Abstract

Aquatic ecosystem is the one of the most productive ecosystems. Aquatic ecosystem provides human with numerous benefits in addition to direct use. Even the human civilization was centered on water . Industrialization coupled with intensive agriculture in early 1980's to meet the growing demand of ever increasing populations lead to the over exploitation of these valuable resources and has threatened the very existence of it. To conserve these valuable resources from further deterioration there is a need for regular monitoring of the aquatic ecosystem. A comprehensive biomonitoring process involves both physicochemical and biological approach and gives the exact status of the aquatic ecosystem. Biomonitoring of water bodies also helps to understand the composition of biota and its dynamics.

Lakes of Bangalore occupy about 4.8% of city's geographical area (640 sq.km) covering both urban and rural areas. Bangalore lakes have several direct use values apart from replenishing the ground water table and influencing the climate of the city . The study was undertaken to know the current status of selected lakes of Bangalore, considering decline in quality due to anthropogenic activities. A biomonitoring approach incorporates physicochemical and biological (phytoplankton and zooplankton) analysis. The study reveals that Ulsoor lake and Rachenahalli lake are severely affected due to anthropogenic activities. This is evident from large scale fish mortality in Ulsoor lake. The trophic structure in these lakes has been affected. Immediate actions have to be taken by the concerned authorities to reestablish the water quality of these lakes. Compared to these lakes, Sankey lake and Tippagondanahalli lake are relatively unaffected.