Pertanika 13(1), 33-44 (1990)

The Impact of Pollution on the Nematode and HarpacticoidCopepod Species Composition of an Estuarine Mudflat

SHABDIN MOHD LONGMarine Science and Natural Resources,

Universiti Kebangsaan Malaysia, Sabah Campus,Lb 62, 88996-Kota Kinabalu, Sabah.

Key words: Nematodes, harpacticoid copepods, diversity, cluster analysis, ordination of stations.

ABSTRAKKajian ini telah dilakukan untuk melihat kesan daripada buangan industri ke atas spesies nematoda danharpaktikoida pada dataran berlumpur di muara Sungai Forth (Scotland), Spesies nematoda dan harpaktikoidkopepoda di kawasan kajian menunjukkan tindak balasyang berbagai-bagai kepada pencemaran; bermuladaripada spesies yang tiada langsung di kawasan buangan kepada spesies yang wujud pradominan dikawasan sedimen yang paling tercemar. Adalah difikirkan bahawa sekurang-kurangnya beberapa spesiesyang terdapat berdekatan dengan sdluran buangan berhubungan dengan lapisan tebal mikroalga yang ter-dapat di pinggir saluran buangan tersebut. Dua faktoryang nampaknya dominan bagi mengawal taburanspesies nematoda dan harpaktikoida kopepoda di kawasan kajian ialah ketinggian pantai dan pencemaran.Anahsis kelompok data kelimpahan spesies dari stesen pensampelan jelas menunjukkan pengasingan stesenpada paras tikas air tinggi, tikas air pertengahan dan tikas air rendah. Ordinasi terhadap stesen jugamenunjukkan ia dipengaruhi oleh ketinggian pantai dengan bantuan pencemaran,

ABSTRACTA study was carried out in the Forth estuary (Scotland) to determine the impact of industrial effluents onthe nematodes and harpacticoid copepods species of an estuarine mudflat. The nematodes and harpacticoidcopepods species in the area ranging from the species which are absent from the vicinity of the effluents tothe species which occure predominantly in the most highly polluted sediments display a spectrum of responsesto the discharges. It is thought at least some of the species favouring the immmediate vicinity of the effluentchannels would be associated with the dense microalgal mat that fringes the channels. Two factors seemedto be dominant in controlling the species distribution of nematodes and harpacticoid copepods in the area;interdal height and pollution. Cluster analysis of the species abundance data from the sampling stations dear-ly showed the separation of sites on the upper, middle and lower shore. The ordination of the stations wasalso strongly influenced by intertidal height superimposed by pollution.

INTRODUCTIONThe study of the response of nematode com-munities to the presence of oil has been examin-ed by a number of workers (Boucher 1980; 1985;Goarbault 1984; Fleeger & Chandler 1983; Alongiet al 1983; Bonsdorff 1981; Fricke et al 1981;Giere 1979; Wormald 1976). However, the resultsof these studies have been inconsistent.

The effect of oil on nematode and harpacti-coid copepods species compositions has not receiv-ed much attention. The studies on the impact of

oil on nematode and harpacticoid species generallyseem inconsistent. Several workers found that oilhad an impact on the nematode species (Wormald1976; Giere 1979; Boucher 1980; Decker &Fleeger 1984) whereas others did not (Fleeger &Chandler 1983; Fricke et al. 1981; Alongi et al.1983). Similarly several workers found that oilhad an effect on harpacticoid copepods species(Ustach 1979; Decker & Fleeger 1984) while othersdid not (Alongi et al 1983; Dalla Venezia &Fossato 1977).

SHABDIN MOHD LONG

The objective of the present study was toexamine the impact of chronic oil pollution on thespecies composition of the nematode and harpacti-coid copepods of the mudflat in the Forth estuary,Scotland.

MATERIALS AND METHODSThe study area, station location and collection ofcore samples for physico-chemical and biologicalstudies have been described by Mohd Long (1987).The Kinneil mudflat was chosen for the presentstudy because mudflats usually support a largecommunity of meiofauna, and site selection wasbased on the hypothesis that stations which are farfrom the sources of pollution suffer less impact onmeiofauna communities and vise versa. Due to theabundance of nematodes, a subsample of about200 individuals was taken randomly for identifica-tion. Nematodes and harpacticoid copepods wereidentified to the species level.

In order to see the effect of pollution on themeiofaunal species in Forth estuary, the Shannon-Wiener diversity index, Pielou evenness andspecies richness were calculated based on the com-puter programme written by Moore (1983). Thedendrograms illustrating the similarity of the sta-tions were drawn based on density (no. 10 cm ~2)of nematode and harpacticoid species. The com-puter programme used was CLUSTAN (Wishart,1978). The ordination technique was used toseparate the effects of pollution from the effectsof other environmental factors. Therefore thesampling sites were ordinated based on log (x +1) transformed densities (no, 10 cm ~2) of nema-tode and harpacticoid species at 28 stations byusing the computer programme called DECO-RANA (Detrended Correspondence Analysis).

RESULTSNematodes Species CompositionA total of 49 species representing 36 genera wereidentified from 5228 nematodes examined. Thirty-three species were recorded on the upper shore,28 on the middle shore and 38 on the lower shoretransects. A total of 19 species were common toall three transects. A total of 7 - 9 species com-prised more than 90% of the nematodes alongeach of the three transects.

Sabatieria pulchra was the dominant species onthe lower shore (mean, 859 ind. 10 cm 2),Ptycholaimellus ponticus on the middle shore (mean,352 ind. 10 cm"2) and Metachromadora remanei on

the upper shore transect (mean, 569 ind. 10cm-(Fig.l). Four species were common on all threetransects, viz. Sabatieria pulchra, Ptycholaimellusponticus, Atrochromadora microlaima and Daptonemasetosum. However, Sabatieria pulchra showed a drasticreduction in density from the lower to the uppershore transects. Terschellingia longicaudata, Terschel-lingia communis and Desmolaimus zeelandicus werevirtually restricted to the lower shore, and Tri-pyloides gracilis to the middle and upper shore.Innuoconema tentabundum, Neockromadora poecilosoma,Daptonema procerum and Ascolaimus elongatus werevirtually restricted to the lower shore, Sphaerolaimushirsutus and Theristus acer to the middle shore andCalyptronema maxweberi, Metachromadora remanei,Diplolaimella ocellata and Microlaimus globiceps to theupper shore transect.

Three groups of species were observed on theupper shore transect (Fig. 2). Species of the firstgroups were virtually restricted to the Skinflats,namely Halalaimus off. gracilis, Calyptronema maxwe-ben, Paracanthonchus heterodontus, Metachromadoraremanei, Microlaimus globiceps, Ptycholaimellus ponticusand Axonolaimus typicus. The second group contain-ed species which were common towards the endsof the upper shore at Kinneil, viz. Hypodontolaimusbalticus and Tnploides gracilis whilst species of thethird group were present in moderate numbersbetween the discharges, viz. Sabatieria pulchra,Atrochromadora microlaima, Diplolaimella ocellata andDaptonema setosum.

On the middle shore, only 11 species (39%were found at one or both ends of the transect,being unrecorded closer than 288 metres upstreamof the oil and 900 metres downstream of thechemical channels (Fig. 3). Most of these specieswere rare but common forms included Terschel-lingia communis, Eleutherolaimus stenosoma, Sphaero-laimus gracilis and Daptonema tenuispiculum.

Two species were generally very common butdiminished near the effluent channels (Fig. 3),Ptycholaimellus ponticus had a reduced density at sites188 metres and 483 metres downstream of the oilchannel and was unrecorded 190 metres down-stream of the chemical channel. Sabatieria pulchrawas not found 188 metres downstream of the oilchannel. A third common species, Desmolaimuszeelandicus, attained its minimum density at the sitejust downstream of the oil channel, although thedensity of this species was somewhat erratic alongthe transect.

34 PERTANIKA VOL. 13 NO. 1, 1990

IMPACT OF POLLUTION ON NKMATODK AND HARPACTICOID COPEPOD SPECIES COMPOSITION

Mean density (no- 10cm""1)10D 2QD 30, 400 500 600 700 800 900 0 100 200 300 WX)

Sabatieria pulchra

Ptycholaimellus ponticus

Atrochromadora microlaima

Daptonema setosum

Terschellingia longicaudata

Tershcellingia communis

Desmolaimus zeelandicus

Tripyloides gracilis

Paracanthonchus heterodontus

Sphaerolaimus hirsutus

Theristus acer

Innocuonrma tentabundum

Neochromadora poecilosoma

Daptonema procerum

Ascolaimus elongatus

Calyptronema maxweberi

Hypodontolaimus balticus

MetachroTnadora remanei

Dipblaimella ocellata

Muroiaimus globiceps

Axonolaimus typicus

Fig. 1: Bar chart showing mean density (no. ind. 10 cm ) of nematode species along three transects at approximately

Mean Low Water Neap (MLWN), Mid Tide Level (MTL) and Mean High Water Neap (MHWN) at

Grangemoulh mudflats. The species with a mean density lower than 10 ind. 10 cm

excluded.

on all three transects were

Of the remaining common species Atrochro-madora microlaima and Tripyloides gracilis seemedlittle or not effected by the effluents, whereasDaptonema setosum showed strong density peaks atthe sites immediately downstream from botheffluent channels.

Only a few species were recorded in thevicinity of the effluent channels, viz. Adoncholaimus

fuscus, Dipblaimella ocellata, Monhystera parva andMonhystera anophthalma. Densities were, however,low.

On the lower shore, only 8 species (21%) werefound at one or both ends of the transect, beingunrecorded closer than 666 metres upstream of theoil and 600 metres downstream of the Avon chan-nels (Fig. 4).

As on the middle shore, Ptycholaimellusponticus showed a reduction in density in the areaof Avon channel (7 ind. 10 cm"2) and at the siteimmediately downstream of the oil channel (8 ind.10 cm"2) (Fig. 4). Sabatieria pulchra was lowest indensity at the western end station but also show-ed a reduction in density at the 3 sites immediatelydownstream of the oil channel. A third common

species, Desmolaimus zeelandicus, also decreased tominimum density at the station immediatelydownstream of the oil channel. Of the remainingcommon species, Atrochromadora microlaima seem-ed little affected by the effluent channels on themiddle shore.

Five species (13%) were only recorded in thevicinity of the effluent channels, viz, Hypodon-tolaimus balticus, Prochromadorella ditlevseni, Paracan-thonchus caecus, Diplolaimella ocellata and Dorylaimidaesp. However their densities were low. The otherspecies were sporadically distributed along thetransect.

Harpacticoid Copepods Species Composition

Seventeen species of harpacticoids wererecorded but these were dominated by just 4species constituting more than 90%of the copepodfauna on the lower and middle transects, viz.Amphiascoides limicola, Stenhelia palustris, Platychelipushttoralis and Enyhdrosoma longifurcatum (Table 1).

Stenhelia palustris, Amphiascoides limicola andEnhydrosoma longifurcatum were common along thelower transect with other species occurring only

PKRTANIKA VOL. 13 NO. 1. 1990 35

SHABDIN MOHD LONG

Fig. 2 (com.)

Paracanthonckus heterodontus

?S 2u 23 22

Axonolaimus typicus

Halalaimus afT. gracilis

Ptychohimetlus poniicus

Calyptronema maxwebm

MicTolaimus gtobiceps

Metachromadora remanex

Distance along transect [ml Distance along transect (m)

Fig. 2: Density (no. ind. 10 cm ojthe common nematode species along a transect at approximately Mean High Water Neap (MHWN)

at Grangemouth mudflats. A - River A von, C - Chemical effluent channel and 0 - Oil refinery channel. Station numbers are given.

sporadically. The only clear pattern discerniblealong this transect is the virtual diappearance ofall copepod species near the Avon channel (Fig.5). An increase in the density of Platychelipuslittoralis at the stations towards the western end ofthe transect may be associated with the somewhathigher interdal height of these stations (Stations8 & 10).

Most species occurred sporadically along themiddle transect, although Stenhelia palustris, Am-phiascoides limicola and Platychelipus littoralis wereabundant, reaching their highest densities here(Fig. 5). These three species, however, havedifferent patterns of abundance along the transect.Platychelipus littoralis attained maximum density in36 PERTANIKA VOL.

the vicinity of the refinery channel. Stenheliapalustris also peaked in this area but unlikePlatychelipus littoralis, declined to virtual extinctionin the vicinity of the Avon channel. Amphiascoideslimicola was the most abundant of the species overmost of the transect but nearly disappeared, likeStenhelia palustris, near the Avon channel and show-ed a further depression in the vicinity of therefinery channel. Although most'species wereabsent or showed severely depressed populationdensities at station 17 near the Avon, this areaharboured a flourishing population of Mesochralilljeborgi.

The harpacticoid fauna along the uppertransect was somewhat different (Fig. 5). At13 NO. I, 1990

IMPACT OF POLLUTION ON NEMATODE AND HARPACTICOID COPEPOD SPECIES COMPOSITION

< • Tersckeilingia communis

3200 3600 MXK

Fig. 3:

Distance along transect (m)

Density (no. ind. 10cm~ ) of the common nematode species

along a transect at approximately Mid Tide Level (MTL)

at Grangemouth mudflats. A - River Avon, G - Grangeburn

0 - Oil refinery channel, C - Chemical effluent channel.

Station numbers are given.

Skinflats common species included Microarthridionfallax, Stenhelia palustris, Metis ignea and Platychelipuslittoralis. However, at Kinneil, copepods parti-cularly Harpacticus gracilis were found.

Nema'odes Diversity

The number of species fluctuated between 12 and22 with no obvious pattern on the lower shoretransect (Fig. 6). The maximum number ofspecies was recorded at the station immediatelydownstream of the refinery channel (217 metres).The number of species near the Avon channel washigher than those at three other sites. Diversity andevenness followed a similar pattern, peaking atthree sites immediately downstream of the refinery

channel. The mean diversity on the lower shoretransect was 2.4 bits individual l.

On the middle shore transect, the numberof species peaked at 17 - 18 species at the ends ofthe transect and fluctuated between 9-14 speciesover the rest with no obvious localized effect bythe oil and Avon channels. Diversity and even-ness followed a similar pattern showing cleardepressions at site 17 in the vicinity of the Avon,due to strong dominance by Daptonema setosum.Mean diversity was 2.2 bits individual"1 , slight-ly lower than the lower shore transect.

Distance along transect (m)

Fig. 4: Density (no. ind. 10 cm ~) of common nematode species

along a transect at approximately Mean Low Water Neap

(MLWN) at Grangemouth mudflats. A - River Avon, G

- Grangeburn and O - Oil refinery channel. Station numbers

are given.

PKRIAMKA VOL. 13 NO. 1. I99()

SHABDIN MOHD LONG

TABLE 1The mean density (x)(no. 10 cm"2), percentage dominance (D) and frequencyoccurrence (F) of harpacticoid copepod along three transects at approximatelyMean Low Water Neap (MLWN), Mid Tide Level (MTL) and Mean High

Water Neap (MHWN) at Grangemouth mudflats.

Amphiascoides limicola

Stenhelia palustris

Platychelipus littoralis

Enhydrosoma longifurcatum

Microarthridion fallax

Microarthridion littorale

Pseudobradya minor

Cletodes limicola

Harpactkus flexus

Tachidiella minuta

Nannopus palustris

Mesochra lilljeborgi

Tachidius discipes

Enhydrosoma curticauda

Enhydrosoma propinquum

Harpactkus gracilis

Metis ignea

X

18.

12.

3.

10.

2.

1.

0.

0,

0

0

-

-

-

0

-

MLWN

9

87

3

0

9

41

.2

.1

.3

-

-

D

37.3

25.2

7.3

20.3

3.9

3.7

0.8

0.2

0.4

0.2

-

-

-

0.6

-

-

-

F

9/10

9/10

6/10

10/10

4/10

4/10

3/10

1/10

2/10

1/10 !

-

-

-

1/10

-

-

-

X

124.3

50.0

72.8

8.3

3.2

1.5

0.9

0.2

--

3.2

9.1

0.2

-

-

-

-

MTL

D

45.4

18.3

26.6

3.0

1.2

0.5

0.3

0.1

--

1.2

3.3

0.1

-

-

-

-

F

9/9

9/9

9/9

6/9

2/9

3/9

3/9

1/9

--

5.9

1/9

1/9

-

-

-

-

X

0.3

7.2

2.1

0.3

6.9

-

-

-

-

-

-

-

-

0.3

1.3

1.3

MHWN

D

1.5.

36.5

10.7

1.5

35.0

-

-

-

-

-

-

-

-

-

1.5

6.6

6.6

F

1/9

2/9

3/9

2/9

2/9

-

-

-

-

-

-

-

-

-

2/9

4.9

2/9

The number of species on the upper shore ofSkinflats was similar to the middle shore. Thenumber of species was consistently very low atKinneil (6 - 8) except at the westernmost station300 metres from the oil channel, where thenumber of species reached 16. Diversity and even-ness showed peaks closest to the discharges due tothe fact that all species were severely depressed,with no one species showing strong dominance.Mean diversity was 2.0 bits individual"1, lowerthan the middle and the lower shore transects.

Harpacticoid Copepods DiversityThe most obvious feature along the lower shoretransect was the drastic reduction of diversity,eveness and number of species near the Avonchannel ( Fig. 7). On the middle shore transect,the number of species showed depressions aroundthe oil channel and Avon, but diversity showed noclear pattern with respect to the channels. Thenumber of species on the upper shore at Skinflatswas similar to the middle shore but was reducedto 0 - 2 at KinneiL

Cluster AnalysisAt least three major groups of stations can bedetected from the dendrogram (Fig. 8). The firstcluster includes stations close to the discharges atKinneil on the upper shore transect (stations 25to 21). The second cluster, which runs fromstations 17 to 7, is dominated by stations on themiddle shore transect, whilst the third cluster isdominated by stations from the lower shore. Threeupper shore sites were isolated from these threemajor groups : station 20 at Kinneil, which wasfurthest from the refinery discharge, and stations27 and 28 from Skinflats.

Ordination of StationsThe first ordination of all stations sampled wasstrongly dominated by the first axis which onlyserved to separate stations 27 and 28 at Skinflatsfrom the other stations at Kinneil. The eigen valuesindicate the relative importance of axes (axes 1 =0.399, 2 = 0.147, 3 - 0.120 and 4 = 0.072).Therefore, in order to see the effect of pollutionon the meiofauna at Kinneil mudflats in greater

38 PKRTANIKA VOL. 13 NO. 1, 1990

IMPACT OF POLLUTION ON NEMATODE AND HARPACTICOID COPEPOD SPECIES COMPOSITION

.MHWN

23 72 21

WO WSO '70C

f £ wo

O

i

suep

g80

r-t -

A-/ \ « If

X . / i ;-.. j 1

MTL

tOO 80C 1200 1600 ?000 2UJ0 2 6 0 0 3300 ;MC0 COOL

• MLWN

A500 TO -SOP 2000 J 5 M « 0 0

~xr.::Distance along transect (m)

5: The mean density (no. ind. JO cm'2) of the three dominantspecies of harpacticoid copepods along three transects atapproximately Mean High Water Neap (MHWN), Mid TideLevel (MTL) and Mean Low Water Neap (MLWN) atGrangemouth mudflats. A - River Avon, C - Chemicaleffluent channel; G - Grangeburn and 0 - Oil refinerychannel. O O Platychelipus littoralis. • - ^ -Amphiascoides limicola, •—•-••- Stenhelia palustris.

detail, the ordination of the stations was repeatedafter excluding stations 27 and 28 (Table 2). On-ly axes 1 and 2 could be interpreted and these areplotted in Fig. 9.

The ordination of the stations is strongly in-fluenced by interdidal height superimposed bypollution effects. In order to facilitate description,the stations can be divided into groups. The up-per shore stations fall into four groups: first, thestations which are very close to the discharges (sta-tions 21 and 24), second, the stations slightly fur-ther from the discharge (stations 22, 23 and 25),the third and fourth are stations at both ends ofthe transect (stations 20 and 26). On the middleshore transect, the stations are divided into threegroups. Station 17 just downstream of the chemical

channel, is separated from those stations in thearea of the refinery channel (stations 12, 13, 14, 15and 16) and also from those stations far away fromthe discharge channels (stations 10,11,18 and 19).On the lower shore transect, the stations are divid-ed into two groups. The stations near the Avonchannel (station 4) and the oil channel (stations7 and 8) are separated from the cleaner stations(stations 1,2,3,5,6 and 9).

DISCUSSIONThere is clear chemical evidence of pollution

in the sediments from the top to the bottom of theKinneil mudflats. This is especially evident at thetop of the shore where extremely high levels ofhydrocarbons extend at least 173 metres upstream

MHWN

// \

\

//

\

?-

/ ^

^

\ /V /

A

\

Fig. 6.

XXX) 1500 2000 2500 3000 K 0 0 4000 <.S00 SOOC

Distance along transect (m)

Shannon-Wiener diversity (H*)(bits individual ) , Pieloueveness (J), species richness (S) and density (DXno. ind. 10cm~ ) of nematodes along three transects at approximatelyMean High Water Neap (MHWN), Mid Tide Level(MTL) and Mean Low Water Neap (MLWN) atGrangemouth mudflats. Station numbers are given. A - RiverAvon, C - Chemical effluent channel, G - Grangeburn andO - Oil refinery channel V 1 - diversity, * A- eveness, • + - species richness • • - density.

PERTANIKA VOL. 13 NO. 1, 1990 39

SHABDIN MOHD LONG

TABLE 2Detrended correspondence analysis of nematodes and harpactkoid <opcpods species at 26

stations based on log (x + 1) transformed densities (no. 10 cm~^) at Grangemouth mudflats(MLWN - Mean Low Water Neap, MTL - Mid Tide Level, MHWN - Mean High Water Neap).

Transe< i

MLYW

MTL

MHWN

Eigenvalue

Station

123456789

10

111213141516171819

20212223242526

Axis 1

0.000.280,600.660.420.500.900.920.730.52

0.630.961.040.951.031.031.540.610.34

2.141.802.542.071.402.372.60

0.372

Axis scores

Axis 2

1.031.020.911.631.521.141.150.890.710.28

0.17- 0.00

0.250.200.100.130.080.240.27

0.161.071.461.491.391.590.63

0.157

(standard deviation)

Axix 3

0.681.050.611.050.910.571.430.910.711.57

0.951.020.830.830.990.831.060.190.01

1.270.820.520.170.630.001.15

0.101

Axis 4

0.581.180.090.400.530.790.920.930.971.42

1.111.171.071.171.071.030.691.050.84

0.440.421.250.870.291.730.00

0.051

and 1000 metres downstream of the B.P. refineryeffluent channel (i.e. the full extent of the uppershore region at Kinneil). The B.P. refinery andB.P. chemical discharges have led to highly reduc-ing conditions in the sediments throughout the topshore region with the RPD layer occurring withinthe top few milimetres in summer (Mohd Long1987).

The nematode species display a spectrum ofresponses to the discharges, ranging from specieswhich are absent from the vicinity of the effluentsto species which are present predominantly in themost highly polluted sediments. At least 20% ofspecies were totally absent from the area affectedby pollution. Species such as Axonolaimus typicus,Daptonema normandicus, Aegialoalainus elegans, In-

nuoconema tantabundum, Neochromadora poecilosoma,Calyptronema maxweberi, Enoplus brevis, Oxytominaelongata, Spilophorella paradoxa and Paracyatholaimusproximus perhaps cannot tolerate the presence ofoil or chemical pollution, as they were only foundfar away form the sources of pollution (at Skinflatsor at either one or both ends of the bottom andmiddle shore at Kinneil).

Among the common species at Kenneil,Ptycholaimellus ponticus appeared strongly effectedby pollution; however, this species was not sorestricted in distribution as the first group, beingpresent in much of the area affected by pollution,although virtually disappearing in the reducedsediment areas at the bottom and at the top of theshore and becoming extinct just downstream of

40 I'KRTANIKA VOL. 13 NO. 1. 1990

IMPACT OF POLLUTION ON NEMATODE AND HARPACTICOID COPEPOD SPECIES COMPOSITION

no m mo a»Distance along transect (m)

Fig. 7: Shannon-Wiener diversity (H)(bits individual ) , Pielou

evenness (f), species richness (S) and density (D)(no. ind.

10 cm~ ) of harpacticoid copepods along three transects at

approximately Mean High Water Neap (MHWN), Mid Tide

Level (MTL) and Mean Low Water Neap (MLWN) at

Grangemouth mudflats. Station numbers are given. A - River

Avon, C - Chemical effluent channel, G - Grangeburn and

0 - Oil refinery channel • • - diversity, A" ^ -

evenness, 0 # - species richness and • •

density.

the chemical channel on the middle shore. Similar-ly, Bouwman et ai (1984) found Ptycholaimellusport-ticus to be absent in the vicinity of potato flour in-dustry outfall in the EMS-Dollart estuary, but wasone of the dominant species at more than 100metres from the outfall. In contrast, Alongi et ai(1983) found Ptychloimellus ponticus to be one of theearliest species to colonize sediments experimen-tally sprayed with oil.

Sabatieria pulchra is another dominant speciesat Grangemouth. It has frequently been record-ed as dominant in pulluted sediments (Tietjen197?; Bouwman 1978; Tenore^a/. 1982) and theremarkable eurytolerance of Sabatieria pulchra hasbeen observed and demonstrated repeatedly.Jensen (1981) found Sabatieria pulchra to be the onlymesohaline comesomatid and one of the few meta-zoans thriving in the extremely oxygen-depletedsediment in the Baltic sea and he classified itas an inhabitant of the RPD layer in European

201

First Second Thirdcluster cluster cluster722b It. 2 3 P 30 28 271715 16 H O l j n 10 ' b 5 l 19 » 9 8

T

LJ

1V

Fig. 8: Dendrogram illustrating the similarity of the stations at

approximately Mean High Water Neap (MHWN), Mid Tide

Level (MTL) and Mean Low Water Neap (ML WN),

based on density (no. ind. 10 cm~2) of nematode and

Harpacticoid species at Grangemouth mudflats.

% -MHWN, 0 -MTL and A MLWN

0 1Axis 1

Fig. 9: Detrended correspondence analysis of nematode and harpacti-

coid species at 26 stations on Grangemouth mudflats. The

diagram shows the ordination of sites in the space of first two

vectors. The sites are located at approximately

• - MHWN, # - MTL and A - ML WN

sediment, suggesting an ability to toleratesulphides and to utilize the higher microbial den-sities in this layer. Warwick and Price (1979)

PERTANIKA VOL. \3 NO. 1, 1990 41

SHABDIN MOHD LONG

indicated that this species was a facultativeanaerobe. Surprisingly Sabatieria pulchra at Kinneilseemed to be affected by the pollution, itsdensity apparently diminishing in the vicinity ofthe effluents. However, as only the top 3 cm wassampled, it might be that the bulk of the Sabatieriapulchra population was missed. The other commonspecies were slighly or not adversely affected bypollution (Atrochromadora microlaima, Daptonemasetosum and Tripyhidesgracilis). Indeed, Daptonemasetosum density seemed to be enhanced at sites justdownstream of the chemical and the refinery chan-nels on the middle shore. As this species is knownto feed on diatoms (Romeyn et ai 1983; Bouwman1983), this enhancement may be associated withthe dense microalgal mat that fringes the chan-nels. This may also explain the virtual restrictionof species such as Monhystera parva, Monhysteraanophthalma and Diplolaimella ocellata to the vicini-ty of the effluent channels. Hence the nematodespecies in the area seem to show a variety ofresponses to the discharges ranging from in-tolerance to stimulation

It is known that salinity is one of the factorscontrolling the distribution of nematode speciesin estuaries (Gerlach 1953; Warwick 1971; War-wick and Gee 1984; Jensen 1984). Warwick andGee (1984) recorded Ptycholaimellus ponticus wasabundant and Atrochromadora microlaima was absentat Clifton in the Tamar estuary in the month ofOctober where the salinity was below 5 %.However, they found that Atrochromadora microlaimawas present at Neal point and West mud in thesame month where the salinity was higher thanat Clifton. Jensen (1984) and Gerlach (1953) alsorecorded Ptycholaimellus ponticus as having a greatertolerance to the low salinity than Atrochromadoramicrolaima. However, at Kinneil, Ptycholaimellusponticus was absent just downstream of the chemi-al channel near the River Avon on the middleshore and was reduced in density just below theconfluence of the River Avon and chemicalhannels on the lower shore, whilst Atrochromadoramicrolaima was present in moderate density at bothsites. This suggests that the density of Ptycholai-mellus ponticus was influenced by pollution ratherthan by any salinity effects.

Findings on the reaction of benthic harpacti-coid copepods to the presence of oil are contradic-tory in the literature. Several studies have found

that the presence of oil pollution did not affect thecopepod community (Naidu et aL, 1978; Fleeger& Chandler 1983; Alongi et al 1983; Decker &Fleeger 1984; Boucher 1984), while others haverecorded an effect (Giere 1979; Wormald 1976;Bonsdorff 1981). The difference in results mightbe caused by the differences in habitat, level ofpollution, types of oil used, period of studies andtolerance of the copepod species. The benthicharpacticoid copepods at Kinneil were virtuallyabsent at sites close to the discharges on the topshore. Only Harpacticusgracilis was found sporadi-cally distributed among the stations at the top ofthe shore. This contrasts strongly with the situa-tion at similar tidal level at Skinflats, whereStenhelia palustris, Platychelipus littoralis and Micro-arthridionfallax were common. Thus, the absenceof these species at the top shore at kinneil clearlyimplicated pollution as a causative factor.

Over the rest of the shore at Kinneil thecopepod species display a range of response topollution with Amphiascoides limicola apparentlyreduced by both refinery and chemical effluents,Stenhelia palustris by the chemical discharge whilstPlatychelipus littoralis appears to be enhanced in thevicinity of the refinery channel on the middleshore. Mesochra lilljeborgi, generally absent,flourishes just downstream of the chemical chan-nel on the middle shore, presumably as a con-sequence of the enhanced alga flora, as this speciesis usually commonest in phytal habitats.

In this area, species richness seems a bettermeasure of pollution impact than species diversi-ty or evennes. Nematode and harpacticoid speciesrichness seems to be clearly influenced by thedischarges on the top and middle shore. The areadisplaying depressed species richness on the topshore extended at least 200 metres upstream and870 metres downstream of the oil channel and, onthe middle shore, at least 563 metres upstream and938 metres downstream of the oil channel. Therewas no clear impact of pollution on speciesrichness at the bottom of the shore. Species diver-sity was of little value as a pollution indicator onall transects. It is clear that the species richnessof both harpacticoid copepods and nematodeswere affected on the top and middle of the shore.However, the harpacticoid species richness is morestrongly affected than that of the nematodes onthe top of the shore. Species diversity and even-

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ness are again unsuitable measures for bothcopepods and nematodes on the top and middleshores, although there was a big change innematode diversity near the chemical effluent onthe middle shore. On the lower shore, nematodesseemed unaffected by pollution but copepods suf-fered a drastic reduction in species richness, diver-sity and evenness near the River Avon andchemical effluent confluence. It seemed thatspecies diversity was not really suitable as ameasure of pollution impact in the area due to thedrastic reduction of all species, leading sometimesto relatively high diversity in the most pollutedsites as a result of high evenness.

When the totality of species distributions areconsidered, two controlling factors seem domi-nant, intertidal height and pollution. Clusteranalysis of the stations clearly showed the separa-tion of sites on the upper, middle and lower shore.However, on the upper shore, the sites close tothe discharges, which can be considered aspolluted (from the evidence of hydrocarbon valueand RPD depth; Mohd Long (1987), weregrouped together and separated from the site nearthe River Avon, where some recovery of meio-fauna occurred, and the sites at Skinflats whichwere considered as clean. On the mid and lowershore, cluster analysis were not very helpful inseparating effects of pollution from those of naturalfactors. The ordination of stations was also strong-ly influenced by intertidal height, although pollu-tion seemed to play the second major role in con-trolling species composition. The polluted sites onthe upper shore were again isolated from therecovery site near the River Avon and clean sitesat Skinflats. The mid shore site just downstreamof the chemial channel was isolated from the othermid shore sites, indicating a pollution effect. Onthe lower shore, sites immediately upstream anddownstream of the refinery channel and the sitesjust below the confluence of the Riven Avon andthe chemical channel were isolated from theothers. This was also possibly caused by the ef-fects of the refinery and chemical discharges.

ACKNOWLEDGEMENTS

The author wishes to thank Dr. C.G. Mooreof the Department of Brewing and BiologicalSciences, Heriot-Watt University for his com-ments and advice throughout this study.

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(Received 26 October, 1987)

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