Limiting Effect of Some Toxic Heavy Metals on Zooplankton Diversity in Freshwater Lake Ecosystem at Sahebbundh,Purulia,West Bengal

Abstract

Environmental monitoring of inland water bodies is needed for proper introspection of the structural and functional responses of freshwater ecosystem vis-à-vis status of biological components. Above endeavour have been initiated by periodic monitoring of both biological and physico-chemical parameters of a freshwater lake at Sahebbundh, Purulia, West Bengal, which is located at 23°29′42″ N latitude and 86°21′37″ E longitude. Water of this 63-acre lake is widely used for drinking purposes during summer months. But the water body has become a target of several anthropogenic interferences like garage activities, biomedical wastes, disposed sewage, etc., which can potentially hamper the health of the freshwater lake ecosystem. In all 28 species of zooplanktons are recorded from the lake, including some which are reported to be indicator of thermal pollution. Among the heavy metals the study concentrates upon Pb $^{2+}$ , Cr $^{3+}$ and Cd $^{2+}$ . A remarkable change of community dynamics of the zooplankton reflected by diversity fluctuations is observed particularly in those areas with anthropogenic activities including introduction of biomedical wastes, garage activities etc. Interestingly the toxic heavy metal is very high in those spots with direct human interferences. The level of Pb $^{2+}$ is much higher in those sites in comparison to the other two heavy metals, i.e. Cr $^{3+}$ and Cd $^{2+}$ . The Pb2+ is obviously a direct contribution from anthropogenic garage activities, which is established from our findings.