Seasonal effects on diversity of macroinvertebrates in Himalayan Lake Prashar, Himachal Pradesh, India

Abstract

The purpose of this study is to evaluate the seasonal variations in the density and diversity of macroinvertebrates in relation to the dynamics of physicochemical parameters of water quality and study factors which influence the lake ecosystem of Prashar lake of Himachal Pradesh. Monthly sampling from November 2014 to October 2015 at three sites was undertaken to evaluate the community structure of macroinvertebrates in relation to the dynamics of water quality parameters. All three sites (S1, S2, and S3) were identified keeping in view the accessibility, type of substrate and other influencing factors. A total of 25 genera of nine macroinvertebrates groups were identified during the study period. The highest macroinvertebrates abundance was observed in winter and the lowest in monsoon season. Maximum Shannon–Wiener diversity index was recorded at site S3 in winter season as compared to the sites S1 and S2. Water temperature, dissolved oxygen (DO), pH, electrical conductivity (EC), turbidity, total dissolved solids (TDS), and nitrates were important water quality variables that affected the macroinvertebrates diversity of the Prashar lake. The stable and healthy environmental condition of Prashar lake was recorded which was indicated by the presence of Ephemeroptera, Plecoptera, Trichoptera (EPT) during winter season. Factors which disturb the diversity and ecosystem of the lake are attributed to the natural and anthropogenic pressures such as, soil erosion, overgrazing, tourism load and solid waste. The density of macroinvertebrates was further influenced by the growth of riparian vegetation, suitable bottom substrates, and water level fluctuations. A strategy for conservation and management is proposed i.e., ex-situ and in-situ conservation, regular environmental monitoring, restoration of the riparian zone, afforestation in the catchment area, raising awareness, solid waste management and research programmes that will be helpful for sustainable management of Prashar lake.