Metazooplankton Community Structure and Ecological Evaluation of Water Quality of Eriocheir sinesis Ecological Culture Ponds

This study aims to explore the metazooplankton community structure and water status of Eriocheirsinesis ecological breeding ponds. Samples were taken from three ponds and water inlet, and species identification and quantitative analysis of the metazooplankton were then conducted. The biodiversity index was used to evaluate the water quality. A total of 49 metazooplankton species were found, including 22 species of Rotifera, 15 species of Cladocera, and 12 species of Copepoda. Brachionus urceus, Brachionus calyciflorus, and Polyarthra trigla of Rotifera, Ceriodaphnia setosa, Ceriodaphnia pulchella and Moina rectirostris of Cladocera, Nauplii, Microcyclops varicans and Ectocyclops phaleratus of Copepoda were the dominant species. Rotifera had the largest density, but the biomass was the smallest, while the density of Cladocera was the smallest, but they had the largest biomass, followed by the density and biomass of Copepoda. RDA ordination analysis shows that T, TN, PO₄^3--P and COD_Mn were the main influencing factors of the metazooplankton community structure in ponds. The evaluation results of biodiversity index on water quality show that both ponds and water inlet were in the state of medium pollution, and the water quality of ponds was not significantly better than that of water inlet, which was related to the high breeding density in this area, and finding a reasonable breeding density should be taken as the research direction in the future.