Eco. Env. & Cons. 26 (2) : 2020; pp. (842-846) Copyright@ EM International ISSN 0971–765X

Diversity, population and spatio-temporal variations in the benthic invertebrates of Sasthamkotta lake In Southern ,

Munisha Murali S. and S. Sheeba

PG & Research Department of Zoology, Sree Narayana College, , Kerala, India

(Received 6 October, 2019; accepted 20 November, 2019)

ABSTRACT Benthic invertebrates are widely used in the evaluation of environmental biomonitoring. The present investigation focused on the bottom-dwelling invertebrates from ten different stations of Sasthamkotta Lake during the period from January to December 2016. A total of eight species was observed. Six species belong to Order Diptera, one species each on Order Trichoptera and Order Tubificida. The order Diptera consists of Phaenopsectra sp., Sumatendipes tobaterdecimus, Procladius sp., Chaoborus asiaticus, family Chironomidae and family Ceratopogonidae. Order Trichoptera was the rare group including the species Ecnomus puntung. Pristina leidyi was the oligochate organism. Phaenopsectra sp. (97.927%) was abundant benthic invertebrate and the scarce organisms was Ecnomus puntung (0.005%). The highest diversity was recorded during postmonsoon period due to optimum nutrient conditions for their distribution after monsoon. Therefore the organism can be used as bioindicator to assess the health status of the ecosystem.

Key words: Benthic invertebrates, Diptera, Phaenopsectra sp., Bioindicators

Introduction benthic animals. Benthic fauna are extensively used to monitor the water quality in aquatic environ- The biotic communities in the fresh water ecosystem ment. They are the major indicators of Bio-assess- determine the quality of the aquatic environment by ment. Sasthamkotta Lake is a cradle for a rich characterizing the type of species in it. Climatic pro- biodiversity. The benthic environment of the lake cesses affect the abundance and species composition support variety of aquatic life. The luxuriant growth of lakebed which directly influence the distribution of macrophytes in the shoreline is a shelter to vari- of food for bottom organisms. Any change in the ous benthic-pelagic forms. The benthic invertebrate benthic communities could regulate the rate and in lake have prime role in maintaining the healthy timing of processes such as nutrient cycling, avail- status of the ecosystem. ability of food to organism and organic waste ab- sorption (Frid and Moore, 2008). The spatial and Materials and Methods temporal distribution of these microinvertebrate communities suggest that they have preference for Sasthamkotta Lake, lies between 9ˆ00’-9ˆ05’ North different abiotic factors. These differences make latitude and 76°35’-76°40’ East longitude and falls them disperse to live in distinct microhabitats. Dead under the Kunnathur Taluk of of organic matter is the key source of energy for Kerala, India (Map 1). The lake spread over a huge MURALI AND SHEEBA 843 area of 375 hectares and an average breadth is 0.5 Procladius sp., Chaoborus asiaticus, family km. The average depth of the lake varies between Chironomidae and family Ceratopogonidae. Order 6.8 meter and 13.9 meter. The lake is surrounded by Trichoptera include the species Ecnomus puntung. freshwater bodies namely Chelurpola Kayal, Order Tubificida include the Pristina leidyi. Annual Chirayattu Kayal, Chira and on one side variation in quantitative estimation of benthic fauna is River. It is a major source of drinking wa- revealed that Phaenopsectra sp. was the dominant ter to half a million people of Kollam district. Un- organism followed by Sumatendipes tobaterdecimus derground aquifers and rainfall is the source of and Pristina leidyi. Species belonging to water to the lake. The lake has no inlet and outlet Ceratopoginidae family and Chironomidae family, connections with other water masses andthe lake is Procladius sp., Chaoborus asiaticus and Ecnomus completely isolated. Sasthamkotta Lake is desig- puntung were the least group found throughout the nated as Ramsar site since November 2002. study period. The monthly and annual variation of benthicin vertebrates population in Sasthamkotta Lake is de- picted in Table 1. Seasonal average population of benthic organisms (No/m2) is illustrated in Fig. 1. Monthly variation of Phaenopsectra sp. revealed that it was minimum (903 No/m2) at Station IX (Novem- ber) and maximum (32279 No/m2) at Station X (February). Seasonal average of Phaenopsectra sp. population was ranging from 6164 No/m2 during postmonsoon and 11461 No/m2 during premonsoon. Annualvariation of the organism was minimum of 6446 No/m2 at Station V and maxi- mum of 10541 No/m2 at Station I. Monthly varia- tion of Sumatendipes tobaterdecimus showed that it was absent in November and recorded high (1333 Map. 1. Sasthamkotta Lake, Kollam, Kerala No/m2) during June at Station V. Seasonal average showed that it was minimum during postmonsoon Benthic organisms were collected from lake sedi- (37 No/m2) and maximum during monsoon (199 ments during the period from January to December No/m2). Annual average revealed that it was maxi- 2016. Ten stations are randomly selected for the mum (155 No/m2) at Station V and minimum (35 study. Sediments were collected with the help of No/m2) at Station VIII. Family Chironomidae was Ekman dredge. The organisms from each sediment present only in November (47 No/m2) at Station I. sample were preserved in 70% ethyl alcohol and stained with Rose Bengal. Organisms from each sediment samples were sorted and picked manu- ally. Quantitative and qualitative analysis of the or- ganisms were done as per the methods of Michael (1984); Morse et al., (1994); Merrit and Cummin (2008); Tonapi (1980) and other relevant publica- tions.

Results

The benthic fauna of Sasthamkotta Lake comprised of eight species. Order Diptera is the dominant group comprising of six species, one species on Or- der Trichoptera and one species on Order Fig. 1. Seasonal average population of benthic organisms Tubificida. The order Diptera consists of (No/m2) in Sasthamkotta Lake during the period Phaenopsectra sp., Sumatendipes tobaterdecimus, from January to December 2016 844 Eco. Env. & Cons. 26 (2) : 2020

Procladius sp. was present in July at Station V (234 No/m2) and November at Station I (47 No/m2). Sea- 10541 sonal variation of Procladius sp. population exhib- ited monsoon and postmonsoon. Chaoborus asiaticus was present in December at Station I (47 No/m2) and IV (95 No/m2). It was found only during the post monsoon period. Monthly variation of Ceratopogonidae family showed that it was present in June at Station IX and December at Station IX (47 No/m2). The organism was present in monsoon and postmonsoon. Ecnomus puntung was present in No- vember at Station I (47 No/m2). Seasonal variation revealed that it was present in postmonsoon. Pristina leidyi was absent during January, August, November and December and recorded high at June at Station X (1571 No/m2). Seasonal average was ranging from 27 No/m2during premonsoon and 94 No/m2 during monsoon. Annual average showed that it was minimum (16 No/m2) at Station VII and maximum at Station X (173 No/m2). Phaenopsectra sp. was the abundant benthic inver- tebrate in Sasthamkotta Lake accounting to about Months Annual 97.927% (Fig. 2). This is followed by Sumatendipes tobaterdecimus (1.233%) and Pristina leidyi belonging to family Naididae was the third dominant group (0.745%). Procladius sp. (0.029%), family Chironomidae (0.037%), family Ceratopogonidae (0.010%) and Chaoborus asiaticus (0.014%) were the least organisms. Order Trichoptera include Ecnomus puntung (0.005%) was the very rare organism. )at ten different stations ofSasthamkotta lake during the period from January to December 2016 2 00000000000 - 4700-4 - 000000000000 00 0 - 95 0 0 -190 0 - 142 0 0 - 285 0 - 1571 0 - 428 0 0 0 0 - 476 0 - 476 0 0 0 0 16-173 0 0 0 0-95 0-8 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Average 0 - 95 0 - 47 0 - 333 0 - 523 0 - 142 142 - 1333 0 - 285 0 - 618 0 - 238 0 - 285 0 0-95 35-155 18948 32279 25423 25423 30666 26089 7236 5236 11188 9140 11045 19947 6446- Fig. 2. Percentage abundance of benthic organisms in Sasthamkotta Lake during the period from Janu- ary to December 2016

Statistical analysis 2 ANOVA sp. 1142 - 4046 - 7426 - 7426- 6046 - 2141 - 2571 - 1237 - 2427- 3761- 903 - 1713- Range sp. 0 0 0 0 0 0 0 - 234 0 0 0 - 47 0 0 0-20

The ANOVA result revealed that the mean values of Benthic invertebrates population (No/m all the benthic organisms are not significantly dif- fered between the stations except Ceratopogonidae. Table 1. Benthic Invertebrates (Range) No/m Sumatendipes tobaterdecimus ChironomidaeProcladius 0 0 0 0 0 0 0 0 0 0 0 - 47 0 0-27 Chaoborus asiaticus CeratopogonidaeEcnomus puntung Pristina leidyi 0 0 0 0 0 0 - 47 0 0 0 0 0 0-47 0-8 Phaenopsectra MURALI AND SHEEBA 845

The organism Ceratipogonidae is statistically sig- Lake dominate in silty clayey bottom and catchment nificant among stations at 5% level of significance. area is thickly populated. The depth of the lake ANOVA result in relation to seasons revealed that showed that larvae are living at a substratum where the mean values of Phaenopsectra sp. and detritus is prevailing. Since the larva is detritivore Sumatendipes tobaterdecimus differed significantly the habitat is suitable for its growth. The silty clayey between seasons at 1% level of significance and lake bed with high organic carbon content has po- other benthic organisms are not statistically signifi- tential feeding environment to retain this larvae. cant from each other between seasons. The presence of pollution-tolerant microinvertebrate organism such as Chironomus sp. Correlation could be due to the entry of the domestic and indus- trial effluents to the aquatic environment. The low Phaenopsectra sp. showed a negative correlation with dissolved oxygen favour the growth of these pollu- Sumatendipes tobaterdecimus. Sumatendipes tion indicator species (Sharma et al., 2013). tobaterdecimus showed positive correlation with Krishnakumar et al., (2005) reported that in Ceratopognidae (r=0.307)and Pristina leidyi Sasthamkotta Lake 72.71% of the bottom sediment (r=0.279). Chironomidae showed a positive correla- is mud. The lake bed with silty clay and muddy tion with Ecnomus puntung (r=1.000) and weak posi- habitat is accompanied with decomposed fragments tive correlation with Procladius sp. (r=0.189). of macrophytes or water plants and animal materi- Procladius sp. showed weak positive correlation als. Phaenopsectra sp. is the ecologically important with Ecnomus puntung. And all other remaining pa- dominant organism in Sasthamkotta Lake. Tem- rameter has very weak correlation with each other. perature and dissolved oxygen concentration condi- tions in the lake bed are suitable for this sediment- Discussion dwelling larva. Sasthamkotta Lake is also a wetland with moderate nutrient level so the present study Two groups of aquatic insects such as Diptera and revealed that of Phaenopsectra sp. survives and Trichoptera was found in Sasthamkotta Lake. These grows in low productive lake. It is important to note larva survived and spend a part of their life within that Sumatendipes tobaterdecimus inhabitin a moder- the sediments. Eight species of benthic invertebrates ate nutrient loading aquatic environment with luxu- were observed during study period. Ten species of riant growth of macrophytes. High organic carbon microbenthic invertebrate were found from Kislo- in the sediment also contributes a suitable thriving Sladkoye Lake in Moscow (Malyshkoet al., 2014). In ground for benthic organisms. It is evident that a the lake order Diptera, Order Gastropoda, good dietary requirement of the larva was sup- Oligochaeta, Nematoda and Chironomidae were ported by the lake bed. Sasthamkotta Lake is con- identified. Bhenthic fauna in Bhoj wetland (Bhopal) fined within hillocks with no inlet and outlet for have seven different classes including Mollusca, water flow. Therefore the aquatic environment is Diptera, Trichoptera, Oligochaeta, Crustaceae, suitable for the growth and widespread distribution Hirudina and Ephemeroptera (Ashwani et al., 2011). of Phaenopsectra sp. The organism is mainly a Maximum diversity of benthic invertebrates was detritivores and exhibit more than one mode of noticed during postmonsoon and least during feeding behavior, such as grazers, scrapers, shed- premonsoon. The abundant organism Phaenopsectra ders and collectors (gatherers and filter feeders) sp. was maximum during premonsoon. Population (Saigo et al., 2016). Their diet comprises of materials of Phaenopsectra sp. lowered during monsoon sea- that are responsible for aquatic environment pollu- son as the rainy showers diluted the water column. tion. Pristina leidyi, third dominant organism, is a The organism was least during postmonsoon gatherer collector which ingests decomposed matter mainly due to the monsoon showers they become (Saigo et al., 2016). Chaoborus larvae is a voracious drift to poor habitat conditions. The larvae of predator feeding on small zooplankton such as cla- Phaenopsectra sp. is prevalent in slowly flowing or docerans, copepods, rotifers, phytoflagellates, di- stagnant waters (Moller Pilot, 2009). The larvae are noflagellates, chironomid larvae, mosquito larvae, primarily detritivores, they can also feed as grazers oligochaetes and other Chaoborus larvae (Stahl, and also active, filter feeders (Moong, 2002). In the 1996). present study Phaenopsectra sp. in Sasthamkotta The dominance and mode of feeding of 846 Eco. Env. & Cons. 26 (2) : 2020

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