Health assessment of aquatic ecosystems in the Songhua River Basin on the basis of water quality and biological indicators

The overexploitation and overloaded utilization of water resources from river basins not only affect the health of aquatic ecosystems increasingly,but also have a direct threat to the sustainable development of social economy and the survival environment of human beings. Through our investigation on aquatic ecosystems of the Songhua River Basin,combined with current research results at home and abroad,the index system of health assessment for aquatic ecosystems was constructed on the basis of water quality and biological indicators,and the health assessment score of various samples from the Songhua River Basin was calculated by the comprehensive pollution index method. Ultimately,a comprehensive assessment for ecological health of the Songhua River Basin was accomplished. The upstream watershed was in good health,while the health situation in the downstream part of the Basin was moderate and even poor. The assessment of the health status among samples from the Songhua River Basin indicated that there was a significant correlation between nutrients and planktonic algae,between nutrients and fishes as well,and the assessment result by using biological indicators was overall better than that by using water quality indicators. The results showed that the health of aquatic ecosystems of the Songhua River Basin was at a moderate level as a whole.