The use of fish community structure as a measure of ecological degradation: a case study in two tropical rivers of India.

Fish community structure and water chemistry of two tropical rivers of West Bengal, an eastern province of India, were studied for two annual cycles (January 2003-December 2004) and a higher degree of pollution was found in one river (the Churni) than in the other river (the Jalangi). This was reflected in the water quality as well as in fish community structure of the rivers. We observed that 63.6% of fish species appeared to have been eliminated from the polluted Churni river since 1983 in 20 years. For the protection of fish biodiversity and enhancement of fish production, a rational management program should be implemented for the Churni river.