Seasonal variations in zooplankton with reference to physicochemical conditions in temple pond at Thiruvottiyur, Chennai

Abstract

Seasonal dynamics of plankton diversity with reference to physico-chemical conditions in a fresh water pond was studied in temple pond at Thiruvottiyur, Chennai. Along with the physico-chemical parameters, water samples were also characterized for plankton community composition and density. The physico-chemical parameters also showed positive correlation with different zooplankton group. The water samples were analyzed for various physico-chemical factors. Totally 4 groups of zooplankton taxa were identified (Rotifera, Cladocerans, Ostracodans and Copepods). Zooplankton population density was maximum during summer (100 units/litre) and minimum (8.85 units/litre) during monsoon season. A total of 19 taxa were recorded (Rotifera 3, cladocerans 4, Ostracodans 6 and Copepods 6). Among the Rotifera, Branchionus and Keratella species; among the Cladocerans, Moina and Bosmina species; among the Ostracodans, Heterocypris and Physocypria species and among Copepods, Undinula and Pontellopsis species were abundant. The abundance of zooplankton in the pond follows a sequence as: Ostracodans = Copepods > Cladocerans > Rotifera. Correlation between various physico-chemical parameters and zooplankton density was calculated. Some of the changes in zooplankton community structure were found associated with seasonal changes in temperature and nutrient content of water. Rise in DO and nutrient levels of nitrate, phosphate and silicate suggested favorable conditions for plankton growth. This study revealed that the presence of above mentioned species are considered to be biological indicator for eutrophication.