Longitudinal Patterns In Fish Assemblages And Ecological Health Assessment In The Taizi River

The Taizi River flows through the cities of the old industrial base in Northeast China,serving the social and economic development in the basin.Human disturbance causes the serious decline of ecological environment,which has greatly weakened the ecological service function of the Taizi River.For promoting the green and high-quality development and revitalizing the old industrial base in Northeast China,the state and local governments have carried out comprehensive governance and restoration of the Taizi River since the 11 th Five-year Plan.How has the ecological health been restored after more than 10 years of ecological restoration? And how can the current management policies be optimized and adjusted? Assessing the current health status of the river is a prerequisite to answer the above questions scientifically.For this purpose,the longitudinal patterns in fish assemblages and ecological health after long-term ecological rehabilitation in the Taizi River were studied in this paper.The main work and conclusions are as follows:(1)A total of 50 fish species from 13 families were collected,and the dominant species were Phoxinus lagowskii,Zacco platypus,Carassius auratus and Pseudorasbora parva.The longitudinal spatial pattern of fish assemblages was changed from three fish zones to two fish zones.And the fish assemvlages pattern was mainly shaped by cultivated land coverage and urban land coverage.(2)The ecological health of the Taizi River was assessed using the Fish-based Index of Biological Integrity and the Multi-Indicator Health Evaluation Index.Both methods had similar assessment results,indicating that the overall health of the Taizi River was fair and had significant spatial heterogeneity in health class: the middle and upper reaches had better health status with high vegetation coverage and weak human interference,while the downstream stream was in poor health status with overintensive agriculture and higher urbanization level.(3)The current management policy was assessed and improved according to the ecological health different areas of the Taizi River.The suggestions of local ecological restoration were put forward: the management objectives in the upper and middle of Taizi River should focus on species and natural habitat protection,while the lower reaches should be paied more attention to ecological restoration of aquatic environment.