minimum of three sites were included in the MDS analysis in order to ensure suffi cient data for ordination thus reducing the total number of taxa from 223 to 98 A high stress value for the MDS output indicated that additional analyses should be conducted to confi rm the MDS ordination Therefore the clustering of sites based on species- or genera-level similarity for both a reduced and complete taxa list was examined using a dendrogram of group-average linking of Bray Curtis similarities The cluster analysis using the complete species list is presented in this study because the overall patterns were similar between the two methods and the use of the complete spe-cies list provided a more inclusive picture of the wetwall communities and information on some of the unique wetwall sites Elevation pH latitude longitude watershed and microhabitat type (epiphytic [bryophyte associ-ated] or epilithic) were used as factors for examining clustering patterns Statistical tests were performed with Primer 5 version 529 (PrimerndashE Ltd 2002) Unique communities of algae were identifi ed as those sets of sites with either gt85 relative abundance of a single taxon or lt10 similarity with other sets of sites based on the cluster analysis Clusters were further subdivided into ten subclusters based on a similarity cutoff of 15 Com-mon wetwall taxa were selected based on species and genera that were found at gt3 overall relative abundance (calculated with all sites considered to-gether) or present at gt20 of the sites

Results

Site pH ranged from 38ndash55 with the exception of three unique sites that had pH between 72ndash77 Acidic areas were generally found at the higher elevation sites The three sites with pH gt 7 were all found in the Whiteoak Sink area of the GSMNP Forty-one genera and 223 species were identifi ed from the wetwall sites Nineteen wetwall genera were commonly present across all sites (Table 1) Achnanthes Diadesmis Eunotia Navicula Nupela and Pinnularia were present at gt50 of the sites and Chamaepinnularia Encyonema Frustulia Gomphonema and Nitzschia at gt20 of the sites (Table 1) Of these genera Diadesmis (15) and Eunotia (21) also had high overall relative abundance across sites (Table 1) Within these genera 23 wetwall species were consid-ered notable either because they had a higher mean relative abundance or were frequently present at sites Nitzschia hantzschiana Rabenhorst (58) Eunotia praerupta v bigibba (Kuumltzing) Grunow (55) Cymbopleura rupic-ola (Grunow) Krammer (57) and Navicula keeleyi Patrick (96) had the highest overall relative abundances (Table 1) Diadesmis contenta v biceps (Grunow) Hamilton Diadesmis contenta (Grunow) DG Mann Diadesmis

RL Lowe PC Furey JA Ress and JR Johansen 1392007

perpusilla (Kuumltzing) DG Mann Navicula keeleyi Achnanthes subrostrata v appalachiana Camburn and Lowe Navicula angusta Grunow Nitzschia hantzschiana and Nupela neglecta Ponader Lowe and Potapova were pres-ent at over 35 of the sites (Table 1) Four site-groups ([A] [B] [C D E] and [F G H I J J

1 J

2] were identifi ed by the 2-D MDS ordination (Fig 1 stress

Table 1 Table of common species based on overall relative abundance (all sites considered together) or taxa frequently present across sites Species were selected if overall abundance was gt3 or the taxa were present at gt20 of the sites

Mean relative of sites Taxon abundance where present

Achnanthes subrostrata v appalachiana 39 388Achnanthidium exiguum 05 225Chamaepinnularia spp 05 408Cymbopleura rupicola 57 61Decussata placenta 07 245Diadesmis contenta 16 469Diadesmis contenta v biceps 20 388Diatoma mesodon 29 204Encyonema minutum 14 246Eunotia exigua 26 347Eunotia nymanniana 04 245Eunotia praerupta v bigibba 55 204Frustulia crassinervia 08 204Frustulia krammeri 29 265Gomphonema parvulum 05 204Meridion circulare 07 306Microcostatus krasskei 34 327Navicula angusta 18 449Navicula keeleyi 96 592Nitzschia hantzschiana 58 388Nupela spp 28 510Pinularia spp 39 519Planothidium lanceolatum 26 286Psammothidium marginulatum 23 225

Navicula keeleyi to be transferred to Diadesmis in a subsequent manuscript

Figure 1 Two-dimen-sional non-metric mul-tidimensional scaling (MDS) ordination for the 49 wetwall sites based on the Bray-Cur-tis similarities on arc sine root transformed relative abundance data for species present at gt 3 sites MDS stress = 016 Codes (A through J J1 and J2) represent grops of sites identifi ed in the cluster analysis for all species data (see Fig 2) Four general site-groups were identifi ed (A) (B) (C D E) and (F G H I J J1 J2)

Southeastern Naturalist140 Special Issue 1

value 016) Due to the high stress value these patterns were also examined with a cluster analysis both for the reduced taxa list and for all taxa Similar patterns were observed for both cluster analyses Therefore the dendrogram with all taxa considered is shown since it provides the most information on diatom community composition across sites (Fig 2) The four sitendashgroups identifi ed by the MDS ordination also clustered with less than a 10 site similarity threshold (Fig 2) At lt15 similarity 10 site-groups or clusters were identifi ed (Fig 2) With notable exceptions all sites clustered at lt50 similarity which suggests that the diatom community composition was quite variable at the different wetwall sites The two sites forming cluster A (CR-J1C and NDT-V1A) were strongly dominated by Pinnularia subcapitata v hilseana (Janisch ex Rabenhorst) Muumlller with Eunotia cf glacialis Meister also being very abundant at CR-J1C (Fig 2 Table 2) The sites forming cluster B were dominated by

Table 2 Sites where community composition was comprised of one taxon ge 85 relative abun-dance = sites identifi ed as unique in the dendrogram

Site code Species Relative abundance

ACT-15 Eunotia praerupta v bigibba 955CDR-J5E Eunotia cf fallax 920CR-CAT1C Nitzschia hantzshciana 970CR-J1C Pinnularia subcapitata v hilseana 950NG-J9A Tetracyclus rupestris 850WS-4A Cymbopleura rupicola 995WSF-6C Cymbopleura rupicola 995

Figure 2 Dendrogram of the 49 seep-wall sites using group-average clustering from Bray Curtis similarities on arc sine root transformed relative abundances of the all species A lt10 (dashedndashdot line) and lt15 (dotted line) similarity threshold are identifi ed The unique sites and locations separated at a lt15 (dotted line) similarity threshold are indicated by AndashJ below the xndashaxis

RL Lowe PC Furey JA Ress and JR Johansen 1412007

Cymbopleura rupicola with relative abundances of 995 at site WS-4A and WSF-6C and 82 at WSF-6B (Fig 2 Table 2) Cymbopleura rupicola was only present at these three alkaline sites Cluster C site LF-5A was comprised mainly of Frustulia crassinervia (Breacutebisson ex W Smith) Lange-Bertalot and Frustulia krammeri Lange-Bertalot and Metzeltin (Fig 2 Table 2) The two sites forming cluster D included RC-PF6F which was characterized by Eunotia exigua (Breacutebisson ex Kuumltzing) Rabenhorst and Eunotia sp12 with relative abundances at 675 and 225 respectively and LCR-7B which was primarily composed of Psammothidium margi-nulatum (Grunow) Bukhtiyarova and Round and secondarily of Eunotia exigua with relative abundances of 75 and 205 respectively Psam-mothidium marginulatum was found in only fi ve other communities in low relative abundance (Fig 2) Cluster E included six sites that were generally dominated by Eunotia taxa especially Eunotia praerupta v bigibba and Eunotia cf fallax A Cleve (Fig 2 Table 2) Cluster F site TCT-2B was also dominated by Eunotia taxa (Fig 2) The two sites in Cluster G were dominated by different taxa but Diatoma mesodon Kuumltzing and Fragilari-aforma virescens (Ralfs) Williams and Round were present at both Cluster H site NG-J9A was dominated by a single taxon Tetracyclus rupestris (Braun) Grunow that was absent from all other sites (Fig 2 Table 2) The three sites forming Cluster I (LRR-2 LRT-PF1 and CR-CAT1C) all had Nitzschia hantzschiana as a common taxon at 165 79 and 97 relative abundances respectively (Fig 2 Table 2) Cluster J was the largest cluster of sites and overall these sites were highly variable in their taxonomic composition Cluster J1 tended to be comprised of Diadesmis taxa (includ-ing Navicula keeleyi yet to be transferred to Diadesmis) and sites at Cluster J2 were dominated by Microcostatus krasskei (Hustedt) Johansen and Sray (Fig 2) Within all the clusters (AndashJ) seven communities were characterized as unique based on a relative abundance of ge85 of one taxon (Table 2) Within the MDS ordination factor codes and bubble plots of pH geology elevation latitude longitude and watershed were examined to explore the site-clustering patterns in response to the environmental variables and to examine taxon-specifi c clustering with environmental variables (plots not shown) However no patterns were observed for any of the environmental variables alone or considered with a specifi c taxon (with the exception of Cymbopleura rupestris which was found at the three sites with the highest pH)

Discussion

Two hundred and twenty-three diatom species and varieties within 41 genera were recorded from the wetwall communities in GSMNP (see Figs 3ndash35 for illustrations of some of the more common taxa ) These communi-ties were dominated by several taxa that are common in subaerial habitats Many species in the genus Diadesmis for example have been reported from numerous wetwall studies (Dayner and Johansen 1991 Johansen et al 1983a Lowe and Collins 1973 McMillim and Rushforth 1985) Wetwall

Southeastern Naturalist142 Special Issue 1

Figures 3ndash22 Common taxa denoted in Table 1 ldquordquo signifi es taxa denoted in Table 2 3) Achnanthes subrostrata v appalachiana raphe valve 4) Achnanthes subrostrata v appalachiana rapheless valve 5) Achnanthidium exiguum raphe valve 6) Ach-nanthidium exiguum (Grun) Czarnezki rapheless valve 7) Diatoma mesodon 8) Diatoma mesodon girdle view 9) Chamaepinnularia mediocris (Krasske) Lange-Bertalot 10) Diadesmis contenta 11) Diadesmis contenta v biceps 12) Navicula keeleyi 13) Diadesmis perpusilla 14) Gomphonema cf parvulum Kuumltz 15) Pin-nularia subcapitata v hilseana 16) Decussata placenta (Ehr) Lange-Bertalot amp Mezeltin 17) Cymbopleura rupicola 18) Eunotia praerupta v bigibba 19) Euno-tia nymanianna Grun 20) Eunotia cf fallax 21) Eunotia exigua 22) Encyonema minutum (Hilse ex Rabh) DG Mann

RL Lowe PC Furey JA Ress and JR Johansen 1432007

diatoms must withstand a greater range of environmental variables than aquatic species (Patrick 1977) Unlike truly aquatic habitats subaerial envi-

Figures 23ndash35 Common taxa denoted in Table 1 ldquordquo signifi es taxa denoted in Table 2 23) Frustulia krammeri 24) Frustulia crassinervia 25) Meridion circulare (Grev) Ag 26) Navicula angusta 27) Nitzschia hantzschiana 28) Microcostatus krasskei 29) Nupela sp 30) Planothidium lanceolatum raphe valve 31) Planothid-ium lanceolatum (Breacuteb ex Kuumltz) Round amp Bukhtiyarova rapheless valve 32) Psammothidium marginulatum raphe valve 33) Psammothidium marginulatum rapheless valve 34) Tetracyclus rupestris 35) Tetracyclus rupestris girdle view

Southeastern Naturalist144 Special Issue 1

ronments are moist but can periodically become dry for long periods Also because these diatoms often live in a fi lm of water they do not experience the thermal stability that aquatic taxa experience Wetwall diatoms may also experience more intense ultraviolet radiation than aquatic forms that are more protected by water (Johansen 1999) Many wetwall diatoms have a reduced number of areolae or possess areolae that are occluded with a siliceous lamina (eg species of Nupela Diadesmis Chamaepinnularia and Eunotia Figs 36ndash39) These morpho-logical features may be adaptations to reduce water loss in periodically dry habitats Some common taxa without obviously reduced external openings such as Decussata Luticola Microcostatus and Nitzschia (Figs 40ndash43) are also typical of diatom communities in subaerial habitats Diatom community structure on the wetwall habitats observed in this study was diverse and highly variable Higher pH appeared to be an im-portant variable separating the three Whiteoak Sink samples from the more acidic sites throughout the park However we anticipated that diatom com-munities from habitats with similar bedrock mineralogy and pH would be very similar and this pattern was not usually the case with the acidic wetwalls Even diatom collections from the same acidic wetwall separated by a few centimeters were often very dissimilar In retrospect this is less surprising since the microscale patchiness of algal communities in streams is common We expect that subtle differences in shading and moisture probably play a large role in determining diatom community structure Diatom communities that are only a few cm apart can occupy very dif-ferent microhabitats as rock faces possess subtle differences in surface morphology that influence exposure of the community to sunlight and dry-ing These subtle differences can also regulate the distribution of sympatric patches of non-diatom algae and bryophytes that are also likely to play a role in diatom distribution Several of the wetwalls supported macroscopic growths of algae rich in extracellular water-retaining polysaccharides that can provide a moist environment for diatoms during otherwise dry peri-ods These kinds of habitats seemed favorable to Nitzschia hantzschiana for example Macroscopic growths of Nostoc Stigonema Mesotaenium and several coccoid cyanobacteria were common but highly patchy on the wetwalls which might also reflect patchy environmental variables or the history of chance colonization by propogules We did not examine potential top-down impacts of grazers in these communities but noted the presence of protozoa and occasional dipteran larvae Grazers may be selec-tive in consumption of algae (Gresens and Lowe 1994) The cluster analysis (Fig 2) illustrates the dissimilarity among diatom communities and again probably indicates that parameters that we did not measure are generating these differences However we did identify several notable assemblages that were lt15 similar to the rest of the as-semblages sampled

RL Lowe PC Furey JA Ress and JR Johansen 1452007

The two assemblages in cluster A were largely separated by dominant populations of Pinnularia subcapitata v hilseana and Eunotia cf gla-cialis These two diatoms have been reported from subaerial and acid habitats from both Europe and North America (Beyens 1989 Dixit et al 1999) Both collections in this cluster were from drippy bryophytes similar to the report of Beyens (1989) which may indicate that this is a preferred habitat of Pinnularia subcapitata v hilseana Eunotia is also common on mosses The three collections from wetwalls in Whiteoak Sinks (cluster B) were the only samples that we collected from limestone-dominated alkaline bed-rock Cymbopleura rupicola dominated these communities and was found nowhere else This taxon has been reported from similar alkaline subaerial habitats (Klemenčič 2002) Its disjunct distribution on wetwalls in the GSMNP may indicate its strong habitat specifi city Cluster C is represented by a single collection from a bryophyte-covered rock of Thunderhead Sandstone in a spray zone of Laurel Falls Waterfall spray zones are wetted for longer periods than many of the wetwall habitats and also have a continuous source of diatom immigrants and this may in part account for its uniqueness The assemblage was dominated by two spe-cies of Frustulia

Figures 36ndash39 Species of diatoms showing reduced external openings 36) Nupela sp 37) Diadesmis perpusilla (Kuumltz) DG Mann 38) Eunotia sp 39) Chamaepin-nulari soehrensis (Krasske) Lange-Bertalot (scale bar = 4 μm)

Southeastern Naturalist146 Special Issue 1

Cluster D was another small cluster of only two collections (Thunderhead Sandstone near a waterfall at Ramsay Cascade and Metcalf Phyllite on Lau-rel Creek Road) These two communities were only 23 similar to each other but lt15 similar to the remainder of the assemblages (Fig 2) These two assemblages were related by their relatively dense populations of Euno-tia exigua a cosmopolitan acidophilic species (Lowe 1974) Cluster E with six collections was separated from the other sites largely by species of Eunotia Although these six collections are less than 15 simi-lar to the rest of the assemblages they are not closely related to each other (Fig 2) Cluster F contained a single unique assemblage dominated by Eunotia diodon Ehrenberg and Eunotia rhomboidea Hustedt This was the only collection in this analysis that came from a soil seep and may reflect pe-culiar aspects of this unique environment Surveys of diatom soil flora are few but an extensive study by Lund (1945) illustrates the richness of the flora GSMNP with diverse soil types should hold a large number of soil diatom species We hope to pursue the algal soil flora of GSMNP in suc-ceeding years Cluster G consisted of two assemblages collected from disjunct sites (Thunderhead Sandstone seep and Logarm Quartzite dripwall) Both collection sites had the same pH however (50) The sites were relatively

Figures 40ndash43 Common wetwall diatom species without obviously reduced external openings 40) Decussata placenta 41) Luticola sp 42) Microcostatus krasskei 43) Nitzschia hantzschiana (scale bar = 5μm)

RL Lowe PC Furey JA Ress and JR Johansen 1472007

dissimilar to each other (Fig 2) but were distinct from the remainder of the assemblages primarily due to large populations of Diatoma mesodon and Fragilariaforma virescens Although Diatoma mesodon is often found in a large variety of habitats Fragilariaforma virescens is typically restricted to acidic or low alkalinity habitats (Camburn and Charles 2000) Cluster H is defi ned by Tetracyclus rupestris which occurred only in this single collection and accounted for 85 of the diatoms in this assemblage This is a unique community and is signifi cant in that Tetracyclus rupestris is seldom reported from the North American fl ora The collection site was a drippy Anakeesta bedrock formation at 1500 m elevation Anakeesta pro-vides an acidic environment and is often high in aluminum although we did not measure that element in this study Cluster I is composed of three assemblages each with Nitzschia hantzschiana as a common taxon This diatom is one of the most common subaerial species of the genus Nitzschia and has been reported from many different studies of subaerial algae (Dayner and Johansen 1991 Johansen et al 1983a Lund 1945) The three samples in this cluster are all from drippy wetwalls along road cuts All three of these samples contained conspicuous quantities of green algae or cyanobacteria Such algae might facilitate the presence of Nitzschia which is highly motile and would be capable of mov-ing through the algal matrix The remaining 28 collections all cluster together (J) but within this large cluster several subndashclusters can be identifi ed driven by assemblages with large populations of Diadesmis species and by Microcostatus krasskei These taxa have strong fi delity to subaerial habitats and are generally not seen in abundance in aquatic habitats In addition to the challenges of working with the vertical nature of wetwalls the highly variable and heterogeneous nature of the algal com-munities along with some of the variations in microhabitat discussed above highlights the need to consider both spatial scale and sampling strategy when designing wetwall studies or biodiversity surveys For ex-ample to minimize the effects of microhabitat variation artificial wetwall substrates may be helpful in elucidating the impact of microscale habitat features on algal community structure or several wetwall areas may need to be sampled in order to adequately characterize the diversity of an area or to track changes in algal assemblages over time or in response to en-vironmental changes Additionally the range of values covered for pH for the majority of our sites (pH 38ndash55) was narrow and future studies should include a broader range of pH especially across the intermediate values not examined in this study (pH 55ndash72) Similarly elevation and geology gave no apparent environmental signal in the diatom composition although these influences may have been masked by microscale variability or small sample size and future studies may require more intensive sam-pling experimental work or finer-scale bedrock determination

Southeastern Naturalist148 Special Issue 1

Conclusions

We described the diatom fl ora from several wetwalls throughout GSMNP Some of the species from this research appear to be new species and will be described and published elsewhere Aside from these new taxa many of the diatoms have been reported from other wetwall studies and have been noted as typical subaerial species Although we found little correlation with bedrock mineralogy chemistry including pH and wetwall elevation we did observe highly variable and very diverse diatom community structure among the wetwall habitats We found unique diatom communities along with wetwall-specifi c diatom taxa that appeared to have special adaptations to these subaerial habitats In order to better understand these understud-ied communities future research should explore these subaerial habitat adaptations such as presence of additional external siliceous membranes or interactions with soft algal communities Additionally further research is needed to understand the complexities of these unique algal communi-ties and habitats including examination of factors that may have a more dominant role in shaping wetwall community structure such as moisture gradients and sources infl uences of microscale variability substrate type and shading or the role of ultraviolet radiation We feel that it is particularly important to examine these communities at an appropriate scale Habitat variables and community structure could vary over millimeter distances on wetwalls and the small and spatially unique nature of these microhabitats should be taken into consideration in the experimental design and sampling in future wetwall studies

Acknowledgments

This research was supported by the National Science Foundation (DEB 0315979) and grants from Discover Life In America We are also very grateful for support and facilitation from the National Park Service Jeanie Hilton and volunteers from Dis-cover Life In America and the Appalachian Highlands Learning Center interns This manuscript was greatly improved thanks to detailed reviews by Marina Potapova Peter Siver and one anonymous reviewer

Literature Cited

Beyens L 1989 Moss-dwelling diatom assemblages from Edgeoslashya (Svalbard) Polar Biology 9423ndash430

Camburn KE and DF Charles 2000 Diatoms of Low-alkalinity Lakes in the Northeastern United States Academy of Natural Sciences of Philadelphia Spe-cial Publication 18 Philadelphia PA 152 pp

Dayner DM and JR Johansen 1991 Observations on the algal fl ora of Seneca Caverns Seneca County Ohio Ohio Journal of Science 91118ndash121

Dixit SS JP Smol DF Charles RM Hughes SG Paulsen and GB Collins 1999 Assessing water quality changes in the lakes of the northeastern United States using sediment diatoms Canadian Journal of Fisheries and Aquatic Sci-ences 56(1)131ndash152

RL Lowe PC Furey JA Ress and JR Johansen 1492007

Gomez S 2002 Epilithic aerial algae of Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 78 pp

Gomez SR JR Johansen and RL Lowe 2003 Epilithic aerial algae of Great Smoky Mountains National Park Biologia Bratislava 58603ndash615

Gresens SE and RL Lowe 1994 Periphyton patch preference in grazing chiron-omid larvae Journal of the North American Benthological Society 1389ndash99

Johansen JR 1999 Diatoms of aerial habitats Pp 264ndash273 In EF Stoermer and JP Smol (Eds) The Diatoms Applications for the Environmental and Earth Sciences Cambridge University Press Cambridge UK

Johansen JR and RL Lowe In press Draparnaldia appalachiana sp Nov (Chaetophoraceae Chlorophyceae) from the Great Smoky Mountains National Park

Johansen JR and JC Sray 1998 Microcostatus Gen Nov a new aerophilic dia-tom genus based on Navicula Krasskei Hustedt Diatom Research 1393ndash101

Johansen JR RL Lowe SR Gomez JP Kociolek and SA Makosky 2004 New algal species records for the Great Smoky Mountains National Park USA with an annotated checklist of all reported algal species for the park Algological Studies 11117ndash44

Johansen JR SR Rushforth and JD Brotherson 1983a The algal fl ora of Navajo National Monument Arizona USA Nova Hedwigia 38501ndash553

Johansen JR SR Rushforth R Orbendorfer N Fungladda and J Grimes 1983b The algal fl ora of selected wet walls in Zion National Park Utah USA Nova Hedwigia 38765ndash808

Klemencic AK 2002 Kopenske alge na bentonskem zidu kamniten zidu apnen-casti skali in deblu lipe (Tilia platyphyllos) v Sloveniji Natura Sloveniae 421ndash30

Krammer K and H Lange-Bertalot 1986 Bacillariophyceae 1 Teil Navicula-ceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasser fl ora von Mitteleuropa Band 21 Gustav Fischer Verlag Stuttgart New York 876 pp

Krammer K and H Lange-Bertalot 1988 Bacillariophyceae 2 Teil Bacilla-riaceae Epithemiaceae Surirellaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 22 VEB Gustav Fischer Verlag Jena Germany 596 pp

Krammer K and H Lange-Bertalot 1991a Bacillariophyceae 3 Teil Centrales Fragilariaceae Eunotiaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 23 Gustav Fischer Verlag Stuttgart Jena Germany 576 pp

Krammer K and H Lange-Bertalot 1991b Bacillariophyceae 4 Teil Achnantha-ceae Kritische Ergaumlnzungen zu Navicula (Lineolatae) und Gomphonema Gesamtliteraturverzeichnis Teil 1-4 in Ettl H Gaumlrtner G Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 24 Gustav Fischer Verlag Stuttgart Jena Germany 437 pp

Lowe RL 1974 Environmental requirements and pollution tolerance of freshwater diatoms Environmental Protection Agency Washington DC PA-6704-74-007 340 pp

Lowe RL and GB Collins 1973 An aerophilous diatom community from Hocking Co Ohio Transactions of the American Microscopical Society 92492ndash496

Southeastern Naturalist150 Special Issue 1

Lund JWG 1945 Observations on soil algae I The ecology size and taxonomy of British soil diatoms The New Phytologist 4456ndash110

McMillim M and SR Rushforth 1985 The diatom fl ora of a steam vent of Kilauea Crater Island of Hawaii Pacifi c Science 39294ndash301

Olsen CE 2004 The algal fl ora of selected seeps and waterfalls in the Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 106 pp

Patrick R 1977 Ecology of freshwater diatoms-diatom communities Pp 133ndash191 In D Werner (Ed) The Biology of Diatoms Blackwell Scientifi c Publications London UK

Patrick R and CW Reimer 1966 The diatoms of the United States V1 Mono-graph Academy of Natural Science Philadelphia 13(1)1ndash688

Potapova MG KC Ponader RL Lowe TA Clason and LA Bahls 2003 Small-celled Nupela species from USA rivers Diatom Research 18293ndash306

Pederson D 1999 Scientists are trying to identify every living thing in the Smokies National Park Newsweek November 22 1999

Sharkey MJ 2001 The all taxa biological inventory of the Great Smoky Mountains National Park Florida Entomologist 84556ndash564

Sokal RR and FJ Rohlf 1995 Biometry 3rd Edition WH Freeman New York NY 468 pp

Southworth S A Schultz and D Denenny 2005 Generalized geological map of Bedrock Lithologies and surfi cial deposits in the Great Smoky Mountains National Park Region Tennessee and North Carolina US Geological Survey Resten VA Open-File Report 2004-1410

Wallace BJ J Webster and RL Lowe 1992 High-gradient streams of the Ap-palachians Pp 133ndash191 In CT Hackney SM Adams and WA Martin (Eds) Biodiversity of the Southeastern United StatesAquatic Communities John Wiley and Sons Inc Hoboken NJ USA pp 133-191

Werum M and H Lange-Bertalot 2004 Diatoms in springs and elsewhere under the infl uence of hydrogeology and anthropogenic impacts Iconographia Diato-mologica 131ndash480

RL Lowe PC Furey JA Ress and JR Johansen 1512007

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Southeastern Naturalist152 Special Issue 1C

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Southeastern Naturalist138 Special Issue 1

Relative abundance of diatoms at each site calculated both at the species and genus levels were normalized with an arcsine transformation (arcsine of the square root Sokal and Rohlf 1995) Ordination of sites was fi rst conducted based on a reduced species list using non-metric multidimension-al scaling (MDS) of Bray Curtis similarities Diatom taxa that occurred at a minimum of three sites were included in the MDS analysis in order to ensure suffi cient data for ordination thus reducing the total number of taxa from 223 to 98 A high stress value for the MDS output indicated that additional analyses should be conducted to confi rm the MDS ordination Therefore the clustering of sites based on species- or genera-level similarity for both a reduced and complete taxa list was examined using a dendrogram of group-average linking of Bray Curtis similarities The cluster analysis using the complete species list is presented in this study because the overall patterns were similar between the two methods and the use of the complete spe-cies list provided a more inclusive picture of the wetwall communities and information on some of the unique wetwall sites Elevation pH latitude longitude watershed and microhabitat type (epiphytic [bryophyte associ-ated] or epilithic) were used as factors for examining clustering patterns Statistical tests were performed with Primer 5 version 529 (PrimerndashE Ltd 2002) Unique communities of algae were identifi ed as those sets of sites with either gt85 relative abundance of a single taxon or lt10 similarity with other sets of sites based on the cluster analysis Clusters were further subdivided into ten subclusters based on a similarity cutoff of 15 Com-mon wetwall taxa were selected based on species and genera that were found at gt3 overall relative abundance (calculated with all sites considered to-gether) or present at gt20 of the sites

Results

Site pH ranged from 38ndash55 with the exception of three unique sites that had pH between 72ndash77 Acidic areas were generally found at the higher elevation sites The three sites with pH gt 7 were all found in the Whiteoak Sink area of the GSMNP Forty-one genera and 223 species were identifi ed from the wetwall sites Nineteen wetwall genera were commonly present across all sites (Table 1) Achnanthes Diadesmis Eunotia Navicula Nupela and Pinnularia were present at gt50 of the sites and Chamaepinnularia Encyonema Frustulia Gomphonema and Nitzschia at gt20 of the sites (Table 1) Of these genera Diadesmis (15) and Eunotia (21) also had high overall relative abundance across sites (Table 1) Within these genera 23 wetwall species were consid-ered notable either because they had a higher mean relative abundance or were frequently present at sites Nitzschia hantzschiana Rabenhorst (58) Eunotia praerupta v bigibba (Kuumltzing) Grunow (55) Cymbopleura rupic-ola (Grunow) Krammer (57) and Navicula keeleyi Patrick (96) had the highest overall relative abundances (Table 1) Diadesmis contenta v biceps (Grunow) Hamilton Diadesmis contenta (Grunow) DG Mann Diadesmis

RL Lowe PC Furey JA Ress and JR Johansen 1392007

perpusilla (Kuumltzing) DG Mann Navicula keeleyi Achnanthes subrostrata v appalachiana Camburn and Lowe Navicula angusta Grunow Nitzschia hantzschiana and Nupela neglecta Ponader Lowe and Potapova were pres-ent at over 35 of the sites (Table 1) Four site-groups ([A] [B] [C D E] and [F G H I J J

1 J

2] were identifi ed by the 2-D MDS ordination (Fig 1 stress

Table 1 Table of common species based on overall relative abundance (all sites considered together) or taxa frequently present across sites Species were selected if overall abundance was gt3 or the taxa were present at gt20 of the sites

Mean relative of sites Taxon abundance where present

Achnanthes subrostrata v appalachiana 39 388Achnanthidium exiguum 05 225Chamaepinnularia spp 05 408Cymbopleura rupicola 57 61Decussata placenta 07 245Diadesmis contenta 16 469Diadesmis contenta v biceps 20 388Diatoma mesodon 29 204Encyonema minutum 14 246Eunotia exigua 26 347Eunotia nymanniana 04 245Eunotia praerupta v bigibba 55 204Frustulia crassinervia 08 204Frustulia krammeri 29 265Gomphonema parvulum 05 204Meridion circulare 07 306Microcostatus krasskei 34 327Navicula angusta 18 449Navicula keeleyi 96 592Nitzschia hantzschiana 58 388Nupela spp 28 510Pinularia spp 39 519Planothidium lanceolatum 26 286Psammothidium marginulatum 23 225

Navicula keeleyi to be transferred to Diadesmis in a subsequent manuscript

Figure 1 Two-dimen-sional non-metric mul-tidimensional scaling (MDS) ordination for the 49 wetwall sites based on the Bray-Cur-tis similarities on arc sine root transformed relative abundance data for species present at gt 3 sites MDS stress = 016 Codes (A through J J1 and J2) represent grops of sites identifi ed in the cluster analysis for all species data (see Fig 2) Four general site-groups were identifi ed (A) (B) (C D E) and (F G H I J J1 J2)

Southeastern Naturalist140 Special Issue 1

value 016) Due to the high stress value these patterns were also examined with a cluster analysis both for the reduced taxa list and for all taxa Similar patterns were observed for both cluster analyses Therefore the dendrogram with all taxa considered is shown since it provides the most information on diatom community composition across sites (Fig 2) The four sitendashgroups identifi ed by the MDS ordination also clustered with less than a 10 site similarity threshold (Fig 2) At lt15 similarity 10 site-groups or clusters were identifi ed (Fig 2) With notable exceptions all sites clustered at lt50 similarity which suggests that the diatom community composition was quite variable at the different wetwall sites The two sites forming cluster A (CR-J1C and NDT-V1A) were strongly dominated by Pinnularia subcapitata v hilseana (Janisch ex Rabenhorst) Muumlller with Eunotia cf glacialis Meister also being very abundant at CR-J1C (Fig 2 Table 2) The sites forming cluster B were dominated by

Table 2 Sites where community composition was comprised of one taxon ge 85 relative abun-dance = sites identifi ed as unique in the dendrogram

Site code Species Relative abundance

ACT-15 Eunotia praerupta v bigibba 955CDR-J5E Eunotia cf fallax 920CR-CAT1C Nitzschia hantzshciana 970CR-J1C Pinnularia subcapitata v hilseana 950NG-J9A Tetracyclus rupestris 850WS-4A Cymbopleura rupicola 995WSF-6C Cymbopleura rupicola 995

Figure 2 Dendrogram of the 49 seep-wall sites using group-average clustering from Bray Curtis similarities on arc sine root transformed relative abundances of the all species A lt10 (dashedndashdot line) and lt15 (dotted line) similarity threshold are identifi ed The unique sites and locations separated at a lt15 (dotted line) similarity threshold are indicated by AndashJ below the xndashaxis

RL Lowe PC Furey JA Ress and JR Johansen 1412007

Cymbopleura rupicola with relative abundances of 995 at site WS-4A and WSF-6C and 82 at WSF-6B (Fig 2 Table 2) Cymbopleura rupicola was only present at these three alkaline sites Cluster C site LF-5A was comprised mainly of Frustulia crassinervia (Breacutebisson ex W Smith) Lange-Bertalot and Frustulia krammeri Lange-Bertalot and Metzeltin (Fig 2 Table 2) The two sites forming cluster D included RC-PF6F which was characterized by Eunotia exigua (Breacutebisson ex Kuumltzing) Rabenhorst and Eunotia sp12 with relative abundances at 675 and 225 respectively and LCR-7B which was primarily composed of Psammothidium margi-nulatum (Grunow) Bukhtiyarova and Round and secondarily of Eunotia exigua with relative abundances of 75 and 205 respectively Psam-mothidium marginulatum was found in only fi ve other communities in low relative abundance (Fig 2) Cluster E included six sites that were generally dominated by Eunotia taxa especially Eunotia praerupta v bigibba and Eunotia cf fallax A Cleve (Fig 2 Table 2) Cluster F site TCT-2B was also dominated by Eunotia taxa (Fig 2) The two sites in Cluster G were dominated by different taxa but Diatoma mesodon Kuumltzing and Fragilari-aforma virescens (Ralfs) Williams and Round were present at both Cluster H site NG-J9A was dominated by a single taxon Tetracyclus rupestris (Braun) Grunow that was absent from all other sites (Fig 2 Table 2) The three sites forming Cluster I (LRR-2 LRT-PF1 and CR-CAT1C) all had Nitzschia hantzschiana as a common taxon at 165 79 and 97 relative abundances respectively (Fig 2 Table 2) Cluster J was the largest cluster of sites and overall these sites were highly variable in their taxonomic composition Cluster J1 tended to be comprised of Diadesmis taxa (includ-ing Navicula keeleyi yet to be transferred to Diadesmis) and sites at Cluster J2 were dominated by Microcostatus krasskei (Hustedt) Johansen and Sray (Fig 2) Within all the clusters (AndashJ) seven communities were characterized as unique based on a relative abundance of ge85 of one taxon (Table 2) Within the MDS ordination factor codes and bubble plots of pH geology elevation latitude longitude and watershed were examined to explore the site-clustering patterns in response to the environmental variables and to examine taxon-specifi c clustering with environmental variables (plots not shown) However no patterns were observed for any of the environmental variables alone or considered with a specifi c taxon (with the exception of Cymbopleura rupestris which was found at the three sites with the highest pH)

Discussion

Two hundred and twenty-three diatom species and varieties within 41 genera were recorded from the wetwall communities in GSMNP (see Figs 3ndash35 for illustrations of some of the more common taxa ) These communi-ties were dominated by several taxa that are common in subaerial habitats Many species in the genus Diadesmis for example have been reported from numerous wetwall studies (Dayner and Johansen 1991 Johansen et al 1983a Lowe and Collins 1973 McMillim and Rushforth 1985) Wetwall

Southeastern Naturalist142 Special Issue 1

Figures 3ndash22 Common taxa denoted in Table 1 ldquordquo signifi es taxa denoted in Table 2 3) Achnanthes subrostrata v appalachiana raphe valve 4) Achnanthes subrostrata v appalachiana rapheless valve 5) Achnanthidium exiguum raphe valve 6) Ach-nanthidium exiguum (Grun) Czarnezki rapheless valve 7) Diatoma mesodon 8) Diatoma mesodon girdle view 9) Chamaepinnularia mediocris (Krasske) Lange-Bertalot 10) Diadesmis contenta 11) Diadesmis contenta v biceps 12) Navicula keeleyi 13) Diadesmis perpusilla 14) Gomphonema cf parvulum Kuumltz 15) Pin-nularia subcapitata v hilseana 16) Decussata placenta (Ehr) Lange-Bertalot amp Mezeltin 17) Cymbopleura rupicola 18) Eunotia praerupta v bigibba 19) Euno-tia nymanianna Grun 20) Eunotia cf fallax 21) Eunotia exigua 22) Encyonema minutum (Hilse ex Rabh) DG Mann

RL Lowe PC Furey JA Ress and JR Johansen 1432007

diatoms must withstand a greater range of environmental variables than aquatic species (Patrick 1977) Unlike truly aquatic habitats subaerial envi-

Figures 23ndash35 Common taxa denoted in Table 1 ldquordquo signifi es taxa denoted in Table 2 23) Frustulia krammeri 24) Frustulia crassinervia 25) Meridion circulare (Grev) Ag 26) Navicula angusta 27) Nitzschia hantzschiana 28) Microcostatus krasskei 29) Nupela sp 30) Planothidium lanceolatum raphe valve 31) Planothid-ium lanceolatum (Breacuteb ex Kuumltz) Round amp Bukhtiyarova rapheless valve 32) Psammothidium marginulatum raphe valve 33) Psammothidium marginulatum rapheless valve 34) Tetracyclus rupestris 35) Tetracyclus rupestris girdle view

Southeastern Naturalist144 Special Issue 1

ronments are moist but can periodically become dry for long periods Also because these diatoms often live in a fi lm of water they do not experience the thermal stability that aquatic taxa experience Wetwall diatoms may also experience more intense ultraviolet radiation than aquatic forms that are more protected by water (Johansen 1999) Many wetwall diatoms have a reduced number of areolae or possess areolae that are occluded with a siliceous lamina (eg species of Nupela Diadesmis Chamaepinnularia and Eunotia Figs 36ndash39) These morpho-logical features may be adaptations to reduce water loss in periodically dry habitats Some common taxa without obviously reduced external openings such as Decussata Luticola Microcostatus and Nitzschia (Figs 40ndash43) are also typical of diatom communities in subaerial habitats Diatom community structure on the wetwall habitats observed in this study was diverse and highly variable Higher pH appeared to be an im-portant variable separating the three Whiteoak Sink samples from the more acidic sites throughout the park However we anticipated that diatom com-munities from habitats with similar bedrock mineralogy and pH would be very similar and this pattern was not usually the case with the acidic wetwalls Even diatom collections from the same acidic wetwall separated by a few centimeters were often very dissimilar In retrospect this is less surprising since the microscale patchiness of algal communities in streams is common We expect that subtle differences in shading and moisture probably play a large role in determining diatom community structure Diatom communities that are only a few cm apart can occupy very dif-ferent microhabitats as rock faces possess subtle differences in surface morphology that influence exposure of the community to sunlight and dry-ing These subtle differences can also regulate the distribution of sympatric patches of non-diatom algae and bryophytes that are also likely to play a role in diatom distribution Several of the wetwalls supported macroscopic growths of algae rich in extracellular water-retaining polysaccharides that can provide a moist environment for diatoms during otherwise dry peri-ods These kinds of habitats seemed favorable to Nitzschia hantzschiana for example Macroscopic growths of Nostoc Stigonema Mesotaenium and several coccoid cyanobacteria were common but highly patchy on the wetwalls which might also reflect patchy environmental variables or the history of chance colonization by propogules We did not examine potential top-down impacts of grazers in these communities but noted the presence of protozoa and occasional dipteran larvae Grazers may be selec-tive in consumption of algae (Gresens and Lowe 1994) The cluster analysis (Fig 2) illustrates the dissimilarity among diatom communities and again probably indicates that parameters that we did not measure are generating these differences However we did identify several notable assemblages that were lt15 similar to the rest of the as-semblages sampled

RL Lowe PC Furey JA Ress and JR Johansen 1452007

The two assemblages in cluster A were largely separated by dominant populations of Pinnularia subcapitata v hilseana and Eunotia cf gla-cialis These two diatoms have been reported from subaerial and acid habitats from both Europe and North America (Beyens 1989 Dixit et al 1999) Both collections in this cluster were from drippy bryophytes similar to the report of Beyens (1989) which may indicate that this is a preferred habitat of Pinnularia subcapitata v hilseana Eunotia is also common on mosses The three collections from wetwalls in Whiteoak Sinks (cluster B) were the only samples that we collected from limestone-dominated alkaline bed-rock Cymbopleura rupicola dominated these communities and was found nowhere else This taxon has been reported from similar alkaline subaerial habitats (Klemenčič 2002) Its disjunct distribution on wetwalls in the GSMNP may indicate its strong habitat specifi city Cluster C is represented by a single collection from a bryophyte-covered rock of Thunderhead Sandstone in a spray zone of Laurel Falls Waterfall spray zones are wetted for longer periods than many of the wetwall habitats and also have a continuous source of diatom immigrants and this may in part account for its uniqueness The assemblage was dominated by two spe-cies of Frustulia

Figures 36ndash39 Species of diatoms showing reduced external openings 36) Nupela sp 37) Diadesmis perpusilla (Kuumltz) DG Mann 38) Eunotia sp 39) Chamaepin-nulari soehrensis (Krasske) Lange-Bertalot (scale bar = 4 μm)

Southeastern Naturalist146 Special Issue 1

Cluster D was another small cluster of only two collections (Thunderhead Sandstone near a waterfall at Ramsay Cascade and Metcalf Phyllite on Lau-rel Creek Road) These two communities were only 23 similar to each other but lt15 similar to the remainder of the assemblages (Fig 2) These two assemblages were related by their relatively dense populations of Euno-tia exigua a cosmopolitan acidophilic species (Lowe 1974) Cluster E with six collections was separated from the other sites largely by species of Eunotia Although these six collections are less than 15 simi-lar to the rest of the assemblages they are not closely related to each other (Fig 2) Cluster F contained a single unique assemblage dominated by Eunotia diodon Ehrenberg and Eunotia rhomboidea Hustedt This was the only collection in this analysis that came from a soil seep and may reflect pe-culiar aspects of this unique environment Surveys of diatom soil flora are few but an extensive study by Lund (1945) illustrates the richness of the flora GSMNP with diverse soil types should hold a large number of soil diatom species We hope to pursue the algal soil flora of GSMNP in suc-ceeding years Cluster G consisted of two assemblages collected from disjunct sites (Thunderhead Sandstone seep and Logarm Quartzite dripwall) Both collection sites had the same pH however (50) The sites were relatively

Figures 40ndash43 Common wetwall diatom species without obviously reduced external openings 40) Decussata placenta 41) Luticola sp 42) Microcostatus krasskei 43) Nitzschia hantzschiana (scale bar = 5μm)

RL Lowe PC Furey JA Ress and JR Johansen 1472007

dissimilar to each other (Fig 2) but were distinct from the remainder of the assemblages primarily due to large populations of Diatoma mesodon and Fragilariaforma virescens Although Diatoma mesodon is often found in a large variety of habitats Fragilariaforma virescens is typically restricted to acidic or low alkalinity habitats (Camburn and Charles 2000) Cluster H is defi ned by Tetracyclus rupestris which occurred only in this single collection and accounted for 85 of the diatoms in this assemblage This is a unique community and is signifi cant in that Tetracyclus rupestris is seldom reported from the North American fl ora The collection site was a drippy Anakeesta bedrock formation at 1500 m elevation Anakeesta pro-vides an acidic environment and is often high in aluminum although we did not measure that element in this study Cluster I is composed of three assemblages each with Nitzschia hantzschiana as a common taxon This diatom is one of the most common subaerial species of the genus Nitzschia and has been reported from many different studies of subaerial algae (Dayner and Johansen 1991 Johansen et al 1983a Lund 1945) The three samples in this cluster are all from drippy wetwalls along road cuts All three of these samples contained conspicuous quantities of green algae or cyanobacteria Such algae might facilitate the presence of Nitzschia which is highly motile and would be capable of mov-ing through the algal matrix The remaining 28 collections all cluster together (J) but within this large cluster several subndashclusters can be identifi ed driven by assemblages with large populations of Diadesmis species and by Microcostatus krasskei These taxa have strong fi delity to subaerial habitats and are generally not seen in abundance in aquatic habitats In addition to the challenges of working with the vertical nature of wetwalls the highly variable and heterogeneous nature of the algal com-munities along with some of the variations in microhabitat discussed above highlights the need to consider both spatial scale and sampling strategy when designing wetwall studies or biodiversity surveys For ex-ample to minimize the effects of microhabitat variation artificial wetwall substrates may be helpful in elucidating the impact of microscale habitat features on algal community structure or several wetwall areas may need to be sampled in order to adequately characterize the diversity of an area or to track changes in algal assemblages over time or in response to en-vironmental changes Additionally the range of values covered for pH for the majority of our sites (pH 38ndash55) was narrow and future studies should include a broader range of pH especially across the intermediate values not examined in this study (pH 55ndash72) Similarly elevation and geology gave no apparent environmental signal in the diatom composition although these influences may have been masked by microscale variability or small sample size and future studies may require more intensive sam-pling experimental work or finer-scale bedrock determination

Southeastern Naturalist148 Special Issue 1

Conclusions

We described the diatom fl ora from several wetwalls throughout GSMNP Some of the species from this research appear to be new species and will be described and published elsewhere Aside from these new taxa many of the diatoms have been reported from other wetwall studies and have been noted as typical subaerial species Although we found little correlation with bedrock mineralogy chemistry including pH and wetwall elevation we did observe highly variable and very diverse diatom community structure among the wetwall habitats We found unique diatom communities along with wetwall-specifi c diatom taxa that appeared to have special adaptations to these subaerial habitats In order to better understand these understud-ied communities future research should explore these subaerial habitat adaptations such as presence of additional external siliceous membranes or interactions with soft algal communities Additionally further research is needed to understand the complexities of these unique algal communi-ties and habitats including examination of factors that may have a more dominant role in shaping wetwall community structure such as moisture gradients and sources infl uences of microscale variability substrate type and shading or the role of ultraviolet radiation We feel that it is particularly important to examine these communities at an appropriate scale Habitat variables and community structure could vary over millimeter distances on wetwalls and the small and spatially unique nature of these microhabitats should be taken into consideration in the experimental design and sampling in future wetwall studies

Acknowledgments

This research was supported by the National Science Foundation (DEB 0315979) and grants from Discover Life In America We are also very grateful for support and facilitation from the National Park Service Jeanie Hilton and volunteers from Dis-cover Life In America and the Appalachian Highlands Learning Center interns This manuscript was greatly improved thanks to detailed reviews by Marina Potapova Peter Siver and one anonymous reviewer

Literature Cited

Beyens L 1989 Moss-dwelling diatom assemblages from Edgeoslashya (Svalbard) Polar Biology 9423ndash430

Camburn KE and DF Charles 2000 Diatoms of Low-alkalinity Lakes in the Northeastern United States Academy of Natural Sciences of Philadelphia Spe-cial Publication 18 Philadelphia PA 152 pp

Dayner DM and JR Johansen 1991 Observations on the algal fl ora of Seneca Caverns Seneca County Ohio Ohio Journal of Science 91118ndash121

Dixit SS JP Smol DF Charles RM Hughes SG Paulsen and GB Collins 1999 Assessing water quality changes in the lakes of the northeastern United States using sediment diatoms Canadian Journal of Fisheries and Aquatic Sci-ences 56(1)131ndash152

RL Lowe PC Furey JA Ress and JR Johansen 1492007

Gomez S 2002 Epilithic aerial algae of Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 78 pp

Gomez SR JR Johansen and RL Lowe 2003 Epilithic aerial algae of Great Smoky Mountains National Park Biologia Bratislava 58603ndash615

Gresens SE and RL Lowe 1994 Periphyton patch preference in grazing chiron-omid larvae Journal of the North American Benthological Society 1389ndash99

Johansen JR 1999 Diatoms of aerial habitats Pp 264ndash273 In EF Stoermer and JP Smol (Eds) The Diatoms Applications for the Environmental and Earth Sciences Cambridge University Press Cambridge UK

Johansen JR and RL Lowe In press Draparnaldia appalachiana sp Nov (Chaetophoraceae Chlorophyceae) from the Great Smoky Mountains National Park

Johansen JR and JC Sray 1998 Microcostatus Gen Nov a new aerophilic dia-tom genus based on Navicula Krasskei Hustedt Diatom Research 1393ndash101

Johansen JR RL Lowe SR Gomez JP Kociolek and SA Makosky 2004 New algal species records for the Great Smoky Mountains National Park USA with an annotated checklist of all reported algal species for the park Algological Studies 11117ndash44

Johansen JR SR Rushforth and JD Brotherson 1983a The algal fl ora of Navajo National Monument Arizona USA Nova Hedwigia 38501ndash553

Johansen JR SR Rushforth R Orbendorfer N Fungladda and J Grimes 1983b The algal fl ora of selected wet walls in Zion National Park Utah USA Nova Hedwigia 38765ndash808

Klemencic AK 2002 Kopenske alge na bentonskem zidu kamniten zidu apnen-casti skali in deblu lipe (Tilia platyphyllos) v Sloveniji Natura Sloveniae 421ndash30

Krammer K and H Lange-Bertalot 1986 Bacillariophyceae 1 Teil Navicula-ceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasser fl ora von Mitteleuropa Band 21 Gustav Fischer Verlag Stuttgart New York 876 pp

Krammer K and H Lange-Bertalot 1988 Bacillariophyceae 2 Teil Bacilla-riaceae Epithemiaceae Surirellaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 22 VEB Gustav Fischer Verlag Jena Germany 596 pp

Krammer K and H Lange-Bertalot 1991a Bacillariophyceae 3 Teil Centrales Fragilariaceae Eunotiaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 23 Gustav Fischer Verlag Stuttgart Jena Germany 576 pp

Krammer K and H Lange-Bertalot 1991b Bacillariophyceae 4 Teil Achnantha-ceae Kritische Ergaumlnzungen zu Navicula (Lineolatae) und Gomphonema Gesamtliteraturverzeichnis Teil 1-4 in Ettl H Gaumlrtner G Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 24 Gustav Fischer Verlag Stuttgart Jena Germany 437 pp

Lowe RL 1974 Environmental requirements and pollution tolerance of freshwater diatoms Environmental Protection Agency Washington DC PA-6704-74-007 340 pp

Lowe RL and GB Collins 1973 An aerophilous diatom community from Hocking Co Ohio Transactions of the American Microscopical Society 92492ndash496

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Lund JWG 1945 Observations on soil algae I The ecology size and taxonomy of British soil diatoms The New Phytologist 4456ndash110

McMillim M and SR Rushforth 1985 The diatom fl ora of a steam vent of Kilauea Crater Island of Hawaii Pacifi c Science 39294ndash301

Olsen CE 2004 The algal fl ora of selected seeps and waterfalls in the Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 106 pp

Patrick R 1977 Ecology of freshwater diatoms-diatom communities Pp 133ndash191 In D Werner (Ed) The Biology of Diatoms Blackwell Scientifi c Publications London UK

Patrick R and CW Reimer 1966 The diatoms of the United States V1 Mono-graph Academy of Natural Science Philadelphia 13(1)1ndash688

Potapova MG KC Ponader RL Lowe TA Clason and LA Bahls 2003 Small-celled Nupela species from USA rivers Diatom Research 18293ndash306

Pederson D 1999 Scientists are trying to identify every living thing in the Smokies National Park Newsweek November 22 1999

Sharkey MJ 2001 The all taxa biological inventory of the Great Smoky Mountains National Park Florida Entomologist 84556ndash564

Sokal RR and FJ Rohlf 1995 Biometry 3rd Edition WH Freeman New York NY 468 pp

Southworth S A Schultz and D Denenny 2005 Generalized geological map of Bedrock Lithologies and surfi cial deposits in the Great Smoky Mountains National Park Region Tennessee and North Carolina US Geological Survey Resten VA Open-File Report 2004-1410

Wallace BJ J Webster and RL Lowe 1992 High-gradient streams of the Ap-palachians Pp 133ndash191 In CT Hackney SM Adams and WA Martin (Eds) Biodiversity of the Southeastern United StatesAquatic Communities John Wiley and Sons Inc Hoboken NJ USA pp 133-191

Werum M and H Lange-Bertalot 2004 Diatoms in springs and elsewhere under the infl uence of hydrogeology and anthropogenic impacts Iconographia Diato-mologica 131ndash480

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Roc

k ou

tcro

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Tra

il t

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en W

allo

w F

alls

C

ocke

TN

WS

-4A

Lim

esto

neD

olom

ite

77

N35

636

58deg

W83

749

00deg

500

L

arge

roc

k ou

tcro

p in

Whi

teoa

k S

ink

Blo

unt

TN

WS

F-6

B

C

ades

San

dsto

ne

72

N35

638

86deg

W83

748

04deg

518

Wet

roc

k ou

tsid

e of

spr

ay z

one

at W

hite

oak

Sin

k F

alls

B

loun

t T

N

WS

F-6

C

C

ades

San

dsto

ne

72

N35

638

86deg

W83

748

04deg

518

Wet

roc

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Sin

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RL Lowe PC Furey JA Ress and JR Johansen 1392007

perpusilla (Kuumltzing) DG Mann Navicula keeleyi Achnanthes subrostrata v appalachiana Camburn and Lowe Navicula angusta Grunow Nitzschia hantzschiana and Nupela neglecta Ponader Lowe and Potapova were pres-ent at over 35 of the sites (Table 1) Four site-groups ([A] [B] [C D E] and [F G H I J J

1 J

2] were identifi ed by the 2-D MDS ordination (Fig 1 stress

Table 1 Table of common species based on overall relative abundance (all sites considered together) or taxa frequently present across sites Species were selected if overall abundance was gt3 or the taxa were present at gt20 of the sites

Mean relative of sites Taxon abundance where present

Achnanthes subrostrata v appalachiana 39 388Achnanthidium exiguum 05 225Chamaepinnularia spp 05 408Cymbopleura rupicola 57 61Decussata placenta 07 245Diadesmis contenta 16 469Diadesmis contenta v biceps 20 388Diatoma mesodon 29 204Encyonema minutum 14 246Eunotia exigua 26 347Eunotia nymanniana 04 245Eunotia praerupta v bigibba 55 204Frustulia crassinervia 08 204Frustulia krammeri 29 265Gomphonema parvulum 05 204Meridion circulare 07 306Microcostatus krasskei 34 327Navicula angusta 18 449Navicula keeleyi 96 592Nitzschia hantzschiana 58 388Nupela spp 28 510Pinularia spp 39 519Planothidium lanceolatum 26 286Psammothidium marginulatum 23 225

Navicula keeleyi to be transferred to Diadesmis in a subsequent manuscript

Figure 1 Two-dimen-sional non-metric mul-tidimensional scaling (MDS) ordination for the 49 wetwall sites based on the Bray-Cur-tis similarities on arc sine root transformed relative abundance data for species present at gt 3 sites MDS stress = 016 Codes (A through J J1 and J2) represent grops of sites identifi ed in the cluster analysis for all species data (see Fig 2) Four general site-groups were identifi ed (A) (B) (C D E) and (F G H I J J1 J2)

Southeastern Naturalist140 Special Issue 1

value 016) Due to the high stress value these patterns were also examined with a cluster analysis both for the reduced taxa list and for all taxa Similar patterns were observed for both cluster analyses Therefore the dendrogram with all taxa considered is shown since it provides the most information on diatom community composition across sites (Fig 2) The four sitendashgroups identifi ed by the MDS ordination also clustered with less than a 10 site similarity threshold (Fig 2) At lt15 similarity 10 site-groups or clusters were identifi ed (Fig 2) With notable exceptions all sites clustered at lt50 similarity which suggests that the diatom community composition was quite variable at the different wetwall sites The two sites forming cluster A (CR-J1C and NDT-V1A) were strongly dominated by Pinnularia subcapitata v hilseana (Janisch ex Rabenhorst) Muumlller with Eunotia cf glacialis Meister also being very abundant at CR-J1C (Fig 2 Table 2) The sites forming cluster B were dominated by

Table 2 Sites where community composition was comprised of one taxon ge 85 relative abun-dance = sites identifi ed as unique in the dendrogram

Site code Species Relative abundance

ACT-15 Eunotia praerupta v bigibba 955CDR-J5E Eunotia cf fallax 920CR-CAT1C Nitzschia hantzshciana 970CR-J1C Pinnularia subcapitata v hilseana 950NG-J9A Tetracyclus rupestris 850WS-4A Cymbopleura rupicola 995WSF-6C Cymbopleura rupicola 995

Figure 2 Dendrogram of the 49 seep-wall sites using group-average clustering from Bray Curtis similarities on arc sine root transformed relative abundances of the all species A lt10 (dashedndashdot line) and lt15 (dotted line) similarity threshold are identifi ed The unique sites and locations separated at a lt15 (dotted line) similarity threshold are indicated by AndashJ below the xndashaxis

RL Lowe PC Furey JA Ress and JR Johansen 1412007

Cymbopleura rupicola with relative abundances of 995 at site WS-4A and WSF-6C and 82 at WSF-6B (Fig 2 Table 2) Cymbopleura rupicola was only present at these three alkaline sites Cluster C site LF-5A was comprised mainly of Frustulia crassinervia (Breacutebisson ex W Smith) Lange-Bertalot and Frustulia krammeri Lange-Bertalot and Metzeltin (Fig 2 Table 2) The two sites forming cluster D included RC-PF6F which was characterized by Eunotia exigua (Breacutebisson ex Kuumltzing) Rabenhorst and Eunotia sp12 with relative abundances at 675 and 225 respectively and LCR-7B which was primarily composed of Psammothidium margi-nulatum (Grunow) Bukhtiyarova and Round and secondarily of Eunotia exigua with relative abundances of 75 and 205 respectively Psam-mothidium marginulatum was found in only fi ve other communities in low relative abundance (Fig 2) Cluster E included six sites that were generally dominated by Eunotia taxa especially Eunotia praerupta v bigibba and Eunotia cf fallax A Cleve (Fig 2 Table 2) Cluster F site TCT-2B was also dominated by Eunotia taxa (Fig 2) The two sites in Cluster G were dominated by different taxa but Diatoma mesodon Kuumltzing and Fragilari-aforma virescens (Ralfs) Williams and Round were present at both Cluster H site NG-J9A was dominated by a single taxon Tetracyclus rupestris (Braun) Grunow that was absent from all other sites (Fig 2 Table 2) The three sites forming Cluster I (LRR-2 LRT-PF1 and CR-CAT1C) all had Nitzschia hantzschiana as a common taxon at 165 79 and 97 relative abundances respectively (Fig 2 Table 2) Cluster J was the largest cluster of sites and overall these sites were highly variable in their taxonomic composition Cluster J1 tended to be comprised of Diadesmis taxa (includ-ing Navicula keeleyi yet to be transferred to Diadesmis) and sites at Cluster J2 were dominated by Microcostatus krasskei (Hustedt) Johansen and Sray (Fig 2) Within all the clusters (AndashJ) seven communities were characterized as unique based on a relative abundance of ge85 of one taxon (Table 2) Within the MDS ordination factor codes and bubble plots of pH geology elevation latitude longitude and watershed were examined to explore the site-clustering patterns in response to the environmental variables and to examine taxon-specifi c clustering with environmental variables (plots not shown) However no patterns were observed for any of the environmental variables alone or considered with a specifi c taxon (with the exception of Cymbopleura rupestris which was found at the three sites with the highest pH)

Discussion

Two hundred and twenty-three diatom species and varieties within 41 genera were recorded from the wetwall communities in GSMNP (see Figs 3ndash35 for illustrations of some of the more common taxa ) These communi-ties were dominated by several taxa that are common in subaerial habitats Many species in the genus Diadesmis for example have been reported from numerous wetwall studies (Dayner and Johansen 1991 Johansen et al 1983a Lowe and Collins 1973 McMillim and Rushforth 1985) Wetwall

Southeastern Naturalist142 Special Issue 1

Figures 3ndash22 Common taxa denoted in Table 1 ldquordquo signifi es taxa denoted in Table 2 3) Achnanthes subrostrata v appalachiana raphe valve 4) Achnanthes subrostrata v appalachiana rapheless valve 5) Achnanthidium exiguum raphe valve 6) Ach-nanthidium exiguum (Grun) Czarnezki rapheless valve 7) Diatoma mesodon 8) Diatoma mesodon girdle view 9) Chamaepinnularia mediocris (Krasske) Lange-Bertalot 10) Diadesmis contenta 11) Diadesmis contenta v biceps 12) Navicula keeleyi 13) Diadesmis perpusilla 14) Gomphonema cf parvulum Kuumltz 15) Pin-nularia subcapitata v hilseana 16) Decussata placenta (Ehr) Lange-Bertalot amp Mezeltin 17) Cymbopleura rupicola 18) Eunotia praerupta v bigibba 19) Euno-tia nymanianna Grun 20) Eunotia cf fallax 21) Eunotia exigua 22) Encyonema minutum (Hilse ex Rabh) DG Mann

RL Lowe PC Furey JA Ress and JR Johansen 1432007

diatoms must withstand a greater range of environmental variables than aquatic species (Patrick 1977) Unlike truly aquatic habitats subaerial envi-

Figures 23ndash35 Common taxa denoted in Table 1 ldquordquo signifi es taxa denoted in Table 2 23) Frustulia krammeri 24) Frustulia crassinervia 25) Meridion circulare (Grev) Ag 26) Navicula angusta 27) Nitzschia hantzschiana 28) Microcostatus krasskei 29) Nupela sp 30) Planothidium lanceolatum raphe valve 31) Planothid-ium lanceolatum (Breacuteb ex Kuumltz) Round amp Bukhtiyarova rapheless valve 32) Psammothidium marginulatum raphe valve 33) Psammothidium marginulatum rapheless valve 34) Tetracyclus rupestris 35) Tetracyclus rupestris girdle view

Southeastern Naturalist144 Special Issue 1

ronments are moist but can periodically become dry for long periods Also because these diatoms often live in a fi lm of water they do not experience the thermal stability that aquatic taxa experience Wetwall diatoms may also experience more intense ultraviolet radiation than aquatic forms that are more protected by water (Johansen 1999) Many wetwall diatoms have a reduced number of areolae or possess areolae that are occluded with a siliceous lamina (eg species of Nupela Diadesmis Chamaepinnularia and Eunotia Figs 36ndash39) These morpho-logical features may be adaptations to reduce water loss in periodically dry habitats Some common taxa without obviously reduced external openings such as Decussata Luticola Microcostatus and Nitzschia (Figs 40ndash43) are also typical of diatom communities in subaerial habitats Diatom community structure on the wetwall habitats observed in this study was diverse and highly variable Higher pH appeared to be an im-portant variable separating the three Whiteoak Sink samples from the more acidic sites throughout the park However we anticipated that diatom com-munities from habitats with similar bedrock mineralogy and pH would be very similar and this pattern was not usually the case with the acidic wetwalls Even diatom collections from the same acidic wetwall separated by a few centimeters were often very dissimilar In retrospect this is less surprising since the microscale patchiness of algal communities in streams is common We expect that subtle differences in shading and moisture probably play a large role in determining diatom community structure Diatom communities that are only a few cm apart can occupy very dif-ferent microhabitats as rock faces possess subtle differences in surface morphology that influence exposure of the community to sunlight and dry-ing These subtle differences can also regulate the distribution of sympatric patches of non-diatom algae and bryophytes that are also likely to play a role in diatom distribution Several of the wetwalls supported macroscopic growths of algae rich in extracellular water-retaining polysaccharides that can provide a moist environment for diatoms during otherwise dry peri-ods These kinds of habitats seemed favorable to Nitzschia hantzschiana for example Macroscopic growths of Nostoc Stigonema Mesotaenium and several coccoid cyanobacteria were common but highly patchy on the wetwalls which might also reflect patchy environmental variables or the history of chance colonization by propogules We did not examine potential top-down impacts of grazers in these communities but noted the presence of protozoa and occasional dipteran larvae Grazers may be selec-tive in consumption of algae (Gresens and Lowe 1994) The cluster analysis (Fig 2) illustrates the dissimilarity among diatom communities and again probably indicates that parameters that we did not measure are generating these differences However we did identify several notable assemblages that were lt15 similar to the rest of the as-semblages sampled

RL Lowe PC Furey JA Ress and JR Johansen 1452007

The two assemblages in cluster A were largely separated by dominant populations of Pinnularia subcapitata v hilseana and Eunotia cf gla-cialis These two diatoms have been reported from subaerial and acid habitats from both Europe and North America (Beyens 1989 Dixit et al 1999) Both collections in this cluster were from drippy bryophytes similar to the report of Beyens (1989) which may indicate that this is a preferred habitat of Pinnularia subcapitata v hilseana Eunotia is also common on mosses The three collections from wetwalls in Whiteoak Sinks (cluster B) were the only samples that we collected from limestone-dominated alkaline bed-rock Cymbopleura rupicola dominated these communities and was found nowhere else This taxon has been reported from similar alkaline subaerial habitats (Klemenčič 2002) Its disjunct distribution on wetwalls in the GSMNP may indicate its strong habitat specifi city Cluster C is represented by a single collection from a bryophyte-covered rock of Thunderhead Sandstone in a spray zone of Laurel Falls Waterfall spray zones are wetted for longer periods than many of the wetwall habitats and also have a continuous source of diatom immigrants and this may in part account for its uniqueness The assemblage was dominated by two spe-cies of Frustulia

Figures 36ndash39 Species of diatoms showing reduced external openings 36) Nupela sp 37) Diadesmis perpusilla (Kuumltz) DG Mann 38) Eunotia sp 39) Chamaepin-nulari soehrensis (Krasske) Lange-Bertalot (scale bar = 4 μm)

Southeastern Naturalist146 Special Issue 1

Cluster D was another small cluster of only two collections (Thunderhead Sandstone near a waterfall at Ramsay Cascade and Metcalf Phyllite on Lau-rel Creek Road) These two communities were only 23 similar to each other but lt15 similar to the remainder of the assemblages (Fig 2) These two assemblages were related by their relatively dense populations of Euno-tia exigua a cosmopolitan acidophilic species (Lowe 1974) Cluster E with six collections was separated from the other sites largely by species of Eunotia Although these six collections are less than 15 simi-lar to the rest of the assemblages they are not closely related to each other (Fig 2) Cluster F contained a single unique assemblage dominated by Eunotia diodon Ehrenberg and Eunotia rhomboidea Hustedt This was the only collection in this analysis that came from a soil seep and may reflect pe-culiar aspects of this unique environment Surveys of diatom soil flora are few but an extensive study by Lund (1945) illustrates the richness of the flora GSMNP with diverse soil types should hold a large number of soil diatom species We hope to pursue the algal soil flora of GSMNP in suc-ceeding years Cluster G consisted of two assemblages collected from disjunct sites (Thunderhead Sandstone seep and Logarm Quartzite dripwall) Both collection sites had the same pH however (50) The sites were relatively

Figures 40ndash43 Common wetwall diatom species without obviously reduced external openings 40) Decussata placenta 41) Luticola sp 42) Microcostatus krasskei 43) Nitzschia hantzschiana (scale bar = 5μm)

RL Lowe PC Furey JA Ress and JR Johansen 1472007

dissimilar to each other (Fig 2) but were distinct from the remainder of the assemblages primarily due to large populations of Diatoma mesodon and Fragilariaforma virescens Although Diatoma mesodon is often found in a large variety of habitats Fragilariaforma virescens is typically restricted to acidic or low alkalinity habitats (Camburn and Charles 2000) Cluster H is defi ned by Tetracyclus rupestris which occurred only in this single collection and accounted for 85 of the diatoms in this assemblage This is a unique community and is signifi cant in that Tetracyclus rupestris is seldom reported from the North American fl ora The collection site was a drippy Anakeesta bedrock formation at 1500 m elevation Anakeesta pro-vides an acidic environment and is often high in aluminum although we did not measure that element in this study Cluster I is composed of three assemblages each with Nitzschia hantzschiana as a common taxon This diatom is one of the most common subaerial species of the genus Nitzschia and has been reported from many different studies of subaerial algae (Dayner and Johansen 1991 Johansen et al 1983a Lund 1945) The three samples in this cluster are all from drippy wetwalls along road cuts All three of these samples contained conspicuous quantities of green algae or cyanobacteria Such algae might facilitate the presence of Nitzschia which is highly motile and would be capable of mov-ing through the algal matrix The remaining 28 collections all cluster together (J) but within this large cluster several subndashclusters can be identifi ed driven by assemblages with large populations of Diadesmis species and by Microcostatus krasskei These taxa have strong fi delity to subaerial habitats and are generally not seen in abundance in aquatic habitats In addition to the challenges of working with the vertical nature of wetwalls the highly variable and heterogeneous nature of the algal com-munities along with some of the variations in microhabitat discussed above highlights the need to consider both spatial scale and sampling strategy when designing wetwall studies or biodiversity surveys For ex-ample to minimize the effects of microhabitat variation artificial wetwall substrates may be helpful in elucidating the impact of microscale habitat features on algal community structure or several wetwall areas may need to be sampled in order to adequately characterize the diversity of an area or to track changes in algal assemblages over time or in response to en-vironmental changes Additionally the range of values covered for pH for the majority of our sites (pH 38ndash55) was narrow and future studies should include a broader range of pH especially across the intermediate values not examined in this study (pH 55ndash72) Similarly elevation and geology gave no apparent environmental signal in the diatom composition although these influences may have been masked by microscale variability or small sample size and future studies may require more intensive sam-pling experimental work or finer-scale bedrock determination

Southeastern Naturalist148 Special Issue 1

Conclusions

We described the diatom fl ora from several wetwalls throughout GSMNP Some of the species from this research appear to be new species and will be described and published elsewhere Aside from these new taxa many of the diatoms have been reported from other wetwall studies and have been noted as typical subaerial species Although we found little correlation with bedrock mineralogy chemistry including pH and wetwall elevation we did observe highly variable and very diverse diatom community structure among the wetwall habitats We found unique diatom communities along with wetwall-specifi c diatom taxa that appeared to have special adaptations to these subaerial habitats In order to better understand these understud-ied communities future research should explore these subaerial habitat adaptations such as presence of additional external siliceous membranes or interactions with soft algal communities Additionally further research is needed to understand the complexities of these unique algal communi-ties and habitats including examination of factors that may have a more dominant role in shaping wetwall community structure such as moisture gradients and sources infl uences of microscale variability substrate type and shading or the role of ultraviolet radiation We feel that it is particularly important to examine these communities at an appropriate scale Habitat variables and community structure could vary over millimeter distances on wetwalls and the small and spatially unique nature of these microhabitats should be taken into consideration in the experimental design and sampling in future wetwall studies

Acknowledgments

This research was supported by the National Science Foundation (DEB 0315979) and grants from Discover Life In America We are also very grateful for support and facilitation from the National Park Service Jeanie Hilton and volunteers from Dis-cover Life In America and the Appalachian Highlands Learning Center interns This manuscript was greatly improved thanks to detailed reviews by Marina Potapova Peter Siver and one anonymous reviewer

Literature Cited

Beyens L 1989 Moss-dwelling diatom assemblages from Edgeoslashya (Svalbard) Polar Biology 9423ndash430

Camburn KE and DF Charles 2000 Diatoms of Low-alkalinity Lakes in the Northeastern United States Academy of Natural Sciences of Philadelphia Spe-cial Publication 18 Philadelphia PA 152 pp

Dayner DM and JR Johansen 1991 Observations on the algal fl ora of Seneca Caverns Seneca County Ohio Ohio Journal of Science 91118ndash121

Dixit SS JP Smol DF Charles RM Hughes SG Paulsen and GB Collins 1999 Assessing water quality changes in the lakes of the northeastern United States using sediment diatoms Canadian Journal of Fisheries and Aquatic Sci-ences 56(1)131ndash152

RL Lowe PC Furey JA Ress and JR Johansen 1492007

Gomez S 2002 Epilithic aerial algae of Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 78 pp

Gomez SR JR Johansen and RL Lowe 2003 Epilithic aerial algae of Great Smoky Mountains National Park Biologia Bratislava 58603ndash615

Gresens SE and RL Lowe 1994 Periphyton patch preference in grazing chiron-omid larvae Journal of the North American Benthological Society 1389ndash99

Johansen JR 1999 Diatoms of aerial habitats Pp 264ndash273 In EF Stoermer and JP Smol (Eds) The Diatoms Applications for the Environmental and Earth Sciences Cambridge University Press Cambridge UK

Johansen JR and RL Lowe In press Draparnaldia appalachiana sp Nov (Chaetophoraceae Chlorophyceae) from the Great Smoky Mountains National Park

Johansen JR and JC Sray 1998 Microcostatus Gen Nov a new aerophilic dia-tom genus based on Navicula Krasskei Hustedt Diatom Research 1393ndash101

Johansen JR RL Lowe SR Gomez JP Kociolek and SA Makosky 2004 New algal species records for the Great Smoky Mountains National Park USA with an annotated checklist of all reported algal species for the park Algological Studies 11117ndash44

Johansen JR SR Rushforth and JD Brotherson 1983a The algal fl ora of Navajo National Monument Arizona USA Nova Hedwigia 38501ndash553

Johansen JR SR Rushforth R Orbendorfer N Fungladda and J Grimes 1983b The algal fl ora of selected wet walls in Zion National Park Utah USA Nova Hedwigia 38765ndash808

Klemencic AK 2002 Kopenske alge na bentonskem zidu kamniten zidu apnen-casti skali in deblu lipe (Tilia platyphyllos) v Sloveniji Natura Sloveniae 421ndash30

Krammer K and H Lange-Bertalot 1986 Bacillariophyceae 1 Teil Navicula-ceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasser fl ora von Mitteleuropa Band 21 Gustav Fischer Verlag Stuttgart New York 876 pp

Krammer K and H Lange-Bertalot 1988 Bacillariophyceae 2 Teil Bacilla-riaceae Epithemiaceae Surirellaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 22 VEB Gustav Fischer Verlag Jena Germany 596 pp

Krammer K and H Lange-Bertalot 1991a Bacillariophyceae 3 Teil Centrales Fragilariaceae Eunotiaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 23 Gustav Fischer Verlag Stuttgart Jena Germany 576 pp

Krammer K and H Lange-Bertalot 1991b Bacillariophyceae 4 Teil Achnantha-ceae Kritische Ergaumlnzungen zu Navicula (Lineolatae) und Gomphonema Gesamtliteraturverzeichnis Teil 1-4 in Ettl H Gaumlrtner G Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 24 Gustav Fischer Verlag Stuttgart Jena Germany 437 pp

Lowe RL 1974 Environmental requirements and pollution tolerance of freshwater diatoms Environmental Protection Agency Washington DC PA-6704-74-007 340 pp

Lowe RL and GB Collins 1973 An aerophilous diatom community from Hocking Co Ohio Transactions of the American Microscopical Society 92492ndash496

Southeastern Naturalist150 Special Issue 1

Lund JWG 1945 Observations on soil algae I The ecology size and taxonomy of British soil diatoms The New Phytologist 4456ndash110

McMillim M and SR Rushforth 1985 The diatom fl ora of a steam vent of Kilauea Crater Island of Hawaii Pacifi c Science 39294ndash301

Olsen CE 2004 The algal fl ora of selected seeps and waterfalls in the Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 106 pp

Patrick R 1977 Ecology of freshwater diatoms-diatom communities Pp 133ndash191 In D Werner (Ed) The Biology of Diatoms Blackwell Scientifi c Publications London UK

Patrick R and CW Reimer 1966 The diatoms of the United States V1 Mono-graph Academy of Natural Science Philadelphia 13(1)1ndash688

Potapova MG KC Ponader RL Lowe TA Clason and LA Bahls 2003 Small-celled Nupela species from USA rivers Diatom Research 18293ndash306

Pederson D 1999 Scientists are trying to identify every living thing in the Smokies National Park Newsweek November 22 1999

Sharkey MJ 2001 The all taxa biological inventory of the Great Smoky Mountains National Park Florida Entomologist 84556ndash564

Sokal RR and FJ Rohlf 1995 Biometry 3rd Edition WH Freeman New York NY 468 pp

Southworth S A Schultz and D Denenny 2005 Generalized geological map of Bedrock Lithologies and surfi cial deposits in the Great Smoky Mountains National Park Region Tennessee and North Carolina US Geological Survey Resten VA Open-File Report 2004-1410

Wallace BJ J Webster and RL Lowe 1992 High-gradient streams of the Ap-palachians Pp 133ndash191 In CT Hackney SM Adams and WA Martin (Eds) Biodiversity of the Southeastern United StatesAquatic Communities John Wiley and Sons Inc Hoboken NJ USA pp 133-191

Werum M and H Lange-Bertalot 2004 Diatoms in springs and elsewhere under the infl uence of hydrogeology and anthropogenic impacts Iconographia Diato-mologica 131ndash480

RL Lowe PC Furey JA Ress and JR Johansen 1512007

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Southeastern Naturalist152 Special Issue 1C

ode

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Southeastern Naturalist140 Special Issue 1

value 016) Due to the high stress value these patterns were also examined with a cluster analysis both for the reduced taxa list and for all taxa Similar patterns were observed for both cluster analyses Therefore the dendrogram with all taxa considered is shown since it provides the most information on diatom community composition across sites (Fig 2) The four sitendashgroups identifi ed by the MDS ordination also clustered with less than a 10 site similarity threshold (Fig 2) At lt15 similarity 10 site-groups or clusters were identifi ed (Fig 2) With notable exceptions all sites clustered at lt50 similarity which suggests that the diatom community composition was quite variable at the different wetwall sites The two sites forming cluster A (CR-J1C and NDT-V1A) were strongly dominated by Pinnularia subcapitata v hilseana (Janisch ex Rabenhorst) Muumlller with Eunotia cf glacialis Meister also being very abundant at CR-J1C (Fig 2 Table 2) The sites forming cluster B were dominated by

Table 2 Sites where community composition was comprised of one taxon ge 85 relative abun-dance = sites identifi ed as unique in the dendrogram

Site code Species Relative abundance

ACT-15 Eunotia praerupta v bigibba 955CDR-J5E Eunotia cf fallax 920CR-CAT1C Nitzschia hantzshciana 970CR-J1C Pinnularia subcapitata v hilseana 950NG-J9A Tetracyclus rupestris 850WS-4A Cymbopleura rupicola 995WSF-6C Cymbopleura rupicola 995

Figure 2 Dendrogram of the 49 seep-wall sites using group-average clustering from Bray Curtis similarities on arc sine root transformed relative abundances of the all species A lt10 (dashedndashdot line) and lt15 (dotted line) similarity threshold are identifi ed The unique sites and locations separated at a lt15 (dotted line) similarity threshold are indicated by AndashJ below the xndashaxis

RL Lowe PC Furey JA Ress and JR Johansen 1412007

Cymbopleura rupicola with relative abundances of 995 at site WS-4A and WSF-6C and 82 at WSF-6B (Fig 2 Table 2) Cymbopleura rupicola was only present at these three alkaline sites Cluster C site LF-5A was comprised mainly of Frustulia crassinervia (Breacutebisson ex W Smith) Lange-Bertalot and Frustulia krammeri Lange-Bertalot and Metzeltin (Fig 2 Table 2) The two sites forming cluster D included RC-PF6F which was characterized by Eunotia exigua (Breacutebisson ex Kuumltzing) Rabenhorst and Eunotia sp12 with relative abundances at 675 and 225 respectively and LCR-7B which was primarily composed of Psammothidium margi-nulatum (Grunow) Bukhtiyarova and Round and secondarily of Eunotia exigua with relative abundances of 75 and 205 respectively Psam-mothidium marginulatum was found in only fi ve other communities in low relative abundance (Fig 2) Cluster E included six sites that were generally dominated by Eunotia taxa especially Eunotia praerupta v bigibba and Eunotia cf fallax A Cleve (Fig 2 Table 2) Cluster F site TCT-2B was also dominated by Eunotia taxa (Fig 2) The two sites in Cluster G were dominated by different taxa but Diatoma mesodon Kuumltzing and Fragilari-aforma virescens (Ralfs) Williams and Round were present at both Cluster H site NG-J9A was dominated by a single taxon Tetracyclus rupestris (Braun) Grunow that was absent from all other sites (Fig 2 Table 2) The three sites forming Cluster I (LRR-2 LRT-PF1 and CR-CAT1C) all had Nitzschia hantzschiana as a common taxon at 165 79 and 97 relative abundances respectively (Fig 2 Table 2) Cluster J was the largest cluster of sites and overall these sites were highly variable in their taxonomic composition Cluster J1 tended to be comprised of Diadesmis taxa (includ-ing Navicula keeleyi yet to be transferred to Diadesmis) and sites at Cluster J2 were dominated by Microcostatus krasskei (Hustedt) Johansen and Sray (Fig 2) Within all the clusters (AndashJ) seven communities were characterized as unique based on a relative abundance of ge85 of one taxon (Table 2) Within the MDS ordination factor codes and bubble plots of pH geology elevation latitude longitude and watershed were examined to explore the site-clustering patterns in response to the environmental variables and to examine taxon-specifi c clustering with environmental variables (plots not shown) However no patterns were observed for any of the environmental variables alone or considered with a specifi c taxon (with the exception of Cymbopleura rupestris which was found at the three sites with the highest pH)

Discussion

Two hundred and twenty-three diatom species and varieties within 41 genera were recorded from the wetwall communities in GSMNP (see Figs 3ndash35 for illustrations of some of the more common taxa ) These communi-ties were dominated by several taxa that are common in subaerial habitats Many species in the genus Diadesmis for example have been reported from numerous wetwall studies (Dayner and Johansen 1991 Johansen et al 1983a Lowe and Collins 1973 McMillim and Rushforth 1985) Wetwall

Southeastern Naturalist142 Special Issue 1

Figures 3ndash22 Common taxa denoted in Table 1 ldquordquo signifi es taxa denoted in Table 2 3) Achnanthes subrostrata v appalachiana raphe valve 4) Achnanthes subrostrata v appalachiana rapheless valve 5) Achnanthidium exiguum raphe valve 6) Ach-nanthidium exiguum (Grun) Czarnezki rapheless valve 7) Diatoma mesodon 8) Diatoma mesodon girdle view 9) Chamaepinnularia mediocris (Krasske) Lange-Bertalot 10) Diadesmis contenta 11) Diadesmis contenta v biceps 12) Navicula keeleyi 13) Diadesmis perpusilla 14) Gomphonema cf parvulum Kuumltz 15) Pin-nularia subcapitata v hilseana 16) Decussata placenta (Ehr) Lange-Bertalot amp Mezeltin 17) Cymbopleura rupicola 18) Eunotia praerupta v bigibba 19) Euno-tia nymanianna Grun 20) Eunotia cf fallax 21) Eunotia exigua 22) Encyonema minutum (Hilse ex Rabh) DG Mann

RL Lowe PC Furey JA Ress and JR Johansen 1432007

diatoms must withstand a greater range of environmental variables than aquatic species (Patrick 1977) Unlike truly aquatic habitats subaerial envi-

Figures 23ndash35 Common taxa denoted in Table 1 ldquordquo signifi es taxa denoted in Table 2 23) Frustulia krammeri 24) Frustulia crassinervia 25) Meridion circulare (Grev) Ag 26) Navicula angusta 27) Nitzschia hantzschiana 28) Microcostatus krasskei 29) Nupela sp 30) Planothidium lanceolatum raphe valve 31) Planothid-ium lanceolatum (Breacuteb ex Kuumltz) Round amp Bukhtiyarova rapheless valve 32) Psammothidium marginulatum raphe valve 33) Psammothidium marginulatum rapheless valve 34) Tetracyclus rupestris 35) Tetracyclus rupestris girdle view

Southeastern Naturalist144 Special Issue 1

ronments are moist but can periodically become dry for long periods Also because these diatoms often live in a fi lm of water they do not experience the thermal stability that aquatic taxa experience Wetwall diatoms may also experience more intense ultraviolet radiation than aquatic forms that are more protected by water (Johansen 1999) Many wetwall diatoms have a reduced number of areolae or possess areolae that are occluded with a siliceous lamina (eg species of Nupela Diadesmis Chamaepinnularia and Eunotia Figs 36ndash39) These morpho-logical features may be adaptations to reduce water loss in periodically dry habitats Some common taxa without obviously reduced external openings such as Decussata Luticola Microcostatus and Nitzschia (Figs 40ndash43) are also typical of diatom communities in subaerial habitats Diatom community structure on the wetwall habitats observed in this study was diverse and highly variable Higher pH appeared to be an im-portant variable separating the three Whiteoak Sink samples from the more acidic sites throughout the park However we anticipated that diatom com-munities from habitats with similar bedrock mineralogy and pH would be very similar and this pattern was not usually the case with the acidic wetwalls Even diatom collections from the same acidic wetwall separated by a few centimeters were often very dissimilar In retrospect this is less surprising since the microscale patchiness of algal communities in streams is common We expect that subtle differences in shading and moisture probably play a large role in determining diatom community structure Diatom communities that are only a few cm apart can occupy very dif-ferent microhabitats as rock faces possess subtle differences in surface morphology that influence exposure of the community to sunlight and dry-ing These subtle differences can also regulate the distribution of sympatric patches of non-diatom algae and bryophytes that are also likely to play a role in diatom distribution Several of the wetwalls supported macroscopic growths of algae rich in extracellular water-retaining polysaccharides that can provide a moist environment for diatoms during otherwise dry peri-ods These kinds of habitats seemed favorable to Nitzschia hantzschiana for example Macroscopic growths of Nostoc Stigonema Mesotaenium and several coccoid cyanobacteria were common but highly patchy on the wetwalls which might also reflect patchy environmental variables or the history of chance colonization by propogules We did not examine potential top-down impacts of grazers in these communities but noted the presence of protozoa and occasional dipteran larvae Grazers may be selec-tive in consumption of algae (Gresens and Lowe 1994) The cluster analysis (Fig 2) illustrates the dissimilarity among diatom communities and again probably indicates that parameters that we did not measure are generating these differences However we did identify several notable assemblages that were lt15 similar to the rest of the as-semblages sampled

RL Lowe PC Furey JA Ress and JR Johansen 1452007

The two assemblages in cluster A were largely separated by dominant populations of Pinnularia subcapitata v hilseana and Eunotia cf gla-cialis These two diatoms have been reported from subaerial and acid habitats from both Europe and North America (Beyens 1989 Dixit et al 1999) Both collections in this cluster were from drippy bryophytes similar to the report of Beyens (1989) which may indicate that this is a preferred habitat of Pinnularia subcapitata v hilseana Eunotia is also common on mosses The three collections from wetwalls in Whiteoak Sinks (cluster B) were the only samples that we collected from limestone-dominated alkaline bed-rock Cymbopleura rupicola dominated these communities and was found nowhere else This taxon has been reported from similar alkaline subaerial habitats (Klemenčič 2002) Its disjunct distribution on wetwalls in the GSMNP may indicate its strong habitat specifi city Cluster C is represented by a single collection from a bryophyte-covered rock of Thunderhead Sandstone in a spray zone of Laurel Falls Waterfall spray zones are wetted for longer periods than many of the wetwall habitats and also have a continuous source of diatom immigrants and this may in part account for its uniqueness The assemblage was dominated by two spe-cies of Frustulia

Figures 36ndash39 Species of diatoms showing reduced external openings 36) Nupela sp 37) Diadesmis perpusilla (Kuumltz) DG Mann 38) Eunotia sp 39) Chamaepin-nulari soehrensis (Krasske) Lange-Bertalot (scale bar = 4 μm)

Southeastern Naturalist146 Special Issue 1

Cluster D was another small cluster of only two collections (Thunderhead Sandstone near a waterfall at Ramsay Cascade and Metcalf Phyllite on Lau-rel Creek Road) These two communities were only 23 similar to each other but lt15 similar to the remainder of the assemblages (Fig 2) These two assemblages were related by their relatively dense populations of Euno-tia exigua a cosmopolitan acidophilic species (Lowe 1974) Cluster E with six collections was separated from the other sites largely by species of Eunotia Although these six collections are less than 15 simi-lar to the rest of the assemblages they are not closely related to each other (Fig 2) Cluster F contained a single unique assemblage dominated by Eunotia diodon Ehrenberg and Eunotia rhomboidea Hustedt This was the only collection in this analysis that came from a soil seep and may reflect pe-culiar aspects of this unique environment Surveys of diatom soil flora are few but an extensive study by Lund (1945) illustrates the richness of the flora GSMNP with diverse soil types should hold a large number of soil diatom species We hope to pursue the algal soil flora of GSMNP in suc-ceeding years Cluster G consisted of two assemblages collected from disjunct sites (Thunderhead Sandstone seep and Logarm Quartzite dripwall) Both collection sites had the same pH however (50) The sites were relatively

Figures 40ndash43 Common wetwall diatom species without obviously reduced external openings 40) Decussata placenta 41) Luticola sp 42) Microcostatus krasskei 43) Nitzschia hantzschiana (scale bar = 5μm)

RL Lowe PC Furey JA Ress and JR Johansen 1472007

dissimilar to each other (Fig 2) but were distinct from the remainder of the assemblages primarily due to large populations of Diatoma mesodon and Fragilariaforma virescens Although Diatoma mesodon is often found in a large variety of habitats Fragilariaforma virescens is typically restricted to acidic or low alkalinity habitats (Camburn and Charles 2000) Cluster H is defi ned by Tetracyclus rupestris which occurred only in this single collection and accounted for 85 of the diatoms in this assemblage This is a unique community and is signifi cant in that Tetracyclus rupestris is seldom reported from the North American fl ora The collection site was a drippy Anakeesta bedrock formation at 1500 m elevation Anakeesta pro-vides an acidic environment and is often high in aluminum although we did not measure that element in this study Cluster I is composed of three assemblages each with Nitzschia hantzschiana as a common taxon This diatom is one of the most common subaerial species of the genus Nitzschia and has been reported from many different studies of subaerial algae (Dayner and Johansen 1991 Johansen et al 1983a Lund 1945) The three samples in this cluster are all from drippy wetwalls along road cuts All three of these samples contained conspicuous quantities of green algae or cyanobacteria Such algae might facilitate the presence of Nitzschia which is highly motile and would be capable of mov-ing through the algal matrix The remaining 28 collections all cluster together (J) but within this large cluster several subndashclusters can be identifi ed driven by assemblages with large populations of Diadesmis species and by Microcostatus krasskei These taxa have strong fi delity to subaerial habitats and are generally not seen in abundance in aquatic habitats In addition to the challenges of working with the vertical nature of wetwalls the highly variable and heterogeneous nature of the algal com-munities along with some of the variations in microhabitat discussed above highlights the need to consider both spatial scale and sampling strategy when designing wetwall studies or biodiversity surveys For ex-ample to minimize the effects of microhabitat variation artificial wetwall substrates may be helpful in elucidating the impact of microscale habitat features on algal community structure or several wetwall areas may need to be sampled in order to adequately characterize the diversity of an area or to track changes in algal assemblages over time or in response to en-vironmental changes Additionally the range of values covered for pH for the majority of our sites (pH 38ndash55) was narrow and future studies should include a broader range of pH especially across the intermediate values not examined in this study (pH 55ndash72) Similarly elevation and geology gave no apparent environmental signal in the diatom composition although these influences may have been masked by microscale variability or small sample size and future studies may require more intensive sam-pling experimental work or finer-scale bedrock determination

Southeastern Naturalist148 Special Issue 1

Conclusions

We described the diatom fl ora from several wetwalls throughout GSMNP Some of the species from this research appear to be new species and will be described and published elsewhere Aside from these new taxa many of the diatoms have been reported from other wetwall studies and have been noted as typical subaerial species Although we found little correlation with bedrock mineralogy chemistry including pH and wetwall elevation we did observe highly variable and very diverse diatom community structure among the wetwall habitats We found unique diatom communities along with wetwall-specifi c diatom taxa that appeared to have special adaptations to these subaerial habitats In order to better understand these understud-ied communities future research should explore these subaerial habitat adaptations such as presence of additional external siliceous membranes or interactions with soft algal communities Additionally further research is needed to understand the complexities of these unique algal communi-ties and habitats including examination of factors that may have a more dominant role in shaping wetwall community structure such as moisture gradients and sources infl uences of microscale variability substrate type and shading or the role of ultraviolet radiation We feel that it is particularly important to examine these communities at an appropriate scale Habitat variables and community structure could vary over millimeter distances on wetwalls and the small and spatially unique nature of these microhabitats should be taken into consideration in the experimental design and sampling in future wetwall studies

Acknowledgments

This research was supported by the National Science Foundation (DEB 0315979) and grants from Discover Life In America We are also very grateful for support and facilitation from the National Park Service Jeanie Hilton and volunteers from Dis-cover Life In America and the Appalachian Highlands Learning Center interns This manuscript was greatly improved thanks to detailed reviews by Marina Potapova Peter Siver and one anonymous reviewer

Literature Cited

Beyens L 1989 Moss-dwelling diatom assemblages from Edgeoslashya (Svalbard) Polar Biology 9423ndash430

Camburn KE and DF Charles 2000 Diatoms of Low-alkalinity Lakes in the Northeastern United States Academy of Natural Sciences of Philadelphia Spe-cial Publication 18 Philadelphia PA 152 pp

Dayner DM and JR Johansen 1991 Observations on the algal fl ora of Seneca Caverns Seneca County Ohio Ohio Journal of Science 91118ndash121

Dixit SS JP Smol DF Charles RM Hughes SG Paulsen and GB Collins 1999 Assessing water quality changes in the lakes of the northeastern United States using sediment diatoms Canadian Journal of Fisheries and Aquatic Sci-ences 56(1)131ndash152

RL Lowe PC Furey JA Ress and JR Johansen 1492007

Gomez S 2002 Epilithic aerial algae of Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 78 pp

Gomez SR JR Johansen and RL Lowe 2003 Epilithic aerial algae of Great Smoky Mountains National Park Biologia Bratislava 58603ndash615

Gresens SE and RL Lowe 1994 Periphyton patch preference in grazing chiron-omid larvae Journal of the North American Benthological Society 1389ndash99

Johansen JR 1999 Diatoms of aerial habitats Pp 264ndash273 In EF Stoermer and JP Smol (Eds) The Diatoms Applications for the Environmental and Earth Sciences Cambridge University Press Cambridge UK

Johansen JR and RL Lowe In press Draparnaldia appalachiana sp Nov (Chaetophoraceae Chlorophyceae) from the Great Smoky Mountains National Park

Johansen JR and JC Sray 1998 Microcostatus Gen Nov a new aerophilic dia-tom genus based on Navicula Krasskei Hustedt Diatom Research 1393ndash101

Johansen JR RL Lowe SR Gomez JP Kociolek and SA Makosky 2004 New algal species records for the Great Smoky Mountains National Park USA with an annotated checklist of all reported algal species for the park Algological Studies 11117ndash44

Johansen JR SR Rushforth and JD Brotherson 1983a The algal fl ora of Navajo National Monument Arizona USA Nova Hedwigia 38501ndash553

Johansen JR SR Rushforth R Orbendorfer N Fungladda and J Grimes 1983b The algal fl ora of selected wet walls in Zion National Park Utah USA Nova Hedwigia 38765ndash808

Klemencic AK 2002 Kopenske alge na bentonskem zidu kamniten zidu apnen-casti skali in deblu lipe (Tilia platyphyllos) v Sloveniji Natura Sloveniae 421ndash30

Krammer K and H Lange-Bertalot 1986 Bacillariophyceae 1 Teil Navicula-ceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasser fl ora von Mitteleuropa Band 21 Gustav Fischer Verlag Stuttgart New York 876 pp

Krammer K and H Lange-Bertalot 1988 Bacillariophyceae 2 Teil Bacilla-riaceae Epithemiaceae Surirellaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 22 VEB Gustav Fischer Verlag Jena Germany 596 pp

Krammer K and H Lange-Bertalot 1991a Bacillariophyceae 3 Teil Centrales Fragilariaceae Eunotiaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 23 Gustav Fischer Verlag Stuttgart Jena Germany 576 pp

Krammer K and H Lange-Bertalot 1991b Bacillariophyceae 4 Teil Achnantha-ceae Kritische Ergaumlnzungen zu Navicula (Lineolatae) und Gomphonema Gesamtliteraturverzeichnis Teil 1-4 in Ettl H Gaumlrtner G Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 24 Gustav Fischer Verlag Stuttgart Jena Germany 437 pp

Lowe RL 1974 Environmental requirements and pollution tolerance of freshwater diatoms Environmental Protection Agency Washington DC PA-6704-74-007 340 pp

Lowe RL and GB Collins 1973 An aerophilous diatom community from Hocking Co Ohio Transactions of the American Microscopical Society 92492ndash496

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Lund JWG 1945 Observations on soil algae I The ecology size and taxonomy of British soil diatoms The New Phytologist 4456ndash110

McMillim M and SR Rushforth 1985 The diatom fl ora of a steam vent of Kilauea Crater Island of Hawaii Pacifi c Science 39294ndash301

Olsen CE 2004 The algal fl ora of selected seeps and waterfalls in the Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 106 pp

Patrick R 1977 Ecology of freshwater diatoms-diatom communities Pp 133ndash191 In D Werner (Ed) The Biology of Diatoms Blackwell Scientifi c Publications London UK

Patrick R and CW Reimer 1966 The diatoms of the United States V1 Mono-graph Academy of Natural Science Philadelphia 13(1)1ndash688

Potapova MG KC Ponader RL Lowe TA Clason and LA Bahls 2003 Small-celled Nupela species from USA rivers Diatom Research 18293ndash306

Pederson D 1999 Scientists are trying to identify every living thing in the Smokies National Park Newsweek November 22 1999

Sharkey MJ 2001 The all taxa biological inventory of the Great Smoky Mountains National Park Florida Entomologist 84556ndash564

Sokal RR and FJ Rohlf 1995 Biometry 3rd Edition WH Freeman New York NY 468 pp

Southworth S A Schultz and D Denenny 2005 Generalized geological map of Bedrock Lithologies and surfi cial deposits in the Great Smoky Mountains National Park Region Tennessee and North Carolina US Geological Survey Resten VA Open-File Report 2004-1410

Wallace BJ J Webster and RL Lowe 1992 High-gradient streams of the Ap-palachians Pp 133ndash191 In CT Hackney SM Adams and WA Martin (Eds) Biodiversity of the Southeastern United StatesAquatic Communities John Wiley and Sons Inc Hoboken NJ USA pp 133-191

Werum M and H Lange-Bertalot 2004 Diatoms in springs and elsewhere under the infl uence of hydrogeology and anthropogenic impacts Iconographia Diato-mologica 131ndash480

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arge

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ink

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ades

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dsto

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72

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638

86deg

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748

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roc

k ou

tsid

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ay z

one

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Sin

k F

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loun

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ades

San

dsto

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72

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638

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Wet

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RL Lowe PC Furey JA Ress and JR Johansen 1412007

Cymbopleura rupicola with relative abundances of 995 at site WS-4A and WSF-6C and 82 at WSF-6B (Fig 2 Table 2) Cymbopleura rupicola was only present at these three alkaline sites Cluster C site LF-5A was comprised mainly of Frustulia crassinervia (Breacutebisson ex W Smith) Lange-Bertalot and Frustulia krammeri Lange-Bertalot and Metzeltin (Fig 2 Table 2) The two sites forming cluster D included RC-PF6F which was characterized by Eunotia exigua (Breacutebisson ex Kuumltzing) Rabenhorst and Eunotia sp12 with relative abundances at 675 and 225 respectively and LCR-7B which was primarily composed of Psammothidium margi-nulatum (Grunow) Bukhtiyarova and Round and secondarily of Eunotia exigua with relative abundances of 75 and 205 respectively Psam-mothidium marginulatum was found in only fi ve other communities in low relative abundance (Fig 2) Cluster E included six sites that were generally dominated by Eunotia taxa especially Eunotia praerupta v bigibba and Eunotia cf fallax A Cleve (Fig 2 Table 2) Cluster F site TCT-2B was also dominated by Eunotia taxa (Fig 2) The two sites in Cluster G were dominated by different taxa but Diatoma mesodon Kuumltzing and Fragilari-aforma virescens (Ralfs) Williams and Round were present at both Cluster H site NG-J9A was dominated by a single taxon Tetracyclus rupestris (Braun) Grunow that was absent from all other sites (Fig 2 Table 2) The three sites forming Cluster I (LRR-2 LRT-PF1 and CR-CAT1C) all had Nitzschia hantzschiana as a common taxon at 165 79 and 97 relative abundances respectively (Fig 2 Table 2) Cluster J was the largest cluster of sites and overall these sites were highly variable in their taxonomic composition Cluster J1 tended to be comprised of Diadesmis taxa (includ-ing Navicula keeleyi yet to be transferred to Diadesmis) and sites at Cluster J2 were dominated by Microcostatus krasskei (Hustedt) Johansen and Sray (Fig 2) Within all the clusters (AndashJ) seven communities were characterized as unique based on a relative abundance of ge85 of one taxon (Table 2) Within the MDS ordination factor codes and bubble plots of pH geology elevation latitude longitude and watershed were examined to explore the site-clustering patterns in response to the environmental variables and to examine taxon-specifi c clustering with environmental variables (plots not shown) However no patterns were observed for any of the environmental variables alone or considered with a specifi c taxon (with the exception of Cymbopleura rupestris which was found at the three sites with the highest pH)

Discussion

Two hundred and twenty-three diatom species and varieties within 41 genera were recorded from the wetwall communities in GSMNP (see Figs 3ndash35 for illustrations of some of the more common taxa ) These communi-ties were dominated by several taxa that are common in subaerial habitats Many species in the genus Diadesmis for example have been reported from numerous wetwall studies (Dayner and Johansen 1991 Johansen et al 1983a Lowe and Collins 1973 McMillim and Rushforth 1985) Wetwall

Southeastern Naturalist142 Special Issue 1

Figures 3ndash22 Common taxa denoted in Table 1 ldquordquo signifi es taxa denoted in Table 2 3) Achnanthes subrostrata v appalachiana raphe valve 4) Achnanthes subrostrata v appalachiana rapheless valve 5) Achnanthidium exiguum raphe valve 6) Ach-nanthidium exiguum (Grun) Czarnezki rapheless valve 7) Diatoma mesodon 8) Diatoma mesodon girdle view 9) Chamaepinnularia mediocris (Krasske) Lange-Bertalot 10) Diadesmis contenta 11) Diadesmis contenta v biceps 12) Navicula keeleyi 13) Diadesmis perpusilla 14) Gomphonema cf parvulum Kuumltz 15) Pin-nularia subcapitata v hilseana 16) Decussata placenta (Ehr) Lange-Bertalot amp Mezeltin 17) Cymbopleura rupicola 18) Eunotia praerupta v bigibba 19) Euno-tia nymanianna Grun 20) Eunotia cf fallax 21) Eunotia exigua 22) Encyonema minutum (Hilse ex Rabh) DG Mann

RL Lowe PC Furey JA Ress and JR Johansen 1432007

diatoms must withstand a greater range of environmental variables than aquatic species (Patrick 1977) Unlike truly aquatic habitats subaerial envi-

Figures 23ndash35 Common taxa denoted in Table 1 ldquordquo signifi es taxa denoted in Table 2 23) Frustulia krammeri 24) Frustulia crassinervia 25) Meridion circulare (Grev) Ag 26) Navicula angusta 27) Nitzschia hantzschiana 28) Microcostatus krasskei 29) Nupela sp 30) Planothidium lanceolatum raphe valve 31) Planothid-ium lanceolatum (Breacuteb ex Kuumltz) Round amp Bukhtiyarova rapheless valve 32) Psammothidium marginulatum raphe valve 33) Psammothidium marginulatum rapheless valve 34) Tetracyclus rupestris 35) Tetracyclus rupestris girdle view

Southeastern Naturalist144 Special Issue 1

ronments are moist but can periodically become dry for long periods Also because these diatoms often live in a fi lm of water they do not experience the thermal stability that aquatic taxa experience Wetwall diatoms may also experience more intense ultraviolet radiation than aquatic forms that are more protected by water (Johansen 1999) Many wetwall diatoms have a reduced number of areolae or possess areolae that are occluded with a siliceous lamina (eg species of Nupela Diadesmis Chamaepinnularia and Eunotia Figs 36ndash39) These morpho-logical features may be adaptations to reduce water loss in periodically dry habitats Some common taxa without obviously reduced external openings such as Decussata Luticola Microcostatus and Nitzschia (Figs 40ndash43) are also typical of diatom communities in subaerial habitats Diatom community structure on the wetwall habitats observed in this study was diverse and highly variable Higher pH appeared to be an im-portant variable separating the three Whiteoak Sink samples from the more acidic sites throughout the park However we anticipated that diatom com-munities from habitats with similar bedrock mineralogy and pH would be very similar and this pattern was not usually the case with the acidic wetwalls Even diatom collections from the same acidic wetwall separated by a few centimeters were often very dissimilar In retrospect this is less surprising since the microscale patchiness of algal communities in streams is common We expect that subtle differences in shading and moisture probably play a large role in determining diatom community structure Diatom communities that are only a few cm apart can occupy very dif-ferent microhabitats as rock faces possess subtle differences in surface morphology that influence exposure of the community to sunlight and dry-ing These subtle differences can also regulate the distribution of sympatric patches of non-diatom algae and bryophytes that are also likely to play a role in diatom distribution Several of the wetwalls supported macroscopic growths of algae rich in extracellular water-retaining polysaccharides that can provide a moist environment for diatoms during otherwise dry peri-ods These kinds of habitats seemed favorable to Nitzschia hantzschiana for example Macroscopic growths of Nostoc Stigonema Mesotaenium and several coccoid cyanobacteria were common but highly patchy on the wetwalls which might also reflect patchy environmental variables or the history of chance colonization by propogules We did not examine potential top-down impacts of grazers in these communities but noted the presence of protozoa and occasional dipteran larvae Grazers may be selec-tive in consumption of algae (Gresens and Lowe 1994) The cluster analysis (Fig 2) illustrates the dissimilarity among diatom communities and again probably indicates that parameters that we did not measure are generating these differences However we did identify several notable assemblages that were lt15 similar to the rest of the as-semblages sampled

RL Lowe PC Furey JA Ress and JR Johansen 1452007

The two assemblages in cluster A were largely separated by dominant populations of Pinnularia subcapitata v hilseana and Eunotia cf gla-cialis These two diatoms have been reported from subaerial and acid habitats from both Europe and North America (Beyens 1989 Dixit et al 1999) Both collections in this cluster were from drippy bryophytes similar to the report of Beyens (1989) which may indicate that this is a preferred habitat of Pinnularia subcapitata v hilseana Eunotia is also common on mosses The three collections from wetwalls in Whiteoak Sinks (cluster B) were the only samples that we collected from limestone-dominated alkaline bed-rock Cymbopleura rupicola dominated these communities and was found nowhere else This taxon has been reported from similar alkaline subaerial habitats (Klemenčič 2002) Its disjunct distribution on wetwalls in the GSMNP may indicate its strong habitat specifi city Cluster C is represented by a single collection from a bryophyte-covered rock of Thunderhead Sandstone in a spray zone of Laurel Falls Waterfall spray zones are wetted for longer periods than many of the wetwall habitats and also have a continuous source of diatom immigrants and this may in part account for its uniqueness The assemblage was dominated by two spe-cies of Frustulia

Figures 36ndash39 Species of diatoms showing reduced external openings 36) Nupela sp 37) Diadesmis perpusilla (Kuumltz) DG Mann 38) Eunotia sp 39) Chamaepin-nulari soehrensis (Krasske) Lange-Bertalot (scale bar = 4 μm)

Southeastern Naturalist146 Special Issue 1

Cluster D was another small cluster of only two collections (Thunderhead Sandstone near a waterfall at Ramsay Cascade and Metcalf Phyllite on Lau-rel Creek Road) These two communities were only 23 similar to each other but lt15 similar to the remainder of the assemblages (Fig 2) These two assemblages were related by their relatively dense populations of Euno-tia exigua a cosmopolitan acidophilic species (Lowe 1974) Cluster E with six collections was separated from the other sites largely by species of Eunotia Although these six collections are less than 15 simi-lar to the rest of the assemblages they are not closely related to each other (Fig 2) Cluster F contained a single unique assemblage dominated by Eunotia diodon Ehrenberg and Eunotia rhomboidea Hustedt This was the only collection in this analysis that came from a soil seep and may reflect pe-culiar aspects of this unique environment Surveys of diatom soil flora are few but an extensive study by Lund (1945) illustrates the richness of the flora GSMNP with diverse soil types should hold a large number of soil diatom species We hope to pursue the algal soil flora of GSMNP in suc-ceeding years Cluster G consisted of two assemblages collected from disjunct sites (Thunderhead Sandstone seep and Logarm Quartzite dripwall) Both collection sites had the same pH however (50) The sites were relatively

Figures 40ndash43 Common wetwall diatom species without obviously reduced external openings 40) Decussata placenta 41) Luticola sp 42) Microcostatus krasskei 43) Nitzschia hantzschiana (scale bar = 5μm)

RL Lowe PC Furey JA Ress and JR Johansen 1472007

dissimilar to each other (Fig 2) but were distinct from the remainder of the assemblages primarily due to large populations of Diatoma mesodon and Fragilariaforma virescens Although Diatoma mesodon is often found in a large variety of habitats Fragilariaforma virescens is typically restricted to acidic or low alkalinity habitats (Camburn and Charles 2000) Cluster H is defi ned by Tetracyclus rupestris which occurred only in this single collection and accounted for 85 of the diatoms in this assemblage This is a unique community and is signifi cant in that Tetracyclus rupestris is seldom reported from the North American fl ora The collection site was a drippy Anakeesta bedrock formation at 1500 m elevation Anakeesta pro-vides an acidic environment and is often high in aluminum although we did not measure that element in this study Cluster I is composed of three assemblages each with Nitzschia hantzschiana as a common taxon This diatom is one of the most common subaerial species of the genus Nitzschia and has been reported from many different studies of subaerial algae (Dayner and Johansen 1991 Johansen et al 1983a Lund 1945) The three samples in this cluster are all from drippy wetwalls along road cuts All three of these samples contained conspicuous quantities of green algae or cyanobacteria Such algae might facilitate the presence of Nitzschia which is highly motile and would be capable of mov-ing through the algal matrix The remaining 28 collections all cluster together (J) but within this large cluster several subndashclusters can be identifi ed driven by assemblages with large populations of Diadesmis species and by Microcostatus krasskei These taxa have strong fi delity to subaerial habitats and are generally not seen in abundance in aquatic habitats In addition to the challenges of working with the vertical nature of wetwalls the highly variable and heterogeneous nature of the algal com-munities along with some of the variations in microhabitat discussed above highlights the need to consider both spatial scale and sampling strategy when designing wetwall studies or biodiversity surveys For ex-ample to minimize the effects of microhabitat variation artificial wetwall substrates may be helpful in elucidating the impact of microscale habitat features on algal community structure or several wetwall areas may need to be sampled in order to adequately characterize the diversity of an area or to track changes in algal assemblages over time or in response to en-vironmental changes Additionally the range of values covered for pH for the majority of our sites (pH 38ndash55) was narrow and future studies should include a broader range of pH especially across the intermediate values not examined in this study (pH 55ndash72) Similarly elevation and geology gave no apparent environmental signal in the diatom composition although these influences may have been masked by microscale variability or small sample size and future studies may require more intensive sam-pling experimental work or finer-scale bedrock determination

Southeastern Naturalist148 Special Issue 1

Conclusions

We described the diatom fl ora from several wetwalls throughout GSMNP Some of the species from this research appear to be new species and will be described and published elsewhere Aside from these new taxa many of the diatoms have been reported from other wetwall studies and have been noted as typical subaerial species Although we found little correlation with bedrock mineralogy chemistry including pH and wetwall elevation we did observe highly variable and very diverse diatom community structure among the wetwall habitats We found unique diatom communities along with wetwall-specifi c diatom taxa that appeared to have special adaptations to these subaerial habitats In order to better understand these understud-ied communities future research should explore these subaerial habitat adaptations such as presence of additional external siliceous membranes or interactions with soft algal communities Additionally further research is needed to understand the complexities of these unique algal communi-ties and habitats including examination of factors that may have a more dominant role in shaping wetwall community structure such as moisture gradients and sources infl uences of microscale variability substrate type and shading or the role of ultraviolet radiation We feel that it is particularly important to examine these communities at an appropriate scale Habitat variables and community structure could vary over millimeter distances on wetwalls and the small and spatially unique nature of these microhabitats should be taken into consideration in the experimental design and sampling in future wetwall studies

Acknowledgments

This research was supported by the National Science Foundation (DEB 0315979) and grants from Discover Life In America We are also very grateful for support and facilitation from the National Park Service Jeanie Hilton and volunteers from Dis-cover Life In America and the Appalachian Highlands Learning Center interns This manuscript was greatly improved thanks to detailed reviews by Marina Potapova Peter Siver and one anonymous reviewer

Literature Cited

Beyens L 1989 Moss-dwelling diatom assemblages from Edgeoslashya (Svalbard) Polar Biology 9423ndash430

Camburn KE and DF Charles 2000 Diatoms of Low-alkalinity Lakes in the Northeastern United States Academy of Natural Sciences of Philadelphia Spe-cial Publication 18 Philadelphia PA 152 pp

Dayner DM and JR Johansen 1991 Observations on the algal fl ora of Seneca Caverns Seneca County Ohio Ohio Journal of Science 91118ndash121

Dixit SS JP Smol DF Charles RM Hughes SG Paulsen and GB Collins 1999 Assessing water quality changes in the lakes of the northeastern United States using sediment diatoms Canadian Journal of Fisheries and Aquatic Sci-ences 56(1)131ndash152

RL Lowe PC Furey JA Ress and JR Johansen 1492007

Gomez S 2002 Epilithic aerial algae of Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 78 pp

Gomez SR JR Johansen and RL Lowe 2003 Epilithic aerial algae of Great Smoky Mountains National Park Biologia Bratislava 58603ndash615

Gresens SE and RL Lowe 1994 Periphyton patch preference in grazing chiron-omid larvae Journal of the North American Benthological Society 1389ndash99

Johansen JR 1999 Diatoms of aerial habitats Pp 264ndash273 In EF Stoermer and JP Smol (Eds) The Diatoms Applications for the Environmental and Earth Sciences Cambridge University Press Cambridge UK

Johansen JR and RL Lowe In press Draparnaldia appalachiana sp Nov (Chaetophoraceae Chlorophyceae) from the Great Smoky Mountains National Park

Johansen JR and JC Sray 1998 Microcostatus Gen Nov a new aerophilic dia-tom genus based on Navicula Krasskei Hustedt Diatom Research 1393ndash101

Johansen JR RL Lowe SR Gomez JP Kociolek and SA Makosky 2004 New algal species records for the Great Smoky Mountains National Park USA with an annotated checklist of all reported algal species for the park Algological Studies 11117ndash44

Johansen JR SR Rushforth and JD Brotherson 1983a The algal fl ora of Navajo National Monument Arizona USA Nova Hedwigia 38501ndash553

Johansen JR SR Rushforth R Orbendorfer N Fungladda and J Grimes 1983b The algal fl ora of selected wet walls in Zion National Park Utah USA Nova Hedwigia 38765ndash808

Klemencic AK 2002 Kopenske alge na bentonskem zidu kamniten zidu apnen-casti skali in deblu lipe (Tilia platyphyllos) v Sloveniji Natura Sloveniae 421ndash30

Krammer K and H Lange-Bertalot 1986 Bacillariophyceae 1 Teil Navicula-ceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasser fl ora von Mitteleuropa Band 21 Gustav Fischer Verlag Stuttgart New York 876 pp

Krammer K and H Lange-Bertalot 1988 Bacillariophyceae 2 Teil Bacilla-riaceae Epithemiaceae Surirellaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 22 VEB Gustav Fischer Verlag Jena Germany 596 pp

Krammer K and H Lange-Bertalot 1991a Bacillariophyceae 3 Teil Centrales Fragilariaceae Eunotiaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 23 Gustav Fischer Verlag Stuttgart Jena Germany 576 pp

Krammer K and H Lange-Bertalot 1991b Bacillariophyceae 4 Teil Achnantha-ceae Kritische Ergaumlnzungen zu Navicula (Lineolatae) und Gomphonema Gesamtliteraturverzeichnis Teil 1-4 in Ettl H Gaumlrtner G Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 24 Gustav Fischer Verlag Stuttgart Jena Germany 437 pp

Lowe RL 1974 Environmental requirements and pollution tolerance of freshwater diatoms Environmental Protection Agency Washington DC PA-6704-74-007 340 pp

Lowe RL and GB Collins 1973 An aerophilous diatom community from Hocking Co Ohio Transactions of the American Microscopical Society 92492ndash496

Southeastern Naturalist150 Special Issue 1

Lund JWG 1945 Observations on soil algae I The ecology size and taxonomy of British soil diatoms The New Phytologist 4456ndash110

McMillim M and SR Rushforth 1985 The diatom fl ora of a steam vent of Kilauea Crater Island of Hawaii Pacifi c Science 39294ndash301

Olsen CE 2004 The algal fl ora of selected seeps and waterfalls in the Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 106 pp

Patrick R 1977 Ecology of freshwater diatoms-diatom communities Pp 133ndash191 In D Werner (Ed) The Biology of Diatoms Blackwell Scientifi c Publications London UK

Patrick R and CW Reimer 1966 The diatoms of the United States V1 Mono-graph Academy of Natural Science Philadelphia 13(1)1ndash688

Potapova MG KC Ponader RL Lowe TA Clason and LA Bahls 2003 Small-celled Nupela species from USA rivers Diatom Research 18293ndash306

Pederson D 1999 Scientists are trying to identify every living thing in the Smokies National Park Newsweek November 22 1999

Sharkey MJ 2001 The all taxa biological inventory of the Great Smoky Mountains National Park Florida Entomologist 84556ndash564

Sokal RR and FJ Rohlf 1995 Biometry 3rd Edition WH Freeman New York NY 468 pp

Southworth S A Schultz and D Denenny 2005 Generalized geological map of Bedrock Lithologies and surfi cial deposits in the Great Smoky Mountains National Park Region Tennessee and North Carolina US Geological Survey Resten VA Open-File Report 2004-1410

Wallace BJ J Webster and RL Lowe 1992 High-gradient streams of the Ap-palachians Pp 133ndash191 In CT Hackney SM Adams and WA Martin (Eds) Biodiversity of the Southeastern United StatesAquatic Communities John Wiley and Sons Inc Hoboken NJ USA pp 133-191

Werum M and H Lange-Bertalot 2004 Diatoms in springs and elsewhere under the infl uence of hydrogeology and anthropogenic impacts Iconographia Diato-mologica 131ndash480

RL Lowe PC Furey JA Ress and JR Johansen 1512007

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Southeastern Naturalist152 Special Issue 1C

ode

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Sin

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loun

t T

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Southeastern Naturalist142 Special Issue 1

Figures 3ndash22 Common taxa denoted in Table 1 ldquordquo signifi es taxa denoted in Table 2 3) Achnanthes subrostrata v appalachiana raphe valve 4) Achnanthes subrostrata v appalachiana rapheless valve 5) Achnanthidium exiguum raphe valve 6) Ach-nanthidium exiguum (Grun) Czarnezki rapheless valve 7) Diatoma mesodon 8) Diatoma mesodon girdle view 9) Chamaepinnularia mediocris (Krasske) Lange-Bertalot 10) Diadesmis contenta 11) Diadesmis contenta v biceps 12) Navicula keeleyi 13) Diadesmis perpusilla 14) Gomphonema cf parvulum Kuumltz 15) Pin-nularia subcapitata v hilseana 16) Decussata placenta (Ehr) Lange-Bertalot amp Mezeltin 17) Cymbopleura rupicola 18) Eunotia praerupta v bigibba 19) Euno-tia nymanianna Grun 20) Eunotia cf fallax 21) Eunotia exigua 22) Encyonema minutum (Hilse ex Rabh) DG Mann

RL Lowe PC Furey JA Ress and JR Johansen 1432007

diatoms must withstand a greater range of environmental variables than aquatic species (Patrick 1977) Unlike truly aquatic habitats subaerial envi-

Figures 23ndash35 Common taxa denoted in Table 1 ldquordquo signifi es taxa denoted in Table 2 23) Frustulia krammeri 24) Frustulia crassinervia 25) Meridion circulare (Grev) Ag 26) Navicula angusta 27) Nitzschia hantzschiana 28) Microcostatus krasskei 29) Nupela sp 30) Planothidium lanceolatum raphe valve 31) Planothid-ium lanceolatum (Breacuteb ex Kuumltz) Round amp Bukhtiyarova rapheless valve 32) Psammothidium marginulatum raphe valve 33) Psammothidium marginulatum rapheless valve 34) Tetracyclus rupestris 35) Tetracyclus rupestris girdle view

Southeastern Naturalist144 Special Issue 1

ronments are moist but can periodically become dry for long periods Also because these diatoms often live in a fi lm of water they do not experience the thermal stability that aquatic taxa experience Wetwall diatoms may also experience more intense ultraviolet radiation than aquatic forms that are more protected by water (Johansen 1999) Many wetwall diatoms have a reduced number of areolae or possess areolae that are occluded with a siliceous lamina (eg species of Nupela Diadesmis Chamaepinnularia and Eunotia Figs 36ndash39) These morpho-logical features may be adaptations to reduce water loss in periodically dry habitats Some common taxa without obviously reduced external openings such as Decussata Luticola Microcostatus and Nitzschia (Figs 40ndash43) are also typical of diatom communities in subaerial habitats Diatom community structure on the wetwall habitats observed in this study was diverse and highly variable Higher pH appeared to be an im-portant variable separating the three Whiteoak Sink samples from the more acidic sites throughout the park However we anticipated that diatom com-munities from habitats with similar bedrock mineralogy and pH would be very similar and this pattern was not usually the case with the acidic wetwalls Even diatom collections from the same acidic wetwall separated by a few centimeters were often very dissimilar In retrospect this is less surprising since the microscale patchiness of algal communities in streams is common We expect that subtle differences in shading and moisture probably play a large role in determining diatom community structure Diatom communities that are only a few cm apart can occupy very dif-ferent microhabitats as rock faces possess subtle differences in surface morphology that influence exposure of the community to sunlight and dry-ing These subtle differences can also regulate the distribution of sympatric patches of non-diatom algae and bryophytes that are also likely to play a role in diatom distribution Several of the wetwalls supported macroscopic growths of algae rich in extracellular water-retaining polysaccharides that can provide a moist environment for diatoms during otherwise dry peri-ods These kinds of habitats seemed favorable to Nitzschia hantzschiana for example Macroscopic growths of Nostoc Stigonema Mesotaenium and several coccoid cyanobacteria were common but highly patchy on the wetwalls which might also reflect patchy environmental variables or the history of chance colonization by propogules We did not examine potential top-down impacts of grazers in these communities but noted the presence of protozoa and occasional dipteran larvae Grazers may be selec-tive in consumption of algae (Gresens and Lowe 1994) The cluster analysis (Fig 2) illustrates the dissimilarity among diatom communities and again probably indicates that parameters that we did not measure are generating these differences However we did identify several notable assemblages that were lt15 similar to the rest of the as-semblages sampled

RL Lowe PC Furey JA Ress and JR Johansen 1452007

The two assemblages in cluster A were largely separated by dominant populations of Pinnularia subcapitata v hilseana and Eunotia cf gla-cialis These two diatoms have been reported from subaerial and acid habitats from both Europe and North America (Beyens 1989 Dixit et al 1999) Both collections in this cluster were from drippy bryophytes similar to the report of Beyens (1989) which may indicate that this is a preferred habitat of Pinnularia subcapitata v hilseana Eunotia is also common on mosses The three collections from wetwalls in Whiteoak Sinks (cluster B) were the only samples that we collected from limestone-dominated alkaline bed-rock Cymbopleura rupicola dominated these communities and was found nowhere else This taxon has been reported from similar alkaline subaerial habitats (Klemenčič 2002) Its disjunct distribution on wetwalls in the GSMNP may indicate its strong habitat specifi city Cluster C is represented by a single collection from a bryophyte-covered rock of Thunderhead Sandstone in a spray zone of Laurel Falls Waterfall spray zones are wetted for longer periods than many of the wetwall habitats and also have a continuous source of diatom immigrants and this may in part account for its uniqueness The assemblage was dominated by two spe-cies of Frustulia

Figures 36ndash39 Species of diatoms showing reduced external openings 36) Nupela sp 37) Diadesmis perpusilla (Kuumltz) DG Mann 38) Eunotia sp 39) Chamaepin-nulari soehrensis (Krasske) Lange-Bertalot (scale bar = 4 μm)

Southeastern Naturalist146 Special Issue 1

Cluster D was another small cluster of only two collections (Thunderhead Sandstone near a waterfall at Ramsay Cascade and Metcalf Phyllite on Lau-rel Creek Road) These two communities were only 23 similar to each other but lt15 similar to the remainder of the assemblages (Fig 2) These two assemblages were related by their relatively dense populations of Euno-tia exigua a cosmopolitan acidophilic species (Lowe 1974) Cluster E with six collections was separated from the other sites largely by species of Eunotia Although these six collections are less than 15 simi-lar to the rest of the assemblages they are not closely related to each other (Fig 2) Cluster F contained a single unique assemblage dominated by Eunotia diodon Ehrenberg and Eunotia rhomboidea Hustedt This was the only collection in this analysis that came from a soil seep and may reflect pe-culiar aspects of this unique environment Surveys of diatom soil flora are few but an extensive study by Lund (1945) illustrates the richness of the flora GSMNP with diverse soil types should hold a large number of soil diatom species We hope to pursue the algal soil flora of GSMNP in suc-ceeding years Cluster G consisted of two assemblages collected from disjunct sites (Thunderhead Sandstone seep and Logarm Quartzite dripwall) Both collection sites had the same pH however (50) The sites were relatively

Figures 40ndash43 Common wetwall diatom species without obviously reduced external openings 40) Decussata placenta 41) Luticola sp 42) Microcostatus krasskei 43) Nitzschia hantzschiana (scale bar = 5μm)

RL Lowe PC Furey JA Ress and JR Johansen 1472007

dissimilar to each other (Fig 2) but were distinct from the remainder of the assemblages primarily due to large populations of Diatoma mesodon and Fragilariaforma virescens Although Diatoma mesodon is often found in a large variety of habitats Fragilariaforma virescens is typically restricted to acidic or low alkalinity habitats (Camburn and Charles 2000) Cluster H is defi ned by Tetracyclus rupestris which occurred only in this single collection and accounted for 85 of the diatoms in this assemblage This is a unique community and is signifi cant in that Tetracyclus rupestris is seldom reported from the North American fl ora The collection site was a drippy Anakeesta bedrock formation at 1500 m elevation Anakeesta pro-vides an acidic environment and is often high in aluminum although we did not measure that element in this study Cluster I is composed of three assemblages each with Nitzschia hantzschiana as a common taxon This diatom is one of the most common subaerial species of the genus Nitzschia and has been reported from many different studies of subaerial algae (Dayner and Johansen 1991 Johansen et al 1983a Lund 1945) The three samples in this cluster are all from drippy wetwalls along road cuts All three of these samples contained conspicuous quantities of green algae or cyanobacteria Such algae might facilitate the presence of Nitzschia which is highly motile and would be capable of mov-ing through the algal matrix The remaining 28 collections all cluster together (J) but within this large cluster several subndashclusters can be identifi ed driven by assemblages with large populations of Diadesmis species and by Microcostatus krasskei These taxa have strong fi delity to subaerial habitats and are generally not seen in abundance in aquatic habitats In addition to the challenges of working with the vertical nature of wetwalls the highly variable and heterogeneous nature of the algal com-munities along with some of the variations in microhabitat discussed above highlights the need to consider both spatial scale and sampling strategy when designing wetwall studies or biodiversity surveys For ex-ample to minimize the effects of microhabitat variation artificial wetwall substrates may be helpful in elucidating the impact of microscale habitat features on algal community structure or several wetwall areas may need to be sampled in order to adequately characterize the diversity of an area or to track changes in algal assemblages over time or in response to en-vironmental changes Additionally the range of values covered for pH for the majority of our sites (pH 38ndash55) was narrow and future studies should include a broader range of pH especially across the intermediate values not examined in this study (pH 55ndash72) Similarly elevation and geology gave no apparent environmental signal in the diatom composition although these influences may have been masked by microscale variability or small sample size and future studies may require more intensive sam-pling experimental work or finer-scale bedrock determination

Southeastern Naturalist148 Special Issue 1

Conclusions

We described the diatom fl ora from several wetwalls throughout GSMNP Some of the species from this research appear to be new species and will be described and published elsewhere Aside from these new taxa many of the diatoms have been reported from other wetwall studies and have been noted as typical subaerial species Although we found little correlation with bedrock mineralogy chemistry including pH and wetwall elevation we did observe highly variable and very diverse diatom community structure among the wetwall habitats We found unique diatom communities along with wetwall-specifi c diatom taxa that appeared to have special adaptations to these subaerial habitats In order to better understand these understud-ied communities future research should explore these subaerial habitat adaptations such as presence of additional external siliceous membranes or interactions with soft algal communities Additionally further research is needed to understand the complexities of these unique algal communi-ties and habitats including examination of factors that may have a more dominant role in shaping wetwall community structure such as moisture gradients and sources infl uences of microscale variability substrate type and shading or the role of ultraviolet radiation We feel that it is particularly important to examine these communities at an appropriate scale Habitat variables and community structure could vary over millimeter distances on wetwalls and the small and spatially unique nature of these microhabitats should be taken into consideration in the experimental design and sampling in future wetwall studies

Acknowledgments

This research was supported by the National Science Foundation (DEB 0315979) and grants from Discover Life In America We are also very grateful for support and facilitation from the National Park Service Jeanie Hilton and volunteers from Dis-cover Life In America and the Appalachian Highlands Learning Center interns This manuscript was greatly improved thanks to detailed reviews by Marina Potapova Peter Siver and one anonymous reviewer

Literature Cited

Beyens L 1989 Moss-dwelling diatom assemblages from Edgeoslashya (Svalbard) Polar Biology 9423ndash430

Camburn KE and DF Charles 2000 Diatoms of Low-alkalinity Lakes in the Northeastern United States Academy of Natural Sciences of Philadelphia Spe-cial Publication 18 Philadelphia PA 152 pp

Dayner DM and JR Johansen 1991 Observations on the algal fl ora of Seneca Caverns Seneca County Ohio Ohio Journal of Science 91118ndash121

Dixit SS JP Smol DF Charles RM Hughes SG Paulsen and GB Collins 1999 Assessing water quality changes in the lakes of the northeastern United States using sediment diatoms Canadian Journal of Fisheries and Aquatic Sci-ences 56(1)131ndash152

RL Lowe PC Furey JA Ress and JR Johansen 1492007

Gomez S 2002 Epilithic aerial algae of Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 78 pp

Gomez SR JR Johansen and RL Lowe 2003 Epilithic aerial algae of Great Smoky Mountains National Park Biologia Bratislava 58603ndash615

Gresens SE and RL Lowe 1994 Periphyton patch preference in grazing chiron-omid larvae Journal of the North American Benthological Society 1389ndash99

Johansen JR 1999 Diatoms of aerial habitats Pp 264ndash273 In EF Stoermer and JP Smol (Eds) The Diatoms Applications for the Environmental and Earth Sciences Cambridge University Press Cambridge UK

Johansen JR and RL Lowe In press Draparnaldia appalachiana sp Nov (Chaetophoraceae Chlorophyceae) from the Great Smoky Mountains National Park

Johansen JR and JC Sray 1998 Microcostatus Gen Nov a new aerophilic dia-tom genus based on Navicula Krasskei Hustedt Diatom Research 1393ndash101

Johansen JR RL Lowe SR Gomez JP Kociolek and SA Makosky 2004 New algal species records for the Great Smoky Mountains National Park USA with an annotated checklist of all reported algal species for the park Algological Studies 11117ndash44

Johansen JR SR Rushforth and JD Brotherson 1983a The algal fl ora of Navajo National Monument Arizona USA Nova Hedwigia 38501ndash553

Johansen JR SR Rushforth R Orbendorfer N Fungladda and J Grimes 1983b The algal fl ora of selected wet walls in Zion National Park Utah USA Nova Hedwigia 38765ndash808

Klemencic AK 2002 Kopenske alge na bentonskem zidu kamniten zidu apnen-casti skali in deblu lipe (Tilia platyphyllos) v Sloveniji Natura Sloveniae 421ndash30

Krammer K and H Lange-Bertalot 1986 Bacillariophyceae 1 Teil Navicula-ceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasser fl ora von Mitteleuropa Band 21 Gustav Fischer Verlag Stuttgart New York 876 pp

Krammer K and H Lange-Bertalot 1988 Bacillariophyceae 2 Teil Bacilla-riaceae Epithemiaceae Surirellaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 22 VEB Gustav Fischer Verlag Jena Germany 596 pp

Krammer K and H Lange-Bertalot 1991a Bacillariophyceae 3 Teil Centrales Fragilariaceae Eunotiaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 23 Gustav Fischer Verlag Stuttgart Jena Germany 576 pp

Krammer K and H Lange-Bertalot 1991b Bacillariophyceae 4 Teil Achnantha-ceae Kritische Ergaumlnzungen zu Navicula (Lineolatae) und Gomphonema Gesamtliteraturverzeichnis Teil 1-4 in Ettl H Gaumlrtner G Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 24 Gustav Fischer Verlag Stuttgart Jena Germany 437 pp

Lowe RL 1974 Environmental requirements and pollution tolerance of freshwater diatoms Environmental Protection Agency Washington DC PA-6704-74-007 340 pp

Lowe RL and GB Collins 1973 An aerophilous diatom community from Hocking Co Ohio Transactions of the American Microscopical Society 92492ndash496

Southeastern Naturalist150 Special Issue 1

Lund JWG 1945 Observations on soil algae I The ecology size and taxonomy of British soil diatoms The New Phytologist 4456ndash110

McMillim M and SR Rushforth 1985 The diatom fl ora of a steam vent of Kilauea Crater Island of Hawaii Pacifi c Science 39294ndash301

Olsen CE 2004 The algal fl ora of selected seeps and waterfalls in the Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 106 pp

Patrick R 1977 Ecology of freshwater diatoms-diatom communities Pp 133ndash191 In D Werner (Ed) The Biology of Diatoms Blackwell Scientifi c Publications London UK

Patrick R and CW Reimer 1966 The diatoms of the United States V1 Mono-graph Academy of Natural Science Philadelphia 13(1)1ndash688

Potapova MG KC Ponader RL Lowe TA Clason and LA Bahls 2003 Small-celled Nupela species from USA rivers Diatom Research 18293ndash306

Pederson D 1999 Scientists are trying to identify every living thing in the Smokies National Park Newsweek November 22 1999

Sharkey MJ 2001 The all taxa biological inventory of the Great Smoky Mountains National Park Florida Entomologist 84556ndash564

Sokal RR and FJ Rohlf 1995 Biometry 3rd Edition WH Freeman New York NY 468 pp

Southworth S A Schultz and D Denenny 2005 Generalized geological map of Bedrock Lithologies and surfi cial deposits in the Great Smoky Mountains National Park Region Tennessee and North Carolina US Geological Survey Resten VA Open-File Report 2004-1410

Wallace BJ J Webster and RL Lowe 1992 High-gradient streams of the Ap-palachians Pp 133ndash191 In CT Hackney SM Adams and WA Martin (Eds) Biodiversity of the Southeastern United StatesAquatic Communities John Wiley and Sons Inc Hoboken NJ USA pp 133-191

Werum M and H Lange-Bertalot 2004 Diatoms in springs and elsewhere under the infl uence of hydrogeology and anthropogenic impacts Iconographia Diato-mologica 131ndash480

RL Lowe PC Furey JA Ress and JR Johansen 1512007

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Southeastern Naturalist152 Special Issue 1C

ode

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RL Lowe PC Furey JA Ress and JR Johansen 1432007

diatoms must withstand a greater range of environmental variables than aquatic species (Patrick 1977) Unlike truly aquatic habitats subaerial envi-

Figures 23ndash35 Common taxa denoted in Table 1 ldquordquo signifi es taxa denoted in Table 2 23) Frustulia krammeri 24) Frustulia crassinervia 25) Meridion circulare (Grev) Ag 26) Navicula angusta 27) Nitzschia hantzschiana 28) Microcostatus krasskei 29) Nupela sp 30) Planothidium lanceolatum raphe valve 31) Planothid-ium lanceolatum (Breacuteb ex Kuumltz) Round amp Bukhtiyarova rapheless valve 32) Psammothidium marginulatum raphe valve 33) Psammothidium marginulatum rapheless valve 34) Tetracyclus rupestris 35) Tetracyclus rupestris girdle view

Southeastern Naturalist144 Special Issue 1

ronments are moist but can periodically become dry for long periods Also because these diatoms often live in a fi lm of water they do not experience the thermal stability that aquatic taxa experience Wetwall diatoms may also experience more intense ultraviolet radiation than aquatic forms that are more protected by water (Johansen 1999) Many wetwall diatoms have a reduced number of areolae or possess areolae that are occluded with a siliceous lamina (eg species of Nupela Diadesmis Chamaepinnularia and Eunotia Figs 36ndash39) These morpho-logical features may be adaptations to reduce water loss in periodically dry habitats Some common taxa without obviously reduced external openings such as Decussata Luticola Microcostatus and Nitzschia (Figs 40ndash43) are also typical of diatom communities in subaerial habitats Diatom community structure on the wetwall habitats observed in this study was diverse and highly variable Higher pH appeared to be an im-portant variable separating the three Whiteoak Sink samples from the more acidic sites throughout the park However we anticipated that diatom com-munities from habitats with similar bedrock mineralogy and pH would be very similar and this pattern was not usually the case with the acidic wetwalls Even diatom collections from the same acidic wetwall separated by a few centimeters were often very dissimilar In retrospect this is less surprising since the microscale patchiness of algal communities in streams is common We expect that subtle differences in shading and moisture probably play a large role in determining diatom community structure Diatom communities that are only a few cm apart can occupy very dif-ferent microhabitats as rock faces possess subtle differences in surface morphology that influence exposure of the community to sunlight and dry-ing These subtle differences can also regulate the distribution of sympatric patches of non-diatom algae and bryophytes that are also likely to play a role in diatom distribution Several of the wetwalls supported macroscopic growths of algae rich in extracellular water-retaining polysaccharides that can provide a moist environment for diatoms during otherwise dry peri-ods These kinds of habitats seemed favorable to Nitzschia hantzschiana for example Macroscopic growths of Nostoc Stigonema Mesotaenium and several coccoid cyanobacteria were common but highly patchy on the wetwalls which might also reflect patchy environmental variables or the history of chance colonization by propogules We did not examine potential top-down impacts of grazers in these communities but noted the presence of protozoa and occasional dipteran larvae Grazers may be selec-tive in consumption of algae (Gresens and Lowe 1994) The cluster analysis (Fig 2) illustrates the dissimilarity among diatom communities and again probably indicates that parameters that we did not measure are generating these differences However we did identify several notable assemblages that were lt15 similar to the rest of the as-semblages sampled

RL Lowe PC Furey JA Ress and JR Johansen 1452007

The two assemblages in cluster A were largely separated by dominant populations of Pinnularia subcapitata v hilseana and Eunotia cf gla-cialis These two diatoms have been reported from subaerial and acid habitats from both Europe and North America (Beyens 1989 Dixit et al 1999) Both collections in this cluster were from drippy bryophytes similar to the report of Beyens (1989) which may indicate that this is a preferred habitat of Pinnularia subcapitata v hilseana Eunotia is also common on mosses The three collections from wetwalls in Whiteoak Sinks (cluster B) were the only samples that we collected from limestone-dominated alkaline bed-rock Cymbopleura rupicola dominated these communities and was found nowhere else This taxon has been reported from similar alkaline subaerial habitats (Klemenčič 2002) Its disjunct distribution on wetwalls in the GSMNP may indicate its strong habitat specifi city Cluster C is represented by a single collection from a bryophyte-covered rock of Thunderhead Sandstone in a spray zone of Laurel Falls Waterfall spray zones are wetted for longer periods than many of the wetwall habitats and also have a continuous source of diatom immigrants and this may in part account for its uniqueness The assemblage was dominated by two spe-cies of Frustulia

Figures 36ndash39 Species of diatoms showing reduced external openings 36) Nupela sp 37) Diadesmis perpusilla (Kuumltz) DG Mann 38) Eunotia sp 39) Chamaepin-nulari soehrensis (Krasske) Lange-Bertalot (scale bar = 4 μm)

Southeastern Naturalist146 Special Issue 1

Cluster D was another small cluster of only two collections (Thunderhead Sandstone near a waterfall at Ramsay Cascade and Metcalf Phyllite on Lau-rel Creek Road) These two communities were only 23 similar to each other but lt15 similar to the remainder of the assemblages (Fig 2) These two assemblages were related by their relatively dense populations of Euno-tia exigua a cosmopolitan acidophilic species (Lowe 1974) Cluster E with six collections was separated from the other sites largely by species of Eunotia Although these six collections are less than 15 simi-lar to the rest of the assemblages they are not closely related to each other (Fig 2) Cluster F contained a single unique assemblage dominated by Eunotia diodon Ehrenberg and Eunotia rhomboidea Hustedt This was the only collection in this analysis that came from a soil seep and may reflect pe-culiar aspects of this unique environment Surveys of diatom soil flora are few but an extensive study by Lund (1945) illustrates the richness of the flora GSMNP with diverse soil types should hold a large number of soil diatom species We hope to pursue the algal soil flora of GSMNP in suc-ceeding years Cluster G consisted of two assemblages collected from disjunct sites (Thunderhead Sandstone seep and Logarm Quartzite dripwall) Both collection sites had the same pH however (50) The sites were relatively

Figures 40ndash43 Common wetwall diatom species without obviously reduced external openings 40) Decussata placenta 41) Luticola sp 42) Microcostatus krasskei 43) Nitzschia hantzschiana (scale bar = 5μm)

RL Lowe PC Furey JA Ress and JR Johansen 1472007

dissimilar to each other (Fig 2) but were distinct from the remainder of the assemblages primarily due to large populations of Diatoma mesodon and Fragilariaforma virescens Although Diatoma mesodon is often found in a large variety of habitats Fragilariaforma virescens is typically restricted to acidic or low alkalinity habitats (Camburn and Charles 2000) Cluster H is defi ned by Tetracyclus rupestris which occurred only in this single collection and accounted for 85 of the diatoms in this assemblage This is a unique community and is signifi cant in that Tetracyclus rupestris is seldom reported from the North American fl ora The collection site was a drippy Anakeesta bedrock formation at 1500 m elevation Anakeesta pro-vides an acidic environment and is often high in aluminum although we did not measure that element in this study Cluster I is composed of three assemblages each with Nitzschia hantzschiana as a common taxon This diatom is one of the most common subaerial species of the genus Nitzschia and has been reported from many different studies of subaerial algae (Dayner and Johansen 1991 Johansen et al 1983a Lund 1945) The three samples in this cluster are all from drippy wetwalls along road cuts All three of these samples contained conspicuous quantities of green algae or cyanobacteria Such algae might facilitate the presence of Nitzschia which is highly motile and would be capable of mov-ing through the algal matrix The remaining 28 collections all cluster together (J) but within this large cluster several subndashclusters can be identifi ed driven by assemblages with large populations of Diadesmis species and by Microcostatus krasskei These taxa have strong fi delity to subaerial habitats and are generally not seen in abundance in aquatic habitats In addition to the challenges of working with the vertical nature of wetwalls the highly variable and heterogeneous nature of the algal com-munities along with some of the variations in microhabitat discussed above highlights the need to consider both spatial scale and sampling strategy when designing wetwall studies or biodiversity surveys For ex-ample to minimize the effects of microhabitat variation artificial wetwall substrates may be helpful in elucidating the impact of microscale habitat features on algal community structure or several wetwall areas may need to be sampled in order to adequately characterize the diversity of an area or to track changes in algal assemblages over time or in response to en-vironmental changes Additionally the range of values covered for pH for the majority of our sites (pH 38ndash55) was narrow and future studies should include a broader range of pH especially across the intermediate values not examined in this study (pH 55ndash72) Similarly elevation and geology gave no apparent environmental signal in the diatom composition although these influences may have been masked by microscale variability or small sample size and future studies may require more intensive sam-pling experimental work or finer-scale bedrock determination

Southeastern Naturalist148 Special Issue 1

Conclusions

We described the diatom fl ora from several wetwalls throughout GSMNP Some of the species from this research appear to be new species and will be described and published elsewhere Aside from these new taxa many of the diatoms have been reported from other wetwall studies and have been noted as typical subaerial species Although we found little correlation with bedrock mineralogy chemistry including pH and wetwall elevation we did observe highly variable and very diverse diatom community structure among the wetwall habitats We found unique diatom communities along with wetwall-specifi c diatom taxa that appeared to have special adaptations to these subaerial habitats In order to better understand these understud-ied communities future research should explore these subaerial habitat adaptations such as presence of additional external siliceous membranes or interactions with soft algal communities Additionally further research is needed to understand the complexities of these unique algal communi-ties and habitats including examination of factors that may have a more dominant role in shaping wetwall community structure such as moisture gradients and sources infl uences of microscale variability substrate type and shading or the role of ultraviolet radiation We feel that it is particularly important to examine these communities at an appropriate scale Habitat variables and community structure could vary over millimeter distances on wetwalls and the small and spatially unique nature of these microhabitats should be taken into consideration in the experimental design and sampling in future wetwall studies

Acknowledgments

This research was supported by the National Science Foundation (DEB 0315979) and grants from Discover Life In America We are also very grateful for support and facilitation from the National Park Service Jeanie Hilton and volunteers from Dis-cover Life In America and the Appalachian Highlands Learning Center interns This manuscript was greatly improved thanks to detailed reviews by Marina Potapova Peter Siver and one anonymous reviewer

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Dixit SS JP Smol DF Charles RM Hughes SG Paulsen and GB Collins 1999 Assessing water quality changes in the lakes of the northeastern United States using sediment diatoms Canadian Journal of Fisheries and Aquatic Sci-ences 56(1)131ndash152

RL Lowe PC Furey JA Ress and JR Johansen 1492007

Gomez S 2002 Epilithic aerial algae of Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 78 pp

Gomez SR JR Johansen and RL Lowe 2003 Epilithic aerial algae of Great Smoky Mountains National Park Biologia Bratislava 58603ndash615

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Johansen JR and RL Lowe In press Draparnaldia appalachiana sp Nov (Chaetophoraceae Chlorophyceae) from the Great Smoky Mountains National Park

Johansen JR and JC Sray 1998 Microcostatus Gen Nov a new aerophilic dia-tom genus based on Navicula Krasskei Hustedt Diatom Research 1393ndash101

Johansen JR RL Lowe SR Gomez JP Kociolek and SA Makosky 2004 New algal species records for the Great Smoky Mountains National Park USA with an annotated checklist of all reported algal species for the park Algological Studies 11117ndash44

Johansen JR SR Rushforth and JD Brotherson 1983a The algal fl ora of Navajo National Monument Arizona USA Nova Hedwigia 38501ndash553

Johansen JR SR Rushforth R Orbendorfer N Fungladda and J Grimes 1983b The algal fl ora of selected wet walls in Zion National Park Utah USA Nova Hedwigia 38765ndash808

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Krammer K and H Lange-Bertalot 1991a Bacillariophyceae 3 Teil Centrales Fragilariaceae Eunotiaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 23 Gustav Fischer Verlag Stuttgart Jena Germany 576 pp

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Wallace BJ J Webster and RL Lowe 1992 High-gradient streams of the Ap-palachians Pp 133ndash191 In CT Hackney SM Adams and WA Martin (Eds) Biodiversity of the Southeastern United StatesAquatic Communities John Wiley and Sons Inc Hoboken NJ USA pp 133-191

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RL Lowe PC Furey JA Ress and JR Johansen 1512007

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Southeastern Naturalist144 Special Issue 1

ronments are moist but can periodically become dry for long periods Also because these diatoms often live in a fi lm of water they do not experience the thermal stability that aquatic taxa experience Wetwall diatoms may also experience more intense ultraviolet radiation than aquatic forms that are more protected by water (Johansen 1999) Many wetwall diatoms have a reduced number of areolae or possess areolae that are occluded with a siliceous lamina (eg species of Nupela Diadesmis Chamaepinnularia and Eunotia Figs 36ndash39) These morpho-logical features may be adaptations to reduce water loss in periodically dry habitats Some common taxa without obviously reduced external openings such as Decussata Luticola Microcostatus and Nitzschia (Figs 40ndash43) are also typical of diatom communities in subaerial habitats Diatom community structure on the wetwall habitats observed in this study was diverse and highly variable Higher pH appeared to be an im-portant variable separating the three Whiteoak Sink samples from the more acidic sites throughout the park However we anticipated that diatom com-munities from habitats with similar bedrock mineralogy and pH would be very similar and this pattern was not usually the case with the acidic wetwalls Even diatom collections from the same acidic wetwall separated by a few centimeters were often very dissimilar In retrospect this is less surprising since the microscale patchiness of algal communities in streams is common We expect that subtle differences in shading and moisture probably play a large role in determining diatom community structure Diatom communities that are only a few cm apart can occupy very dif-ferent microhabitats as rock faces possess subtle differences in surface morphology that influence exposure of the community to sunlight and dry-ing These subtle differences can also regulate the distribution of sympatric patches of non-diatom algae and bryophytes that are also likely to play a role in diatom distribution Several of the wetwalls supported macroscopic growths of algae rich in extracellular water-retaining polysaccharides that can provide a moist environment for diatoms during otherwise dry peri-ods These kinds of habitats seemed favorable to Nitzschia hantzschiana for example Macroscopic growths of Nostoc Stigonema Mesotaenium and several coccoid cyanobacteria were common but highly patchy on the wetwalls which might also reflect patchy environmental variables or the history of chance colonization by propogules We did not examine potential top-down impacts of grazers in these communities but noted the presence of protozoa and occasional dipteran larvae Grazers may be selec-tive in consumption of algae (Gresens and Lowe 1994) The cluster analysis (Fig 2) illustrates the dissimilarity among diatom communities and again probably indicates that parameters that we did not measure are generating these differences However we did identify several notable assemblages that were lt15 similar to the rest of the as-semblages sampled

RL Lowe PC Furey JA Ress and JR Johansen 1452007

The two assemblages in cluster A were largely separated by dominant populations of Pinnularia subcapitata v hilseana and Eunotia cf gla-cialis These two diatoms have been reported from subaerial and acid habitats from both Europe and North America (Beyens 1989 Dixit et al 1999) Both collections in this cluster were from drippy bryophytes similar to the report of Beyens (1989) which may indicate that this is a preferred habitat of Pinnularia subcapitata v hilseana Eunotia is also common on mosses The three collections from wetwalls in Whiteoak Sinks (cluster B) were the only samples that we collected from limestone-dominated alkaline bed-rock Cymbopleura rupicola dominated these communities and was found nowhere else This taxon has been reported from similar alkaline subaerial habitats (Klemenčič 2002) Its disjunct distribution on wetwalls in the GSMNP may indicate its strong habitat specifi city Cluster C is represented by a single collection from a bryophyte-covered rock of Thunderhead Sandstone in a spray zone of Laurel Falls Waterfall spray zones are wetted for longer periods than many of the wetwall habitats and also have a continuous source of diatom immigrants and this may in part account for its uniqueness The assemblage was dominated by two spe-cies of Frustulia

Figures 36ndash39 Species of diatoms showing reduced external openings 36) Nupela sp 37) Diadesmis perpusilla (Kuumltz) DG Mann 38) Eunotia sp 39) Chamaepin-nulari soehrensis (Krasske) Lange-Bertalot (scale bar = 4 μm)

Southeastern Naturalist146 Special Issue 1

Cluster D was another small cluster of only two collections (Thunderhead Sandstone near a waterfall at Ramsay Cascade and Metcalf Phyllite on Lau-rel Creek Road) These two communities were only 23 similar to each other but lt15 similar to the remainder of the assemblages (Fig 2) These two assemblages were related by their relatively dense populations of Euno-tia exigua a cosmopolitan acidophilic species (Lowe 1974) Cluster E with six collections was separated from the other sites largely by species of Eunotia Although these six collections are less than 15 simi-lar to the rest of the assemblages they are not closely related to each other (Fig 2) Cluster F contained a single unique assemblage dominated by Eunotia diodon Ehrenberg and Eunotia rhomboidea Hustedt This was the only collection in this analysis that came from a soil seep and may reflect pe-culiar aspects of this unique environment Surveys of diatom soil flora are few but an extensive study by Lund (1945) illustrates the richness of the flora GSMNP with diverse soil types should hold a large number of soil diatom species We hope to pursue the algal soil flora of GSMNP in suc-ceeding years Cluster G consisted of two assemblages collected from disjunct sites (Thunderhead Sandstone seep and Logarm Quartzite dripwall) Both collection sites had the same pH however (50) The sites were relatively

Figures 40ndash43 Common wetwall diatom species without obviously reduced external openings 40) Decussata placenta 41) Luticola sp 42) Microcostatus krasskei 43) Nitzschia hantzschiana (scale bar = 5μm)

RL Lowe PC Furey JA Ress and JR Johansen 1472007

dissimilar to each other (Fig 2) but were distinct from the remainder of the assemblages primarily due to large populations of Diatoma mesodon and Fragilariaforma virescens Although Diatoma mesodon is often found in a large variety of habitats Fragilariaforma virescens is typically restricted to acidic or low alkalinity habitats (Camburn and Charles 2000) Cluster H is defi ned by Tetracyclus rupestris which occurred only in this single collection and accounted for 85 of the diatoms in this assemblage This is a unique community and is signifi cant in that Tetracyclus rupestris is seldom reported from the North American fl ora The collection site was a drippy Anakeesta bedrock formation at 1500 m elevation Anakeesta pro-vides an acidic environment and is often high in aluminum although we did not measure that element in this study Cluster I is composed of three assemblages each with Nitzschia hantzschiana as a common taxon This diatom is one of the most common subaerial species of the genus Nitzschia and has been reported from many different studies of subaerial algae (Dayner and Johansen 1991 Johansen et al 1983a Lund 1945) The three samples in this cluster are all from drippy wetwalls along road cuts All three of these samples contained conspicuous quantities of green algae or cyanobacteria Such algae might facilitate the presence of Nitzschia which is highly motile and would be capable of mov-ing through the algal matrix The remaining 28 collections all cluster together (J) but within this large cluster several subndashclusters can be identifi ed driven by assemblages with large populations of Diadesmis species and by Microcostatus krasskei These taxa have strong fi delity to subaerial habitats and are generally not seen in abundance in aquatic habitats In addition to the challenges of working with the vertical nature of wetwalls the highly variable and heterogeneous nature of the algal com-munities along with some of the variations in microhabitat discussed above highlights the need to consider both spatial scale and sampling strategy when designing wetwall studies or biodiversity surveys For ex-ample to minimize the effects of microhabitat variation artificial wetwall substrates may be helpful in elucidating the impact of microscale habitat features on algal community structure or several wetwall areas may need to be sampled in order to adequately characterize the diversity of an area or to track changes in algal assemblages over time or in response to en-vironmental changes Additionally the range of values covered for pH for the majority of our sites (pH 38ndash55) was narrow and future studies should include a broader range of pH especially across the intermediate values not examined in this study (pH 55ndash72) Similarly elevation and geology gave no apparent environmental signal in the diatom composition although these influences may have been masked by microscale variability or small sample size and future studies may require more intensive sam-pling experimental work or finer-scale bedrock determination

Southeastern Naturalist148 Special Issue 1

Conclusions

We described the diatom fl ora from several wetwalls throughout GSMNP Some of the species from this research appear to be new species and will be described and published elsewhere Aside from these new taxa many of the diatoms have been reported from other wetwall studies and have been noted as typical subaerial species Although we found little correlation with bedrock mineralogy chemistry including pH and wetwall elevation we did observe highly variable and very diverse diatom community structure among the wetwall habitats We found unique diatom communities along with wetwall-specifi c diatom taxa that appeared to have special adaptations to these subaerial habitats In order to better understand these understud-ied communities future research should explore these subaerial habitat adaptations such as presence of additional external siliceous membranes or interactions with soft algal communities Additionally further research is needed to understand the complexities of these unique algal communi-ties and habitats including examination of factors that may have a more dominant role in shaping wetwall community structure such as moisture gradients and sources infl uences of microscale variability substrate type and shading or the role of ultraviolet radiation We feel that it is particularly important to examine these communities at an appropriate scale Habitat variables and community structure could vary over millimeter distances on wetwalls and the small and spatially unique nature of these microhabitats should be taken into consideration in the experimental design and sampling in future wetwall studies

Acknowledgments

This research was supported by the National Science Foundation (DEB 0315979) and grants from Discover Life In America We are also very grateful for support and facilitation from the National Park Service Jeanie Hilton and volunteers from Dis-cover Life In America and the Appalachian Highlands Learning Center interns This manuscript was greatly improved thanks to detailed reviews by Marina Potapova Peter Siver and one anonymous reviewer

Literature Cited

Beyens L 1989 Moss-dwelling diatom assemblages from Edgeoslashya (Svalbard) Polar Biology 9423ndash430

Camburn KE and DF Charles 2000 Diatoms of Low-alkalinity Lakes in the Northeastern United States Academy of Natural Sciences of Philadelphia Spe-cial Publication 18 Philadelphia PA 152 pp

Dayner DM and JR Johansen 1991 Observations on the algal fl ora of Seneca Caverns Seneca County Ohio Ohio Journal of Science 91118ndash121

Dixit SS JP Smol DF Charles RM Hughes SG Paulsen and GB Collins 1999 Assessing water quality changes in the lakes of the northeastern United States using sediment diatoms Canadian Journal of Fisheries and Aquatic Sci-ences 56(1)131ndash152

RL Lowe PC Furey JA Ress and JR Johansen 1492007

Gomez S 2002 Epilithic aerial algae of Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 78 pp

Gomez SR JR Johansen and RL Lowe 2003 Epilithic aerial algae of Great Smoky Mountains National Park Biologia Bratislava 58603ndash615

Gresens SE and RL Lowe 1994 Periphyton patch preference in grazing chiron-omid larvae Journal of the North American Benthological Society 1389ndash99

Johansen JR 1999 Diatoms of aerial habitats Pp 264ndash273 In EF Stoermer and JP Smol (Eds) The Diatoms Applications for the Environmental and Earth Sciences Cambridge University Press Cambridge UK

Johansen JR and RL Lowe In press Draparnaldia appalachiana sp Nov (Chaetophoraceae Chlorophyceae) from the Great Smoky Mountains National Park

Johansen JR and JC Sray 1998 Microcostatus Gen Nov a new aerophilic dia-tom genus based on Navicula Krasskei Hustedt Diatom Research 1393ndash101

Johansen JR RL Lowe SR Gomez JP Kociolek and SA Makosky 2004 New algal species records for the Great Smoky Mountains National Park USA with an annotated checklist of all reported algal species for the park Algological Studies 11117ndash44

Johansen JR SR Rushforth and JD Brotherson 1983a The algal fl ora of Navajo National Monument Arizona USA Nova Hedwigia 38501ndash553

Johansen JR SR Rushforth R Orbendorfer N Fungladda and J Grimes 1983b The algal fl ora of selected wet walls in Zion National Park Utah USA Nova Hedwigia 38765ndash808

Klemencic AK 2002 Kopenske alge na bentonskem zidu kamniten zidu apnen-casti skali in deblu lipe (Tilia platyphyllos) v Sloveniji Natura Sloveniae 421ndash30

Krammer K and H Lange-Bertalot 1986 Bacillariophyceae 1 Teil Navicula-ceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasser fl ora von Mitteleuropa Band 21 Gustav Fischer Verlag Stuttgart New York 876 pp

Krammer K and H Lange-Bertalot 1988 Bacillariophyceae 2 Teil Bacilla-riaceae Epithemiaceae Surirellaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 22 VEB Gustav Fischer Verlag Jena Germany 596 pp

Krammer K and H Lange-Bertalot 1991a Bacillariophyceae 3 Teil Centrales Fragilariaceae Eunotiaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 23 Gustav Fischer Verlag Stuttgart Jena Germany 576 pp

Krammer K and H Lange-Bertalot 1991b Bacillariophyceae 4 Teil Achnantha-ceae Kritische Ergaumlnzungen zu Navicula (Lineolatae) und Gomphonema Gesamtliteraturverzeichnis Teil 1-4 in Ettl H Gaumlrtner G Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 24 Gustav Fischer Verlag Stuttgart Jena Germany 437 pp

Lowe RL 1974 Environmental requirements and pollution tolerance of freshwater diatoms Environmental Protection Agency Washington DC PA-6704-74-007 340 pp

Lowe RL and GB Collins 1973 An aerophilous diatom community from Hocking Co Ohio Transactions of the American Microscopical Society 92492ndash496

Southeastern Naturalist150 Special Issue 1

Lund JWG 1945 Observations on soil algae I The ecology size and taxonomy of British soil diatoms The New Phytologist 4456ndash110

McMillim M and SR Rushforth 1985 The diatom fl ora of a steam vent of Kilauea Crater Island of Hawaii Pacifi c Science 39294ndash301

Olsen CE 2004 The algal fl ora of selected seeps and waterfalls in the Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 106 pp

Patrick R 1977 Ecology of freshwater diatoms-diatom communities Pp 133ndash191 In D Werner (Ed) The Biology of Diatoms Blackwell Scientifi c Publications London UK

Patrick R and CW Reimer 1966 The diatoms of the United States V1 Mono-graph Academy of Natural Science Philadelphia 13(1)1ndash688

Potapova MG KC Ponader RL Lowe TA Clason and LA Bahls 2003 Small-celled Nupela species from USA rivers Diatom Research 18293ndash306

Pederson D 1999 Scientists are trying to identify every living thing in the Smokies National Park Newsweek November 22 1999

Sharkey MJ 2001 The all taxa biological inventory of the Great Smoky Mountains National Park Florida Entomologist 84556ndash564

Sokal RR and FJ Rohlf 1995 Biometry 3rd Edition WH Freeman New York NY 468 pp

Southworth S A Schultz and D Denenny 2005 Generalized geological map of Bedrock Lithologies and surfi cial deposits in the Great Smoky Mountains National Park Region Tennessee and North Carolina US Geological Survey Resten VA Open-File Report 2004-1410

Wallace BJ J Webster and RL Lowe 1992 High-gradient streams of the Ap-palachians Pp 133ndash191 In CT Hackney SM Adams and WA Martin (Eds) Biodiversity of the Southeastern United StatesAquatic Communities John Wiley and Sons Inc Hoboken NJ USA pp 133-191

Werum M and H Lange-Bertalot 2004 Diatoms in springs and elsewhere under the infl uence of hydrogeology and anthropogenic impacts Iconographia Diato-mologica 131ndash480

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RL Lowe PC Furey JA Ress and JR Johansen 1452007

The two assemblages in cluster A were largely separated by dominant populations of Pinnularia subcapitata v hilseana and Eunotia cf gla-cialis These two diatoms have been reported from subaerial and acid habitats from both Europe and North America (Beyens 1989 Dixit et al 1999) Both collections in this cluster were from drippy bryophytes similar to the report of Beyens (1989) which may indicate that this is a preferred habitat of Pinnularia subcapitata v hilseana Eunotia is also common on mosses The three collections from wetwalls in Whiteoak Sinks (cluster B) were the only samples that we collected from limestone-dominated alkaline bed-rock Cymbopleura rupicola dominated these communities and was found nowhere else This taxon has been reported from similar alkaline subaerial habitats (Klemenčič 2002) Its disjunct distribution on wetwalls in the GSMNP may indicate its strong habitat specifi city Cluster C is represented by a single collection from a bryophyte-covered rock of Thunderhead Sandstone in a spray zone of Laurel Falls Waterfall spray zones are wetted for longer periods than many of the wetwall habitats and also have a continuous source of diatom immigrants and this may in part account for its uniqueness The assemblage was dominated by two spe-cies of Frustulia

Figures 36ndash39 Species of diatoms showing reduced external openings 36) Nupela sp 37) Diadesmis perpusilla (Kuumltz) DG Mann 38) Eunotia sp 39) Chamaepin-nulari soehrensis (Krasske) Lange-Bertalot (scale bar = 4 μm)

Southeastern Naturalist146 Special Issue 1

Cluster D was another small cluster of only two collections (Thunderhead Sandstone near a waterfall at Ramsay Cascade and Metcalf Phyllite on Lau-rel Creek Road) These two communities were only 23 similar to each other but lt15 similar to the remainder of the assemblages (Fig 2) These two assemblages were related by their relatively dense populations of Euno-tia exigua a cosmopolitan acidophilic species (Lowe 1974) Cluster E with six collections was separated from the other sites largely by species of Eunotia Although these six collections are less than 15 simi-lar to the rest of the assemblages they are not closely related to each other (Fig 2) Cluster F contained a single unique assemblage dominated by Eunotia diodon Ehrenberg and Eunotia rhomboidea Hustedt This was the only collection in this analysis that came from a soil seep and may reflect pe-culiar aspects of this unique environment Surveys of diatom soil flora are few but an extensive study by Lund (1945) illustrates the richness of the flora GSMNP with diverse soil types should hold a large number of soil diatom species We hope to pursue the algal soil flora of GSMNP in suc-ceeding years Cluster G consisted of two assemblages collected from disjunct sites (Thunderhead Sandstone seep and Logarm Quartzite dripwall) Both collection sites had the same pH however (50) The sites were relatively

Figures 40ndash43 Common wetwall diatom species without obviously reduced external openings 40) Decussata placenta 41) Luticola sp 42) Microcostatus krasskei 43) Nitzschia hantzschiana (scale bar = 5μm)

RL Lowe PC Furey JA Ress and JR Johansen 1472007

dissimilar to each other (Fig 2) but were distinct from the remainder of the assemblages primarily due to large populations of Diatoma mesodon and Fragilariaforma virescens Although Diatoma mesodon is often found in a large variety of habitats Fragilariaforma virescens is typically restricted to acidic or low alkalinity habitats (Camburn and Charles 2000) Cluster H is defi ned by Tetracyclus rupestris which occurred only in this single collection and accounted for 85 of the diatoms in this assemblage This is a unique community and is signifi cant in that Tetracyclus rupestris is seldom reported from the North American fl ora The collection site was a drippy Anakeesta bedrock formation at 1500 m elevation Anakeesta pro-vides an acidic environment and is often high in aluminum although we did not measure that element in this study Cluster I is composed of three assemblages each with Nitzschia hantzschiana as a common taxon This diatom is one of the most common subaerial species of the genus Nitzschia and has been reported from many different studies of subaerial algae (Dayner and Johansen 1991 Johansen et al 1983a Lund 1945) The three samples in this cluster are all from drippy wetwalls along road cuts All three of these samples contained conspicuous quantities of green algae or cyanobacteria Such algae might facilitate the presence of Nitzschia which is highly motile and would be capable of mov-ing through the algal matrix The remaining 28 collections all cluster together (J) but within this large cluster several subndashclusters can be identifi ed driven by assemblages with large populations of Diadesmis species and by Microcostatus krasskei These taxa have strong fi delity to subaerial habitats and are generally not seen in abundance in aquatic habitats In addition to the challenges of working with the vertical nature of wetwalls the highly variable and heterogeneous nature of the algal com-munities along with some of the variations in microhabitat discussed above highlights the need to consider both spatial scale and sampling strategy when designing wetwall studies or biodiversity surveys For ex-ample to minimize the effects of microhabitat variation artificial wetwall substrates may be helpful in elucidating the impact of microscale habitat features on algal community structure or several wetwall areas may need to be sampled in order to adequately characterize the diversity of an area or to track changes in algal assemblages over time or in response to en-vironmental changes Additionally the range of values covered for pH for the majority of our sites (pH 38ndash55) was narrow and future studies should include a broader range of pH especially across the intermediate values not examined in this study (pH 55ndash72) Similarly elevation and geology gave no apparent environmental signal in the diatom composition although these influences may have been masked by microscale variability or small sample size and future studies may require more intensive sam-pling experimental work or finer-scale bedrock determination

Southeastern Naturalist148 Special Issue 1

Conclusions

We described the diatom fl ora from several wetwalls throughout GSMNP Some of the species from this research appear to be new species and will be described and published elsewhere Aside from these new taxa many of the diatoms have been reported from other wetwall studies and have been noted as typical subaerial species Although we found little correlation with bedrock mineralogy chemistry including pH and wetwall elevation we did observe highly variable and very diverse diatom community structure among the wetwall habitats We found unique diatom communities along with wetwall-specifi c diatom taxa that appeared to have special adaptations to these subaerial habitats In order to better understand these understud-ied communities future research should explore these subaerial habitat adaptations such as presence of additional external siliceous membranes or interactions with soft algal communities Additionally further research is needed to understand the complexities of these unique algal communi-ties and habitats including examination of factors that may have a more dominant role in shaping wetwall community structure such as moisture gradients and sources infl uences of microscale variability substrate type and shading or the role of ultraviolet radiation We feel that it is particularly important to examine these communities at an appropriate scale Habitat variables and community structure could vary over millimeter distances on wetwalls and the small and spatially unique nature of these microhabitats should be taken into consideration in the experimental design and sampling in future wetwall studies

Acknowledgments

This research was supported by the National Science Foundation (DEB 0315979) and grants from Discover Life In America We are also very grateful for support and facilitation from the National Park Service Jeanie Hilton and volunteers from Dis-cover Life In America and the Appalachian Highlands Learning Center interns This manuscript was greatly improved thanks to detailed reviews by Marina Potapova Peter Siver and one anonymous reviewer

Literature Cited

Beyens L 1989 Moss-dwelling diatom assemblages from Edgeoslashya (Svalbard) Polar Biology 9423ndash430

Camburn KE and DF Charles 2000 Diatoms of Low-alkalinity Lakes in the Northeastern United States Academy of Natural Sciences of Philadelphia Spe-cial Publication 18 Philadelphia PA 152 pp

Dayner DM and JR Johansen 1991 Observations on the algal fl ora of Seneca Caverns Seneca County Ohio Ohio Journal of Science 91118ndash121

Dixit SS JP Smol DF Charles RM Hughes SG Paulsen and GB Collins 1999 Assessing water quality changes in the lakes of the northeastern United States using sediment diatoms Canadian Journal of Fisheries and Aquatic Sci-ences 56(1)131ndash152

RL Lowe PC Furey JA Ress and JR Johansen 1492007

Gomez S 2002 Epilithic aerial algae of Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 78 pp

Gomez SR JR Johansen and RL Lowe 2003 Epilithic aerial algae of Great Smoky Mountains National Park Biologia Bratislava 58603ndash615

Gresens SE and RL Lowe 1994 Periphyton patch preference in grazing chiron-omid larvae Journal of the North American Benthological Society 1389ndash99

Johansen JR 1999 Diatoms of aerial habitats Pp 264ndash273 In EF Stoermer and JP Smol (Eds) The Diatoms Applications for the Environmental and Earth Sciences Cambridge University Press Cambridge UK

Johansen JR and RL Lowe In press Draparnaldia appalachiana sp Nov (Chaetophoraceae Chlorophyceae) from the Great Smoky Mountains National Park

Johansen JR and JC Sray 1998 Microcostatus Gen Nov a new aerophilic dia-tom genus based on Navicula Krasskei Hustedt Diatom Research 1393ndash101

Johansen JR RL Lowe SR Gomez JP Kociolek and SA Makosky 2004 New algal species records for the Great Smoky Mountains National Park USA with an annotated checklist of all reported algal species for the park Algological Studies 11117ndash44

Johansen JR SR Rushforth and JD Brotherson 1983a The algal fl ora of Navajo National Monument Arizona USA Nova Hedwigia 38501ndash553

Johansen JR SR Rushforth R Orbendorfer N Fungladda and J Grimes 1983b The algal fl ora of selected wet walls in Zion National Park Utah USA Nova Hedwigia 38765ndash808

Klemencic AK 2002 Kopenske alge na bentonskem zidu kamniten zidu apnen-casti skali in deblu lipe (Tilia platyphyllos) v Sloveniji Natura Sloveniae 421ndash30

Krammer K and H Lange-Bertalot 1986 Bacillariophyceae 1 Teil Navicula-ceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasser fl ora von Mitteleuropa Band 21 Gustav Fischer Verlag Stuttgart New York 876 pp

Krammer K and H Lange-Bertalot 1988 Bacillariophyceae 2 Teil Bacilla-riaceae Epithemiaceae Surirellaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 22 VEB Gustav Fischer Verlag Jena Germany 596 pp

Krammer K and H Lange-Bertalot 1991a Bacillariophyceae 3 Teil Centrales Fragilariaceae Eunotiaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 23 Gustav Fischer Verlag Stuttgart Jena Germany 576 pp

Krammer K and H Lange-Bertalot 1991b Bacillariophyceae 4 Teil Achnantha-ceae Kritische Ergaumlnzungen zu Navicula (Lineolatae) und Gomphonema Gesamtliteraturverzeichnis Teil 1-4 in Ettl H Gaumlrtner G Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 24 Gustav Fischer Verlag Stuttgart Jena Germany 437 pp

Lowe RL 1974 Environmental requirements and pollution tolerance of freshwater diatoms Environmental Protection Agency Washington DC PA-6704-74-007 340 pp

Lowe RL and GB Collins 1973 An aerophilous diatom community from Hocking Co Ohio Transactions of the American Microscopical Society 92492ndash496

Southeastern Naturalist150 Special Issue 1

Lund JWG 1945 Observations on soil algae I The ecology size and taxonomy of British soil diatoms The New Phytologist 4456ndash110

McMillim M and SR Rushforth 1985 The diatom fl ora of a steam vent of Kilauea Crater Island of Hawaii Pacifi c Science 39294ndash301

Olsen CE 2004 The algal fl ora of selected seeps and waterfalls in the Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 106 pp

Patrick R 1977 Ecology of freshwater diatoms-diatom communities Pp 133ndash191 In D Werner (Ed) The Biology of Diatoms Blackwell Scientifi c Publications London UK

Patrick R and CW Reimer 1966 The diatoms of the United States V1 Mono-graph Academy of Natural Science Philadelphia 13(1)1ndash688

Potapova MG KC Ponader RL Lowe TA Clason and LA Bahls 2003 Small-celled Nupela species from USA rivers Diatom Research 18293ndash306

Pederson D 1999 Scientists are trying to identify every living thing in the Smokies National Park Newsweek November 22 1999

Sharkey MJ 2001 The all taxa biological inventory of the Great Smoky Mountains National Park Florida Entomologist 84556ndash564

Sokal RR and FJ Rohlf 1995 Biometry 3rd Edition WH Freeman New York NY 468 pp

Southworth S A Schultz and D Denenny 2005 Generalized geological map of Bedrock Lithologies and surfi cial deposits in the Great Smoky Mountains National Park Region Tennessee and North Carolina US Geological Survey Resten VA Open-File Report 2004-1410

Wallace BJ J Webster and RL Lowe 1992 High-gradient streams of the Ap-palachians Pp 133ndash191 In CT Hackney SM Adams and WA Martin (Eds) Biodiversity of the Southeastern United StatesAquatic Communities John Wiley and Sons Inc Hoboken NJ USA pp 133-191

Werum M and H Lange-Bertalot 2004 Diatoms in springs and elsewhere under the infl uence of hydrogeology and anthropogenic impacts Iconographia Diato-mologica 131ndash480

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Southeastern Naturalist146 Special Issue 1

Cluster D was another small cluster of only two collections (Thunderhead Sandstone near a waterfall at Ramsay Cascade and Metcalf Phyllite on Lau-rel Creek Road) These two communities were only 23 similar to each other but lt15 similar to the remainder of the assemblages (Fig 2) These two assemblages were related by their relatively dense populations of Euno-tia exigua a cosmopolitan acidophilic species (Lowe 1974) Cluster E with six collections was separated from the other sites largely by species of Eunotia Although these six collections are less than 15 simi-lar to the rest of the assemblages they are not closely related to each other (Fig 2) Cluster F contained a single unique assemblage dominated by Eunotia diodon Ehrenberg and Eunotia rhomboidea Hustedt This was the only collection in this analysis that came from a soil seep and may reflect pe-culiar aspects of this unique environment Surveys of diatom soil flora are few but an extensive study by Lund (1945) illustrates the richness of the flora GSMNP with diverse soil types should hold a large number of soil diatom species We hope to pursue the algal soil flora of GSMNP in suc-ceeding years Cluster G consisted of two assemblages collected from disjunct sites (Thunderhead Sandstone seep and Logarm Quartzite dripwall) Both collection sites had the same pH however (50) The sites were relatively

Figures 40ndash43 Common wetwall diatom species without obviously reduced external openings 40) Decussata placenta 41) Luticola sp 42) Microcostatus krasskei 43) Nitzschia hantzschiana (scale bar = 5μm)

RL Lowe PC Furey JA Ress and JR Johansen 1472007

dissimilar to each other (Fig 2) but were distinct from the remainder of the assemblages primarily due to large populations of Diatoma mesodon and Fragilariaforma virescens Although Diatoma mesodon is often found in a large variety of habitats Fragilariaforma virescens is typically restricted to acidic or low alkalinity habitats (Camburn and Charles 2000) Cluster H is defi ned by Tetracyclus rupestris which occurred only in this single collection and accounted for 85 of the diatoms in this assemblage This is a unique community and is signifi cant in that Tetracyclus rupestris is seldom reported from the North American fl ora The collection site was a drippy Anakeesta bedrock formation at 1500 m elevation Anakeesta pro-vides an acidic environment and is often high in aluminum although we did not measure that element in this study Cluster I is composed of three assemblages each with Nitzschia hantzschiana as a common taxon This diatom is one of the most common subaerial species of the genus Nitzschia and has been reported from many different studies of subaerial algae (Dayner and Johansen 1991 Johansen et al 1983a Lund 1945) The three samples in this cluster are all from drippy wetwalls along road cuts All three of these samples contained conspicuous quantities of green algae or cyanobacteria Such algae might facilitate the presence of Nitzschia which is highly motile and would be capable of mov-ing through the algal matrix The remaining 28 collections all cluster together (J) but within this large cluster several subndashclusters can be identifi ed driven by assemblages with large populations of Diadesmis species and by Microcostatus krasskei These taxa have strong fi delity to subaerial habitats and are generally not seen in abundance in aquatic habitats In addition to the challenges of working with the vertical nature of wetwalls the highly variable and heterogeneous nature of the algal com-munities along with some of the variations in microhabitat discussed above highlights the need to consider both spatial scale and sampling strategy when designing wetwall studies or biodiversity surveys For ex-ample to minimize the effects of microhabitat variation artificial wetwall substrates may be helpful in elucidating the impact of microscale habitat features on algal community structure or several wetwall areas may need to be sampled in order to adequately characterize the diversity of an area or to track changes in algal assemblages over time or in response to en-vironmental changes Additionally the range of values covered for pH for the majority of our sites (pH 38ndash55) was narrow and future studies should include a broader range of pH especially across the intermediate values not examined in this study (pH 55ndash72) Similarly elevation and geology gave no apparent environmental signal in the diatom composition although these influences may have been masked by microscale variability or small sample size and future studies may require more intensive sam-pling experimental work or finer-scale bedrock determination

Southeastern Naturalist148 Special Issue 1

Conclusions

We described the diatom fl ora from several wetwalls throughout GSMNP Some of the species from this research appear to be new species and will be described and published elsewhere Aside from these new taxa many of the diatoms have been reported from other wetwall studies and have been noted as typical subaerial species Although we found little correlation with bedrock mineralogy chemistry including pH and wetwall elevation we did observe highly variable and very diverse diatom community structure among the wetwall habitats We found unique diatom communities along with wetwall-specifi c diatom taxa that appeared to have special adaptations to these subaerial habitats In order to better understand these understud-ied communities future research should explore these subaerial habitat adaptations such as presence of additional external siliceous membranes or interactions with soft algal communities Additionally further research is needed to understand the complexities of these unique algal communi-ties and habitats including examination of factors that may have a more dominant role in shaping wetwall community structure such as moisture gradients and sources infl uences of microscale variability substrate type and shading or the role of ultraviolet radiation We feel that it is particularly important to examine these communities at an appropriate scale Habitat variables and community structure could vary over millimeter distances on wetwalls and the small and spatially unique nature of these microhabitats should be taken into consideration in the experimental design and sampling in future wetwall studies

Acknowledgments

This research was supported by the National Science Foundation (DEB 0315979) and grants from Discover Life In America We are also very grateful for support and facilitation from the National Park Service Jeanie Hilton and volunteers from Dis-cover Life In America and the Appalachian Highlands Learning Center interns This manuscript was greatly improved thanks to detailed reviews by Marina Potapova Peter Siver and one anonymous reviewer

Literature Cited

Beyens L 1989 Moss-dwelling diatom assemblages from Edgeoslashya (Svalbard) Polar Biology 9423ndash430

Camburn KE and DF Charles 2000 Diatoms of Low-alkalinity Lakes in the Northeastern United States Academy of Natural Sciences of Philadelphia Spe-cial Publication 18 Philadelphia PA 152 pp

Dayner DM and JR Johansen 1991 Observations on the algal fl ora of Seneca Caverns Seneca County Ohio Ohio Journal of Science 91118ndash121

Dixit SS JP Smol DF Charles RM Hughes SG Paulsen and GB Collins 1999 Assessing water quality changes in the lakes of the northeastern United States using sediment diatoms Canadian Journal of Fisheries and Aquatic Sci-ences 56(1)131ndash152

RL Lowe PC Furey JA Ress and JR Johansen 1492007

Gomez S 2002 Epilithic aerial algae of Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 78 pp

Gomez SR JR Johansen and RL Lowe 2003 Epilithic aerial algae of Great Smoky Mountains National Park Biologia Bratislava 58603ndash615

Gresens SE and RL Lowe 1994 Periphyton patch preference in grazing chiron-omid larvae Journal of the North American Benthological Society 1389ndash99

Johansen JR 1999 Diatoms of aerial habitats Pp 264ndash273 In EF Stoermer and JP Smol (Eds) The Diatoms Applications for the Environmental and Earth Sciences Cambridge University Press Cambridge UK

Johansen JR and RL Lowe In press Draparnaldia appalachiana sp Nov (Chaetophoraceae Chlorophyceae) from the Great Smoky Mountains National Park

Johansen JR and JC Sray 1998 Microcostatus Gen Nov a new aerophilic dia-tom genus based on Navicula Krasskei Hustedt Diatom Research 1393ndash101

Johansen JR RL Lowe SR Gomez JP Kociolek and SA Makosky 2004 New algal species records for the Great Smoky Mountains National Park USA with an annotated checklist of all reported algal species for the park Algological Studies 11117ndash44

Johansen JR SR Rushforth and JD Brotherson 1983a The algal fl ora of Navajo National Monument Arizona USA Nova Hedwigia 38501ndash553

Johansen JR SR Rushforth R Orbendorfer N Fungladda and J Grimes 1983b The algal fl ora of selected wet walls in Zion National Park Utah USA Nova Hedwigia 38765ndash808

Klemencic AK 2002 Kopenske alge na bentonskem zidu kamniten zidu apnen-casti skali in deblu lipe (Tilia platyphyllos) v Sloveniji Natura Sloveniae 421ndash30

Krammer K and H Lange-Bertalot 1986 Bacillariophyceae 1 Teil Navicula-ceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasser fl ora von Mitteleuropa Band 21 Gustav Fischer Verlag Stuttgart New York 876 pp

Krammer K and H Lange-Bertalot 1988 Bacillariophyceae 2 Teil Bacilla-riaceae Epithemiaceae Surirellaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 22 VEB Gustav Fischer Verlag Jena Germany 596 pp

Krammer K and H Lange-Bertalot 1991a Bacillariophyceae 3 Teil Centrales Fragilariaceae Eunotiaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 23 Gustav Fischer Verlag Stuttgart Jena Germany 576 pp

Krammer K and H Lange-Bertalot 1991b Bacillariophyceae 4 Teil Achnantha-ceae Kritische Ergaumlnzungen zu Navicula (Lineolatae) und Gomphonema Gesamtliteraturverzeichnis Teil 1-4 in Ettl H Gaumlrtner G Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 24 Gustav Fischer Verlag Stuttgart Jena Germany 437 pp

Lowe RL 1974 Environmental requirements and pollution tolerance of freshwater diatoms Environmental Protection Agency Washington DC PA-6704-74-007 340 pp

Lowe RL and GB Collins 1973 An aerophilous diatom community from Hocking Co Ohio Transactions of the American Microscopical Society 92492ndash496

Southeastern Naturalist150 Special Issue 1

Lund JWG 1945 Observations on soil algae I The ecology size and taxonomy of British soil diatoms The New Phytologist 4456ndash110

McMillim M and SR Rushforth 1985 The diatom fl ora of a steam vent of Kilauea Crater Island of Hawaii Pacifi c Science 39294ndash301

Olsen CE 2004 The algal fl ora of selected seeps and waterfalls in the Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 106 pp

Patrick R 1977 Ecology of freshwater diatoms-diatom communities Pp 133ndash191 In D Werner (Ed) The Biology of Diatoms Blackwell Scientifi c Publications London UK

Patrick R and CW Reimer 1966 The diatoms of the United States V1 Mono-graph Academy of Natural Science Philadelphia 13(1)1ndash688

Potapova MG KC Ponader RL Lowe TA Clason and LA Bahls 2003 Small-celled Nupela species from USA rivers Diatom Research 18293ndash306

Pederson D 1999 Scientists are trying to identify every living thing in the Smokies National Park Newsweek November 22 1999

Sharkey MJ 2001 The all taxa biological inventory of the Great Smoky Mountains National Park Florida Entomologist 84556ndash564

Sokal RR and FJ Rohlf 1995 Biometry 3rd Edition WH Freeman New York NY 468 pp

Southworth S A Schultz and D Denenny 2005 Generalized geological map of Bedrock Lithologies and surfi cial deposits in the Great Smoky Mountains National Park Region Tennessee and North Carolina US Geological Survey Resten VA Open-File Report 2004-1410

Wallace BJ J Webster and RL Lowe 1992 High-gradient streams of the Ap-palachians Pp 133ndash191 In CT Hackney SM Adams and WA Martin (Eds) Biodiversity of the Southeastern United StatesAquatic Communities John Wiley and Sons Inc Hoboken NJ USA pp 133-191

Werum M and H Lange-Bertalot 2004 Diatoms in springs and elsewhere under the infl uence of hydrogeology and anthropogenic impacts Iconographia Diato-mologica 131ndash480

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Southeastern Naturalist152 Special Issue 1C

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RL Lowe PC Furey JA Ress and JR Johansen 1472007

dissimilar to each other (Fig 2) but were distinct from the remainder of the assemblages primarily due to large populations of Diatoma mesodon and Fragilariaforma virescens Although Diatoma mesodon is often found in a large variety of habitats Fragilariaforma virescens is typically restricted to acidic or low alkalinity habitats (Camburn and Charles 2000) Cluster H is defi ned by Tetracyclus rupestris which occurred only in this single collection and accounted for 85 of the diatoms in this assemblage This is a unique community and is signifi cant in that Tetracyclus rupestris is seldom reported from the North American fl ora The collection site was a drippy Anakeesta bedrock formation at 1500 m elevation Anakeesta pro-vides an acidic environment and is often high in aluminum although we did not measure that element in this study Cluster I is composed of three assemblages each with Nitzschia hantzschiana as a common taxon This diatom is one of the most common subaerial species of the genus Nitzschia and has been reported from many different studies of subaerial algae (Dayner and Johansen 1991 Johansen et al 1983a Lund 1945) The three samples in this cluster are all from drippy wetwalls along road cuts All three of these samples contained conspicuous quantities of green algae or cyanobacteria Such algae might facilitate the presence of Nitzschia which is highly motile and would be capable of mov-ing through the algal matrix The remaining 28 collections all cluster together (J) but within this large cluster several subndashclusters can be identifi ed driven by assemblages with large populations of Diadesmis species and by Microcostatus krasskei These taxa have strong fi delity to subaerial habitats and are generally not seen in abundance in aquatic habitats In addition to the challenges of working with the vertical nature of wetwalls the highly variable and heterogeneous nature of the algal com-munities along with some of the variations in microhabitat discussed above highlights the need to consider both spatial scale and sampling strategy when designing wetwall studies or biodiversity surveys For ex-ample to minimize the effects of microhabitat variation artificial wetwall substrates may be helpful in elucidating the impact of microscale habitat features on algal community structure or several wetwall areas may need to be sampled in order to adequately characterize the diversity of an area or to track changes in algal assemblages over time or in response to en-vironmental changes Additionally the range of values covered for pH for the majority of our sites (pH 38ndash55) was narrow and future studies should include a broader range of pH especially across the intermediate values not examined in this study (pH 55ndash72) Similarly elevation and geology gave no apparent environmental signal in the diatom composition although these influences may have been masked by microscale variability or small sample size and future studies may require more intensive sam-pling experimental work or finer-scale bedrock determination

Southeastern Naturalist148 Special Issue 1

Conclusions

We described the diatom fl ora from several wetwalls throughout GSMNP Some of the species from this research appear to be new species and will be described and published elsewhere Aside from these new taxa many of the diatoms have been reported from other wetwall studies and have been noted as typical subaerial species Although we found little correlation with bedrock mineralogy chemistry including pH and wetwall elevation we did observe highly variable and very diverse diatom community structure among the wetwall habitats We found unique diatom communities along with wetwall-specifi c diatom taxa that appeared to have special adaptations to these subaerial habitats In order to better understand these understud-ied communities future research should explore these subaerial habitat adaptations such as presence of additional external siliceous membranes or interactions with soft algal communities Additionally further research is needed to understand the complexities of these unique algal communi-ties and habitats including examination of factors that may have a more dominant role in shaping wetwall community structure such as moisture gradients and sources infl uences of microscale variability substrate type and shading or the role of ultraviolet radiation We feel that it is particularly important to examine these communities at an appropriate scale Habitat variables and community structure could vary over millimeter distances on wetwalls and the small and spatially unique nature of these microhabitats should be taken into consideration in the experimental design and sampling in future wetwall studies

Acknowledgments

This research was supported by the National Science Foundation (DEB 0315979) and grants from Discover Life In America We are also very grateful for support and facilitation from the National Park Service Jeanie Hilton and volunteers from Dis-cover Life In America and the Appalachian Highlands Learning Center interns This manuscript was greatly improved thanks to detailed reviews by Marina Potapova Peter Siver and one anonymous reviewer

Literature Cited

Beyens L 1989 Moss-dwelling diatom assemblages from Edgeoslashya (Svalbard) Polar Biology 9423ndash430

Camburn KE and DF Charles 2000 Diatoms of Low-alkalinity Lakes in the Northeastern United States Academy of Natural Sciences of Philadelphia Spe-cial Publication 18 Philadelphia PA 152 pp

Dayner DM and JR Johansen 1991 Observations on the algal fl ora of Seneca Caverns Seneca County Ohio Ohio Journal of Science 91118ndash121

Dixit SS JP Smol DF Charles RM Hughes SG Paulsen and GB Collins 1999 Assessing water quality changes in the lakes of the northeastern United States using sediment diatoms Canadian Journal of Fisheries and Aquatic Sci-ences 56(1)131ndash152

RL Lowe PC Furey JA Ress and JR Johansen 1492007

Gomez S 2002 Epilithic aerial algae of Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 78 pp

Gomez SR JR Johansen and RL Lowe 2003 Epilithic aerial algae of Great Smoky Mountains National Park Biologia Bratislava 58603ndash615

Gresens SE and RL Lowe 1994 Periphyton patch preference in grazing chiron-omid larvae Journal of the North American Benthological Society 1389ndash99

Johansen JR 1999 Diatoms of aerial habitats Pp 264ndash273 In EF Stoermer and JP Smol (Eds) The Diatoms Applications for the Environmental and Earth Sciences Cambridge University Press Cambridge UK

Johansen JR and RL Lowe In press Draparnaldia appalachiana sp Nov (Chaetophoraceae Chlorophyceae) from the Great Smoky Mountains National Park

Johansen JR and JC Sray 1998 Microcostatus Gen Nov a new aerophilic dia-tom genus based on Navicula Krasskei Hustedt Diatom Research 1393ndash101

Johansen JR RL Lowe SR Gomez JP Kociolek and SA Makosky 2004 New algal species records for the Great Smoky Mountains National Park USA with an annotated checklist of all reported algal species for the park Algological Studies 11117ndash44

Johansen JR SR Rushforth and JD Brotherson 1983a The algal fl ora of Navajo National Monument Arizona USA Nova Hedwigia 38501ndash553

Johansen JR SR Rushforth R Orbendorfer N Fungladda and J Grimes 1983b The algal fl ora of selected wet walls in Zion National Park Utah USA Nova Hedwigia 38765ndash808

Klemencic AK 2002 Kopenske alge na bentonskem zidu kamniten zidu apnen-casti skali in deblu lipe (Tilia platyphyllos) v Sloveniji Natura Sloveniae 421ndash30

Krammer K and H Lange-Bertalot 1986 Bacillariophyceae 1 Teil Navicula-ceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasser fl ora von Mitteleuropa Band 21 Gustav Fischer Verlag Stuttgart New York 876 pp

Krammer K and H Lange-Bertalot 1988 Bacillariophyceae 2 Teil Bacilla-riaceae Epithemiaceae Surirellaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 22 VEB Gustav Fischer Verlag Jena Germany 596 pp

Krammer K and H Lange-Bertalot 1991a Bacillariophyceae 3 Teil Centrales Fragilariaceae Eunotiaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 23 Gustav Fischer Verlag Stuttgart Jena Germany 576 pp

Krammer K and H Lange-Bertalot 1991b Bacillariophyceae 4 Teil Achnantha-ceae Kritische Ergaumlnzungen zu Navicula (Lineolatae) und Gomphonema Gesamtliteraturverzeichnis Teil 1-4 in Ettl H Gaumlrtner G Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 24 Gustav Fischer Verlag Stuttgart Jena Germany 437 pp

Lowe RL 1974 Environmental requirements and pollution tolerance of freshwater diatoms Environmental Protection Agency Washington DC PA-6704-74-007 340 pp

Lowe RL and GB Collins 1973 An aerophilous diatom community from Hocking Co Ohio Transactions of the American Microscopical Society 92492ndash496

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Lund JWG 1945 Observations on soil algae I The ecology size and taxonomy of British soil diatoms The New Phytologist 4456ndash110

McMillim M and SR Rushforth 1985 The diatom fl ora of a steam vent of Kilauea Crater Island of Hawaii Pacifi c Science 39294ndash301

Olsen CE 2004 The algal fl ora of selected seeps and waterfalls in the Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 106 pp

Patrick R 1977 Ecology of freshwater diatoms-diatom communities Pp 133ndash191 In D Werner (Ed) The Biology of Diatoms Blackwell Scientifi c Publications London UK

Patrick R and CW Reimer 1966 The diatoms of the United States V1 Mono-graph Academy of Natural Science Philadelphia 13(1)1ndash688

Potapova MG KC Ponader RL Lowe TA Clason and LA Bahls 2003 Small-celled Nupela species from USA rivers Diatom Research 18293ndash306

Pederson D 1999 Scientists are trying to identify every living thing in the Smokies National Park Newsweek November 22 1999

Sharkey MJ 2001 The all taxa biological inventory of the Great Smoky Mountains National Park Florida Entomologist 84556ndash564

Sokal RR and FJ Rohlf 1995 Biometry 3rd Edition WH Freeman New York NY 468 pp

Southworth S A Schultz and D Denenny 2005 Generalized geological map of Bedrock Lithologies and surfi cial deposits in the Great Smoky Mountains National Park Region Tennessee and North Carolina US Geological Survey Resten VA Open-File Report 2004-1410

Wallace BJ J Webster and RL Lowe 1992 High-gradient streams of the Ap-palachians Pp 133ndash191 In CT Hackney SM Adams and WA Martin (Eds) Biodiversity of the Southeastern United StatesAquatic Communities John Wiley and Sons Inc Hoboken NJ USA pp 133-191

Werum M and H Lange-Bertalot 2004 Diatoms in springs and elsewhere under the infl uence of hydrogeology and anthropogenic impacts Iconographia Diato-mologica 131ndash480

RL Lowe PC Furey JA Ress and JR Johansen 1512007

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Southeastern Naturalist148 Special Issue 1

Conclusions

We described the diatom fl ora from several wetwalls throughout GSMNP Some of the species from this research appear to be new species and will be described and published elsewhere Aside from these new taxa many of the diatoms have been reported from other wetwall studies and have been noted as typical subaerial species Although we found little correlation with bedrock mineralogy chemistry including pH and wetwall elevation we did observe highly variable and very diverse diatom community structure among the wetwall habitats We found unique diatom communities along with wetwall-specifi c diatom taxa that appeared to have special adaptations to these subaerial habitats In order to better understand these understud-ied communities future research should explore these subaerial habitat adaptations such as presence of additional external siliceous membranes or interactions with soft algal communities Additionally further research is needed to understand the complexities of these unique algal communi-ties and habitats including examination of factors that may have a more dominant role in shaping wetwall community structure such as moisture gradients and sources infl uences of microscale variability substrate type and shading or the role of ultraviolet radiation We feel that it is particularly important to examine these communities at an appropriate scale Habitat variables and community structure could vary over millimeter distances on wetwalls and the small and spatially unique nature of these microhabitats should be taken into consideration in the experimental design and sampling in future wetwall studies

Acknowledgments

This research was supported by the National Science Foundation (DEB 0315979) and grants from Discover Life In America We are also very grateful for support and facilitation from the National Park Service Jeanie Hilton and volunteers from Dis-cover Life In America and the Appalachian Highlands Learning Center interns This manuscript was greatly improved thanks to detailed reviews by Marina Potapova Peter Siver and one anonymous reviewer

Literature Cited

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Camburn KE and DF Charles 2000 Diatoms of Low-alkalinity Lakes in the Northeastern United States Academy of Natural Sciences of Philadelphia Spe-cial Publication 18 Philadelphia PA 152 pp

Dayner DM and JR Johansen 1991 Observations on the algal fl ora of Seneca Caverns Seneca County Ohio Ohio Journal of Science 91118ndash121

Dixit SS JP Smol DF Charles RM Hughes SG Paulsen and GB Collins 1999 Assessing water quality changes in the lakes of the northeastern United States using sediment diatoms Canadian Journal of Fisheries and Aquatic Sci-ences 56(1)131ndash152

RL Lowe PC Furey JA Ress and JR Johansen 1492007

Gomez S 2002 Epilithic aerial algae of Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 78 pp

Gomez SR JR Johansen and RL Lowe 2003 Epilithic aerial algae of Great Smoky Mountains National Park Biologia Bratislava 58603ndash615

Gresens SE and RL Lowe 1994 Periphyton patch preference in grazing chiron-omid larvae Journal of the North American Benthological Society 1389ndash99

Johansen JR 1999 Diatoms of aerial habitats Pp 264ndash273 In EF Stoermer and JP Smol (Eds) The Diatoms Applications for the Environmental and Earth Sciences Cambridge University Press Cambridge UK

Johansen JR and RL Lowe In press Draparnaldia appalachiana sp Nov (Chaetophoraceae Chlorophyceae) from the Great Smoky Mountains National Park

Johansen JR and JC Sray 1998 Microcostatus Gen Nov a new aerophilic dia-tom genus based on Navicula Krasskei Hustedt Diatom Research 1393ndash101

Johansen JR RL Lowe SR Gomez JP Kociolek and SA Makosky 2004 New algal species records for the Great Smoky Mountains National Park USA with an annotated checklist of all reported algal species for the park Algological Studies 11117ndash44

Johansen JR SR Rushforth and JD Brotherson 1983a The algal fl ora of Navajo National Monument Arizona USA Nova Hedwigia 38501ndash553

Johansen JR SR Rushforth R Orbendorfer N Fungladda and J Grimes 1983b The algal fl ora of selected wet walls in Zion National Park Utah USA Nova Hedwigia 38765ndash808

Klemencic AK 2002 Kopenske alge na bentonskem zidu kamniten zidu apnen-casti skali in deblu lipe (Tilia platyphyllos) v Sloveniji Natura Sloveniae 421ndash30

Krammer K and H Lange-Bertalot 1986 Bacillariophyceae 1 Teil Navicula-ceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasser fl ora von Mitteleuropa Band 21 Gustav Fischer Verlag Stuttgart New York 876 pp

Krammer K and H Lange-Bertalot 1988 Bacillariophyceae 2 Teil Bacilla-riaceae Epithemiaceae Surirellaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 22 VEB Gustav Fischer Verlag Jena Germany 596 pp

Krammer K and H Lange-Bertalot 1991a Bacillariophyceae 3 Teil Centrales Fragilariaceae Eunotiaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 23 Gustav Fischer Verlag Stuttgart Jena Germany 576 pp

Krammer K and H Lange-Bertalot 1991b Bacillariophyceae 4 Teil Achnantha-ceae Kritische Ergaumlnzungen zu Navicula (Lineolatae) und Gomphonema Gesamtliteraturverzeichnis Teil 1-4 in Ettl H Gaumlrtner G Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 24 Gustav Fischer Verlag Stuttgart Jena Germany 437 pp

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Lund JWG 1945 Observations on soil algae I The ecology size and taxonomy of British soil diatoms The New Phytologist 4456ndash110

McMillim M and SR Rushforth 1985 The diatom fl ora of a steam vent of Kilauea Crater Island of Hawaii Pacifi c Science 39294ndash301

Olsen CE 2004 The algal fl ora of selected seeps and waterfalls in the Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 106 pp

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Patrick R and CW Reimer 1966 The diatoms of the United States V1 Mono-graph Academy of Natural Science Philadelphia 13(1)1ndash688

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Pederson D 1999 Scientists are trying to identify every living thing in the Smokies National Park Newsweek November 22 1999

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Wallace BJ J Webster and RL Lowe 1992 High-gradient streams of the Ap-palachians Pp 133ndash191 In CT Hackney SM Adams and WA Martin (Eds) Biodiversity of the Southeastern United StatesAquatic Communities John Wiley and Sons Inc Hoboken NJ USA pp 133-191

Werum M and H Lange-Bertalot 2004 Diatoms in springs and elsewhere under the infl uence of hydrogeology and anthropogenic impacts Iconographia Diato-mologica 131ndash480

RL Lowe PC Furey JA Ress and JR Johansen 1512007

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RL Lowe PC Furey JA Ress and JR Johansen 1492007

Gomez S 2002 Epilithic aerial algae of Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 78 pp

Gomez SR JR Johansen and RL Lowe 2003 Epilithic aerial algae of Great Smoky Mountains National Park Biologia Bratislava 58603ndash615

Gresens SE and RL Lowe 1994 Periphyton patch preference in grazing chiron-omid larvae Journal of the North American Benthological Society 1389ndash99

Johansen JR 1999 Diatoms of aerial habitats Pp 264ndash273 In EF Stoermer and JP Smol (Eds) The Diatoms Applications for the Environmental and Earth Sciences Cambridge University Press Cambridge UK

Johansen JR and RL Lowe In press Draparnaldia appalachiana sp Nov (Chaetophoraceae Chlorophyceae) from the Great Smoky Mountains National Park

Johansen JR and JC Sray 1998 Microcostatus Gen Nov a new aerophilic dia-tom genus based on Navicula Krasskei Hustedt Diatom Research 1393ndash101

Johansen JR RL Lowe SR Gomez JP Kociolek and SA Makosky 2004 New algal species records for the Great Smoky Mountains National Park USA with an annotated checklist of all reported algal species for the park Algological Studies 11117ndash44

Johansen JR SR Rushforth and JD Brotherson 1983a The algal fl ora of Navajo National Monument Arizona USA Nova Hedwigia 38501ndash553

Johansen JR SR Rushforth R Orbendorfer N Fungladda and J Grimes 1983b The algal fl ora of selected wet walls in Zion National Park Utah USA Nova Hedwigia 38765ndash808

Klemencic AK 2002 Kopenske alge na bentonskem zidu kamniten zidu apnen-casti skali in deblu lipe (Tilia platyphyllos) v Sloveniji Natura Sloveniae 421ndash30

Krammer K and H Lange-Bertalot 1986 Bacillariophyceae 1 Teil Navicula-ceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasser fl ora von Mitteleuropa Band 21 Gustav Fischer Verlag Stuttgart New York 876 pp

Krammer K and H Lange-Bertalot 1988 Bacillariophyceae 2 Teil Bacilla-riaceae Epithemiaceae Surirellaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 22 VEB Gustav Fischer Verlag Jena Germany 596 pp

Krammer K and H Lange-Bertalot 1991a Bacillariophyceae 3 Teil Centrales Fragilariaceae Eunotiaceae in Ettl H Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 23 Gustav Fischer Verlag Stuttgart Jena Germany 576 pp

Krammer K and H Lange-Bertalot 1991b Bacillariophyceae 4 Teil Achnantha-ceae Kritische Ergaumlnzungen zu Navicula (Lineolatae) und Gomphonema Gesamtliteraturverzeichnis Teil 1-4 in Ettl H Gaumlrtner G Gerloff J Heynig H and Mollenhauer D (Eds) Suumlsswasserfl ora von Mitteleuropa Band 24 Gustav Fischer Verlag Stuttgart Jena Germany 437 pp

Lowe RL 1974 Environmental requirements and pollution tolerance of freshwater diatoms Environmental Protection Agency Washington DC PA-6704-74-007 340 pp

Lowe RL and GB Collins 1973 An aerophilous diatom community from Hocking Co Ohio Transactions of the American Microscopical Society 92492ndash496

Southeastern Naturalist150 Special Issue 1

Lund JWG 1945 Observations on soil algae I The ecology size and taxonomy of British soil diatoms The New Phytologist 4456ndash110

McMillim M and SR Rushforth 1985 The diatom fl ora of a steam vent of Kilauea Crater Island of Hawaii Pacifi c Science 39294ndash301

Olsen CE 2004 The algal fl ora of selected seeps and waterfalls in the Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 106 pp

Patrick R 1977 Ecology of freshwater diatoms-diatom communities Pp 133ndash191 In D Werner (Ed) The Biology of Diatoms Blackwell Scientifi c Publications London UK

Patrick R and CW Reimer 1966 The diatoms of the United States V1 Mono-graph Academy of Natural Science Philadelphia 13(1)1ndash688

Potapova MG KC Ponader RL Lowe TA Clason and LA Bahls 2003 Small-celled Nupela species from USA rivers Diatom Research 18293ndash306

Pederson D 1999 Scientists are trying to identify every living thing in the Smokies National Park Newsweek November 22 1999

Sharkey MJ 2001 The all taxa biological inventory of the Great Smoky Mountains National Park Florida Entomologist 84556ndash564

Sokal RR and FJ Rohlf 1995 Biometry 3rd Edition WH Freeman New York NY 468 pp

Southworth S A Schultz and D Denenny 2005 Generalized geological map of Bedrock Lithologies and surfi cial deposits in the Great Smoky Mountains National Park Region Tennessee and North Carolina US Geological Survey Resten VA Open-File Report 2004-1410

Wallace BJ J Webster and RL Lowe 1992 High-gradient streams of the Ap-palachians Pp 133ndash191 In CT Hackney SM Adams and WA Martin (Eds) Biodiversity of the Southeastern United StatesAquatic Communities John Wiley and Sons Inc Hoboken NJ USA pp 133-191

Werum M and H Lange-Bertalot 2004 Diatoms in springs and elsewhere under the infl uence of hydrogeology and anthropogenic impacts Iconographia Diato-mologica 131ndash480

RL Lowe PC Furey JA Ress and JR Johansen 1512007

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Southeastern Naturalist150 Special Issue 1

Lund JWG 1945 Observations on soil algae I The ecology size and taxonomy of British soil diatoms The New Phytologist 4456ndash110

McMillim M and SR Rushforth 1985 The diatom fl ora of a steam vent of Kilauea Crater Island of Hawaii Pacifi c Science 39294ndash301

Olsen CE 2004 The algal fl ora of selected seeps and waterfalls in the Great Smoky Mountains National Park MSc Thesis John Carroll University University Heights OH 106 pp

Patrick R 1977 Ecology of freshwater diatoms-diatom communities Pp 133ndash191 In D Werner (Ed) The Biology of Diatoms Blackwell Scientifi c Publications London UK

Patrick R and CW Reimer 1966 The diatoms of the United States V1 Mono-graph Academy of Natural Science Philadelphia 13(1)1ndash688

Potapova MG KC Ponader RL Lowe TA Clason and LA Bahls 2003 Small-celled Nupela species from USA rivers Diatom Research 18293ndash306

Pederson D 1999 Scientists are trying to identify every living thing in the Smokies National Park Newsweek November 22 1999

Sharkey MJ 2001 The all taxa biological inventory of the Great Smoky Mountains National Park Florida Entomologist 84556ndash564

Sokal RR and FJ Rohlf 1995 Biometry 3rd Edition WH Freeman New York NY 468 pp

Southworth S A Schultz and D Denenny 2005 Generalized geological map of Bedrock Lithologies and surfi cial deposits in the Great Smoky Mountains National Park Region Tennessee and North Carolina US Geological Survey Resten VA Open-File Report 2004-1410

Wallace BJ J Webster and RL Lowe 1992 High-gradient streams of the Ap-palachians Pp 133ndash191 In CT Hackney SM Adams and WA Martin (Eds) Biodiversity of the Southeastern United StatesAquatic Communities John Wiley and Sons Inc Hoboken NJ USA pp 133-191

Werum M and H Lange-Bertalot 2004 Diatoms in springs and elsewhere under the infl uence of hydrogeology and anthropogenic impacts Iconographia Diato-mologica 131ndash480

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Southeastern Naturalist152 Special Issue 1C

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