[Aquatic Community Structure and Biological Assessment of Water Quality in Urban Lakes of the Yangtze River Downstream： A Case Study of Three Lakes in Wuhu City].

Abstract

The Yangtze River constitutes a crucial aquatic system in China, and lakes downstream play a significant role in the stability of ecosystem functions. However, human activities have caused the lakes to suffer from eutrophication. Moreover, it is important to investigate the aquatic ecosystems of Qingting Lake, Fengming Lake, and Yin Lake in Wuhu City, Anhui Province, China, for tracing and controlling eutrophication. We focused on the differences in aquatic communities and their relationships with environmental variables. A total of 61 species of zooplankton, 69 species of phytoplankton, and 15 species of benthos were detected in the three lakes. Dragonfly Lake had the highest number of zooplankton and phytoplankton species； the number of phytoplankton species was 17.65% and 22.06%, significantly higher than those of Fengming Lake and Silver Lake, respectively （P<0.05）. Inconsistently, the benthic biomass was 97.46% and 97.64% significantly higher in Silver Lake [（149.39±10.97） g·m^-2] compared with those in Dragonfly Lake and Fengming Lake （P<0.01）. The zooplankton with high dominance included Pseudoanabaena sp., Merismopedia sp., Polyarthra vulgaris, Moina micrura, and Strobilidium sp., and those in benthos were Limnodrilus sp. and Tanypus sp. Water nitrogen and phosphorus, sediment nitrogen and phosphorus, water depth, salinity, pH, oxidation-reduction potential, and dissolved oxygen were the important environmental factors leading to differences in dominant species of zooplankton, phytoplankton, and benthos among the lakes, with a total influence of 70.70%, 76.69%, and 70.32%, respectively （redundancy analysis）. Finally, the results indicated that Dragonfly Lake and Fengming Lake were both characterized as eutrophic, but Silver Lake was mesotrophic when we calculated water parameters, integrated trophic state index, and biological index together.