Journal of Plankton Research Vol.23 no.6 pp.571-584, 2001
© Oxford University Press 2001
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 Protozoa in the changing environment in Lake Naini Tal, this study was carried out for a period of one year from November 1995 to October 1996. Samplings were done from the mud–water interface at two stations which differed considerably in their magnitude of pollution. Station I was moderately polluted while Station II was highly polluted. Some physico-chemical parameters of water such as temperature, dissolved oxygen, free CO2, pH, nitrate-nitrogen, phosphate-phosphorus and BOD were also measured. A total of 23 ciliates were found at the mud–water interface of the two stations during the sampling period. The annual mean of species richness at Station I was significantly greater (19 species) than that of Station II (13 species). The species composition was also different at the two stations. In general, Station I supported larger ciliated species (1249 x 103 µm3 taxon–1) than Station II (348 x 103 µm3 taxon–1). Among different feeding groups of ciliates, the groups ‘Algivore-Bacterivore’ and ‘Bacterivore’ were about twice as common at Station II (116 x 103 cells–1) than at Station I (55 x 103 cells–1). The annual average ciliate community abundance was more diverse at Station I than Station II. The annual average biomass in terms of carbon content for both stations was almost the same (6.0 mg Cl–1 for Station I and 6.1 mg Cl–1 Station II). However, different species were responsible for the contribution to the biomass at the two stations. The values for Shannon-Weiner's diversity indices at Staion I were higher that those for Station II.