| Eriocheir sinensis（as known as crab）is one of the important aquaculture resources in China due to its delicious meat and high economic benefits.However,the river crab traditional culture mode of long-term high density and a large amount of feed easy to pollute the aquatic ecology and surrounding environment.The ecological pond aquaculture mode of river crab pays attention to the material and energy flow circulation,are better to the ecological benefits as well as the higher economic benefits,in order to realize the balance the ecological and economics in river crab aquaculture.In this study,physicochemical and biochemical indexes of water quality and plankton community were monitored in three river crab farming ponds of Jiangyuan Agriculture and Animal Husbandry Co.,Ltd.,Taixing city,Jiangsu province and their water sources were monitored from June to October 2019.Ten water quality indexes,such as water temperature and pH,as well as plankton abundance,biomass and community structure,were analyzed in taixing high sandy soil area.Through these indexes,the water environment of crab aquaculture pond in high sandy soil area of Taixing city was comprehensively evaluated,which may provided theoretical guidance for the sustainable development of ecological farming ponds of the adult crab in this area.1.The results showed that the water temperature and pH of ecological farming ponds of the adult crab were not significantly different from their water source for 8sampling days.The total nitrogen content and ammonia nitrogen content were not significantly different from their source water bodies,or were significantly smaller than or significantly greater than their source water bodies.The contents of soluble phosphate and permanganate index were significantly greater than or significantly less than or not significantly different from their source water bodies.The ecological farming model of adult crab had no significant effect on the permanganate index of the ponds in the sandy soil area of Taixing city,Jiangsu province.Crab farming in this area will not pollute the surrounding waters.2.Identification of zooplankton community structure in ecological farming ponds of the adult crab in Taixing high sandy soil areaA total of 44 species of zooplankton were detected in water sources and crab ponds,including 18 species of rotifers,14 species of cladoceras and 12 species of copepods,respectively.Among the zooplankton detected,11 dominant species were found,including 4 rotifers,4 copepods and 3 cladophora.The average density and biomass of rotifers,copepods and cladoceras were 145.28 ind/L,42.44 ind/L and 105.05 ind/L,0.80 mg/L,9.37 mg/L and 12.49 mg/L,respectively.The RDA ranking results showed that the main environmental factors affecting the distribution of zooplankton functional groups were T,NO-3-N,DO and CODMN.Shannon-wiener diversity index（H’）,Margalef richness index（D）and Pielou evenness index（J）were 2.30,3.64 and 0.78,respectively.These results showed that the water quality of crab ponds were in a state of light to moderate pollution,indicating that ecological farming ponds of the adult crab.in high sandy soil area had poor purification effect on water body.3.Identification of phytoplankton community structure in ecological farming ponds of the adult crab in Taixing High sandy soil areaSeven phylum and 109 species of phytoplankton were observed in the crab ponds,belonging to eight functional groups:L0,W0,X1,J,MP,D,M and B.The average density and biomass of phytoplankton in were detected in water sources and crab ponds were 4.84×106cells/L and 4.59×106cells/L,5.18 mg/L and 5.38 mg/L,respectively.RDA ranking showed that the main environmental factors affecting the phytoplankton community structure were T,TN and CODMN..The mean values of H’,D and J were2.60,2.84 and 0.69,respectively.These results showed that the the water quality of crab ponds were moderately polluted,indicating that the ecological farming ponds of the adult crab in high sandy soil area has poor purification effect on water quality.In conclusion,the above three experimental results show that the pond culture of adult crabs in the high sandy soil area of Taixing will not pollute the surrounding water environment. |
