COMMUNITY CHARACTERISTICS OF ZOOPLANKTON AND ASSESSMENT OF WATER QUALITY IN AQUACULTURE PONDS OF THE PEARL RIVER DELTA

To understand the community characteristics of zooplankton and further assess the water quality in aquaculture ponds, a field survey of zooplankton and environmental parameters was conducted in 30 ponds with six aquaculture models from July to August 2016. The results showed that: (1) a total of 55 species were identified, which included 17 Protozoa, 29 Rotifera, 4 Cladocera, and 5 Copepoda. Among the six model ponds, the most species were found in largemouth bass ponds fed by feedstuff (34 species), while the fewest species were present in grass carp ponds (18 species); (2) eight dominant species were recorded in 30 ponds, including 4 Protozoa and 4 Rotifera. The dominant species in the six model ponds was also composed of Protozoa and Rotifera, and there were between 5 and 8 species; (3) the average density and biomass of zooplankton in 30 ponds were 21354 ind./L and 9.36 mg/L, respectively. However, variance analyses showed that the density and biomass of zooplankton among the six model ponds were not significantly different; and (4) RDA analysis indicated that total phosphorus (TP) and pH were the main factors influencing the distribution of zooplankton in the Pearl River Delta. Water quality results showed that all of the six model ponds were in the state of eutrophication, using richness and biomass of zooplankton, and α-mesosaprobic, using the Shannon-Wiener index and the Margalef index. This study is the first assessment of aquaculture ponds using zooplankton in Pearl River Delta, and the results provide guidance for the ecological restoration and management of aquaculture ponds.