The Study Of Ecological Responses Of Metazooplankton Community To Different Environmental Factors In The Water Bodies In Shanghai

Zooplankton is an important secondary producer in freshwater ecosystems.It may play important role in ecosystem integrity and bio-geochemical cycles.Zooplankton are sensitive to changes in aquatic environment and have been suggested to be good biological indicators for water quality.Global warming and rapid economic development have led to significant changes in environmental factors of water bodies,which have significant impact on zooplankton.The main factors which affecting zooplankton community structure were detected through field investigation.And the response of zooplankton community structure to environmental factors would be further explored by simulated emission of outdoor.The results are as follow:1.Monthly investigations of the zooplankton community and the associated physic-chemical variables and phytoplankton in 2017 in Dianshan Lake,largest freshwater lake of Shanghai,China revealed the effect of habitat heterogeneity on zooplankton in subtropical shallow lakes.The results showed that seasonal variations in zooplankton communities were significantly different?P<0.05?,while there was only spatial difference in spring and summer?P<0.05?.When the temperature is less than13.07?,it is characterized by winter zooplankton community.When the temperature is 13.07?¹9.57?,it is characterized by spring zooplankton community.When the temperature is greater than 19.07?,the concentration of chlorophyll-a?Chla?is greater than 9.03 mg·L^-1,which is summer zooplankton community,when the concentration of chlorophyll-a?Chla?is less than 9.03 mg·L^-1,it is characterized by autumn zooplankton community.Dianshan Lake was divided into three regions by cluster analysis of zooplankton communities;When the concentration of ammonia nitrogen is greater than 1.11 mg·L^-1,the zooplankton communities of area II?upstream of Dianshan Lake?were significantly different from other two regions in spring.Cyanobacteria was dominated on driving temporal changes in summer.When the cyanobacteria biomass is greater than 2.58 mg·L^-1,the zooplankton communities of area I were significantly different from other regions.The indicator species score?Indval analysis?also showed that there were differences indicated species in different regions.The representative species are mainly indicators by eutrophication.It indicated that Dianshan Lake was in eutrophication.But these different region of Dianshan Lake differ greatly in eutrophication.2.The effects of cyanobacteria on zooplankton community structure were studied by simulated emission of outdoor.The results showed that there were significant difference in the zooplankton community structure between the control group and the treatment group?P<0.01?.Redundancy analysis?RDA?indicated that several environmental factors such as cyanobacteria?including chlorophyll a?,total dissolved nitrogen?DTN?,nitrate-nitrogen?NO₃^--N?,nitrous-nitrogen?NO₂^--N?,dissolved inorganic phosphate?DIP?,total nitrogen?TN?and total phosphorus?TP?had significant effect on the zooplankton community structure.The indicator species score?Indval analysis?also showed that there were differences indicated species in different treatments.The representative species of the control group are Trichocerca pusilla and Neodiaptomus schmackeri.While the representative species of the treatment group?cyanobacteria?are Pentatrocha gigantean,Cephalodella gibba and Trichocerca pusillar.Secondly,C.ovalisporum could significantly inhibit the growth of cladocerans?Daphnia carinata and Simocephalus vetulus?.And with the increase of cyanobacteria biomass,it may delay the first reproduction time of cladocerans?Daphnia carinata and Simocephalus vetulus?3.The effects of ammonia nitrogen on zooplankton community structure were investigated by simulated emission of outdoor.PCoA analysis demonstrated structures of zooplankton communities were distinct between samples of lesser(?1.8 mg·L^-1)and greater concentrations of ammonia nitrogen(>1.8 mg·L^-1).Redundancy analysis?RDA?indicated that main environmental factors such as total dissolved phosphorus?DTP?,total dissolved nitrogen?DTN?,dissolved oxygen?DO?and dissolved inorganic phosphate?DIP?had significant effect on the zooplankton community structure..In addition,The representative species of lesser concentrations of ammonia nitrogen(?1.8 mg·L^-1)were mainly Monommata longiseta,Colurella obtuse,Monostyla thethis,Colurella uninata,Schmackeria forbesi and Diplois daviesiae.The representative species of greater concentrations of ammonia nitrogen(>1.8 mg·L^-1)were mainly Brachionus calyciflorus,Copepodite,Brachionus diversicornis,Brachionus urceus and Polyarthra dolichoptera.4.The effect of phosphorus on zooplankton community structure were discussed by simulated emission of outdoor.The results showed that structures of zooplankton communities were distinct between samples of lesser(?0.08 mg·L^-1)and greater concentrations of ammonia nitrogen(>0.08 mg·L^-1)?P<0.01?.Results of the RDA analysis indicated that the main factors affecting the zooplankton community structure were total dissolved phosphorus?DTP?,total dissolved nitrogen?DTN?,dissolved oxygen?DO?,and chlorophyll a?Chla?.The indicator species score?Indval analysis?also showed that there were differences indicated species in different treatments.The representative species lesser concentrations of total phosphorus(?0.08 mg·L^-1)included Alona eximia and Daphnia carinata.While representative species of the high phosphorus group mainly included Brachionus caudatus,Brachionus angularis,Brachionus diversicornis,Keratella valga,Cephalodella sp.and Brachionus calyciflorus.