Assemblage of Ciliated Protozoan Community in a Polluted and Non-polluted Environment in a Tropical Lake of Central Himalaya: Lake Naini Tal, India

In order to obtain information on the assemblage of Protozoain the changing environment in Lake Naini Tal, this study wascarried out for a period of one year from November 1995 to October1996. Samplings were done from the mud–water interfaceat two stations which differed considerably in their magnitudeof pollution. Station I was moderately polluted while StationII was highly polluted. Some physico-chemical parameters ofwater such as temperature, dissolved oxygen, free CO₂, pH, nitrate-nitrogen,phosphate-phosphorus and BOD were also measured. A total of23 ciliates were found at the mud–water interface of thetwo stations during the sampling period. The annual mean ofspecies richness at Station I was significantly greater (19species) than that of Station II (13 species). The species compositionwas also different at the two stations. In general, StationI supported larger ciliated species (1249 x 10³ µm³ taxon^–1)than Station II (348 x 10³ µm³ taxon^–1). Among differentfeeding groups of ciliates, the groups ‘Algivore-Bacterivore’and ‘Bacterivore’ were about twice as common atStation II (116 x 10³ cells^–1) than at Station I (55 x10³ cells^–1). The annual average ciliate community abundancewas more diverse at Station I than Station II. The annual averagebiomass in terms of carbon content for both stations was almostthe same (6.0 mg Cl^–1 for Station I and 6.1 mg Cl^–1Station II). However, different species were responsible forthe contribution to the biomass at the two stations. The valuesfor Shannon-Weiner's diversity indices at Staion I were higherthat those for Station II.