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Benthic Foraminifera as Environmental Indicatorsin Torres Strait–Gulf of Papua

*Alexandra L. Post, Laura Sbaffi, Vicki Passlow and Dylan C. CollinsGeoscience Australia, GPO Box 378, Canberra, ACT 2601, Australia

*Corresponding author, E-mail: Alix.Post@ga.gov.au

Post, A.L., Sbaffi, L., Passlow, V., and Collins, D.C., 2007, Benthic foraminifera as environmental indicators in TorresStrait–Gulf of Papua, in Todd, B.J., and Greene, H.G., eds., Mapping the Seafloor for Habitat Characterization:Geological Association of Canada, Special Paper 47, p. 329-347.

Abstract

Three areas in the Torres Strait–Gulf of Papua region were selected for detailed study of sediments and benthic fossilbiota. These areas form a transect across the shelf from the Fly River Delta to the shelf edge, near the northern extrem-ity of the Great Barrier Reef. The Torres Strait–Gulf of Papua shelf is a shallow, low-gradient platform, where the shelfedge occurs between 120 and 140 m depth. In the study area, where the sediments range from muddy to gravelly car-bonate sands, the sediment deposition rates are low and the relict content of sediment is often high.

The three areas show distinct differences in benthic foraminiferal assemblages as indicated by relative abundances atthe order level, as well as distribution patterns of individual species; these differences are also reflected in the totalmicrobiotic communities. Given the high relict content in the surface material across these sites, a foraminiferal preser-vation scale was developed to assess the extent of reworking. Taphonomic features indicate that abrasion is the mainfactor affecting preservation.

Despite poor preservation of the foraminiferal tests, the benthic foraminiferal species have a strong correlation to waterdepth, indicating that transportation pathways are short. Application of multivariate statistics to analyze the relation-ship between environmental attributes and the distributions of the microbiota and foraminiferal species indicates theadditional importance of factors including percent carbonate mud, percent gravel, organic carbon flux, temperature,salinity and mean grain size. The benthic foraminifera produce a much stronger correlation to the environmental vari-ables than the microbiota, indicating that these organisms can provide a detailed assessment of habitat types.

Résumé

Trois zones dans le détroit de Torres, golfe de la région de la Papouasie, ont été sélectionnées pour l'étude détaillée dessédiments et du biote fossile benthique. Ces zones forment un transect dans la plate-forme du delta du fleuve Fly jusqu'àl'accore du plateau, près de l'extrémité nord de la Grande Barrière de corail. Le détroit de Torres dans le plateau dugolfe de la Papouasie est une plate-forme de faible gradient, où l'accore du plateau se trouve entre 120 et 140 m de pro-

INTRODUCTION

Analysis of the relationships between marine organisms and theirenvironment is becoming an important tool for understanding andmanaging marine communities (Hockey and Branch, 1997;Williams and Bax, 2001; Roff et al., 2003). Benthic foraminiferaare a group of organisms that are ubiquitous throughout the world’soceans, but the distribution of individual species is constrained bytheir environmental preferences. Therefore, these organisms havethe potential to provide important environmental information.Benthic foraminiferal species distributions may vary according toany combination of factors such as substrate type, light intensity,water temperature, food availability, oxygen, salinity and currentenergy (Murray, 1991). Many of these attributes vary with waterdepth, so depth may capture variations in these parameters and inspecies distributions. Understanding the response of the wholeecosystem to environmental change is important for marine man-agement. This study tests the environmental controls on the distri-bution and abundance of benthic foraminiferal species and othermicrobiota preserved in surface sediments as a means of character-izing habitats. The environmental-biota relationships determined inthis study will also allow interpretation of environmental andecosystem change through time, when applied to down-core recordsof cores collected from this region.

Benthic habitat mapping from offshore Canada and NewZealand illustrates the success of defining biological communitiesbased on the nature of the substrate as well as water depth (e.g.,Thouzeau et al., 1991; Kostylev et al., 2001; Hayward et al., 2002).However, studies from other regions, including northern Australia,reveal the difficulties of relating biological and habitat data inregions of slow sedimentation with strong reworking (e.g., Orpin etal., 1999). In these areas of high reworking, the relationshipbetween sedimentary biotic material and physical parameters, suchas the substrate type and water depth, is degraded, making it diffi-cult to define key habitat attributes. The use of sedimentary materi-al to delineate habitats and benthic communities may therefore failin high-energy regions.

In this study, surface sediments from across the Torres Strait–Gulf of Papua region are analyzed to assess the relationshipbetween environmental attributes and the distribution of benthicforaminiferal species and other microbiota. The Torres Strait area isa very dynamic region, encompassing sub-delta to open marineenvironments. The dynamic nature of this region provides a goodbasis for testing the relationship between the sedimentary bioticrecord and physical features of the environment. Further, this studyincorporates taphonomic data to determine the extent to whichreworking can alter the relationship between biota and environmen-tal attributes. Sediment transport, sediment mixing and test dissolu-tion have been found to alter the composition of foraminiferalassemblages from the Fly River Delta (Torres Strait; Cole, 1995).

SETTING

Sampling was conducted across three main areas: Areas A, B and C(Figure 1). Area A is located at the distal edge of the Fly River Deltawithin 30-40 km of the shoreline and at water depths rangingbetween 25 and 35 m. The area is mainly flat to undulating, has lowrelief ridges (up to 2 m), and swales also occur parallel to the bathy-metric contours. A shallow gully (~3 m) occurs in the southwest andtrends northwest–southeast. Terrigenous sediment transport andaccumulation rates are low across this area as indicated by the thinHolocene section present in cores (typically <1 m thick) and theabundance of semi-lithified mud clasts (Harris et al., 2004). Manysites exhibit a bimodal grain size distribution reflecting the accumu-lation of mud from the tidal flats and from the reworking of finesediments.

Area B is located 75 to 85 km offshore and contains a subma-rine valley system that trends east–west across the shelf in two sep-arate limbs (Figure 1). The northern valley is interpreted as a river/estuarine channel, while the southern system is characterized as atidal channel (Heap et al., 2003). The valley reaches depths of up to130 m, with an overall depth across the area of between 40 and 130m. Shallower areas include shoal reefs that occur in the southern-most section of Area B. Shallow gullies (~10 m) are also found, and

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fondeur. Dans la région à l'étude, où les sédiments varient de sables carbonatés boueux à graveleux, les taux de sédi-mentation sont faibles et le contenu en reliques des sédiments est souvent élevé.

Les trois zones montrent des différences dans les assemblages de foraminifères benthiques comme l'indiquent les abon-dances relatives au niveau de l'ordre, ainsi que les patrons de distribution des espèces individuelles; ces différences sereflètent aussi dans l'ensemble des communautés microbiotiques. Étant donné le fort contenu en reliques du matériel desurface dans ces sites, une échelle de préservation des foraminifères a été définie pour évaluer l'étendue duremaniement. Les caractéristiques taphonomiques indiquent que l'abrasion est le principal facteur qui affecte la préser-vation.

Malgré une faible préservation des tests de foraminifères, les espèces de foraminifères benthiques montrent une fortecorrélation avec la profondeur de l'eau, ce qui indique que les voies de transport sont courtes. L'application de statis-tiques à variables multiples dans l'analyse des relations entre les caractéristiques environnementales et les distributionsdes espèces du microbiote et de foraminifères montre l'importance additionnelle de facteurs comme le pourcentage deboue carbonatée, le pourcentage de gravier, le flux de carbone organique, la température, la salinité et la taille moyennedes grains. Les foraminifères benthiques montrent une corrélation beaucoup plus grande avec les variables environ-nementales que le microbiote, ce qui indique que ces organismes peuvent mener à une évaluation détaillée des typesd'habitats.

these drain into the valley system. The areas that were sampledwere generally flat and included some rocky and reef environments.

Area C is located 105 to 120 km offshore and comprises a sub-marine valley system aligned west-northwest–east-northeast(Figure 1). The valley occurs as two separate limbs with the deepersouthern channels representing relict features formed by tidal cur-rent scour during Pleistocene sea level lowstands (Heap et al.,2003). The water depth at sampling sites across this area rangesfrom 50 to 220 m, and the shallow areas are mapped as platformreefs. The channels across both areas B and C act as conduits forupwelled Coral Sea water, which is relatively cool, saline and nutri-ent-rich (Harris et al., 2004).

Bottom measurements of temperature and salinity at each siteindicate that each of these parameters is tightly correlated withchanges in water depth. As water depth increases, the temperature ofthe bottom water decreases logarithmically (R2 = 0.75) while salini-ty increases (R2 = 0.80). The bottom water temperature rangesbetween 25 and 29°C across all sites, and salinity between 34.33 and35.18‰. The increase in salinity with depth is associated withupwelling of saline, cool water from the Coral Sea into deeper chan-nels of areas B and C (Harris et al., 2004), while shallower nearshoreareas are influenced by fresh water input from the Fly River.

METHODS

Analysis of Environmental Parameters

Surface sediment samples were collected from 64 sites within theTorres Strait–Gulf of Papua region during Geoscience Australia

Survey 234 aboard RV Franklin in January-February 2002 (Figure1). The physical characteristics of each site were determinedthrough several analyses. Surface grab samples were analyzed forgravel, sand and silt content by washing through 2 mm and 63 μmsieves, and the <2 mm fraction was analyzed by laser particle size.Carbonate content was determined on the mud and sand fractionsusing the carbonate bomb method. In addition, the seabed morphol-ogy was characterized based on swath bathymetry data, togetherwith seabed photography. Temperature and salinity measurementswere obtained at each site via conductivity/temperature/depth(CTD) casts. The measurements from nearest the seabed were usedin comparison with the benthic foraminiferal assemblages. Detailsof each of these analyses are available in Harris et al. (2004).

Analysis of Benthic Foraminifera

Surface sediments were collected using a Smith-McIntyre grab. Thegrab material was dry-sieved to the 150 :m to 2 mm size fractionand split into aliquots, each containing at least 300 specimens ofbenthic foraminifera. The foraminifera were identified using abinocular light microscope and referencing the taxonomic studies ofHottinger et al. (1993), Loeblich and Tappan (1994), Hayward et al.(1997) and Haig (2002). The most abundant forms (>2% abundance)were identified to species level (see species list in Appendix I), whilerarer forms were grouped and identified to genera.

Taphonomy

Two foraminiferal genera were selected for assessment of taphono-my, following an overview of preservation in samples from all threeareas. Both genera selected: Amphistegina sp. and Quinqueloculina

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Figure 1. Grab samples were collected at 64 sites within areas A, Band C in the Torres Strait–Gulf of Papua region, southeast of theFly River Delta.

sp., occur in reasonable abundances across the whole study area andtogether encompass robust to fragile forms. The assessment wasrestricted to non-agglutinated forms because of the very differentnature of taphonomic breakdown in agglutinated taxa. A preserva-tion scale was determined for each genera (Table 1), based on fea-tures documented from field and laboratory studies (Peebles andLewis, 1991; Kotler et al., 1992; Shroba, 1993) and the degree towhich they affect the test; typical examples are illustrated in Figure2. The scale was designed to allow comparisons between genera,while taking into account the different types of degradation thatoccur between species.

Analysis of Microbiota

The absolute abundance of the main groups of organisms identi-fied in the sedimentological size fraction 150 :m–2 mm was alsocalculated for this study. The 64 grab samples were repeatedlysplit using a microsplitter and weighed using a Sartorius BP221Sprecision scale to obtain about 0.2 gm of sediment. All the shellsand recognizable fragments present in the subsamples were thencounted and expressed as number of specimens/g of dry sediment.Of the 15 recognized groups, two live in the water column (i.e.,planktonic foraminifera and pteropods) while the others mainlydwell on the seafloor and/or a few centimetres within the sedi-ment. This range of taxa allowed a more complete picture of themarine ecosystem.

DATA ANALYSES

Statistical analysis was conducted using PRIMER-E software(Plymouth Routines In Multivariate Ecological Research; see Clarkeand Ainsworth, 1993; Clarke and Warwick, 2001). Similaritiesbetween sites were analyzed based on benthic foraminiferal speciesdata and environmental attributes to assess inter-relationships.

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Table 1. Preservation scales for Amphistegina sp. and Quiqueloculina sp.

Taphonomic FeaturesScale Amphistegina sp. Quinqueloculina sp.

Fresh Surface transparent, details of pores clearly visible; Surface transparent to translucent, pitting and breakageappearance breakage minor <10% (usually scalloping) minor, <10%

Lightly Surface transparent to translucent; minor breakage or Surface translucent to opaque; minor damage <25% of testmodified scalloping <25% of test; surface ornament minor change edge scalloped or broken or <25% breakage; surface shiny

(e.g., ornament smoothing or removal, pitting) or ornament shows minor change

Moderately Surface transparent to opaque; <50% of edge scalloped Surface opaque ± minor staining; up to 50% of edgemodified or <a of test broken; <50% of surface affected by scalloped and/or up to a of test broken; surface alter-

holes, pitting, ornament smoothing or surface removal ation on <50% of test surface (e.g., ornament smoothing,pitting, surface removal)

Heavily Surface opaque, surface ornament smoothed or surface Surface opaque, ornament smoothed or surface layersmodified layers partially removed, >50%; breakage if present, partially removed, >50%; test may be heavily stained;

>30%; infill if present not lithified breakage and/or abrasion and pitting >30%

Relict Surface ornament smoothed or layers removed or test Surface ornament smoothed or polished, or surface sugary,polished or heavily etched; staining, if present, heavy >75% affected and/or test heavily stained, >75% of area;>75%; breakage usually >50% of edge or whole test; test breakage >50% of test or edge; test infilled and/or lithifiedinfilled and lithified

Figure 2. Preservation styles for Quinqueloculina subimpressa (Aand B) and Amphistegina papillosa (C and D). A shows example ofextensive surface pitting, holes and scalloping of test edges, whileB shows good surface preservation but a high degree of fragmenta-tion of the test. C illustrates a specimen with light, mainly surfacealteration, and D shows heavy surface abrasion and fragmentationof the test.

Analysis of Community Structure

Similarity between sites was determined based on counts of themicrobiota (measured as the number of individuals/gram of sedi-ment) using the Bray–Curtis similarity coefficient. The Bray–Curtissimilarity coefficient provides good results for ecological databecause it does not measure the absence of species (Clarke andAinsworth, 1993). This is important for biological studies becausea species may be absent at either end of its ecological range. For thebenthic foraminifera, species counts were square-root transformedto allow stronger weighting of rarer forms, and only species thathave abundance >2% were used. Microbiota were identified to phy-lum, and these counts were also square-root–transformed. PrincipalComponents Analysis (PCA) was used to obtain a broad indicationof the species which account for the greatest variance in the dataset.

Analysis of Environmental Parameters

Similarity between sites was determined for the environmentalparameters based on normalized Euclidean distance. The key envi-ronmental attributes and their transformations are listed in Table 2.Several attributes were log-transformed to reduce the skewness intheir distribution across sites, allowing a more meaningful normal-ization of the data. Another parameter which was included in theanalysis was the number of benthic foraminifera/g of sand (BF/g).The concentration of benthic foraminifera in the sediment is con-trolled by the flux of organic carbon to the seafloor at depths abovethe lysocline (see Herguera, 1992). For this study the number ofbenthic foraminifera was calculated in a weighed aliquot of sedi-ment in the 150 :m–2 mm size fraction, and this was applied as aproxy for organic carbon flux.

Comparison between Distribution of Biota and Environmental Attributes

The BIO-ENV function in PRIMER was used to determine thestrength of the relationship between the biota and measured envi-ronmental variables (Clarke and Ainsworth, 1993; Clarke andWarwick, 2001). The environmental and biotic matrices were com-pared using Spearman’s rank correlation, which is appropriate forcomparing similarity matrices derived from different types of coef-ficients (i.e., the Bray–Curtis coefficient for the species matrix andEuclidean distance for the environmental matrix). The BIO-ENVfunction proceeds by taking each environmental matrix in turn todetermine which combination of factors best represents the speciesdistribution.

RESULTS

Abundance of Total Microbiota

Benthic foraminifera are the dominant phylum in terms of their rel-ative abundance in sediments across all areas, with abundances of~45% in areas B and C and ~70% in Area A (Table 3, Figure 3).The next most dominant taxa are pteropods (7.5-14.5%), bivalves(5-10%), planktonic foraminifera (1-10.5%) and bryozoa (3-8%).The other phyla have average abundances of less than 5% acrosseach area.

The similarity between sites based on the microbiota abun-dances is shown as a Multi-Dimensional Scale (MDS) plot inFigure 4. MDS plots depict the relative differences between sites bythe distance between points on the plot (Kruskal and Wish, 1978).The site similarity shown in Figure 4 indicates that samples fromArea A form the most distinct grouping. Considerable overlap inmicrobiota abundances is observed within areas B and C. The over-lap between areas B and C reflects overall similarities in the abun-dances of the benthic foraminifera (45 ± 10% in both areas) and ofseveral of the other dominant phylum (e.g., pteropods 14% and bry-ozoan 7-8%).

The dominance by the benthic foraminifera across each of thesites highlights the importance of this group in the region and the

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Table 2. Environmental attributes and their transformation forTorres Strait surface sediments

Environmental attribute Transformation

%Mud Log%Sand None%Gravel LogMean grain size None%CaCO3 (total) Log%CaCO3 mud Log%Terrigenous mud LogWater depth (m) LogBF/g NoneTemperature (°C) NoneSalinity None

Table 3. Average abundances across each area for the 15 groups ofmarine organisms recognized and counted in the Torres Strait grabsamples

Percent relative abundance± standard deviation

Faunal Group Area A Area B Area C

Serpulids 0.05 ± 0.05 0.1 ± 0.2 1.0 ± 0.9Coralline algae 0.1 ± 0.2 0.4 ± 0.3 0.6 ± 0.7

(Halimeda) frCorals fr 0.3 ± 0.4 0.4 ± 0.4 0.6 ± 0.5Brachiopods 0.3 ± 0.2 0.6 ± 0.5 0.7 ± 0.3Porifera fr 0.5 ± 0.3 0.5 ± 0.5 0.6 ± 0.4Planktonic 0.8 ± 0.2 5.8 ± 3.1 10.6 ± 5.2

foraminiferaEchinoderms fr 1.1 ± 1.3 2.2 ± 0.9 2.0 ± 0.9Soft corals fr 1.3 ± 3.3 4.0 ± 3.0 3.6 ± 1.4Gastropods 2.3 ± 1.0 3.1 ± 1.1 3.3 ± 1.5Ostracods 2.5 ± 0.6 2.0 ± 0.9 2.5 ± 1.3Other arthropods fr 3.0 ± 3.0 3.0 ± 1.8 3.0 ± 1.8Bryozoa fr 3.2 ± 5.0 7.3 ± 2.2 8.2 ± 4.2Pteropods 7.6 ± 4.9 14.4 ± 6.9 13.4 ± 4.8Bivalves 7.7 ± 2.1 9.5 ± 3.8 4.8 ± 2.1Benthic foraminifera 69.3 ± 12.4 46.5 ± 10.8 45.1 ± 9.2

Note: fr denotes presence of fragments only

potential for mapping the ecosystem through detailed studies ofspecies within this phylum.

Foraminiferal Abundances

Benthic foraminifera are abundant in each of the grab samplesexamined. Thirty-one species >2% and minor species (numerical)

were incorporated within 15 genera. Species abundances were cal-culated as percentage and the number of foraminifera/g of sedimentin the sand fraction.

Principal components analysis indicates that most of the vari-ance (68%) within the species data can be explained by the distri-bution in the abundances of Amphistegina papillosa, Assilinaammonoides, Cibicides refulgens, Cibicides-type species,Nummulites venosus, Heterolepa subhaidingeri, Pseudogaudryinapacifica and Spiroplectinella pseudocarinata. The distribution ofthese species exhibits distinct trends with respect to water depth(Figure 5). Amphistegina papillosa, A. ammonoides and N. veno-sus are most abundant in waters <60 m deep, and are therefore thedominant species within Area A. At depths below 60 m, A. papil-losa reaches average abundances of 30%, while A. ammonoidesand N. venosus have maximum average abundances of 20% and10%, respectively. Species with maximum abundances at mid-depths (between 50 and 110 m) include P. pacifica (maximum at55 m), S. pseudocarinata (maximum at 110 m) and H. subhaidin-geri (maximum at 85 m). These species tend to increase in abun-dance across Area B and shallower parts of Area C.Pseudogaudryina pacifica maintains its presence across the deep-er water sites and has an abundance of 6%. Cibicides-type speciesand C. refulgens are distributed across all water depths and thehighest abundance occurs at depths >120 m for Cibicides-typespecies. The maximum abundance of C. refulgens occurs at 90 m.However, it maintains high abundances across depths >120 m.These two species are most common within Area C.

The distribution of several of these key species across the sitesis shown in Figures 6A-C, illustrating the relationship betweenbathymetry and species abundances on a site-by-site basis. Assilina

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Figure 3. Average abundances of microbiota across areas A, B and C. The abundance of benthic foraminifera decreases between areas Aand C, while planktonic foraminifera and bryozoa increase.

Figure 4. Site similarity (MDS) based on the abundance of micro-biota (measured as number of specimens/gram of sediment).Similarity is plotted as the relative distance between sites. Siteswithin Area A show a distinct difference in microbiota abundancesto areas B and C. There is substantial overlap in site similaritieswithin areas B and C.

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Figure 5. Percent abundance of major benthic foraminiferal species according to water depth. Trendlines are shown as moving averages.Note that the scale changes between plots.

ammonoides (Figure 6A) has consistently high abundances acrossArea A, while high abundances of this species within areas B and Care restricted to the shallower plateaux, and very low abundancesoccur at deeper sites. A similar distribution is shown for A. papil-losa in Figure 6B, with the highest abundance of this species inareas B and C occurring at the shallowest sites. Spiroplectinellapseudocarinata (Figure 6C), by contrast, shows highest abundancesat the deepest sites, and therefore has very low abundance at sites inareas A and B, with slightly increased numbers occurring at the fewrelatively deeper sites in Area B.

Cluster analysis of the foraminiferal species data reveals 7main clusters. Cluster 1 consists of just one sample from Area A,Site 4, with a similarity to other sites of 50%. Other sites from AreaA form Cluster 2 (Figure 7), with similarities ranging between 70and 90%. The foraminiferal assemblage at Site 4 contains higherabundances of Quinqueloculina philippinensis and Cibicides-typespecies, and much lower abundances of N. venosus compared to theassemblages at other sites within Area A. Clusters in areas B and Cshow some overlap between the two areas, with Cluster 4 the onlydistinct cluster, composed of sites from the deeper parts of Area C(Figure 7). Similarities between sites within these remaining clus-ters range between 60-85%.

Taphonomic Features of Benthic Foraminifera

The taphonomic changes in selected genera of benthic foraminiferahave been analyzed across all the sites. All samples show evidenceof some form of mechanical or chemical breakdown, but with vari-able intensity between sites. Effects observed include pitting, break-age, scalloping of test edges, flattening or removal of surface orna-mentation or surface layers, polishing, test infill and staining(Figure 2). Abrasion features are the most common form of testalteration, indicating mechanical breakdown due to bombardmentwith fine-grained material. Dissolution effects, mainly seen asopacity of the test surface, are also common. The very heavy abra-sion of some specimens indicates their long residence time near thesurface. There appears to be no correlation between species abun-dances and their preservation, implying that preservation is not afunction of species production or transportation to the sites.

The preservation of Amphistegina sp. is poor in Area A, sug-gesting a high degree of reworking in these sediments. Areas B andC, however, are dominated by sites with >25% of tests with a freshappearance or lightly modified (Figure 8). Across the remainingsites, most of the tests fall into the heavily modified or relict cate-gories. Average preservation values of Amphistegina sp. across all

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Figure 6. Percentage abundance of A. ammonoides(A), A. papillosa (B) and S. pseudocarinata (C) ateach site. Species show a clear relationship to depth,with highest abundances of A. ammoinoides and A.papillosa in Area A and the shallower plateaux with-in areas B and C, and highest abundances of S.pseudocarinata associated with the deeper watersites in areas B and C.

three areas are shown in Figure 9. The detailed breakdown ofpreservation for Amphistegina sp. is provided in Appendix II.

In Area A, samples are generally dominated by tests showingheavy abrasion, typically >40-70%. The abundance of both relictand material of fresh appearance is generally low, <10%; 6 sampleshave no relict specimens, while 5 of the 21 samples show values>20%. Similarly, the abundance of material of fresh appearance islow, 0-10%; 3 samples have no tests of fresh appearance.

Area B shows greater variability. Samples are generally domi-nated by tests that are heavily degraded, typically in the range >25-65%. The relict content is variable; 7 samples have no relict speci-mens, the remainder range from 1-35%. However, the percentage ofmaterial of fresh appearance and light modification is generallyhigher than in Area A. Area C also shows a high level of variabili-ty. About half of the samples are dominated by tests in the heavilymodified category, although the dominance is much less clear cutthan in samples from areas A and B. The remaining samples aredominated by light or moderate abrasion, or, in one case, by mate-rial of fresh appearance.

The preservation of Quinqueloculina sp. is poor throughout;sites with poor preservation outnumber sites where well-preservedmaterial dominates (Figure 8). Average preservation values across

all sites are shown in Figure 10. Details of Quinqueloculina sp.preservation are provided in Appendix III. In Area A, samples aredominated by material that has been heavily degraded, >40-78%.Relict content is low (0-20%) to moderate (>20-45%). The contentof material of fresh appearance is low throughout, <5%, with 12 ofthe 21 samples having no specimens. The proportion of lightlymodified material is low, generally in the range 0-20%, with 9 sam-ples having no lightly modified specimens.

Area B samples are generally dominated by material withheavy degradation, 30-50%, although some samples show higherlevels of either relict or moderately abraded material. There isgreater variability in the relict content where 14 out of the 21 sam-ples have low values (0-20%) and the remainder range from 20 to49%. The proportion of material of fresh appearance is similarlyvariable, 0-18%; 14 of 21 samples have no specimens with a freshappearance. Where present, the proportion of material of freshappearance is generally higher than in Area A samples, as is the pro-portion of lightly modified material.

In Area C, samples show greater variability; some contain ahigher content (up to 50%) of material that has a fresh appearanceand light modification, with little or no relict material; others arebiased towards being heavily abraded and relict, and contain lit-tle material with fresh appearance or light modification. Relict

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Figure 7. The distribution of species clusters across areas A, B and C. Data is based on the abundance of benthic foraminiferal species(measured as number of specimens/gram of sediment). Sites within Area A form distinct clusters, with areas B and C showing greater over-lap in clusters between the two areas.

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Figure 8. Preservation of benthic foraminifera for Amphistegina sp. and Quinqueloculina sp. Preservation is shown for sites that have 25-50% and >50% well-preserved specimens (based on the fresh appearance and lightly degraded categories). There are 12 sites with >50%well-preserved Amphistegina sp. and 2 with well-preserved Quinqueloculina sp. Best preservation occurs within Area C.

Figure 9. Relative preservation, averaged across each area, based on Amphistegina spp. The combined relict and heavily degraded catego-ry is highest across areas A and B.

Area A Area B Area C

Amphistegina spp.

moderate

light

fresh

moderate

light

fresh moderate fresh

light

relictrelictrelict

04-070-9

heavyheavy heavy

content varies between 0-60%; 4 samples have no relict material.Heavily modified content varies from 16-70%. Six sampleshave no material of fresh appearance; the remainder variesbetween 3-26%. The proportion of lightly modified material hasa similar range with three samples having no lightly modifiedmaterial.

Relationship between Biota andEnvironmental Variables

Several key environmental attributes vary between the species clus-ters (Table 4). Mean water depth varies substantially between the 7clusters, ranging from 24.5 m in Cluster 1 to 119 m in Cluster 4(Table 4). The grain size and carbonate content also show a largerange in values across the sites. The number of benthicforaminifera/g (BF/g) indicates a high organic flux in Cluster 2(Area A), compared to the exceptionally low flux in Cluster 1 (Site4, also Area A). The organic flux is more moderate across the

remaining clusters in areas B and C, with highest fluxes in Cluster6. There is no correlation between BF/g and grain size across thestudy sites, indicating that the benthic foraminiferal accumulation isnot a reflection of sediment transport. In the following section, therelationship between the distributions of the environmental vari-ables shown in Table 4 and the benthic foraminiferal assemblagesand the general biota are examined and tested.

Benthic Foraminifera

Analysis of individual parameters indicates that depth has a strongcorrelation to the site similarity expressed by the benthic assem-blages, with a Spearman’s rank correlation coefficient (Ds) of 0.68(Figure 11A). Stronger correlations were found when factors werecombined, with the best correlation observed for the combination of% gravel, % CaCO3 mud, depth, organic carbon flux, temperatureand salinity (Ds = 0.802). However, the combination of just threefactors, depth, organic carbon flux and salinity (DOS), explain near-

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Table 4. Average values for environmental variables within each species cluster

Cluster 1 Cluster 2 Cluster 3 Cluster 4 Cluster 5 Cluster 6 Cluster 7

%Mud 3.7 23.4±10.8 15.6±14 8.8±4.8 15.3±5.4 20.5±7.6 2.9±0.4%Sand 26.7 70.8±10.2 71.3±16 81.6±8 71.9±15.8 68.4±21.1 66.8±1.9%Gravel 69.6 5.8±4.8 13.1±10.1 9.6±8.1 12.8±11.8 11.1±16.5 30.2±2.3Mean grain N/A 299±142 277±132 305.9±97 251±47 200±106 623±39%CaCO3 M 0.4 2.8±0.8 10±10.7 7.3±3.9 10.5±3.1 15.2±6.8 2.2±0.6%CaCO3 T 92.1 54.4±11.6 62.5±22.2 64.2±19.4 54.4±14.8 72.8±16 93.8±3Water depth 24.5 31.3±2.0 61.9±14.1 119.2±40.4 76.6±12.9 81.7±28.5 50.0±0BF/g 395 4574±1403 2680±839 2663±921 1747±602 5176±1448 1727±850Temperature 28.9 28.7±0.3 27.5±0.2 25.4±0.4 27.2±0.7 27.1±0.9 27.5±0.4Salinity 34.48 34.50±0.08 34.91±0.06 35.15±0.03 34.97±0.09 34.95±0.13 34.95±0.1

Notes: ‘Mean grain’ refers to the mean grain size <2 mm, '%CaCO3 M' and '%CaCO3 T' refers to percentage carbonate in the mud fractionand in the total sample respectively, water depth is measured in metres, ‘BF/g’ is the number of benthic foraminifera in each gram of sand.There was insufficient material in the sand fraction to measure the mean grain size in sample 4 (Cluster 1).

Area A Area B Area C

Quinqueloculina spp.

fresh

light

moderatemoderate

light

fresh

moderatelight

fresh

relict relict

relict

04-070-10

heavyheavy

heavy

Figure 10. Relative preservation, averaged across each area, based on Quinqueloculina spp. Most sites have a high relict content, with mostmaterial of fresh appearance occurring in Area C.

ly the same degree of variance (Ds = 0.799) as for all 6 variables,indicating that these three factors are most strongly associated withvariations in the benthic assemblages across the sites. There is astrong correlation between salinity and water depth (R2 = 0.80), andthe strong association between these two factors and the benthicforaminiferal distributions emphasizes the influence of water depthand associated variables on the foraminiferal species. The strengthof this relationship is consistent with studies in other settings, asdiscussed later. The organic flux derived from the total number ofBF/g also correlates strongly with the species distributions. Therelationship between these three factors and the species distributionis illustrated in Figure 12, with the physical variables overlain onthe species similarity plot.

Total Microbiota

Compared to the benthic foraminifera, the total microbiota have amuch lower correlation to the measured environmental variables(Figure 11B). The highest correlation is Ds = 0.654, compared to Ds= 0.802 for the benthic foraminifera. Interestingly, however, therelationship to the environmental factors is similar for both analy-ses. The microbiota are most strongly correlated to the factors %gravel, %CaCO3, mud, depth, organic carbon flux, salinity andmean grain size. These factors differ from the benthic foraminiferaonly in the correlation to mean grain size, and the absence of a cor-relation to temperature. This result implies that the response of thebenthic foraminiferal species to the environmental gradients is sim-

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Figure 11. Spearman’s rank correlation for the relationship between benthic foraminiferal species abundances and environmental attributes(A) and abundances of microbiota and the same environmental attributes (B). The correlation to individual parameters (striped bars) ismuch lower than can be obtained with a multivariate approach (solid bars). The benthic foraminifera also show a much stronger correla-tion to the environmental variables.

BioEnv results

BioEnv results

Spearman Rank Correlation

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

Spearman Rank Correlation

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

04-070-11

A

B

% ud

emperature

alinity

epth

M G

S n

M

G

C 3 M

O

T

S

D

ean rain size

% ravel

% a d

% aCO ud

M

% ud

ean rain size

% aCO

emperature

% ravel

alinity

% aCO ud

epth

S n

M

M G

C

T

G

S

C M

D

% a d

(Total)

M G

rganic flux

O rganic flux

OGC D SM

OD S

GC D TSO

ilar to that of the whole micro-ecosystem. The stronger response ofthe foraminiferal species to the environmental parameters, howev-er, suggests that these organisms, when identified to species level,may provide a more robust technique for benthic habitat mapping.

DISCUSSION

Taphonomic Preservation

Overall Patterns

Evident from the study of preservation is the high proportion ofheavily modified and relict material present across the wholeregion, but particularly abundant in Area A. For this study, it isimportant to establish the likely cause of the high relict content, andtherefore whether the use of population data is valid in interpreting

environments. The most likely factors that affect the quantity ofdegraded material in samples are in situ reworking, due to low sed-imentation rates, or transport of material into (and out of) the sites.Because the samples were collected using a Smith-McIntyre grab,the foraminiferal population is likely to be somewhat biasedtowards older material than a sample collected strictly from the sed-iment surface. Abundant material of fresh appearance in some sam-ples, however, indicates that the sampling method is not the solecause of the high relict quantity.

In his discussion of living versus dead foraminiferal assem-blages, Murray (1982) suggests that a ratio of 1:1 would be expect-ed in areas with normal sedimentation rates, while in areas of lowsedimentation, the proportion of living material would be far lower,in the region of 1:10. An example quoted by Murray (1982) calcu-lates rates of 1:4 to 1:6. In this study, although staining was notundertaken as evidence of living populations, the fresh appearance

BENTHIC FORAMS AS ENVIRONMENT INDICATORS

341

Figure 12. Similarity between sites based on the benthic foraminiferal assemblage (A), with the variation in key environmental parametersacross this distribution shown by the bubbles for salinity (B), water depth (C) and organic carbon flux (D). This multi-dimensional scale plotis derived from the species similarity matrix, with the similarity in species composition between sites shown by their relative distance apart.Salinity and water depth increase across the species distribution, with high salinity and greatest depths towards areas B and C. Organic car-bon flux increases towards the lower left of the species distribution.

and light modification of specimens is used as an indication of therelative proportion of in situ production and relict reworking.

The percentages of tests of fresh appearance plus light abra-sion for both taxa in this study are <50% in all samples from AreaA, and typically below 20%, while in areas B and C, they are gen-erally higher and often above 50%. These patterns suggest sub-stantial differences in preservation between areas, possibly relat-ed to differences in sedimentation rates. Dating of cores collectedin areas A and C support this pattern of higher sedimentation with-in Area C compared to Area A. Vibrocores collected from Area Aindicate that Holocene carbonate material is present only in theupper 1 m of most cores, with a transgressive peat sequence belowthis (Harris et al., 2004). Vibrocore 21PC05 from Area A has alense of peat at 45 cm at the base of the Holocene carbonatesequence. Radiocarbon dating of this peat deposit indicates a cor-rected age of 9623 ± 71 years BP, and an age of 10,177 ± 49 yearsBP recorded for peat deposited at 3.1 m in this core (Figure 13;and the calibration based on Stuiver et al., 2005). The age of theupper peat deposit indicates a sedimentation rate of 4.7 cm/1000years within the carbonate sequence. Dating in Area C, based onthe foraminifera A. lessonii in gravity core 59GC17, yields a cor-rected radiocarbon age of 475 ± 38 years BP at a depth of 10 cm,with an age of 5655 ± 53 years BP at a depth of 2.95 m (Figure13). The sedimentation rate for this core in Area C is 52 cm/1000years, an order of magnitude higher than for the core in Area A.These patterns support the interpretation that the foraminiferalpreservation types reflect the relative age of the surface sediments,and are less affected by other chemical or physical processeswhich may degrade the carbonate shells.

The wide range of preservation types in these sediments sug-gests that the foraminifera represent a range of ages. This is prob-ably the biggest constraint on comparison to modern physico-chemical variables.

Differences between Areas

The presence of heavily reworked, large benthic foraminifera andbivalve shells in the gravel fractions of samples from Area A (Harriset al., 2004) suggests a high degree of reworking in situ, with longresidence times of the shells at, or near, the surface and little, orslow, modern sedimentation (Murray, 1991). Cores from the regionalso indicate low sedimentation rates (Harris et al., 2004, see abovediscussion). Such features are not characteristic of sediments inareas B and C. While bioerosion is present on lithoclasts from areasB and C, the intensity is far lower and large, heavily-eroded bio-clasts are absent from sediments.

The nature of the sediment also varies between the three areas.The sediment in Area A has a much higher terrigenous content, par-ticularly in the mud fraction (Harris et al., 2004). Sediments fromArea C typically have higher carbonate content. Lithics, wherepresent, are more commonly found in the sand fraction. Sedimentsfrom Area B are transitional between areas A and C. Lithics in sed-iment from Area C are found in samples from the channels (Harriset al., 2004). These samples are also those which contain the mostabundant relict foraminifera, as would be expected in an environ-ment which has been subject to high levels of sediment reworkingby currents.

The nature of the sedimentary environment can affect abrasionin benthic organisms. A study of abrasion of gastropods and bivalvesin terrigenous sediments shows much more rapid abrasion than incarbonate sediments due to the much more abrasive nature of silici-clastic sediment (Driscoll and Weltin, 1973). Grain size also influ-ences the effect, with the most rapid abrasion occurring in verycoarse sand, less in fine sand and least in medium sand. Mixed car-bonate and siliciclastic sediments produced more rapid abrasion offoraminifera than carbonate sediments (Moberly, 1968). Abrasion ofbivalves increases in either carbonate or mixed carbonate-siliciclas-tic environments with hard grounds, compared to pure siliciclasticenvironments (Best and Kidwell, 2000). The mixed siliciclastic-car-bonates over Area A would therefore suggest intense abrasion of theforaminiferal tests, while the dominantly fine-medium sand compo-nent would lessen the impact of the abrasion. The high abrasion inthis area is likely to reflect a long residence time near the sedimentsurface as a function of slower rates of accumulation.

Differences between Taxa

Experimental work to test the affects of abrasion on species preser-vation indicates that susceptibility to damage varies between taxa.After 2000 hours of tumbling (using foraminiferal specimens as theabrasive), which is equivalent to transport of 34-100 km, 81% of A.gibbosa tests were destroyed, compared to 68% of Q. tricarinatatests (Peebles and Lewis, 1991). However, the Quinqueloculinaspecimens were much more susceptible to dissolution than theAmphistegina specimens. A number of the species ofQuinqueloculina included in this study are more fragile thanAmphistegina sp. due to their relatively smaller mass. Experimentalstudies indicate that susceptibility to destruction by abrasion is con-trolled by size (Peebles and Lewis, 1991). Examples of these morefragile taxa include Q. subimpressa and Q. quinquecarinata.

As a result, the preservation index can be misleading because,particularly in Amphistegina sp., fragmentation can result in a testwhich rates as heavily degraded. In some cases, the surface preser-vation may be excellent, suggesting that the fragmentation hasoccurred relatively recently. This is quite different to a test whichhas heavy surface abrasion. For example, the surface of the testshown in Figure 2B is quite well-preserved although the degree ofbreakage is very high. This is in contrast to the specimen in Figure2D, which exhibits both surface degradation and test breakage. Ahigh level of breakage with relatively good surface preservationwas most evident in samples from Area C and may reflect the abun-dance of sand-sized clastics in some samples. A future refinementof the index, separating the effects of fragmentation from those ofsurface degradation, would be useful.

Transport Pathways across Torres Strait

The foraminiferal dataset provides insight into the longer term sed-iment transport across these areas, where the sediment samples inArea A represent the history over several thousands of years. Themechanical damage to foraminiferal tests collected across this studyregion confirms the low sedimentation rates as indicated by dating.Constraints provided by the species distributions suggest that mostof this reworking is occurring in situ, with very little cross-shelftransport. Transportation pathways across this region are short andare suggested by the angular surfaces on the sediment grains (Harris

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BENTHIC FORAMS AS ENVIRONMENT INDICATORS

343

Figure 13. Core logs for piston core 21PC05 (from Area A) and gravity core 59GC17 (from Area C). Radiocarbon dates are shown at thecollected depths, and are expressed as calibrated and reservoir corrected ages (based on Stuiver et al., 2005). The dates from piston core21PC05 were derived from peat, while those from piston core 59GC17 are from benthic foraminifera.

et al., 2004). A previous study in the Fly River delta by Cole (1995)indicated that foraminiferal transport occurs in bedload and sus-pended sediment transport, with material carried by tidal currentsvia the inter-reef channels. Evidence for this was shown through alandward increase in planktonic foraminifera. Across the samplesites, however, the relationship between planktonic foraminiferaand water depth is preserved, as it is also for many of the benthicforaminiferal species.

The consistency of the relationship between water depth andspecies abundance is particularly striking within areas B and C. Theshallower plateaux in these areas contain relatively higher abun-dances of shallow water species such as A. ammoinoides and A.papillosa (Figure 6A and B), while the adjacent channels containvery low abundances of these species. The deeper water species,such as S. pseudocarinata (Figure 6C), have relatively high abun-dances in the channels and other deeper water sites, and extremelylow abundances across the plateaux. These patterns imply that thefaunas within areas B and C have been preserved in situ and mini-mal transport within these areas has occurred. On this basis, therelationship between the faunas and other environmental attributesshould be well defined, as corroborated by their consistency to pub-lished relationships from other ocean basins (Murray, 1991; Van derZwann et al., 1999; Hayward et al., 2002) as discussed in the fol-lowing section.

The low energy of the mid- to outer-shelf environments ofareas B and C as seen from the foraminiferal preservation patternsand distributions is consistent with observations that suggest thatthe currents across areas B and C, sourced from the upwelling ofCoral Sea water, are very clear with little sediment in suspension,(Harris et al., 2004). The low sediment transport across Area C isalso shown by the muddy sand composition of sand waves sampledwithin the area, suggesting that modern sand mobilization is notoccurring (Harris et al., 2004). The greater taphonomic decay oftests within Area A is consistent with lower sedimentation rates inthe area, as shown also by radiocarbon dating.

Foraminiferal-Environment Relationships

Across the study sites, the benthic foraminiferal assemblages arestrongly correlated to changes in water depth, percent carbonatemud, percent gravel, organic carbon flux, temperature and salinity.These environmental preferences are consistent with those cited inthe literature for other ocean basins. In a study in the northernAdriatic Sea, Jorissen et al. (1992) notes that the foraminiferalspecies composition varies according to the downward flux oforganic matter and the associated oxygen levels, with areas whichexperience seasonally high organic fluxes characterized by oppor-tunistic species. Van der Zwann et al. (1999) note that species ofbenthic foraminifera have a strong response to organic carbon flux,depending on adequate oxygenation of the environment. The rela-tionship between foraminifera and depth is considered to mostlyreflect the associated change in oxygen concentration (Van derZwann et al., 1999). However, other factors which may be depthdependent, such as grain size, salinity and temperature can also beimportant (Murray, 1991; Hayward et al., 2002). Grain size affectsthe distribution of species in different environments due to the dif-ferent habitat modes of foraminiferal species. Gravel and larger

sized components in the sediment, for instance, may provide a habi-tat for those species which attach their tests to hard substrates, whilemuddy sediments may allow a higher proportion of infaunal species(Kitazato, 1994) The strong correlation between species distribu-tions and factors such as grain size, organic flux, depth, temperatureand salinity in this study are therefore consistent with known rela-tionships in other environments.

CONCLUSIONS

This study applied multivariate statistical techniques to determinethe relationships between benthic foraminifera and the wholemicrobiotic community to changes in the environment. Both groupsexhibit a similar association to the environmental gradients.However, the benthic foraminifera show a much stronger correla-tion. The benthic foraminifera are strongly correlated to changes inwater depth, percent carbonate mud, percent gravel, organic carbonflux, temperature and salinity. The application of a preservationindex, based on two foraminiferal genera, and taking into accountboth fragmentation and dissolution, provides a good indication ofthe degree of sediment reworking. However, the strength of theforaminiferal-environment relationship, even at fine scales, sug-gests that preservation is more strongly influenced by the low sedi-mentation rates rather than sediment reworking through transportacross this margin. The consistency between species distributionsand environmental variables, despite the high degree of degradationin many of the samples, provides much greater confidence in apply-ing benthic habitat mapping techniques around the Australian mar-gin, where sedimentation rates are low and reworking high.

ACKNOWLEDGMENTS

Our thanks to all those who provided the technical and scientificsupport for the survey on RV Franklin. In particular, we thank PeterHarris (Cruise leader, Geoscience Australia), Eric Madsen andBernie Heaney (CSIRO), Jon Stratton and Lyndon O’Grady(Geoscience Australia) and Kevin Hooper (James CookUniversity). Captain Ian Sinclair and the officers and crew of theRV Franklin are also thanked for their assistance during the voyage.Laboratory support was provided by Richard Brown, Tony Watson,Alex McLachlan and Neil Ramsay (Sedimentology Laboratory,Geoscience Australia). We thank Lynda Radke and Jon Clarke(Geoscience Australia), Daniela Schmidt (University of Bristol) andRobin Edwards (Trinity College, Dublin) for their constructivereviews of the manuscript. This paper is published with the permis-sion of the Executive Director, Geoscience Australia.

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APPENDIX I

Foraminiferal species list for abundance > 2 percent

Agglutinella arenata (Said)Ammomassilina alveoliniformis (Millet)Ammonia spp.Amphistegina papillosa SaidAmphistegina spp.Assilina ammonoides (Gronovius)Asterorotalia gaimardi (d'Orbigny)Cibicides refulgens (Montfort)Cibicides typeCibicidoides basilanensis McCullochDiscorbia typeElphidium crispum (Linné)Elphidium spp.Gaudryina spp.Hanzawaia spp.Heterolepa subhaidingeri (Parr)Loxostima spp.Melonis spp.Miniacina miniacea (Pallas)Neoconorbina spp.Neoeponides bradyi LeCalvezNeouvigerina spp.Nubeculina advena Cushman

Nummulites venosus (Fitchel and Moll)Peneroplis pertusus (Forskål)Plotnikovina timorea Loeblich and TappanPseudogaudryina pacifica Cushman and McCullochPseudotriloculina patagonica (d'Orbigny)Quinqueloculina crassicarinata CollinsQuinqueloculina incisa VellaQuinqueloculina philippinensis CushmanQuinqueloculina spp.Reussella spp.Rosalina spp.Siphoniferoides siphoniferous (Brady)Siphotextularia mestayerae VellaSpiroloculina subimpressa ParrSpiroplectinella pseudocarinata (Cushman)Spirosigmoilina parri CollinsTextularia cushmani SaidTextularia foliacea Heron-Allen and EarlandTextularia secasensis Lablicker and McCullochTextularia stricta CushmanTextularia truncata HöglundTextularia spp.Triloculina pseudooblonga (Zheng)

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Sample % % % % % Tot. no.no. fresh light moderate heavy relict analyzed

Area A234/1GR1A 1.92 11.54 28.85 57.69 0.00 52234/2GR2A 3.95 14.47 32.89 47.37 1.32 76234/3GR3A 2.11 6.32 23.16 48.42 20.00 95234/4GR4A 5.71 5.71 14.29 65.71 8.57 35234/5GR5A 2.33 11.63 27.91 56.98 1.16 86234/6GR6A 6.02 8.43 25.30 56.63 3.61 83234/7GR7A 3.28 6.56 21.31 68.85 0.00 61234/8GR8A 2.35 16.47 34.12 41.18 5.88 85234/9GR9A 6.03 12.07 30.17 51.72 0.00 116234/10GR10A 4.00 8.00 26.67 56.00 5.33 75234/11GR11A 4.17 13.89 27.78 54.17 0.00 72234/12GR12A 0.00 2.83 21.70 43.40 32.08 106234/13GR13A 3.57 8.93 25.00 58.93 3.57 56234/14GR14A 3.51 14.04 17.54 42.11 22.81 57234/15GR15A 2.75 13.76 31.19 52.29 0.00 109234/16GR16A 3.39 3.39 20.34 69.49 3.39 59234/17GR17A 8.96 19.40 31.34 34.33 5.97 67234/18GR18A 0.00 1.22 24.39 45.12 29.27 82234/19GR19A 10.14 13.04 27.54 49.28 0.00 69234/20GR20A 0.00 2.70 13.51 55.41 28.38 74234/21GR21A 2.78 23.61 34.72 37.50 1.39 72

Area B234/28GR22A 0.00 12.90 25.81 61.29 0.00 31234/29GR23A 15.52 29.31 36.21 17.24 1.72 58234/30GR24A 23.61 23.61 25.00 26.39 1.39 72234/31GR25A 14.06 10.94 37.50 34.38 3.13 64234/32GR26A 0.00 14.29 28.57 57.14 0.00 7234/33GR27A 16.48 23.08 19.78 37.36 3.30 91234/34GR28A 8.57 2.86 11.43 57.14 20.00 35234/35GR29A 0.00 12.00 24.00 48.00 16.00 25234/36GR30A 4.35 8.70 21.74 65.22 0.00 23234/37GR31A 10.45 14.18 14.93 39.55 20.90 134234/38GR32A 0.00 66.67 0.00 33.33 0.00 3234/39GR33A 11.90 11.90 30.95 40.48 4.76 42234/40GR34A 7.14 11.43 21.43 55.71 4.29 70234/41GR35A 22.22 22.22 22.22 33.33 0.00 9234/42GR36A 0.00 15.63 21.88 56.25 6.25 32234/43GR37A 7.89 13.16 21.05 50.00 7.89 38234/44GR38A 4.55 0.00 9.09 50.00 36.36 22234/45GR39A 0.00 20.00 40.00 40.00 0.00 10234/46GR40A 10.00 13.33 40.00 36.67 0.00 30234/47GR41A 15.38 8.97 37.18 37.18 1.28 78234/48GR42A 10.08 10.08 24.37 50.42 5.04 119

Sample % % % % % Tot. no.no. fresh light moderate heavy relict analyzed

Area C234/54GR43A 50.00 0.00 0.00 50.00 0.00 2234/55GR44A 16.67 20.83 37.50 25.00 0.00 24234/57GR45A 20.95 21.90 22.86 27.62 6.67 105234/58GR47A 0.00 25.00 25.00 25.00 25.00 4234/59GR48A 19.57 36.96 19.57 23.91 0.00 46234/60GR49A 0.00 66.67 0.00 0.00 33.33 3234/61GR50A 0.00 20.00 0.00 60.00 20.00 5234/62GR51A 11.11 11.11 66.67 11.11 0.00 9234/63GR52A 0.00 25.00 0.00 75.00 0.00 4234/64GR53A 6.90 3.45 13.79 44.83 31.03 29234/65GR54A 56.86 19.61 15.69 7.84 0.00 51234/66GR55A 14.63 4.88 29.27 46.34 4.88 41234/67GR56A 6.67 20.00 40.00 33.33 0.00 15234/68GR57A 13.51 18.92 16.22 48.65 2.70 37234/69GR58A 9.09 0.00 9.09 45.45 36.36 11234/70GR59A 11.76 31.37 19.61 25.49 11.76 51234/72GR60A 16.67 8.33 25.00 33.33 16.67 12234/73GR61A 0.00 40.00 40.00 20.00 0.00 5234/74GR62A 23.81 9.52 9.52 47.62 9.52 21234/75GR63A 8.33 0.00 25.00 58.33 8.33 12

APPENDIX II

Preservation levels of Amphistegina spp.

BENTHIC FORAMS AS ENVIRONMENT INDICATORS

347

Sample % % % % % Tot. no.no. fresh light moderate heavy relict analyzed

Area A234/1GR1A 0.00 13.64 13.64 50.00 22.73 22234/2GR2A 1.69 6.78 16.95 57.63 16.95 59234/3GR3A 0.00 0.00 14.71 58.82 26.47 34234/4GR4A 3.13 3.13 9.38 78.13 6.25 32234/5GR5A 1.27 15.19 26.58 46.84 10.13 79234/6GR6A 1.75 14.04 17.54 54.39 12.28 57234/7GR7A 0.00 28.00 12.00 60.00 0.00 25234/8GR8A 2.78 5.56 22.22 63.89 5.56 36234/9GR9A 0.00 0.00 23.08 61.54 15.38 26234/10GR10A 2.22 8.89 15.56 57.78 15.56 45234/11GR11A 4.76 14.29 33.33 47.62 0.00 21234/12GR12A 0.00 3.70 3.70 48.15 44.44 27234/13GR13A 0.00 6.45 16.13 41.94 35.48 31234/14GR14A 2.13 6.38 21.28 55.32 14.89 47234/15GR15A 2.50 12.50 27.50 50.00 7.50 40234/16GR16A 0.00 4.55 18.18 56.82 20.45 44234/17GR17A 3.13 0.00 31.25 59.38 6.25 32234/18GR18A 0.00 8.89 35.56 40.00 15.56 45234/19GR19A 4.35 10.87 17.39 65.22 2.17 46234/20GR20A 3.45 3.45 44.83 48.28 0.00 29234/21GR21A 0.00 6.06 18.18 66.67 9.09 33

Area B234/28GR22A 8.51 14.89 23.40 48.94 4.26 47234/29GR23A 6.67 46.67 0.00 46.67 0.00 15234/30GR24A 13.64 18.18 22.73 45.45 0.00 22234/31GR25A 0.00 11.76 11.76 47.06 29.41 17234/32GR26A 9.52 33.33 14.29 38.10 4.76 21234/33GR27A 18.75 6.25 12.50 50.00 12.50 16234/34GR28A 2.70 0.00 13.51 35.14 48.65 37234/35GR29A 0.00 10.71 21.43 50.00 17.86 28234/36GR30A 0.00 9.09 22.73 63.64 4.55 22234/37GR31A 10.53 10.53 26.32 36.84 15.79 19234/38GR32A 0.00 0.00 37.50 25.00 37.50 8234/39GR33A 4.55 13.64 9.09 27.27 45.45 22234/40GR34A 13.04 13.04 21.74 52.17 0.00 23234/41GR35A 0.00 33.33 0.00 50.00 16.67 6234/42GR36A 12.90 3.23 16.13 45.16 22.58 31234/43GR37A 6.90 13.79 31.03 34.48 13.79 29234/44GR38A 5.56 16.67 33.33 38.89 5.56 18234/45GR39A 6.82 20.45 22.73 43.18 6.82 44234/46GR40A 10.00 20.00 10.00 60.00 0.00 10234/47GR41A 0.00 9.09 18.18 54.55 18.18 11234/48GR42A 0.00 6.25 18.75 43.75 31.25 32

Sample % % % % % Tot. no.no. fresh light moderate heavy relict analyzed

Area C234/54GR43A 0.00 11.76 11.76 29.41 47.06 17234/55GR44A 9.09 9.09 45.45 36.36 0.00 11234/57GR45A 6.67 6.67 20.00 33.33 33.33 15234/58GR46A 0.00 15.38 15.38 69.23 0.00 13234/58GR47A 9.09 27.27 27.27 36.36 0.00 11234/59GR48A 21.43 7.14 14.29 28.57 28.57 14234/60GR49A 15.38 11.54 26.92 23.08 23.08 26234/61GR50A 25.81 12.90 22.58 19.35 19.35 31234/62GR51A 5.36 12.50 28.57 42.86 10.71 56234/63GR52A 8.33 25.00 0.00 33.33 33.33 12234/64GR53A 4.00 12.00 4.00 20.00 60.00 25234/65GR54A 24.00 28.00 32.00 16.00 0.00 25234/66GR55A 2.94 2.94 23.53 29.41 41.18 34234/67GR56A 0.00 9.09 18.18 63.64 9.09 22234/68GR57A 12.77 23.40 21.28 29.79 12.77 47234/69GR58A 11.76 23.53 5.88 23.53 35.29 17234/70GR59A 0.00 0.00 25.00 25.00 50.00 4234/72GR60A 10.53 0.00 10.53 36.84 42.11 19234/73GR61A 12.12 6.06 30.30 30.30 21.21 33234/74GR62A 0.00 0.00 4.55 36.36 59.09 22234/75GR63A 0.00 13.64 0.00 45.45 40.91 22

APPENDIX III

Preservation levels of Quinqueloculina spp.

348

POST ET AL.