上行效应和下行效应对小北湖夏季浮游动物功能群的影响OA

To investigate the effects of bottom-up effects(supply of nutrients and phytoplankton resources)and top-down effects(fish predation)on zooplankton functional groups in aquatic ecosystems,an investigation and analysis of aquatic organisms and water environmental factors were conducted at six sampling sites in Xiaobei Lake National Nature Reserve in summer 2023.The results showed that:zooplankton in the study area could be divided into six functional groups:MCC,MCF,PC,PF,RC,and RF.Small-sized zooplankton functional groups RF,PF,and RC were dominant in summer,with bio-mass proportions of 41.49%,30.11%,and 27.49%,respectively.Phytoplankton could be classified into 17 functional groups,among which H1,X2,and MP were dominant in summer,accounting for 64.88%,10.18%,and 10.11%of the total biomass,respectively.Fish could be divided into three functional groups:omnivorous,planktivorous,and carnivo-rous,with biomass proportions of 90.22%,9.02%,and 0.76%,respectively.Redundancy analysis(RDA)and Pearson correlation analysis indicated that water temperature,total nitrogen,total phosphorus,and planktivorous fish biomass were the main factors affecting the structure of zooplankton functional groups in summer.The dominant zooplankton functional group RC was significantly positively correlated with total nitrogen,total phosphorus,5-day biochemical oxygen demand(BOD5),and phytoplankton functional groups X2 and H1,but significantly negatively correlated with phytoplankton func-tional group MP and the omnivorous fish functional group.The dominant functional group PF was significantly positively correlated with the planktivorous fish functional group and significantly negatively correlated with water temperature.Over-all,the regulatory effect of bottom-up effects(nutrient and phytoplankton resource supply)on zooplankton functional groups was significantly stronger than that of top-down effects(fish predation).