Research Article Effects of Mangrove Zonation and …downloads.hindawi.com/journals/ae/2014/564056.pdfResearch Article Effects of Mangrove Zonation and the Physicochemical Parameters

Research ArticleEffects of Mangrove Zonation and the PhysicochemicalParameters of Soil on the Distribution of MacrobenthicFauna in Kadolkele Mangrove Forest a Tropical MangroveForest in Sri Lanka

Navodha Dissanayake and Upali Chandrasekara

Department of Zoology amp Environmental Management University of Kelaniya 11600 Kelaniya Sri Lanka

Correspondence should be addressed to Upali Chandrasekara upaliklnaclk

Received 21 August 2014 Accepted 17 November 2014 Published 16 December 2014

Academic Editor Junbao Yu

Copyright copy 2014 N Dissanayake and U Chandrasekara This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

The ecology of the macrobenthic fauna of the mangrove forests has received little attention compared to the mangrove flora Thepresent study was aimed at filling this information gap and investigated if the diversity and distribution of macrobenthic faunaat Kadolkele mangrove forest a pristine mangrove forest situated at the Negombo estuary in Sri Lanka are governed by themangrove zonation and variation of physicochemical parameters of the mangrove soil Since the aerial photographs identifiedthree distinct mangrove zones at Kadolkele namely Rhizophora Avicennia and Lumnitzera zones fauna were sampled andphysicochemical parameters of the soil were measured in belt transects that were established at each mangrove zone Data werecollected and analyzed using appropriate field sampling techniques and statistical methods respectively Results revealed that thephysicochemical parameters in soil varied between the three mangrove zones and that the distribution of benthic fauna followedthemangrove zonation Further the diversitymeasures of epifauna were found to be higher than those of the infauna of this tropicalestuary

1 Introduction

Mangroves are woody plants that grow at the interfacebetween land and sea in tropical and subtropical latitudeswhere they exist in conditions of high salinity extreme tidesstrong winds high temperature and muddy anaerobic soils[1] Mangrove forests provide shelter food and breeding sitesfor a large number of marine and terrestrial organisms [2]and are also important to humans for a variety of reasonsincluding fisheries tourism agriculture forestry protectionagainst shoreline erosion source of fire-wood and buildingmaterial and other local subsistence uses [1 3]

Mangrove forests can truly be considered as evolutionaryhotspots where terrestrial species have readapted to marinelife and marine species have undergone the transition toterrestrial life [4] The mangrove forest floors harbour adiverse and distinct assemblage of benthic organisms thatrange in size from the minute bacteria and protozoans to

larger (05mm lt size) invertebrates termed as macrobenthos[5] Kumar and Khan [6] emphasized that the distributionabundance and diversity of these mangrove benthic inverte-brates and their relationships to environmental conditions areimportant parts of understanding the structure and functionof mangrove ecosystems

As a detritus based ecosystem leaf litter from the man-groves provides the basis for adjacent aquatic and terrestrialfood webs [7] where the macrobenthos typically occupy thesecond and third trophic levels [8]Most of themacrobenthosassist in the breakdown of particulate organic matter byexposing them to microbes by shredding and their wastematerials contain rich nutrients forming the food for otherconsumers Alongi and Christoffersen [9] emphasized thatthe variations in the distribution and abundance of epiben-thos of themangrove area relate positively to variations in thequantity of exported detritus

Hindawi Publishing CorporationAdvances in EcologyVolume 2014 Article ID 564056 13 pageshttpdxdoiorg1011552014564056

2 Advances in Ecology

Polychaetes gastropods and crustaceans are regardedto be the major macrobenthic organisms in the mangrovesediment The distribution of macrobenthos may vary fromhabitat to habitat within the same mangrove forest Forexample a study carried out by Ellison [10] revealed that thedensity and the biomass of crabs and snails are higher in theyoung mangrove stands than in the intermediate aged standsof Rhizophoraceae These macrobenthic organisms have aprofound effect on the sedimentary environment throughtheir feeding burrowing and ventilatory activities

Macrobenthic assemblage structure is influenced by localenvironmental conditions such as hydroperiod organicmat-ter availability and sediment characteristics [11] Thereforethe mangrove forest is considered to have physical chemicaland biological processes which promote the adaptation ofinhabiting organisms to tolerate greater amplitude of envi-ronmental characters both morphologically and physiologi-cally [7]

Mangrove communities often exhibit distinct patterns ofspecies distribution governed by the complexity of environ-mental factors [12 13] and competition between individualsThe local patterns of tidal inundation influence soil character-istics that control species zonation of mangrove forests [12]With the zonation of mangrove vegetation invertebrates mayoften exhibit amarked zonation pattern and colonize a varietyof specific microenvironments [7] This zonation could takeplace either horizontally or vertically [14] where some speciesdwell on the sediment surface or reside in burrows whileothers live on pneumatophores and lower tree trunks or proproots burrow in decaying wood or can even be found in thetree canopies [15]

Sedimentary characteristics in mangrove forests play amajor role in structuring benthic communities in comparisonto other physicochemical variables According to Safahiehet al [14] the distribution of macrobenthos is mainly deter-mined by the sediment grain size salinity and availability ofwater When there are extreme fluctuations in the physicalfeatures then the abundance of benthic species may decline[1] The spatial occurrence of these fauna is highly irregularthus contributing to both the complexity and heterogeneityof the habitat [11] The most successful benthic species of amangrove forest are the ones who can easily adapt to theprevailing physical properties of that ecosystem

Although there is a wealth of knowledge on the impor-tance of mangroves on a global scale information related tothe ecology of the associated benthic fauna is scanty As forthe Kadolkele mangrove forest in Negombo estuary in SriLanka the above is particularly true where a study carriedout by Priyadarshani et al [16] is perhaps the only detailedstudy focused on the mangrove faunal diversity even thoughtheir study is confined only to the mangrove crabs Yet thediversity and the distribution of macrobenthos existing inthis mangrove forest floor are vast and have not been givendue consideration The present study was therefore designedand carried out to investigate some aspects of the ecologyof macrobenthic fauna of the Kadolkele mangrove forestin relation to the mangrove zonation and physicochemicalparameters of soil

2 Materials and Methods

21 The Study Site The present study was carried out atthe Kadolkelemangrove forest (7∘111015840498210158401015840N 79∘501015840322910158401015840E)(Figure 1) It is situated at the northern extremity of theNegombo estuary of Sri Lanka and is a pristine and relativelyundisturbed small mangrove forest patch that extends withinan area of 10 ha [17] It is also a popular site for mangroverelated field studies [16]

The geographic region of the study area receives anaverage annual rainfall of 2400mm and a monthly high-est rainfall of 348mm during October to November Theaverage temperature varies between 24∘C and 30∘C [18] TheKadolkele mangrove forest contributes to a high productivityand hence supports the ecological balance of the adjacentNegombo estuarine ecosystem [19]

There is a great diversity of mangroves in the Kadolkelemangrove forest According to Dahanayake and Sumanadasa[20] 29 mangrove species are found there and of those 18 areconsidered to be true mangroves They also have recorded33 other mangrove associated vegetation types The highestabundance of mangroves is from the 3 mangrove familiesnamely Rhizophoraceae Avicenniaceae and CombretaceaeThe most abundant species from family Rhizophoraceae areRhizophora apiculata and Rhizophora mucronata Avicenniamarina is the dominant species from family Avicenniaceaewhile Lumnitzera racemosa is the most commonly foundspecies in family Combretaceae in this mangrove forest [20]

There is a distinct mangrove zonation pattern in theKadolkele mangrove forest (Figure 2) For example a narrowmangrove zone approximately 3m in width occupies atthe estuary-land interface and is dominated by Rhizophoraspecies Avicennia species grow at the middle zone and thewidth of this zone is approximately 15m Lumnitzera speciesare more abundant in the deeper areas of the mangrove forestwhere the width ranges from 50m to 30m

22 Field Sampling Three belt transects 40m in length and3m width each were established in the middle of eachmangrove zone (Figure 2) The transects were demarcated byerecting coloured wooden posts at the four corners of eachtransect Along each transect 12 quadrat areas of 2m times 2mwere marked in a similar manner with a 2m gap in betweenTheGPS locations of these transects were recorded separatelyusing a portable Global Positioning System (Garmin-eTrexSUMMIT)

The number of mature mangrove trees mangroveseedlings up to 1m in height and their pencil roots withineach quadrat area were counted separately and recordedThe number of crab holes present in each quadrat were alsocounted and recorded These crab holes were not dug forcrabs due to logistic reasons Therefore it was assumed thateach crab hole is occupied by a single crab of the commonestcrab species recorded previously in each mangrove zone byPriyadarshani et al [16] and that the number of crab holesequals the number of crabs there

The different species of epifauna on the mangrove forestfloor and those who were sitting on the mangrove stemsseedlings and pencil roots to a height of 05m above

Advances in Ecology 3

79∘499984000998400998400E 79∘4999840020998400998400E 79∘4999840040998400998400E 79∘509984000998400998400E 79∘5099840020998400998400E 79∘5099840040998400998400E 79∘519984000998400998400E

79∘499984000998400998400E 79∘4999840020998400998400E 79∘4999840040998400998400E 79∘509984000998400998400E 79∘5099840020998400998400E 79∘5099840040998400998400E 79∘519984000998400998400E

7∘139984000998400998400N

7∘1299840040998400998400N

7∘1299840020998400998400N

7∘129984000998400998400N

7∘1199840040998400998400N

7∘1199840020998400998400N

7∘119984000998400998400N

7∘1099840040998400998400N

7∘139984000998400998400N

7∘1299840040998400998400N

7∘1299840020998400998400N

7∘129984000998400998400N

7∘1199840040998400998400N

7∘1199840020998400998400N

7∘119984000998400998400N

7∘1099840040998400998400N

Kadolkele mangrove forest

Negombo estuary

N

0 04 08 16(km)

Mangrove area

Figure 1 The map of Negombo estuary showing the Kadolkele mangrove forest The location of Negombo estuary in the west coast of SriLanka is also shown

the ground level within each quadrat area were carefullyobserved counted separately and recorded These epifaunawere identified in situ using standard field identification keysof Pinto [3] and Fernando [21] Representative specimens ofthose who were counted but not identified at the site werecollected preserved in 5 formalin and identified later at thelaboratory

Five soil samples were collected from within randomlocations of each quadrate to a depth of 15 cm each usinga soil corer of 6 cm in diameter These soil samples were

wet sieved using a 05mm sieve The residues retained onthe sieve were transferred into labeled polythene bags andpreserved in a solution of 5 formaldehyde containing RoseBengal The fauna in each sample was separated identifiedand enumerated later at the laboratory

Before the soil core samples were wet sieved the approx-imate length of the black coloured soil Redox layer ineach soil sample was measured in situ using a meter rulerThe soil penetrability from within 15 random locations ofeach quadrate area was also measured in situ following


Negombo estuary


0 02 04(km)

L

AR

R = Rhizophora zoneA = Avicennia zoneL = Lumnitzera zone

Figure 2 Aerial photograph of the Kadolkele mangrove forestshowing the distinct mangrove zonation There are three mangrovezones in this mangrove forest Rhizophora zone (R) Avicennia zone(A) and the Lumnitzera zone (L) Three belt transects displayedas white rectangles on the photograph were established along thecenter of each zone for sampling in the present study The GPSlocations of theLumnitzera transectAvicennia transect and theRhi-zophora transect were 7∘191015840559410158401015840N 79∘841015840410110158401015840E 7∘191015840577610158401015840N79∘841015840400310158401015840E and 7∘191015840611410158401015840N 79∘841015840380310158401015840E respectively Imagesource Google Earth satellite maps

the Bob James Pointy Stick method In addition 3 soilcore samples 6 cm in diameter and 15 cm deep each werecollected separately into labeled air tight sealed polythenebags for the determination of soil moisture content organicmatter content pH salinity conductivity and particle sizedistribution later at the laboratory

The study had many field visits that were carried outduring the period of one and a halfmonths starting from Juneto July 2013

23 Laboratory Studies After returning to the laboratoryfrom each field visit the soil moisture content organicmatter content particle size distribution pH conductivityand salinity of the soil samples were determined separatelyusing the methods described below

The soil moisture content was determined by drying themoist soil samples in an oven at 105∘C for 24 hours untila constant weight is gained The organic matter content ofthese dried samples was determined by the dry combustionmethod described by Williams [22] The particle size distri-bution was determined as approximate fraction of sand siltand humus using the method described by Brady and Weil[23]

The soil pH was measured using a digital pH meter(315iSET) after making a soil suspension by adding distilledwater into soil at 1 2 ratio following Jackson [24] Electricalconductivity and salinity of soil were determined using

a digital conductivity meter (Cond 340iSET) by addingdistilled water into soil at 1 5 ratio following Jackson [24]

In the meantime the infauna sampled from the 3 man-grove zones and the epifauna that we did not identify at thefield were identified to the nearest possible taxonomic cate-gory under the binocular microscope using the identificationkeys of Fernando and Mendis [25] and Fernando [21] Pillai[26] Quigley [27] Fauchald [28] Pinto [3] andNesemann etal [29] and enumerated separately

24 Data Analysis The total and percentage abundance ofthe infauna and epifauna recorded in the 3 mangrove zoneswere calculated separately The abundance variation of themost dominant taxa between the 3 mangrove zones wereanalyzed by one-way ANOVA When the ANOVA yielded asignificant result Tukeyrsquos pairwise comparison tests were car-ried out in a pairwisemanner to test for significant differencesbetween the 3 mangrove zones The species richness (SR)Pieloursquos species evenness index (119869) and Shannon Wienerspecies heterogeneity index (1198671015840) with respect to epifaunaland infaunal communities were calculated separately for eachmangrove zone following the diversity indices described inMagurran [30]

The variation of soil pH conductivity salinity moisturecontent organic matter content sand silt clay penetrability and depth of the redox length layer between the3 mangrove zones were analyzed by one-way ANOVAWhenthe ANOVA yielded a significant result Tukeyrsquos pairwisecomparison tests were carried out in a pairwise manner totest for significant differences between the 3 mangrove zones

In order to identify the dominant macrobenthic faunaand sediment characteristics the mean abundance valuesof the epifaunal taxa and the physicochemical parametersbetween the 3 zones were analyzed separately using theprincipal component analysis (PCA) Since there were only2 dominant infaunal taxa PCA was not carried out for theinfaunal community

There were more abundant as well as less abundantinfaunal and epifaunal taxa recorded in the 3 mangrovezones As the data analysis and result interpretation becomeextremely complex and complicated with these less abundanttaxa only the more abundant infaunal taxa (ie infauna withthe total abundance of more than 97) and epifaunal taxa(ie epifauna with the total abundance of more than 90)were considered for the above PCA and one-way ANOVAfollowing Melles et al [31] Finally the relationships betweenthe species richness species heterogeneity and species even-ness of the infaunal community with the score set 1 of thePCA for physicochemical parameters of soil were analyzedseparately using regression analysis The data were analyzedusing the statistical software packages of Minitab version105 for Windows and Primer version 42 for Windows asappropriate at 120572 = 005 level of significance

3 Results

The Rhizophora zone and the Avicennia zone are dominatedonly by the mature trees pencil roots and the seedlings of


Rhizophora and Avicennia species respectively No any otherplant species was recorded from these two zones The upperLumnitzera zone is dominated mostly by the Lumnitzeramature trees and their seedlings (Table 1)

Altogether 7 infaunal taxa belonging to 3 invertebratephyla were recorded from the 3 mangrove zones (Table 2)These 7 taxa were Limnodrilus sp Neanthes negomboensisDorylaimus stagnalis Lembos sp Holotrichia sp Entomo-bryoides sp and tabanid larvae Of these 7 taxa the mostabundant was the Limnodrilus sp (9477) followed by Nnegomboensis (282) Together these 2 taxa accounted formore than 97 of the total infaunal abundance Further theLimnodrilus sp dominated at the Rhizophora and Lumnitzerazones with a relative abundance of 96 and 9435 respec-tively However there were no any infaunal taxa recordedfrom the middle Avicennia zone (Table 2)

The total abundance (119873) species richness (SR) speciesheterogeneity (1198671015840) and species evenness (119869) of the infaunalcommunity varied between the 3 zones (Table 3) As therewere no any infaunal taxa in the middle Avicennia zone theabove diversity indices were ldquo0rdquo there The total abundancespecies richness and species heterogeneity of the infaunalcommunity were higher in the Lumnitzera zone than those inthe Rhizophora zone The infaunal community however waslittle more evenly distributed in the Rhizophora zone than inthe Lumnitzera zone (Table 3)

In summary there weremany infaunal taxa in large num-bers (ie high species richness and high total abundance) inthe upper Lumnitzera zone so that the infaunal community ismore diverse there (ie high species heterogeneity) than thatin the lower Rhizophora zone

Of the 2 dominant infaunal taxa Limnodrilus sp wassignificantly more abundant in the upper Lumnitzera zonethan in the Rhizophora zone (119875 lt 005 Tukeyrsquos pairwisetest after one-wayANOVA) (Table 4)Neanthes negomboensiswas found in more or less similar numbers in both theRhizophora and Lumnitzera zones (119875 gt 005 one-wayANOVA)

In addition to the above infaunal taxa 11 other epibenthictaxa belonging to phylumMollusca and phylum Arthropodawere also recorded from the 3 mangrove zones (Table 5)These 11 taxa were Cassidula nucleus Melampus fasciatusClibanarius longitarsus Episesarma versicolor Sesarma gut-tatum unidentified crab species Sesarma smithii Oecophyllasmaragdina Paratrechina longicornis Solenopsis geminataand Tetragnatha viridorufa Of them 6 epibenthic taxa thatis C nucleus (3688) E versicolor (348) S guttatum(2775) S smithii (391) P longicornis (720) and Sgeminata (1411) contributed to more than 90 of the totalepibenthic abundance (Table 5)

As in the infaunal community the total abundance (119873)species richness (SR) species heterogeneity (1198671015840) and speciesevenness (119869) varied between the 3 mangrove zones (Table 6)Compared to the infaunal community however total abun-dance species richness and species heterogeneity of theepifaunal communitywere higher in theRhizophora zone andhigher than those in the Lumnitzera andAvicennia zonesThe

Sesarma guttatum Solenopsis geminata

Sesarma smithiiParatrechina longicornis

Cassidula nucleus

Avicenniazone

Rhizophorazone

Lumnitzerazone

PC1

PC 2

15

10

05

0

minus05

minus10

minus15

minus25 minus20 minus15 minus10 minus05 0 05 10 15 20

Figure 3 Ordination of the 3 mangrove zones based on the PC1and PC2 scores of principal component analysis of the epifaunalcommunity in Kadolkele mangrove forest (see also Table 7 forfurther details)

middle Avicennia zone recorded the highest species evennessthan that of the other 2 zones (Table 6)

In summary although there were many epifaunal indi-viduals in the Lumnitzera zone (ie high total abundance)the epifaunal community there was dominated by one or afew taxa (low species richness and low species evenness) Inthe middle Avicennia zone there were no dominating taxaand that the abundance of the existing taxa was more or lesssimilar to each other (ie low species richness high speciesheterogeneity and high evenness) In the Rhizophora zonehowever there were many taxa (ie high species richness)with high number of individuals in each taxontaxa (ie highspecies heterogeneity)

Themost abundant epifaunal taxon characteristic to eachmangrove zone is identified by the principal componentanalysis (PCA) According to the PCA analysis carried outfor the 6 most abundant epifaunal taxa the Lumnitzera zoneAvicennia zone and Rhizophora zone were characterized bySesarma guttatum Sesarma smithii and Cassidula nucleus(nucleus Cassidula snail) respectively (Figure 3) FurtherLumnitzera and Avicennia zones are also characterized bySolenopsis geminata (red tropical fire ant) and Paratrechinalongicornis (black ant) respectively

The above PCA result was further endorsed by the one-way ANOVA carried out to test for the abundance of majorepifaunal taxa between the 3 sites A summary of the one-way ANOVA for the 3 mangrove zones is given in Table 8The abundance of Sesarma guttatum Sesarma smithii andCassidula nucleus (nucleus Cassidula snail) was significantlyhigh in the Lumnitzera zoneAvicennia zone and Rhizophorazone respectively (119875 lt 005 Tukeyrsquos pairwise test after one-way ANOVA) Episesarma versicolor (violet vinegar crab)and Paratrechina longicornis (black ant) were significantlyabundant in the middle Avicennia zone (119875 lt 005 Tukeyrsquospairwise test after one-way ANOVA)

Of the physicochemical parameters measured in thesediment PCA analysis showed that the Rhizophora zone is


Table 1 Summary of the vegetation structure of the 3 mangrove zones in Kadolkele mangrove forest Negombo Values are mean plusmn SE andrange in parenthesis (119899 = 12 quadrat samples from each mangrove zone)

Vegetation structure Mangrove zoneRhizophora Avicennia Lumnitzera

Rhizophora zone

Rhizophoramature trees 17 plusmn 041 0 0(0ndash5)

Rhizophora seedlings 95 plusmn 164 0 0(2ndash21)

Rhizophora pencil roots 654 plusmn 1270 0 0(16ndash179)

Avicennia zone

Avicenniamature trees 0 075 plusmn 013 0(0-1)

Avicennia seedlings 0 2933 plusmn 579 0(0ndash62)

Avicennia pencil roots 0 359 plusmn 3060 0(215ndash538)

Lumnitzera zone

Lumnitzeramature trees 008 plusmn 008 0 417 plusmn 064(0-1) (1ndash8)

Lumnitzera seedlings 0 0 017 plusmn 017(0ndash2)

Lumnitzera pencil roots 0 0 0

Table 2 The relative abundance of the infaunal taxa recorded from the 3 mangrove zones in Kadolkele mangrove forest (119899 = 60 soil coresamples from each mangrove zone)

Total abundance in each zone and

Phylum Family Genusspecies relative abundance () in parenthesis Total abundanceall 3 zones

Relativeabundance

()Rhizophora

zoneAvicenniazone

Lumnitzerazone

AnnelidaTubificidae Limnodrilus sp

(oligochaete worms) 120 (96) 0 (0) 351 (9435) 471 9477

Nereididae Neanthes negomboensis(polychaete worm) 4 (32) 0 (0) 10 (269) 14 282

Nematoda Dorylaimida Dorylaimus stagnalis(round worm) 0 (0) 0 (0) 2 (054) 2 040

Arthropoda

Aoridae Lembos sp (amphipod) 0 (0) 0 (0) 6 (161) 6 121Scarabaeidae Holotrichia sp (white grub) 0 (0) 0 (0) 1 (027) 1 020

Entomobryidae Entomobryoides sp(slender springtail) 1 (08) 0 (0) 1 (027) 2 040

Tabanidae Tabanid larvae(horse fly larvae) 0 (0) 0 (0) 1 (027) 1 020

Species richness 3 0 7Total abundance of infauna 125 0 372 497 100

characterized by the higher depth of redox layer high pHand high sand silt and clay percentages while the upperLumnitzera zone is characterized by high pH high clay andhigh penetrability of soil The soil moisture content organicmatter content conductivity salinity and penetrability werehigh in the middle Avicennia zone (Figure 4)

A summary of the ANOVA and variation of the physic-ochemical parameters between the 3 mangrove zones isgiven in Table 10 Almost all these parameters varied eithersignificantly or not significantly between the 3 mangrovezonesThisANOVAendorsedmost of the above PCAanalysis(Figure 4) (Table 9) For example the depth of the redox layer


Table 3 Variation of the total abundance (119873) species richness (SR)species heterogeneity (1198671015840) and species evenness (119869) of the infaunalcommunity between the 3 mangrove zones in Kadolkele mangroveforest (119899 = 60 soil core samples in each zone)

Measure of the infaunaldiversity

Rhizophorazone

Avicenniazone

Lumnitzerazone

Total abundance (119873) 125 0 372Species richness (SR) 3 0 7Species heterogeneity(1198671015840) 019 0 029

Species evenness (119869) 017 infin 015

Table 4 Summary of the 2 major infaunal taxa that contributed tomore than 97 of the total species abundance of the 3 mangrovezones in Kadolkele mangrove forest (119899 = 60 soil core samples fromeach zone)

Infauna taxa Rhizophorazone

Avicenniazone

Lumnitzerazone

Limnodrilus splowast(oligochaete worms)

200 plusmn 040a(0ndash16) 0b 585 plusmn 095c

(0ndash29)Neanthes negomboensislowast(polychaete worm)

007 plusmn 003ab(0-1) 0a 017 plusmn 005b

(0ndash2)Note Values aremeanplusmn SE range in parenthesis Different superscript lettersin a row denote significant differences (119875 lt 005) indicated by Tukeyrsquospairwise significant difference test lowast indicates significantly calculated 119875value detected by ANOVA

clay and pHwere significantly high in theRhizophora zone(119875 lt 005 Tukeyrsquos pairwise test after one-way ANOVA)The soil moisture content organic matter content and soilpenetrability were significantly high in the middle Avicenniazone (119875 lt 005 Tukeyrsquos pairwise test after one-way ANOVA)Further soil pH penetrability and clay were significantlyhigh in the upper Lumnitzera zone (119875 lt 005 Tukeyrsquospairwise test after one-way ANOVA)

Although not significant the total abundance speciesrichness and species heterogeneity increased with theincreasing depth of the redox layer pH clay silt andsand of the sediment (119875 gt 005 regression analysis)(Figures 5 6 and 7) while the species evenness increasedsignificantly with the same (119875 lt 005 regression analysis)(Figure 8)

4 Discussion

Thepresent study was carried out to investigate themangrovezonation and the way in which the physicochemical param-eters of the sedimentary environment affect the distributionand diversity of macrobenthic fauna in the Kadolkele man-grove forest in Negombo estuary The study initially revealedthat there is a distinct mangrove zonation in this mangroveforest where Rhizophora sp occupied the estuarine waterfrontage Lumnitzera sp occupied the landward side whileAvicennia sp dominated in between the above 2 zonesA study by Jayakody et al [32] has also shown a similarmangrove zonation in Kadolkele mangrove forest

PC1

PC2

High length of redox layer

High clay ()High sand ()High silt ()

High pHHigh clayHigh soil

penetrability

High soil moisture contentHigh organic matter contentHigh conductivityHigh salinityHigh soil penetrability

Rhizophorazone

Avicenniazone

Lumnitzerazone

15

20

10

05

0

minus05

minus10

minus15

minus20minus4 minus3 minus2 minus1 0 1 2

Figure 4 Ordination of the 3 mangrove zones based on PC1 andPC2 scores of PCA of the physicochemical parameters of soil inKadolkele mangrove forest Rhizophora zone is characterized bythe higher depth of redox layer high pH and high sand siltand clay percentages while upper Lumnitzera zone is characterizedby high pH high clay and high penetrability of soil The soilmoisture content organic matter content conductivity salinity andpenetrability are high in the middle Avicennia zone (see also Table 9for further details)

0

100

200

300

400

0 1 2 3

Tota

l abu

ndan

ce (N

)

PC1 scores on physicochemical parameters

Lumnitzerazone

Avicenniazone

High pHHigh redox lengthHigh clay ()High sand ()High silt ()

High soil moistureHigh organic matterHigh conductivityHigh salinityHigh penetrability

Rhizophorazone

minus4 minus3 minus2 minus1

y = 48276x + 16567

R2 = 047

Figure 5 The relationship between the total abundance of infaunalcommunity and PC1 scores for physicochemical characteristics ofsoil in the 3 mangrove zones in Kadolkele mangrove forest

In spite of the understanding of ecological economicand social importance of the Kadolkele mangrove forest [32ndash36] little is known about the ecology of its macrobenthicfauna Therefore the present study was designed focusing onsome aspects of the ecology of these macrobenthic fauna andshowed that they exhibited a distinct variation in parallel tothe variation of physicochemical parameters of soil betweenthe 3 mangrove zones there


Table 5 The total and relative abundance of the epifaunal taxa recorded from the 3 mangrove zones in Kadolkele mangrove forest (119899 = 12quadrate samples from each mangrove zone)

Total abundance in each zone

Phylum Genusspecies Relative abundance () in parenthesis Total abundance(3 zones)

Relativeabundance

()Rhizophora

zoneAvicenniazone

Lumnitzerazone

Mollusca

Cassidula nucleus(nucleus Cassidula snail) 784 (6981) 0 (000) 0 (000) 784 3688

Melampus fasciatus(banded melampus snail) 50 (445) 0 (000) 0 (000) 50 235

Arthropoda

Clibanarius longitarsus(hermit crab) 17 (151) 0 (000) 0 (000) 17 080

Episesarma versicolor(violet vinegar crab) 22 (196) 52 (2023) 0 (000) 74 348

Sesarma guttatum 18 (160) 0 (000) 572 (7668) 590 2775Unidentified crab species 22 (197) 0 (000) 0 (000) 22 103

Sesarma smithii 0 (000) 83 (323) 0 (000) 83 391Oecophylla smaragdina (dimiya) 49 (436) 0 (000) 0 (000) 49 230

Paratrechina longicornis(black ant) 26 (232) 116 (4514) 11 (147) 153 720

Solenopsis geminata(Red tropical fire ant) 133 (1184) 5 (194) 162 (2172) 300 1411

Tetragnatha viridorufa(common long jawed orb weaver) 2 (018) 1 (039) 1 (013) 4 019

Species richness 10 5 3Total abundance of epifauna 1123 257 746 2126 100

Table 6 Variation of the total abundance (119873) species richness (SR)species heterogeneity (1198671015840) and species evenness (119869) of epifaunalcommunity between the 3 mangrove zones in Kadolkele mangroveforest (119899 = 12 quadrat samples from each zone)

Measure of the epifaunaldiversity

Rhizophorazone

Avicenniazone

Lumnitzerazone


Species evenness (119869) 05 071 044

Mangrove soils are typically saline anoxic acidic andfrequently waterlogged These soil properties directly affectthe distribution and condition of the mangrove forests [212] Starting from the margin of the Negombo estuary(ie Rhizophora zone) towards more landward side (ieLumnitzera zone) in the Kadolkele mangrove forest it wasfound that the soil moisture content salinity conductivitysand and length of redox layer decreasedwhile the soil pHorganic matter content soil surface penetrability silt andclay increased This is the general pattern in almost all themangrove forests in the world [1]

0

5

10

0 1 2 3

Spec

ies r

ichn

ess

Lumnitzerazone

Avicenniazone

Rhizophorazone


PC1 scores on physicochemical parametersHigh soil moistureHigh organic matterHigh conductivityHigh salinityHigh penetrability


y = 099x + 333

R2 = 058

Figure 6The relationship between the species richness of the infau-nal community and PC1 scores for physicochemical characteristicsof soil in the 3 mangrove zones in Kadolkele mangrove forest

The soilsediment in the Rhizophora zone registeredcomparatively high moisture content and was found that thesediment is mostly wet Owing to the fact that the Rhizophorazone experiences the tidal inundation with O

2saturated


Table 7 Summary of the eigenvalues eigenvectors and PCA scores of the epifaunal community of the 3 mangrove zones in Kadolkelemangrove forest

EigenvaluesPC Eigenvalues Variation Cum variation1 447 746 7462 153 254 1000

EigenvectorsVariable PC1 PC2Cassidula nucleus (Nuclues Cassidula snail) 0129 0779Sesarma smithii minus0458 minus0197Episesarma versicolor (Violet vinegar crab) minus0464 0152Sesarma guttatum 0338 minus0565Paratrechina longicornis (Black Ant) minus0470 minus0092Solenopsis geminata (Red tropical fire ant) 0472 0058

Principal component scoresSample Score 1 Score 2Rhizophora zone 0669 1372Avicennia zone minus2369 minus0348Lumnitzera zone 1700 minus1024

Table 8 Summary of the 6 major epifaunal taxa that contributed to more than 90 of the total species abundance in the 3 mangrove zonesin Kadolkele mangrove forest (119899 = 12 quadrate samples from each zone)

Epifauna species Rhizophora zone Avicennia zone Lumnitzera zone

Cassidula nucleuslowast 6530 plusmn 1360a 0b 0b(5ndash158)

Episesarma versicolorlowast(violet vinegar crab)

183 plusmn 089a 433 plusmn 150a 0b(0ndash10) (0ndash20)

Sesarma guttatumlowast 150 plusmn 073a 0a 4767 plusmn 424b

(0ndash8) (24ndash76)

Sesarma smithiilowast 0a 692 plusmn 087b 0a(3ndash12)

Paratrechina longicornis(black ant)

217 plusmn 010 967 plusmn 852 092 plusmn 054(0ndash10) (0ndash103) (0ndash6)

Solenopsis geminata(red tropical fire ant)


Note Values are mean plusmn SE range in parenthesis Different superscript letters in a row denote significant differences (119875 lt 005) indicated by Tukeyrsquos pairwisesignificant difference test lowast indicates significantly calculated 119875 value detected by ANOVA

estuarine water twice a day causes to increase the moisturecontent in the soil of this zone This zone also contained ahigh amount of sand and silt When the sand percentageincreases the pore spaces are also increased [37] so that theoxygen rich water seeps in creating oxidized condition in soilThis O

2rich moist soil leads to high rate of aerobic microbial

decomposition in this zone and makes the depth of its redoxlayer more wider than those in the other two zones

During the study period a frequent water logged con-dition was observed in the middle Avicennia zone It isnoteworthy that the ground level of this zone is a little lowerand depressed than in the Rhizophora and Lumnitzera zonesThe slow watershed thus resulting in this zone leads the tidewater as well as the rain water to retain for a longer timeThiswas further proven by the presence of very high percentage of

soil moisture in this zone The soil organic matter content ofthis zone was also significantly high compared to the othertwo zones perhaps as a result of the continuous accumulationof organicmatter in this zone due to poor watershed Furtherthis zone recorded the highest density of pencil roots and thelowest depth of redox layer in soil It is therefore evident thatthe soil in this zone is water logged and in highly reducedO2poor anoxic state (ie lowest depth of redox layer) The

lowO2concentration decreases the aerobic decomposition of

organic matter and promotes anaerobic decomposition [38]and produces gases such as H

2S During the study it was

noticed that this zone is dousedwith a pungent smell of rotteneggs indicating the anaerobic decomposition and productionand presence of gaseousH

2S By contrast the soil in the upper

Lumnitzera zone has a high clay percentage and that the soil


0

01

02

03

04

Spec

ies h

eter

ogen

eity Lumnitzera

zone

Avicenniazone

Rhizophorazone

0 1 2 3minus4 minus3 minus2 minus1



y = 0049x + 016

R2 = 081

Figure 7 The relationship between the species heterogeneity of theinfaunal community and PC1 scores for physicochemical character-istics of soil in the 3 mangrove zones in Kadolkele mangrove forest

0

005

01

015

02

Spec

ies e

venn

ess



minus005


Avicenniazone

Lumnitzerazone

Rhizophorazoney = 0432x + 001

R2 = 095


Figure 8 The relationship between the species evenness of theinfaunal community and PC1 scores for physicochemical character-istics of soil in the 3 mangrove zones in Kadolkele mangrove forest

pH was neutral compared to the other two zones Furtherthe absence of aerial roots is a good evidence of having awell-aerated drained soil in this zone This zone is also farfrom the estuarymargin and receives water mostly from rainTherefore the soil salinity is also low as shown in the presentstudy

Apart from the availability of particulate organic matterefficient provision of oxygen to soil could also be a reasonfor the increased numbers of the Limnodrilus sp particularlyin the landward Lumnitzera zone This is made possibleby the large number of crab holes present in this zoneUnder ground these crab holes are interconnected so thatthere is a good supply of oxygen to a deeper area of theinner soil Lee [11] found that the burrowing macrofauna

Table 9 Summary of the eigenvalues eigenvectors and PCA scoresof the physicochemical parameters in soil of the 3 mangrove zonesin Kadolkele mangrove forest


EigenvectorsVariable PC1 PC2Soil moisture () minus0367 minus0103Soil organic matter () minus0371 minus0059Soil pH 0325 0292Conductivity (mScm) minus0339 minus0247Salinity minus0350 minus0204Penetrability (cm) minus0301 0353Redox length (cm) 0305 minus0345Sand 0262 minus0426Silt 0102 minus0576Clay 0350 0204

Principal component scoresSample Score 1 Score 2Rhizophora zone 1825 minus1559Avicennia zone minus3084 minus0203Lumnitzera zone 1259 1761

increase the surface area of the sediment-air-water interfaceso that O

2diffusion to soil is facilitated Although this O

2

enrichment to soil could have been proven experimentallyin the present study too it was not taken into considerationat the initial stage of the experimental design Thereforemeasuring sedimentO

2level in future studies that address the

ecology and distribution of benthic fauna is recommendedThe physicochemical parameters of soil in both Rhi-

zophora and Lumnitzera zones varied within a wide rangeSince Limnodrillus sp is abundant in both zones it suggeststhat this species has a wide tolerance range with respectto the physicochemical parameters measured in this studyYap et al [39] have recorded Limnodrilus sp as a species ofpollution indicator that can tolerate excessive levels of nutri-ent concentrations low levels of oxygen and pH The waterlogged condition creating hyperanoxic conditionsmight haveled to absence of any other infauna other than Limnodrilussp in the middle Avicennia zone A study carried out byThilagavathi et al [7] has shown a similar situation in amangrove sedimentary environment in Tamilnadu in Indiawhere extreme conditions including anoxic conditions inthe mangrove sediment lower the abundance of less tolerantinfaunal species

The primary productivity of mangroves is considered tobe one of the highest in the world [38] but a large portionof it has been left unconsumed and accumulated withinthe mangrove system [11] Thereafter physical and microbialdecomposition begin depleting the available oxygen leadingto hypoxic or anoxic soil conditions [7] This is perhaps thecase with the middle Avicennia zone where there was low


Table 10 Summary of the physicochemical parameters of soil between the 3 mangrove zones in Kadolkele mangrove forest (119899 = 18)

Physicochemical parameter in soil Rhizophora zone Avicennia zone Lumnitzera zone

pHlowast 645 plusmn 026a 509 plusmn 020b 734 plusmn 015c

(422ndash770) (358ndash789) (652ndash814)

Conductivity (mScm)lowast 157 plusmn 011a 220 plusmn 022b 127 plusmn 010a


Salinity (ppt)lowast 057 plusmn 006a 099 plusmn 013b 043 plusmn 006a


Moisture content ()lowast 2923 plusmn 213a 4402 plusmn 266b 2803 plusmn 066a


Organic matter content ()lowast 459 plusmn 051a 1972 plusmn 340b 472 plusmn 020a


Sand 6102 plusmn 396 5289 plusmn 255 5421 plusmn 111(2059ndash8293) (2393ndash7143) (4706ndash6295)

Silt lowast 3125 plusmn 415a 4257 plusmn 259b 3700 plusmn 118a


Clay lowast 773 plusmn 078a 468 plusmn 062b 879 plusmn 089a


Penetrability (cm)lowast 453 plusmn 026a 1162 plusmn 053b 939 plusmn 055c


Redox layer length (cm)lowast 620 plusmn 040a 130 plusmn 0157b 291 plusmn 030c

(262ndash968) (000ndash292) (086ndash476)Note Values are mean plusmn SE range in parenthesis Different superscript letters in a row denote significant differences (119875 lt 005) indicated by Tukeyrsquos pairwisesignificant difference test lowast indicates significantly calculated 119875 value detected by ANOVA

redox depth leading to anoxic hostile conditions As wasdiscussed earlier this is clearly the reason why the middleAvicennia zone had not any infaunal species

Studies conducted by Hettiarachchi [40] and Chathu-rangi [41] on the spatial variation of macrobenthic fauna inNegombo estuary have shown a large number of infaunaltaxa in the sedimentary environment of the open estuaryFor example Hettiarachchi [40] recorded that there were32 infaunal taxa in the open estuary sediment near theKadolkele mangrove forest The true estuarine infaunal taxaprefer to live within the mud rather than on the substratum[42] perhaps in order to overcome the high fish predationcoming along the overlying water column In contrast to Het-tiarachchi [40] and Chathurangi [41] however the presentstudy was carried out within the close by semiterrestrialmangrove environment where the fish predation is zero Yetthe infaunal species richness diversity and abundance inthis mangrove benthic environment were found to be verylow This may be due to the harsh environmental conditionsprevailing within the mangrove sedimentary environment asdescribed above

In contrast to infauna the epifaunal taxa however weremore abundant in the Kadolkelemangrove forestThe epifau-nal community was mainly dominated by the surface depositfeeders such as molluscs and crustaceans For example thecrabs E versicolor and S guttatum and the snails Cassidulasp andMelampus sp were abundant both in the LumnitzeraandAvicennia zonesThese species are restricted to the abovezones as they prefer low salinity ranges [16] When in dangermolluscs in particular find refuge by withdrawing themselvesinto their shells while the crustaceans (crabs) easily find

escape by moving into their or nearby burrows Thesebehaviours provide an added advantage for their survivalparticularly from surface predation [43]

Further these species shredmangrove leaf litter into smallorganic particles for their consumption so that the food isreadily available for them in these mangrove zones Crabsand molluscs can also easily find refuges along the mangrovestems seedlings and roots from the incoming tide This wasobserved at the field where molluscs are seen climbing upthe mangrove tree trunks and on pencil roots while crabsrunning to elevated locations on the ground during thehigh tide These factors directly influence on the increaseddiversity and abundance of epifauna of these molluscs andcrustaceans in the Kadolkele mangrove forest Therefore theability to protect from predation and the presence of aninexhaustible supply of mangrove leaf litter as organic foodmay have helped these epibenthic molluscs and crustaceansto increase their abundance on the surface

The snailsCassidula sp andMelampus sp were recordedin the present study as well It was also found that thesetwo species were restricted only to the Rhizophora zone Itwas interesting to observe that these two species immediatelyclimb down from the tree trunks to the mangrove floor forfeeding when the ebb tide starts and again climb back whenthe next tide starts This tree climbing behaviour has beenobserved by Shokita [44] as well This is a good indicationthat the soil moisturetide controls the distribution andabundance of some benthic fauna in mangrove forests Thesetwo species have been identified as pollution indicator speciesby Kumar and Khan [6] as well


Even though the infaunal predation was low the surfacepredation is high in the Kadolkele mangrove forest Forexample water monitors were seen roaming in the forest andsome birds of prey were also seen perching on the mangroveforest floor As a common response to avoid predation theseepifaunal species are highly camouflaged in the environment[45] in which crabs are coloured dark brown and blackwhile molluscs are seen in shades of brown that suit thesubstrate they inhibit Thus it was observed that almost allthe epifaunal taxa found in the Kadolkele Mangrove forestwere highly camouflaged It is also interesting to note herethat thereweremany birds in the uppermangrove canopy butthey do not get an opportunity to prey on these epibenthicspecies very often Perhaps the thick mangrove canopy andthe aerial root structures obstruct them from immediatelanding to catch these species

Overall the epifaunal diversity was high in the Rhi-zophora zone As it is the zone at the land water interfacetrue estuarine species may find this zone a better refugefrom the open estuary Availability of detritus food and alsothe adequate safety can be the factors that govern the highnumber of epifaunal diversity in this Rhizophora zone

During the study every effort was taken to minimize theseasonal variation if any on the benthic fauna This wasminimized to a greater extent by collecting samples fromwithin all the 3 zones on days where the sampling was carriedout

The Kadolkele mangrove forest is already under pressurebymany anthropogenic activitiesThe biggest challenge is thepollution taking place by domestic waste For example it wasobserved that the tides bring the nondegradable waste suchas polythene and plastics into the mangrove forest and therethey get entangled among the mangrove roots The abovewastes have spread in a vast area on the forest and removal ofthem may be very costly because the tides continually bringthese wastes back again and again into the forest Pilling uppolythene plastic materials and other waste products on soilaffect the burrowing animals such as crabs It also reduces thescenic beauty of the forest

The present study highlighted some aspects of ecologyand the role of physicochemical parameters in sediment instructuring the macrobenthic community in the Kadolkelemangrove forest in Negombo estuary The infaunal commu-nity structure was less diverse than the epifaunal communitymainly due to the harshness of the sediment caused by thewide variation of physicochemical parameters in sedimentand also by the structure of the associated mangrove vege-tation

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] K Kathiresan and L Bingham ldquoBiology of mangroves andmangrove ecosystemsrdquo in Advances in Marine Biology vol 40pp 82ndash251 2001

[2] P Doydee D Doungnamol andW Jaitrong ldquoSoil properties inthe Ranong mangrove ecosystem Ranong Province ThailandrdquoTheThailand National HistoryMuseum Journal vol 4 no 2 pp63ndash70 2010

[3] L Pinto Mangroves of Sri Lanka Natural Resources Energy ampScience Authority of Sri Lanka 1986

[4] S Cannicci F Bartolini G Penha-Lopes S FratiniM Fusi andF Dahdouh-Guebas Functions of macrobenthos in mangroveforests gt20 years of research lessons 2012 httpwwwvlizbeimisdocspublications243885pdf

[5] D E Roberts Spatial Patterns in the Macrobenthic Fauna ofMangrove Forests in the Brisbane Water Estuary Bio AnalysisPty Ltd Marine estuarine Freshwater Ecology 2006

[6] P S Kumar and A B Khan ldquoThe distribution and diversityof benthic macroinvertebrate fauna in Pondicherry mangrovesIndiardquo Aquatic Biosystems vol 9 no 1 article 15 2013

[7] B Thilagavathi D Varadharajan A Babu J ManoharanS Vijayalakshmi and T Balasubramanian ldquoDistribution anddiversity of macrobenthos in different mangrove ecosystems ofTamil Nadu coast Indiardquo Journal of Aquaculture Research andDevelopment vol 4 no 6 Article ID 1000199 2013

[8] M Keshavarz E Kamrani and A R Dabbagh ldquoA descriptionof higher macrobenthic infaunal taxa of mangrove mud flats atKhamir Port Iranrdquo Annals of Biological Research vol 3 no 2pp 1029ndash1043 2012

[9] D M Alongi and P Christoffersen ldquoBenthic infauna andorganism-sediment relations in a shallow tropical coastal areainfluence of outwelled mangrove detritus and physical distur-bancerdquo Marine Ecology Progress Series vol 81 no 3 pp 229ndash245 1992

[10] A M Ellison ldquoManaging mangroves with benthic biodiversityin mind moving beyond roving banditryrdquo Journal of SeaResearch vol 59 no 1-2 pp 2ndash15 2008

[11] S Y Lee ldquoMangrove macrobenthos assemblages services andlinkagesrdquo Journal of Sea Research vol 59 no 1-2 pp 16ndash292008

[12] H Joshi and M Ghose ldquoForest structure and species distribu-tion along soil salinity and pH gradient in mangrove swampsof the Sundarbansrdquo Tropical Ecology vol 44 no 2 pp 195ndash2042003

[13] S Matthijs J Tack D van Speybroeck and N KoedamldquoMangrove species zonation and soil redox state sulphideconcentration and salinity in Gazi Bay (Kenya) a preliminarystudyrdquo Mangroves and Salt Marshes vol 3 no 4 pp 243ndash2491999

[14] A Safahieh M B Nabavi A Vazirizadeh M T Ronagh and RKamalifar ldquoHorizontal zonation in macrofauna community ofBardestanmangrove Creek Persian GulfrdquoWorld Journal of Fishand Marine Sciences vol 4 no 2 pp 142ndash149 2012

[15] I Nagelkerken S J M Blaber S Bouillon et al ldquoThe habitatfunction of mangroves for terrestrial and marine fauna areviewrdquo Aquatic Botany vol 89 no 2 pp 155ndash185 2008

[16] S H R Priyadarshani S C Jayamanne and Y N Hir-imuthugoda ldquoDiversity of Mangrove crabs in KadolkeleNegombo estuary Sri Lanka Sri Lankardquo Journal of Fisheries andAquatic Resources vol 13 pp 109ndash121 2008

[17] K A R S Perera M D J S Saparamadu and M D Ama-rasinghe ldquoNet photosynthetic production and potential carbonassimilation capacity of mangroves of Kadolkele in Negomboestuary Sri Lankardquo in Proceedings of the 12th Annual ResearchSymposium p 113 University of Kelaniya 2011


[18] National Wetland Directory of Sri Lanka The Central Environ-mental Authority (CEA) International Union for Conservationof Nature and Natural Resources (IUCN) and the InternationalWater Management Institute (IWMI) 2006

[19] M de Silva and P K de Silva ldquoStatus diversity and conservationof the mangrove forests of Sri Lankardquo Journal of South AsianNatural History vol 3 no 1 pp 79ndash102 1998

[20] D D G L Dahanayaka and W A Sumanadasa ldquoFloralcomposition and vegetation structure of NARA mangrovereserve Kadolkele Sri Lanka and guidelines for conservationrdquoin Proceedings of the International Forestry and EnvironmentSymposium pp 25ndash26 Department of Forestry and Environ-ment Science University of Sri Jayewardenepura Nugegoda SriLanka 2007

[21] M Fernando Shells of the Sri Lanka Seashore BiodiversitySecretariat Ministry of Environment 2009

[22] L Williams Environmental Chemistry A Modular ApproachJohn Wiley amp Sons Chichester UK 2001

[23] N C Brady and R R Weil The Nature and Properties of SoilPrentice Hall Englewood Cliffs NJ USA 12th edition 1999

[24] M L Jackson Soil Chemical Analysis Prentice Hall of IndiaNew Delhi India 1978

[25] C H Fernando and A S Mendis A Guide to the FreshwaterFauna of Ceylon (Sri Lanka) Fisheries Research Station CeylonSri Lanka 1962

[26] T G Pillai ldquoAnnelida Polychaeta from the Philippines andIndonesiardquo Ceylon Journal of Science (Biological Sciences) vol5 no 2 pp 110ndash175 1965

[27] M Quigley Invertebrates of Streams and Rivers A Key toIdentification Edward Arnold London UK 1977

[28] K FauchaldThe Polychaete Worms Definitions and Keys to theOrders Families and Genera Natural History Museum of LosAngeles Country 1977

[29] H Nesemann G Sharma and R K Sinha ldquoAquatic Annelida(Polychaeta Oligochaeta Hirudinea) of the Ganga River andadjacent water bodies in Patna (India Bihar) with descriptionof a new leech species (Family Salifidae)rdquoAnnalen des Naturhis-torischen Museums in Wien vol 105 pp 139ndash187 2004

[30] A E Magurran Ecological Diversity and Its MeasurementsPrinceton University Press Princeton NJ USA 1st edition1988

[31] S Melles S Glenn and K Martin ldquoUrban bird diversity andlandscape complexity species-environment associations alonga multiscale habitat gradientrdquo Conservation Ecology vol 7 no1 5 pages 2003

[32] J M A L Jayakody M D Amarasinghe V Pahalawat-taarachchi and K H W L de Silva ldquoVegetation structure andpotential gross primary productivity of mangroves at Kadolkelein Meegamuwa (Negombo) estuary Sri Lankardquo Sri LankaJournal of Fisheries and Aquatic resources vol 13 pp 95ndash1082008

[33] M D Amarasinghe ldquoEcological functions of mangrove andrelated ecosystems and their contribution to economic sustain-abilityrdquo Sri Lanka Journal of Aquatic Sciences vol 2 pp 1ndash201997

[34] M D Amarasinghe J A Liyanage and K G S NirbadhaldquoPresence of heavy metals in lands of a tropical freshwaterwetland in Sri Lanka as an indicator of their relative phytore-mediation potential for heavy metal contaminated water fromurban runoffrdquo in Proceedings of the 2nd World Conference onEnvironmentalManagement J M Jahi K Arifin S Surif and S

Idrus Eds pp 311ndash319 Universiti KebangsaanMalaysia BangiMalaysia 2004

[35] A Gayathri ldquoLife at the margins the social economic andecological importance ofmangrovesrdquoMadera y Bosques pp 53ndash60 2002

[36] V Pahalawattaarachchi and M D Amarasinghe ldquoLeaf litterdecomposition and changes in leaf CN ratio in the mangalsof Negombo lagoon (Sri Lanka)rdquo Sri Lanka Journal of AquaticSciences vol 2 pp 29ndash42 1997

[37] T J Smith ldquoMangrove forest structurerdquo in Mangrove EcologyA Manual for a Field Course I C Feller and M Sitnik EdsSmithsonian Institution Washington DC USA 1996

[38] R Reef I C Feller and C E Lovelock ldquoNutrition of man-grovesrdquo Tree Physiology vol 30 no 9 pp 1148ndash1160 2010

[39] C K Yap A Rahimismail M Z Azrina A Ismail and S GTan ldquoThe influential of physico-chemical parameters on thedistributions of oligochateas (Limnodrilus sp) at the polluteddownstream of the tropical Langat Riverrdquo Journal of AppliedSciences and Environmental Management vol 10 no 3 pp 135ndash140 2006

[40] A Hettiarachchi Spatial variation of macrobenthic fauna insome selected sites in Negombo estuary in relation to prevailingphysico chemical parameters in the environment [BSc Spe-cial degree dissertation] University of Kelaniya Colombo SriLanka 2010

[41] N G M ChathurangiThe role of physico-chemical characteris-tics and density of the seagrass cover on the spatial distributionof macrobenthic community in the Negombo estuary [SpecialDegree Dissertation] University of Kelaniya Colombo SriLanka 2011

[42] W H Wilson ldquoCompetition and predation in marine soft-sediment communitiesrdquo Annual Review of Ecology and System-atics vol 21 no 1 pp 221ndash241 1990

[43] PHutchlings ldquoThe fauna ofMangrovesrdquo 2000 httpojslibraryunsweduauindexphpwetlandsarticleview109133

[44] S Shokita ldquoThe role of aquatic animals in mangrove ecosys-temsrdquo in Mangrove Management and Conservation M Van-nucci Ed pp 76ndash110UnitedNationsUniversityNewYorkNYUSA 2004

[45] T Detto J M Hemmi and P R Y Backwell ldquoColouration andcolour changes of the fiddler crabUca capricornis a descriptivestudyrdquo PLoS ONE vol 3 no 2 Article ID e1629 2008

Submit your manuscripts athttpwwwhindawicom

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ClimatologyJournal of


Polychaetes gastropods and crustaceans are regardedto be the major macrobenthic organisms in the mangrovesediment The distribution of macrobenthos may vary fromhabitat to habitat within the same mangrove forest Forexample a study carried out by Ellison [10] revealed that thedensity and the biomass of crabs and snails are higher in theyoung mangrove stands than in the intermediate aged standsof Rhizophoraceae These macrobenthic organisms have aprofound effect on the sedimentary environment throughtheir feeding burrowing and ventilatory activities

Macrobenthic assemblage structure is influenced by localenvironmental conditions such as hydroperiod organicmat-ter availability and sediment characteristics [11] Thereforethe mangrove forest is considered to have physical chemicaland biological processes which promote the adaptation ofinhabiting organisms to tolerate greater amplitude of envi-ronmental characters both morphologically and physiologi-cally [7]

Mangrove communities often exhibit distinct patterns ofspecies distribution governed by the complexity of environ-mental factors [12 13] and competition between individualsThe local patterns of tidal inundation influence soil character-istics that control species zonation of mangrove forests [12]With the zonation of mangrove vegetation invertebrates mayoften exhibit amarked zonation pattern and colonize a varietyof specific microenvironments [7] This zonation could takeplace either horizontally or vertically [14] where some speciesdwell on the sediment surface or reside in burrows whileothers live on pneumatophores and lower tree trunks or proproots burrow in decaying wood or can even be found in thetree canopies [15]

Sedimentary characteristics in mangrove forests play amajor role in structuring benthic communities in comparisonto other physicochemical variables According to Safahiehet al [14] the distribution of macrobenthos is mainly deter-mined by the sediment grain size salinity and availability ofwater When there are extreme fluctuations in the physicalfeatures then the abundance of benthic species may decline[1] The spatial occurrence of these fauna is highly irregularthus contributing to both the complexity and heterogeneityof the habitat [11] The most successful benthic species of amangrove forest are the ones who can easily adapt to theprevailing physical properties of that ecosystem

Although there is a wealth of knowledge on the impor-tance of mangroves on a global scale information related tothe ecology of the associated benthic fauna is scanty As forthe Kadolkele mangrove forest in Negombo estuary in SriLanka the above is particularly true where a study carriedout by Priyadarshani et al [16] is perhaps the only detailedstudy focused on the mangrove faunal diversity even thoughtheir study is confined only to the mangrove crabs Yet thediversity and the distribution of macrobenthos existing inthis mangrove forest floor are vast and have not been givendue consideration The present study was therefore designedand carried out to investigate some aspects of the ecologyof macrobenthic fauna of the Kadolkele mangrove forestin relation to the mangrove zonation and physicochemicalparameters of soil

2 Materials and Methods

21 The Study Site The present study was carried out atthe Kadolkelemangrove forest (7∘111015840498210158401015840N 79∘501015840322910158401015840E)(Figure 1) It is situated at the northern extremity of theNegombo estuary of Sri Lanka and is a pristine and relativelyundisturbed small mangrove forest patch that extends withinan area of 10 ha [17] It is also a popular site for mangroverelated field studies [16]

The geographic region of the study area receives anaverage annual rainfall of 2400mm and a monthly high-est rainfall of 348mm during October to November Theaverage temperature varies between 24∘C and 30∘C [18] TheKadolkele mangrove forest contributes to a high productivityand hence supports the ecological balance of the adjacentNegombo estuarine ecosystem [19]

There is a great diversity of mangroves in the Kadolkelemangrove forest According to Dahanayake and Sumanadasa[20] 29 mangrove species are found there and of those 18 areconsidered to be true mangroves They also have recorded33 other mangrove associated vegetation types The highestabundance of mangroves is from the 3 mangrove familiesnamely Rhizophoraceae Avicenniaceae and CombretaceaeThe most abundant species from family Rhizophoraceae areRhizophora apiculata and Rhizophora mucronata Avicenniamarina is the dominant species from family Avicenniaceaewhile Lumnitzera racemosa is the most commonly foundspecies in family Combretaceae in this mangrove forest [20]

There is a distinct mangrove zonation pattern in theKadolkele mangrove forest (Figure 2) For example a narrowmangrove zone approximately 3m in width occupies atthe estuary-land interface and is dominated by Rhizophoraspecies Avicennia species grow at the middle zone and thewidth of this zone is approximately 15m Lumnitzera speciesare more abundant in the deeper areas of the mangrove forestwhere the width ranges from 50m to 30m

22 Field Sampling Three belt transects 40m in length and3m width each were established in the middle of eachmangrove zone (Figure 2) The transects were demarcated byerecting coloured wooden posts at the four corners of eachtransect Along each transect 12 quadrat areas of 2m times 2mwere marked in a similar manner with a 2m gap in betweenTheGPS locations of these transects were recorded separatelyusing a portable Global Positioning System (Garmin-eTrexSUMMIT)

The number of mature mangrove trees mangroveseedlings up to 1m in height and their pencil roots withineach quadrat area were counted separately and recordedThe number of crab holes present in each quadrat were alsocounted and recorded These crab holes were not dug forcrabs due to logistic reasons Therefore it was assumed thateach crab hole is occupied by a single crab of the commonestcrab species recorded previously in each mangrove zone byPriyadarshani et al [16] and that the number of crab holesequals the number of crabs there

The different species of epifauna on the mangrove forestfloor and those who were sitting on the mangrove stemsseedlings and pencil roots to a height of 05m above


79∘499984000998400998400E 79∘4999840020998400998400E 79∘4999840040998400998400E 79∘509984000998400998400E 79∘5099840020998400998400E 79∘5099840040998400998400E 79∘519984000998400998400E

79∘499984000998400998400E 79∘4999840020998400998400E 79∘4999840040998400998400E 79∘509984000998400998400E 79∘5099840020998400998400E 79∘5099840040998400998400E 79∘519984000998400998400E

7∘139984000998400998400N

7∘1299840040998400998400N

7∘1299840020998400998400N

7∘129984000998400998400N

7∘1199840040998400998400N

7∘1199840020998400998400N

7∘119984000998400998400N

7∘1099840040998400998400N

7∘139984000998400998400N

7∘1299840040998400998400N

7∘1299840020998400998400N

7∘129984000998400998400N

7∘1199840040998400998400N

7∘1199840020998400998400N

7∘119984000998400998400N

7∘1099840040998400998400N


Negombo estuary

N

0 04 08 16(km)

Mangrove area







Negombo estuary


0 02 04(km)

L

AR














3 Results












Cassidula nucleus

Avicenniazone

Rhizophorazone

Lumnitzerazone

PC1

PC 2

15

10

05

0

minus05

minus10

minus15











Rhizophora zone




Avicennia zone




Lumnitzera zone







Relativeabundance

()Rhizophora

zoneAvicenniazone

Lumnitzerazone





Arthropoda










Rhizophorazone

Avicenniazone

Lumnitzerazone





Avicenniazone

Lumnitzerazone








4 Discussion


PC1

PC2




penetrability


Rhizophorazone

Avicenniazone

Lumnitzerazone

15

20

10

05

0

minus05

minus10

minus15



0

100

200

300

400

0 1 2 3

Tota

l abu

ndan

ce (N

)


Lumnitzerazone

Avicenniazone



Rhizophorazone


y = 48276x + 16567

R2 = 047







Relativeabundance

()Rhizophora

zoneAvicenniazone

Lumnitzerazone

Mollusca



Arthropoda











Rhizophorazone

Avicenniazone

Lumnitzerazone




0

5

10

0 1 2 3

Spec

ies r

ichn

ess

Lumnitzerazone

Avicenniazone

Rhizophorazone




y = 099x + 333

R2 = 058



2saturated































0

01

02

03

04

Spec

ies h

eter

ogen

eity Lumnitzera

zone

Avicenniazone

Rhizophorazone




y = 0049x + 016

R2 = 081


0

005

01

015

02

Spec

ies e

venn

ess



minus005


Avicenniazone

Lumnitzerazone


R2 = 095











2










































References




















































Journal of












Volume 2014

Advances in









Geophysics















79∘499984000998400998400E 79∘4999840020998400998400E 79∘4999840040998400998400E 79∘509984000998400998400E 79∘5099840020998400998400E 79∘5099840040998400998400E 79∘519984000998400998400E

79∘499984000998400998400E 79∘4999840020998400998400E 79∘4999840040998400998400E 79∘509984000998400998400E 79∘5099840020998400998400E 79∘5099840040998400998400E 79∘519984000998400998400E

7∘139984000998400998400N

7∘1299840040998400998400N

7∘1299840020998400998400N

7∘129984000998400998400N

7∘1199840040998400998400N

7∘1199840020998400998400N

7∘119984000998400998400N

7∘1099840040998400998400N

7∘139984000998400998400N

7∘1299840040998400998400N

7∘1299840020998400998400N

7∘129984000998400998400N

7∘1199840040998400998400N

7∘1199840020998400998400N

7∘119984000998400998400N

7∘1099840040998400998400N


Negombo estuary

N

0 04 08 16(km)

Mangrove area







Negombo estuary


0 02 04(km)

L

AR














3 Results












Cassidula nucleus

Avicenniazone

Rhizophorazone

Lumnitzerazone

PC1

PC 2

15

10

05

0

minus05

minus10

minus15











Rhizophora zone




Avicennia zone




Lumnitzera zone







Relativeabundance

()Rhizophora

zoneAvicenniazone

Lumnitzerazone





Arthropoda










Rhizophorazone

Avicenniazone

Lumnitzerazone





Avicenniazone

Lumnitzerazone








4 Discussion


PC1

PC2




penetrability


Rhizophorazone

Avicenniazone

Lumnitzerazone

15

20

10

05

0

minus05

minus10

minus15



0

100

200

300

400

0 1 2 3

Tota

l abu

ndan

ce (N

)


Lumnitzerazone

Avicenniazone



Rhizophorazone


y = 48276x + 16567

R2 = 047







Relativeabundance

()Rhizophora

zoneAvicenniazone

Lumnitzerazone

Mollusca



Arthropoda











Rhizophorazone

Avicenniazone

Lumnitzerazone




0

5

10

0 1 2 3

Spec

ies r

ichn

ess

Lumnitzerazone

Avicenniazone

Rhizophorazone




y = 099x + 333

R2 = 058



2saturated































0

01

02

03

04

Spec

ies h

eter

ogen

eity Lumnitzera

zone

Avicenniazone

Rhizophorazone




y = 0049x + 016

R2 = 081


0

005

01

015

02

Spec

ies e

venn

ess



minus005


Avicenniazone

Lumnitzerazone


R2 = 095











2










































References




















































Journal of












Volume 2014

Advances in









Geophysics















Negombo estuary


0 02 04(km)

L

AR














3 Results












Cassidula nucleus

Avicenniazone

Rhizophorazone

Lumnitzerazone

PC1

PC 2

15

10

05

0

minus05

minus10

minus15











Rhizophora zone




Avicennia zone




Lumnitzera zone







Relativeabundance

()Rhizophora

zoneAvicenniazone

Lumnitzerazone





Arthropoda










Rhizophorazone

Avicenniazone

Lumnitzerazone





Avicenniazone

Lumnitzerazone








4 Discussion


PC1

PC2




penetrability


Rhizophorazone

Avicenniazone

Lumnitzerazone

15

20

10

05

0

minus05

minus10

minus15



0

100

200

300

400

0 1 2 3

Tota

l abu

ndan

ce (N

)


Lumnitzerazone

Avicenniazone



Rhizophorazone


y = 48276x + 16567

R2 = 047







Relativeabundance

()Rhizophora

zoneAvicenniazone

Lumnitzerazone

Mollusca



Arthropoda











Rhizophorazone

Avicenniazone

Lumnitzerazone




0

5

10

0 1 2 3

Spec

ies r

ichn

ess

Lumnitzerazone

Avicenniazone

Rhizophorazone




y = 099x + 333

R2 = 058



2saturated































0

01

02

03

04

Spec

ies h

eter

ogen

eity Lumnitzera

zone

Avicenniazone

Rhizophorazone




y = 0049x + 016

R2 = 081


0

005

01

015

02

Spec

ies e

venn

ess



minus005


Avicenniazone

Lumnitzerazone


R2 = 095











2










































References




















































Journal of












Volume 2014

Advances in









Geophysics
























Cassidula nucleus

Avicenniazone

Rhizophorazone

Lumnitzerazone

PC1

PC 2

15

10

05

0

minus05

minus10

minus15











Rhizophora zone




Avicennia zone




Lumnitzera zone







Relativeabundance

()Rhizophora

zoneAvicenniazone

Lumnitzerazone





Arthropoda










Rhizophorazone

Avicenniazone

Lumnitzerazone





Avicenniazone

Lumnitzerazone








4 Discussion


PC1

PC2




penetrability


Rhizophorazone

Avicenniazone

Lumnitzerazone

15

20

10

05

0

minus05

minus10

minus15



0

100

200

300

400

0 1 2 3

Tota

l abu

ndan

ce (N

)


Lumnitzerazone

Avicenniazone



Rhizophorazone


y = 48276x + 16567

R2 = 047







Relativeabundance

()Rhizophora

zoneAvicenniazone

Lumnitzerazone

Mollusca



Arthropoda











Rhizophorazone

Avicenniazone

Lumnitzerazone




0

5

10

0 1 2 3

Spec

ies r

ichn

ess

Lumnitzerazone

Avicenniazone

Rhizophorazone




y = 099x + 333

R2 = 058



2saturated































0

01

02

03

04

Spec

ies h

eter

ogen

eity Lumnitzera

zone

Avicenniazone

Rhizophorazone




y = 0049x + 016

R2 = 081


0

005

01

015

02

Spec

ies e

venn

ess



minus005


Avicenniazone

Lumnitzerazone


R2 = 095











2










































References




















































Journal of












Volume 2014

Advances in









Geophysics

















Rhizophora zone




Avicennia zone




Lumnitzera zone







Relativeabundance

()Rhizophora

zoneAvicenniazone

Lumnitzerazone





Arthropoda










Rhizophorazone

Avicenniazone

Lumnitzerazone





Avicenniazone

Lumnitzerazone








4 Discussion


PC1

PC2




penetrability


Rhizophorazone

Avicenniazone

Lumnitzerazone

15

20

10

05

0

minus05

minus10

minus15



0

100

200

300

400

0 1 2 3

Tota

l abu

ndan

ce (N

)


Lumnitzerazone

Avicenniazone



Rhizophorazone


y = 48276x + 16567

R2 = 047







Relativeabundance

()Rhizophora

zoneAvicenniazone

Lumnitzerazone

Mollusca



Arthropoda











Rhizophorazone

Avicenniazone

Lumnitzerazone




0

5

10

0 1 2 3

Spec

ies r

ichn

ess

Lumnitzerazone

Avicenniazone

Rhizophorazone




y = 099x + 333

R2 = 058



2saturated































0

01

02

03

04

Spec

ies h

eter

ogen

eity Lumnitzera

zone

Avicenniazone

Rhizophorazone




y = 0049x + 016

R2 = 081


0

005

01

015

02

Spec

ies e

venn

ess



minus005


Avicenniazone

Lumnitzerazone


R2 = 095











2










































References




















































Journal of












Volume 2014

Advances in









Geophysics

















Rhizophorazone

Avicenniazone

Lumnitzerazone





Avicenniazone

Lumnitzerazone








4 Discussion


PC1

PC2




penetrability


Rhizophorazone

Avicenniazone

Lumnitzerazone

15

20

10

05

0

minus05

minus10

minus15



0

100

200

300

400

0 1 2 3

Tota

l abu

ndan

ce (N

)


Lumnitzerazone

Avicenniazone



Rhizophorazone


y = 48276x + 16567

R2 = 047







Relativeabundance

()Rhizophora

zoneAvicenniazone

Lumnitzerazone

Mollusca



Arthropoda











Rhizophorazone

Avicenniazone

Lumnitzerazone




0

5

10

0 1 2 3

Spec

ies r

ichn

ess

Lumnitzerazone

Avicenniazone

Rhizophorazone




y = 099x + 333

R2 = 058



2saturated































0

01

02

03

04

Spec

ies h

eter

ogen

eity Lumnitzera

zone

Avicenniazone

Rhizophorazone




y = 0049x + 016

R2 = 081


0

005

01

015

02

Spec

ies e

venn

ess



minus005


Avicenniazone

Lumnitzerazone


R2 = 095











2










































References




















































Journal of












Volume 2014

Advances in









Geophysics


















Relativeabundance

()Rhizophora

zoneAvicenniazone

Lumnitzerazone

Mollusca



Arthropoda











Rhizophorazone

Avicenniazone

Lumnitzerazone




0

5

10

0 1 2 3

Spec

ies r

ichn

ess

Lumnitzerazone

Avicenniazone

Rhizophorazone




y = 099x + 333

R2 = 058



2saturated































0

01

02

03

04

Spec

ies h

eter

ogen

eity Lumnitzera

zone

Avicenniazone

Rhizophorazone




y = 0049x + 016

R2 = 081


0

005

01

015

02

Spec

ies e

venn

ess



minus005


Avicenniazone

Lumnitzerazone


R2 = 095











2










































References




















































Journal of












Volume 2014

Advances in









Geophysics












































0

01

02

03

04

Spec

ies h

eter

ogen

eity Lumnitzera

zone

Avicenniazone

Rhizophorazone




y = 0049x + 016

R2 = 081


0

005

01

015

02

Spec

ies e

venn

ess



minus005


Avicenniazone

Lumnitzerazone


R2 = 095











2










































References




















































Journal of












Volume 2014

Advances in









Geophysics















0

01

02

03

04

Spec

ies h

eter

ogen

eity Lumnitzera

zone

Avicenniazone

Rhizophorazone




y = 0049x + 016

R2 = 081


0

005

01

015

02

Spec

ies e

venn

ess



minus005


Avicenniazone

Lumnitzerazone


R2 = 095











2










































References




















































Journal of












Volume 2014

Advances in









Geophysics


















































References




















































Journal of












Volume 2014

Advances in









Geophysics






















References




















































Journal of












Volume 2014

Advances in









Geophysics
















































Journal of












Volume 2014

Advances in









Geophysics


















Journal of












Volume 2014

Advances in









Geophysics














Documents

Research Article Effects of Mangrove Zonation and …downloads.hindawi.com/journals/ae/2014/564056.pdfResearch Article Effects of Mangrove Zonation and the Physicochemical Parameters