ASSESSMENT ON FRESHWATER ECOSYSTEM INTEGRITY AND HEALTH IN GANGJIANG RIVER BASIN THROUGH THE FISH IBI METHOD

River ecosystem is one of the most complex ecosystems in the world,being involved in each part in the natural environment,and almost being directly or indirectly linked with every aspect of human activities.Ecosystem health assessment is one of the most active fields in river ecology.Fish was first used to construct a biotic integrity and health assessment and now is a widely applied biota group.This paper first assesses the health status of river ecosystem in Gangjiang River Basin through fish index of biotic integrity(F-IBI) after investigating the stock of fish among 17 tributaries and different river zones of main stream.Results show F-IBI scores of about 70% of sampling sites are in the fair status,25% in good and 5% in poor.F-IBI scores of tributaries and main stream in Ganjiang River system are in the poor to fair status.In a word,river ecosystem health of Ganjiang River Basin is at the level of the poor to fair.It is considered that the declined fish integrity of Ganjiang River Basin is related with human activities such as river damming and impoundment.We suggest that the restoration measurements such as addition of fish way or fish ladder should be employed.