Zooplankton Diversity, Species Richness and their Distribution Pattern in Bhimtal Lake of Kumaun Region, (Uttarakhand)

Bhimtal Lake situated in Uttarakhand, India, and has been devastated due to anthropogenic activities. In this study we examined the diversity and distribution pattern of zooplanktons in the Bhimtal Lake, along with evaluation of the relationships among different zooplankton groups and abiotic factors during the period September, 2013 to August, 2014. Sampling was done seasonally, during summer, winter and monsoon seasons, at three sites in Bhimtal lake. Sample analysis revealed the presence of 29 species of zooplankton including 16 species of Rotifers, 8 species of Cladocera and 5 species of Copepods. Rotifera group was the most dominant among all three groups. Positive co-relation was found between zooplankton growth with water temperature and pH while, there growth was adversely affected with increasing alkalinity, nitrates and dissolved oxygen. The diversity of Rotifers, Cladocera and Copepods were highest during summer, and was lowest during winter, while their density and biomass were found to be highest at the surface water during summer. It can be stated that the tropic nature of Bhimtal Lake may have been changed to mesotrophic conditions.