[Assessment on ecological integrity of typical lakes, reservoirs and wetlands in Tianjin, China]

The ecological health assessment of lakes, reservoirs and wetlands can provide decision-making basis for ecosystem restoration and management. We selected 20 typical lakes, reservoirs and wetlands sampling points in Tianjin, based on physical, chemical, and biological community indicators data (zooplankton, phytoplankton, benthos, fish, large aquatic plants, riparian plants) obtained during the survey from August to September 2018. We constructed an index of ecological integrity (IEI) including physical integrity, chemical integrity, and biological integrity to evaluate their ecological health. The reference points were selected based on three aspects using standardized methods: habitat environmental quality index (QHEI), water quality status, and disturbance of human activities. The analytic hierarchy process was used to calculate the weight of the three indicators. The evaluation results of the ecological integrity of typical lakes, reservoirs and wetlands in Tianjin were finally obtained. The results showed that: 1) Among all the samples, "healthy" points accounted for 5.0%, "good" points accounted for 20.0%, "general" points accounted for 35.0%, "worse" points accounted for 30.0%, and "poor" points accounted for 10.0%. Ecological health status of typical lakes, reservoirs and wetlands in Tianjin was at a general level, with a trend that the west was better than the east with significant spatial differences. 2) Reference points were selected based on the combination of habitat score, water quality conditions, and human activity disturbance. Water quality indicators could reduce subjectivity when selecting reference points and promote the application of ecological integrity evaluation. 3) The applicability verification results showed that IEI could better characterize the health status of each point, and the discrimination efficiency was obvious, which was suitable for evaluating the ecological health of lakes, reservoirs and wetlands.