Journal of Environmental Biology January 2007, 28(1) 53-62 (2007) ©Triveni Enterprises, Lucknow () For personal use only Free paper downloaded from: ww w. jeb.co.in Commercial distribution of this copy is illegal Distribution and abundance of zooplankton in relation to petroleum hydrocarbon content along the coast of (Quilon), south west coast of India

B.S. Sharma* 1 and Wilma Cyril 2

1Department of Environmental Studies, School of Life Sciences Dr. Bhim Rao Ambedkar University, Khandari Campus, Agra-282 002, India 2Department of Chemistry, Fatima Mata National College, Kollam-690 013, India

(Received: 15 March, 2005 ; Revised received: September 20, 2005 ; Accepted: 10 October, 2005)

Abstract: In the present study, we examine status, impact and trends in prevailing situation of coastal ecosystem of , , and Paravur zones of Kollam coast in terms of zooplankton density and petroleum hydrocarbon content (PHC). Zooplankton samples and water samples were collected during the period May 2003 to June 2004. The numerical count of zooplankton made and PHC content estimated. Paravur offshore recorded the maximum zooplankton count (1390 no./m 3) and Tangasseri nearshore the lowest (700.5 no/m 3). The petroleum hydrocarbon content was highest at Tangasseri nearshore (21.95 µg/l) and lowest at Paravur offshore (9.40µg/l). We also observe statistically significant negative correlation between zooplankton density and PHC for a few organisms. The overall impact appears minor, yet, coastal ocean monitoring imperative for sustainable development.

Key words: Zooplankton, Kollam coast, Petroleum hydrocarbon content, Marine oil pollution

Introduction abundance of zooplankton. The abundance of zooplankton in the Petroleum hydrocarbon content in aquatic environment can south west coast of India has been reported earlier (Madhupratap cause deleterious effects on biota, effects which are not visible et al., 1992 ; Asha et al., 2002). That the west coast is more and may come to light after a long period of time. Holoplankton as productive and tolerant groups responded differently at different well as meroplanktonic organisms are sensitive to exposure to stations to various physico chemical parameters has been observed (Nair et al. , 1978). hydrocarbons. (Nair, 2001). Lethal concentrations of oil (96hr LC 50 ) ranges from 0.5 to 10mg/l (NIO, 1995). However, in general the Neendakara, which is one of the major fishing harbours eggs and planktonic larval stages of pelagic as well as benthic in , harbours more than three thousand fishing vessels. organisms are sensitive to low oil concentrations of 10-100µg/l Petroleum hydrocarbon content at Neendakara has been reported (Nair, 2001). Plankton and especially the neuston living on the top by many investigators. The boats fitted with outboard engines few centimeters of the sea might be supposed to be particularly at which are being extensively used for fishing in Neendakara are risk because it is exposed to the highest concentration of water the sources of high PHC content (Robin et al., 2002). The soluble constituents leaching from floating oil. The sub lethal effects possibility can not be excluded that the fairly substantial amounts of petroleum encountered in zooplankton vary widely and include of oil that reach the sea are responsible for the expansion of alterations in feeding, growth, reproduction, fecundity, reduction in impoverished, altered coastal environment and disappearance larval life span, reduction in brood size and number of young ones of sensitive types of organisms (Sarthre et al., 2000). Unnithan produced, inhibition of moulting in larval crustaceans, inhibition of et al. (1981) reported tar like deposits appear to be derived from yolk utilization, occurrence of abnormal intermediate larval stages, oil spills and oil tanker washings from fourteen beaches of Kerala. morphogenic abnormalities and alternations in swimming activity Zooplankton can accumulate petroleum hydrocarbon and and food perception. (NIO, 1995). concentrate both aliphatic and aromatic hydrocarbons. Moreover, the metabolites are resistant to depuration. The retention of oil The zooplankton abundance and distribution from may create long term consequences (Nair, 2001). Due to these eutrophic as well as oligotrophic waters have been reported earlier facts, the studies on the relation of zooplankton distribution and (Paulinose and Aravindakshan, 1977; Trainter and George, 1972; abundance to petroleum hydrocarbon content along the coast of Haq et al., 1973; Smith, 1982; Wickstead, 1961; Chua and Chong, Kollam assume key importance and significance. 1975; Rezai et al., 2000; Rezai et al., 2003; Madhupratap et al., 1977; Madhupratap, 1983; Madhupratap et al., 1996; Al-yamini et Materials and Methods al., 1993; Price et al., 1993; Khalil and El-Rahman, 1997; Goswami Kollam, on the south west coast of India, located 1983). Coastal areas of the Arabian Sea are major areas of between 8º45’ and 9º28’ N latitude and 76º28’ and 77º17’ E upwelling (Currie et al., 1973) and this area sustains the maximum longitude has a coastline length of 41 km.

*Corresponding author: E-mail: [email protected], Tel.: 0562-2512104, Fax: 0562-2524672

Journal of Environmental Biology  January, 2007  54 B.S. Sharma and Wilma Cyril During the study period June 2003 to May 2004 (the study period being divided into three seasons, June to September (monsoon), October to January (post monsoon), February to May (pre monsoon)], marine water sampling was done from a mechanized canoe on a monthly basis during the first week of every month from eight sampling stations of the four sites of the

Kollam coast, Chavara nearshore S 1, Chavara offshore S 2,

Neendakara nearshore S 3, Neendakara offshore S 4, Tangasseri nearshore S 5, Tangasseri offshore S 6, Paravur nearshore S 7 and

Paravur offshore S 8 (Fig. 1). The atmospheric temperature and relative humidity were noted and given in Table 1. At each station, zooplankton samples were collected by filtering 25 litre two times of surface seawater using plastic container, through plankton nets (mesh size 30 µm and 150 µm) and preserved with 4% neutral formalin solution. The volume of each sample was concentrated to 100 ml and sub samples of 2 ml were transferred into a counting cell and each zooplankton was counted separately using a research binocular microscope under high magnification. The density of zooplankton organisms was calculated as their total number per cubic meter. For the estimation of petroleum hydrocarbon content, seawater samples were collected in wide mouthed 2.5 litre glass bottles and estimations were done by Partition Gravimetric method (APHA, 1998).

Results and Discussion Fig. 1: Map of Kollam coast showing the sampling stations A total number of 28 zooplanktons were identified along the - 0 km. zone of Kollam Coast, study area. The distribution of zooplankton of Kollam coast (annual - 5 km. westward from the Kollam Coast average) is depicted in Table 2. The mean numerical counts of

Table - 1: Atmospheric temperature ( oC) and relative humidity (%) along Kollam coast S S S S S S S S Season Date of 1 2 3 4 5 6 7 8 sampling THTHTHTHTHTHTHTH

Monsoon 03-06-2003 23.8 88 23.1 94 23.5 88 22.9 94 23.9 88 23.2 98 23.9 88 23.2 86 03-07-2003 24.9 85 24.4 92 24.8 85 24.4 92 24.8 85 24.3 94 24.7 85 24.2 95 03-08-2003 26.8 88 26.6 94 26.7 88 26.2 89 26.4 89 26.8 92 26.3 90 26.7 94 03-09-2003 24.0 85 23.9 94 24.0 85 24.6 89 24.1 85 23.9 94 23.9 98 23.8 98 Post monsoon 02-10-2003 26.0 87 25.8 92 26.3 87 25.9 92 26.3 87 25.9 93 26.3 87 25.9 92 02-11-2003 26.1 89 25.9 91 26.0 89 25.8 89 26.1 89 25.8 91 26.0 89 25.9 91 04-12-2003 25.0 86 24.9 95 24.9 87 24.8 92 24.9 87 24.8 90 25.0 85 24.9 94 03-01-2004 24.9 87 24.8 97 24.8 88 24.7 96 24.8 88 24.8 90 24.9 88 24.7 90 Pre monsoon 03-02-2004 24.0 90 23.9 98 24.2 87 23.9 98 24.2 97 23.9 96 24.1 90 23.9 94 02-03-2004 27.9 88 27.9 92 27.8 88 27.2 92 27.8 88 27.1 92 28.0 88 27.8 90 02-04-2004 29.1 78 28.8 84 29.2 78 28.9 84 29.1 78 28.9 82 29.3 78 28.9 84 02-05-2004 28.9 80 28.8 82 29.2 80 28.8 82 29.1 80 28.8 82 29.2 80 28.6 82

T = Temperature, H = Relative humidity, S1 = Chavara nearshore, S 2 = Chavara offshore, S 3 = Neendakara nearshore, S 4 = Neendakara offshore,

S5 = Tangasseri nearshore, S 6 = Tangasseri offshore, S 7 = Paravur nearshore, S 8 = Paravur offshore different zooplankton community indicate that a regular trend in doliolids at Chavara S 1 and Neendakara S 3, decapod larvae at the distribution is not discernible. The data revealed that even Chavara S 1, fish eggs at Neendakara S 3, fish larvae at Neendakara 3 though the overall zooplankton no/m were more at the offshore S3 foraminiferans at Chavara S 1, gastropod larvae at Tangasseri area, relative abundance was observed at the near shore area for S5, isopods at Chavara S 1 and Paravur S 7, lamellibranch larvae at many organisms at varying sites namely cumaceans at Paravur Neendakara S 3 and Tangasseri S 5, lucifers at Chavara S 1 and

S7, copepods at Neendakara S 3, Tangasseri S 5 and Paravur S 7, Neendakara S 3, mysids at Neendakara S 3 and Tangasseri S 5,

Journal of Environmental Biology  January, 2007  Zooplankton and PHC along Kollam coast 55

Table - 2 : Distribution of zooplankton (no/m 3) of Kollam coast (annual average) during 2003 June to 2004 May

Organism S1 S2 S3 S4 S5 S6 S7 S8 Appendicularians 45.16 48.08 41.41 43.66 41.83 42.66 36.83 41.08 Amphipods 18.75 28.66 23.58 24.25 23.58 27.08 22.91 24.41 Cladocerans 157.41 182.08 173.66 175.91 171.91 180.16 89.41 109.33 Chaetognaths 0.91 14.41 0 12.58 0 16.16 4.08 4.33 Ctenophores 2.58 11 0 9.58 0 7.75 1.5 2.08 Cumaceans 4.08 4.5 0 0 0 0 1.58 0.83 Copepods 221.08 253.83 243.33 233.66 247.25 241.16 785 777.25 Doliolids 4.25 3.08 3.66 3 0 0 4.58 4.83 Decapod larvae 88.91 55.08 32 62.5 34.5 72.33 20.25 21.25 Fish eggs 5.5 10.25 8.16 6.83 6.25 7.66 9.66 12.16 Fish larvae 6.66 7.83 7.75 6.75 6.08 6.75 12 12.41 Foraminiferans 9.25 1.25 8.25 9.91 3.16 11.08 8.41 9 Gastropod larvae 7.75 12.66 6.66 6.66 7.08 6.66 13.83 15.66 Isopods 6.83 1.16 0 0 0 0 4.83 0 Lamellibranch larvae 10.16 12.5 3.66 3.16 4.83 3.33 73.16 78.66 Lucifer 19.25 5.5 6.5 5.83 6.25 8.08 12.83 13.5 Mysids 6.08 7.66 8.33 7.16 7.58 6.91 4.5 4.5 Medusae 3.66 7.08 2.16 3.83 4.83 0 2.91 4.25 Nauplii larvae 43.41 42 88.16 61.58 77.66 57.25 154.91 153.33 Ostracods 3 1.08 0 2.25 0.5 0 2.75 1.25 Polychaete larvae 16.25 17.16 12.33 11.33 10.33 9.16 10.66 17.58 Protozoea larvae 8.41 2.91 7.5 2.58 0.58 4.5 6.16 14.66 Radiolarians 13.75 14.58 7.91 8.16 8.91 8.41 17 17.91 Siphonophores 0 2.16 0.75 1.5 0 0 0.41 0.33 Stomatopods 8.91 2.08 2.66 3.41 2.5 0.25 7.25 3.83 Tintinnids 19.5 17.25 17.5 10.33 19.33 10.75 19 17.91 Veliger larvae 3.16 0 0 2.16 0 0 7.08 7.66 Zoea larvae 17.33 19.75 12.91 9.08 15.5 13.66 18.16 19.91

medusae at Tangasseri S 5, nauplii larvae at all the four sites, not appear during the monsoon and lamellibranch larvae during ostracods at Chavara S 1, Tangasseri S 5 and Paravur S 7, polychaete the pre monsoon. The post monsoon period showed a similar larvae at Neendakara S 3 and Tangasseri S 5, protozoea larvae at trend in the appearance of organisms as the monsoon period.

Chavara S 1 and Neendakara S 3, radiolarians at Tangasseri S 5, Siphonophores were represented more during the pre monsoon.

siphonophores at Paravur S 7, stomatopods at Chavara S 1 and During pre monsoon the dominance of copepods was over Paravur S , tintinnids at all the four sites, veliger larvae at Chavara 7 shadowed by cladocerans at S 1, S 2, S 3, S 4, S 5 and S 6. The pre S1 and zoea larvae at Neendakara S 3 and Tangasseri S 5. monsoonal appearance of cladocerans at Kollam coast has been Copepods emerged as the major group claiming for 41.1% observed earlier also (Robin et al., 2003). The zooplankton peak of the total zooplankton population along the entire study area. was during pre monsoon, which is in conformity with earlier Even though the south west coast of India is considered to be rich observation (Robin et al., 2003; Mathew and Solomon, 1996). in decapod larvae as reported by Menon and Paulinose (1973), During the present study wide variations and fluctuations the studies of Mathew et al. (1984) in the region of Alleppey mud in zooplankton density was noted. At Chavara S 1 and S 2, the bank have shown copepods to be the major group. The dominance overall mean zooplankton density and PHC value during the of copepods in the south central west coast of India has been study period was 767no/m 3, 875.66 no./m 3 and 18.53µg/l, 17.05 reported (Vijayaraghavan et al., 1982). The monthly percentage µg/l respectively. The value of PHC at S 1 was moderately high distribution of a few major zooplanktons namely copepods, during the study period relative to all the four sites. Even though amphipods, cladocerans, decapod larvae and nauplii larvae are a fish landing centre is absent at Chavara, fishing vessels shown in Figs. 2a to 2h. Copepod was one group which was playing across the waters may be responsible for the petroleum uniformly distributed throughout the study area. This observation hydrocarbon content. Correlations derived for petroleum is in agreement with earlier studies (Mathew and Solomon, 1996). hydrocarbon content against zooplankton density showed Along the neustonic realm of Kollam coastal waters, the significant negative correlation for cumaceans (r = – 0.582, zooplankton community varied from station to station and season p< 0.05), lamellibranch larvae (r = – 0.747, p < 0.01), nauplii to season as observed by prior investigators (Robin et al., 2003). larvae (r = – 0.807, p < 0.01), radiolarians (r = – 0.904, p < It was noted that protozoea larvae, medusae and isopods did 0.01), tintinnids (r = – 0.673, p < 0.05), chaetognaths

Journal of Environmental Biology  January, 2007  56 B.S. Sharma and Wilma Cyril

Fig. 2a Monthly percentage distribution of a few major zooplankton at Chavara site S 1 Legend of Fig. 2a

Amphipods x

Cladocerans

Copepods

Decapod larvae

Nauplii larvae x

Fig. 2b Monthly percentage distribution of a few major zooplankton at Chavara site S 2 Legend of Fig. 2b

Amphipods x

Cladocerans

Copepods

Decapod larvae

Nauplii larvae x

Journal of Environmental Biology  January, 2007  Zooplankton and PHC along Kollam coast. 57

Fig. 2c Monthly percentage distribution of a few major zooplankton at Neendakara site S 3 Legend of Fig. 2c

Amphipods x

Cladocerans

Copepods

Decapod larvae

Nauplii larvae x

Fig. 2d Monthly percentage distribution of a few major zooplankton at Neendakara site S 4 Legend of Fig. 2d

Amphipods x

Cladocerans

Copepods

Decapod larvae

Nauplii larvae x

Journal of Environmental Biology  January, 2007  58 B.S. Sharma and Wilma Cyril

Fig. 2e Monthly percentage distribution of a few major zooplankton at Tangasseri site S 5 Legend of Fig. 2e

Amphipods x

Cladocerans

Copepods

Decapod larvae

Nauplii larvae x

Fig. 2f Monthly percentage distribution of a few major zooplankton at Tangasseri site S 6 Legend of Fig. 2f

Amphipods x

Cladocerans

Copepods

Decapod larvae

Nauplii larvae x

Journal of Environmental Biology  January, 2007  Zooplankton and PHC along Kollam coast. 59

90

80

70

60

50

40

30

20

Percentage of Zooplankton Percentage 10

0 Jun-03 July Aug. Sept. Oct. Nov. Dec. Jan.-04 Feb. March April May Months of Sampling

Fig. 2g: Monthly percentage distribution of a few major zooplankton at Paravur site S 7 Legend of Fig. 2g

Amphipods x

Cladocerans

Copepods

Decapod larvae

Nauplii larvae x

80

70

60

50

40

30

20

Percentage of Zooplankton Percentage 10

0 Jun-03 July Aug. Sept. Oct. Nov. Dec. Jan.-04 Feb. March April May Months of Sam pling

Fig. 2h: Monthly percentage distribution of a few major zooplankton at Paravur site S 8 Legend of Fig.2h

Amphipods x

Cladocerans

Copepods

Decapod larvae

Nauplii larvae x

Journal of Environmental Biology  January, 2007  60 B.S. Sharma and Wilma Cyril 5 5 05 .05 0.05 0.05 0.05 p>0.05 8 S 3 p>0.05 5 p>0.05 14 p>0.05 750 p<0.01 05 -0.134 p>0.05 7 S RR -0.195 p>0.05 ERR ERR - Absent. - 6 S RR ERR -0.368 p>0.05 -0.006 p>0.05 ERR ERR ERR 0.146 p>0.05 0.140 p>0.05 5 S .021 p>0.05 ERR ERR 0.666 p<0.05 0.074 p>0.05 0.082 p>0.05 ERR ERR -0.299 p>0.05 -0.378 p>0.05 -0.575 p>0.05 -0.100 p>0.05 -0.359 p>0.05 -0.478 p>0.05 g/l) g/l) along the study area µ 5 ERR ERR ERR ERR -0.364 p>0.05 -0.309 p>0.05 5 0.387 p>0.05 0.021 p>0.05 -0.393 p>0.05 -0.605 p<0.05 0505 ERR ERR ERR -0.487 ERR -0.564 p>0.05 -0.720 p>0.05 -0.465 p<0.01 -0.638 p>0.05 -0.069 p<0.05 p>0.05 01 ERR ERR ERR ERR 0.255 p>0.05 0.079 p>0.05 05 -0.448 p>0.05 -0.300 p>0.05 -0.325 p>0.05 -0.422 p>0.05 .05 -0.888 p<0.01 -0.189 p>0.05 0.106 p>0.05 0.180 p>0.05 0.05 -0.021 p>0.05 0.036 p>0.05 -0.162 p>0.05 0.598 p<0.05 0.05 -0.254 p>0.05 -0.156 p>0.05 -0.780 p<0.01 -0.325 p>0.0 0.05 0.516 p>0.05 0.129 p>0.05 -0.466 p>0.05 -0.341 p>0.05 p>0.05 0.258 p>0.05 -0.112 p>0.05 -0.123 p>0.05 0.210 p>0.0 4 S 6 p>0.05 -0.685 p<0.05 0.077 p>0.05 -0.488 p>0.05 -0.651 p<0 2 p>0.05 0.109 p>0.05 0.314 p>0.05 -0.462 p>0.05 -0.482 p>0. 63 p>0.05 0.699 p<0.05 -0.059 p>0.05 -0.198 p>0.05 -0.274 p> icant at 5%level, >p 0.05 ERR Not significant, 474092 p>0.05 -0.021 p>0.05 -0.800 p>0.05 p<0.01 0.264 -0.175 p>0.05 p>0.05 0.330 0.422 p>0.05 -0.313 p>0.05 0.235 p> p> 0.411 p>0.05 -0.124 p>0.05 0.129 p>0.05 -0.329 p>0.05 -0.48 0.296 p>0.05 -0.640 p<0.05 -0.108 p>0.05 0.152 p>0.05 -0.34 0.420 p>0.05 -0.635 p<0.05 0.033 p>0.05 0.011 p>0.05 -0.038 0.157 p>0.05 -0.462 p>0.05 -0.051 p>0.05 -0.794 p<0.01 -0.5 -0.069 p>0.05 -0.317 p>0.05 -0.253 p>0.05 -0.389 p>0.05 -0. <0.01 -0.668 p<0.05 -0.824 p<0.01 -0.254 p>0.05 -0.230 p>0. 3 S ) ) and hydrocarbonpetroleum content ( 3 on (no/m 2 S < Significant 0.01 at 1% level, p 0.05 < Signif 1 rprprprprprprprp Correlation andprobability coefficient : Zooplankt Amphipods 0.323 p>0.05 0.047 p>0.05 -0.159 p>0.05 -0.327 p> Appendicularians 0.136 p>0.05 -0.238 p>0.05 -0.247 p>0.05 OstracodsPolychaete larvae Protozoea larvaeRadiolarians -0.215Siphonophores -0.064 p>0.05Stomatopods 0.735 p>0.05 0.079Tintinnids p<0.01 larvaeVeliger 0.416 p>0.05 -0.904 0.284 ERR p>0.05 0.312 p<0.01 p>0.05 p>0.05 0.657 -0.246 ERR 0.483 ERR p<0.05 p>0.05 p>0.05 0.456 ERR -0.673 0.149 -0.538 0.375 0. p>0.05 p<0.05 p>0.05 p>0.05 0.615 p>0.05 0.232 -0.323 -0. p<0.05 ERR 0.420 p>0.05 p>0.05 -0 p>0.05 -0.368 0.135 ERR 0.387 p>0.05 p>0.0 ERR p> 0.499 ERR 0.040 p>0.05 ERR Lamellibranch larvae -0.747 p<0.01 -0.348 p>0.05 -0.803 p IsopodsLuciferMysidsMedusaeNaupliilarvae 0.460 p>0.05 0.131 0.369 0.260 -0.807 p>0.05 p>0.05 0.657 p>0.05 p<0.01 -0.124 ERR p<0.05 -0.156 p>0.05 0.515 0.526 ERR -0.272 p>0.05 p>0.05 p>0.05 p>0.05 -0.534 0.163 ERR 0.600 p>0.05 -0.018 p>0.05 p<0.05 - ERR p>0 -0.110 0.598 ERR p>0.05 p<0.05 ERR ERR E CladoceransChaetognathsCtenophoresCumaceans 0.563 0.223 p>0.05 p>0.05 -0.093 0.449 -0.850 p>0.05 -0.582 p>0.05 p<0.01 -0.865 p<0.05 0.430 p<0.01 ERR 0.125 p>0.05 ERR p>0.05 ERR 0.144 ERR -0.558 ERR p> p>0. -0.653 ERR p<0. ERR ERR ERR ERR E CopepodsDoliolidsDecapodlarvae 0.311 -0.078 p>0.05 p>0.05 0.817 0.368 -0.443 p<0.01 p>0.05 p>0.05 0.774 -0.415 0.212 p<0.01 p>0.05 p>0.05 0.680 - 0.106 p<0.05 p>0.0 0.738 p<0. Fish eggsFish larvaeForaminiferans 0.166 0.688 0.166 p>0.05 p<0.05 p>0.05 0.447 -0.760 -0.185 p>0.05 p<0.01 p>0.05 0.332 -0.048 0.771 p>0.05 p>0.05 p<0.01 0.151 -0.05 0.0 p>0. Gastropod larvae 0.283 p>0.05 -0.274 p>0.05 -0.182 p>0.05 Table 3 - : Table Name of organism S Zoealarvae -0.331 p>0.05 0.811 p<0.01 -0.374 p>0.05 -0.08 r = Pearson’s coefficient, p r coefficient, == p Pearson’s Probability,

Journal of Environmental Biology  January, 2007  Zooplankton and PHC along Kollam coast. 61 (r = – 0.850, p < 0.01), ctenophores (r = – 0.865, p < 0.01) and nutrients during the south west monsoon resulting in phytoplankton foraminiferans (r = – 0.760, p < 0.01) at Chavara. The correlation abundance. High concentration of primary food generally results coefficient between zooplankton no/m 3 and PHC along the study in the swarming of a few herbivores/omnivores such as copepods area is given in Table 3. and amphipods (Goswami and Shrivastava, 1996). At Neendakara, the overall mean zooplankton density It is known that the dose and duration of oil exposure will and PHC value during the study period was 718.91 no/m 3, 727.75 never reach the threshold limit in the open sea. Moreover these 3 organisms can reproduce rapidly and any population reduction no./m and 20.96 µg/l, 15.92 µg/l at S 3 and S 4 respectively. Neendakara, which is the cradle of seafood industry, showed can soon be restored (Nair, 2001). In the course of our study, we rather high petroleum hydrocarbon content in the coastal waters have observed negative correlation between PHC and which is in agreement with the observations of prior investigators zooplankton density only for a few organisms. The overall impact appears minor. The observed decrease in the case of certain (Sarthre et al., 2000 and Robin et al., 2002). At S 3 the PHC value was high during the study period, relative to all the four sites. groups was only relative, in the sense that a group was considered Hectic fishing activities during the season are causative to the less abundant because of the very high abundance of certain high oil content. Except for lamellibranch larvae (r = – 0.803, p < other group or groups in the same area, which shadowed all others as observed by Mathew and Solomon (1996). 0.01 at S 3 and r = –0.668, p < 0.05 at S 4) and ctenophores (r = – 0.653, p < 0.05) which was negatively correlated with petroleum Yet, off the upwelling coast of Kollam the inverse hydrocarbon content, no other organism showed significant relationship of zooplankton density to petroleum hydrocarbon negative correlation at Neendakara. content observed for a few organisms is a matter of concern as it At Tangasseri, the overall mean zooplankton density and may in the long run affect the pelagic fishery of the region as a whole. Hence, regular coastal ocean monitoring is imperative for PHC value during the study period was 700.5 no./m 3, 741.88 no/ effective environmental management and sustainable m3 and 21.95 µg/l, 14.41 µg/l respectively. At S , zooplankton 5 development of Kollam coast. density was lowest and PHC value was highest observed during the study period relative to all the four sites. Tangasseri harbours Acknowledgments lesser number of fishing vessels than Neendakara. Yet, the higher The second author (Wilma Cyril is grateful to Dr. J.S. oil content is due to the lower tidal flushing at the promontory, Sharma STA (Japan) Environment, Chief Chemist, ONGC, causing greater deposition of oil at the coastal waters, the oil Krishna Godavari Basin, Rajahmundry Asset, Godawari Bhawan,

being trapped at the headland. The correlations at S 5 for fish Base Complex, Rajahmundry-533 106, Andhra Pradesh (India) larvae (r = – 0.685, p < 0.05), lamellibranch larvae (r = – 0.824, p for the help and encouragement rendered and to the UGC for < 0.01), lucifers (r = – 0.888, p < 0.01), nauplii (r = – 0.635, p < financial assistance in the form ot Teacher Fellowship under FIP 0.05), polychaete larvae (r = – 0.640, p < 0.05) and radiolarians Plan. (r = – 0.800, p < 0.01) were all significant at Tangasseri. References Paravur S and S recorded overall mean zooplankton 7 8 Al Yamini, F.Y., K. Al Rifaie and W. Ismail: Post spill zooplankton distribution in 3 3 density PHC value of 1351.3 no./m , 1390 no./m and 9.93 µg/l, the NW Gulf. Mar. Pollut. Bull. , 27 , 239-244 (1993). APHA.: Standard methods for the examination of water and waste water, 20 th 9.40 µg/l respectively. At S 8, zooplankton density was highest and PHC value lowest during the study period relative to all the four sites. Edn. American public health association, Washington DC, USA. (1998). The low oil content in the Paravur coastal waters is attributed to the Asha, B.S., C.S. Satheesh Kumar and P.P. Ouseph: Plankton characteristics in the marine environment of Cochin. Proc. Fourteenth Kerala Science fact that at this fishing village, country boats are more in vogue than Congress, . Science, technology and environment committee mechanized boats. Amphipod (r = – 0.780, p < 0.01); chaetognaths (STEC), Govt. of Kerala. pp .435-438 (2002). Chua, T.E. and B.J. Chong: Plankton distribution in the straits of Malacca and (r = – 0.720, p < 0.01 at S 7 and r = – 0.638, p < 0.05 at S 8); gastropod larvae (r = – 0.794, p < 0.01); appendicularian (r=-0.750, p < 0.01); its adjacent waters. Proc. of the Pacific Science Association of Marine Science Symposium, Dec. 1973, Hongkong . pp. 17-23 (1975). copepods (r = – 0.605 p < 0.05) and fish larvae (r=– 0.651, p. < 0.05) Currie, R.I., A.E. Fisher and P.M. Hargreaves: In : The biology of the Indian showed significant negative correlation at Paravur. Ocean ( Eds : B. Zeitzschel and S.A. Gerlach ). Springer Verlag, Berlin. pp. 37-52 (1973). Imbalance in zooplankton population arises from the Goswami, S.C.: Production and zooplankton community structure in the lagoon fluctuation in the environmental conditions resulting in poor and surrounding sea at Atoll (Lakshadweep). Indian J.Mar. upwelling, rise in sea surface temperature, under water Sci., 12, 3-14 (1983). disturbances, altered monsoons and water currents, which are Goswami, S.C. and Y. Shrivastava: Zooplankton standing stock, community the main natural causes. Pollution, especially due to oil spills is structure and diversity in the northern Arabian sea. Proc. Second Workshop Sci. Res. FORV Sagar Sampada . pp.127-137 (1996). only one of the major man made causes for the imbalance. The Haq, S.M., J. Ali Khan and S. Chugatai: The distribution and abundance of abundance of phytoplankton supports notable increase in zooplankton along the coast of Pakistan during post monsoon and zooplankton. The coastal belt of the Arabian Sea is enriched with pre monsoon period. In : The biology of Indian Ocean ( Eds : B.

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Journal of Environmental Biology  January, 2007