Comparative Study On The Community Structure Of Crustacean Zooplankton In The River Lake Interconnected Ecosystems Of Changde And Guangzhou

Crustacean zooplanktons are the important organisms in aquatic ecosystems and play important roles in the energy flow and material circulation of ecosystem.To compare the relationship between crustacean community structure and water environment characteristics in the river lake interconnected systems in Changde city and Guangzhou city,samples were collected quarterly in Changde ecosystems composed of Liuye Lake(L1-L9),the Chuanzi River(C1-C3)and the Changde segment of the Yuan River(Y1-Y3)from June 2018 to March 2019,and in Guangzhou ecosystems composed of Haizhu Lake(H1-H3),the Shiliugang River(R1-R3)and the Guangzhou segment of the Pearl River(P1-P3)from December 2018 to September 2019,respectively.The main results were summarized as follows:In Changde ecosystems,the water quality in Liuye Lake was slightly eutrophic,the Chuanzi River moderately eutrophic,and the Changde segment of the Yuan River mesotrophic.In Guangzhou ecosystems,the water quality in Haizhu Lake,the Shiliugang River and Guangzhou segment of the Pearl River was moderately eutrophic.Eutrophication in Guangzhou segment of the Pearl River was more severe.The water quality of the interconnected ecosystems in Changde was better than that in Guangzhou.In Changde ecosystems,a total of 27 species of crustacean zooplankton were identified,including 10 species of copepods and 17 species of cladocerans.The species richness of crustacean zooplankton was the highest in Liuye Lake,followed by the Chuanzi River and the Changde segment of the Yuan River.The cladoceran Moina macrocopa was the first dominant species in the ecosystems.In Guangzhou ecosystems,a total of 26 species of crustacean zooplankton were identified,including 8 species of copepods and 18 species of cladocerans,and the species richness of zooplankton was the highest in Guangzhou segment of the Pearl River,followed by Shiliugang River,and then Haizhu Lake.The copepod Thermocyciops taihokuensis was the first dominant species in Guangzhou ecosystems.The abundance of crustacean zooplankton ranged from 1 to 132 ind./L in Changde ecosystems,which was the highest in Chuanzi River,followed by Liuye Lake,and then Changde segment of the Yuan River.The abundance of crustacean zooplankton ranged from 2 to 134 ind./L in Guangzhou ecosystems,which was the highest in Guangzhou segment of the Pearl River,followed by Haizhu Lake,and then the Shiliugang River.There was no significant difference of abundance of crustacean zooplankton between the two ecosystems(P > 0.05),while,the abundance of Calanidae in Changde ecosystems was significantly greater than that in Guangzhou(P < 0.05).Statistical analysis showed that the main environmental factors affecting crustacean zooplankton community structure in Changde ecosystems were water temperature,transparency and potassium permanganate index,while in Guangzhou were water temperature,transparency,p H,total phosphorus and chlorophyll a.The water environmental problems in Liuye Lake are mainly non-point source pollutions,and the discharge of pollutants from the lake port should be strictly controlled.The Chuanzi River is greatly affected by sewage and industrial wastewater,and the urban drainage network management system should be optimized,and diversion of rain and sewage should be reformed.The water quality of Changde segment of the Yuan River is good,and the inflow of nutrients from the basin should be controlled.Haizhu Lake is connected to the Shiliugang River,and land-based sewage discharge should be controlled.The Shiliugang River is affected by the tide,which causes the pollutants stay in the river for a long time,and the old facilities of sluices and rivers should be upgraded.Guangzhou segment of the Pearl River is greatly affected by human activities,and the discharge of pollutants should be strictly controlled,and ecosystem-based water environment management should be strengthened.The connection of river and lake can improve the self-purification capacity of the water bodies.The urban river lake interconnected ecosystems play important roles in protecting the water environment and improving the utilization efficiency of water resources.