Ecological Studies On The Adaptation Of Rotifers In River Water Changes

In order to study the impact of rotifer community ecological structure and life history changes in eutrophic water bodies,this research conducted field experiments and indoor experiments respectively.The field experiment mainly studied the impact of the sediment dredging project of the Shuangqiao River,a tributary of Chaohu Lake,Anhui Province on the ecological structure of the rotifer community,and the response of rotifers to river water quality monitoring,and mainly compared and analyzed the water quality physical and chemical factors before and after the sediment dredging of the Shuangqiao River.Changes,the ecological structure of the rotifer community and its biological diversity floating changes,the relationship between rotifer density,biomass and water environmental factors,to evaluate the effect of the Shuangqiao River sediment dredging project on eutrophic water and the ecological structure of the rotifer community.The indoor experiment is mainly to simulate the environment of eutrophic water body.The highest density of Brachionus calyciflorus in the Chaohu Lake Basin is selected as the research object to carry out the life table experiment study.The temperature is 15?,25? and 35?.And under different concentrations of Scenedesmus obliquus,to explore the influence of Microcystis aeruginosa on the life history parameters of Brachionus calyciflorus.The results are summaried below:1.Field experiment:A total of 30 species of rotifers were found in the dredging section of the Shuangqiao River,belonging to 3 orders,7 families,and 11 genera.Among them,the genus Brachionus is the most with 10 species,followed by 6 species of Keratella,3 species of Trichocerca,2 species of Platyias,2 species of Asplanchna,2 species of Filinia and 1 species of Rolaria.1 species of Synchaeta,1 species of Asplanchna,1 species of Euchlanis and 1 species of Brachionus.The results indicated that the sediment dredging would greatly improve the water quality and reduce the content of nutrients in Shuangqiao river,the concentrations of nitrogen(N),phosphorus(P)decrease 48.06% and 18.18% respectively.The density of rotifers decreased,the biomass and diversity index of rotifers increased significantly after sediment dredging The Margalef richness index,up from 2.64 before by dredging sediment dredging after 3.62;The Shannon-Wiener diversity index rose from 1.55 before dredging to 1.62 after dredging.Pearson correlation analysis of rotifer density and water environment factors showed that there's a significant positive correlation between sucking rotifers and ammonium or nitrate(P<0.05),and significant negative correlation with soluble phosphorus(P<0.05).The predatory rotifers were positively correlated with temperature,ammonium and nitrate(P<0.01),positively correlated with soluble nitrogen and total nitrogen(P<0.05),while negatively correlated with soluble phosphorus(P<0.05).There was a significant positive correlation between filter-feeding rotifers and predatory rotifers(P<0.01),while there was a significant positive correlation between sucking rotifers and predatory rotifers(P<0.01).This study showed that the sediment dredging project would reduce the content of nutrients and improve the water quality in Shuangqiao river,,The density of sedimentators and predators increase,while the density of raptors and suckers decreased,The changes of different rotifers groups may reflect the improvement of water quality and the safety of water ecosystem,the research of rotifers groups would benefit for the control of phytoplankton's biomass and the improvement of water quality.2.Indoor test:In order to understand the influence of temperature and Microcystis aeruginosa concentration on the life cycle of rotifers,the life table experiment was carried out with the Brachionus calyciflorus as the research object.The changes of Microcystis aeruginosa to the life cycle of Brachionus calyciflorus were investigated at15??25??35? and different concentrations of Scenedesmus obliquus..The results showed that the temperature,the concentration and the interaction of the two had significant effects on the net reproductive rate(R0),generation time(T)and intrinsic growth rate(rm)of the Brachionus calyciflorus(P<0.05).When the concentrations of Scenedesmus obliquus were 105cells/ml and 106cells/ml,R0 decreased by 9.4% and 69.3%,and rm decreased by 20% and 63.6%,respectively,in the treatment group compared with the control group,when the temperature was 15?.The inhibition effect of Microcystis aeruginosa on the reproduction and growth of Brachionus calyciflorus was greater when the concentration of Scenedesmus obliquus was sufficient than when the concentration of Scenedesmus obliquus was deficient.When the temperature was 25?,R0 decreased by 66.3% and 45.6%,respectively,and rm decreased by77.8% and 22.2%,respectively.The inhibitory effect of Microcystis aeruginosa on Brachionus calyciflorus decreased with the increase of the concentration of Scenedesmus obliquus.When the temperature was 35?,R0 decreased by 71.8% and 83%,and rm decreased by 90% and 70.7%,respectively.The inhibitory effect of Microcystis aeruginosa on rotifers increased with the increase of the concentration of Scenedesmus obliquus..The results showed that the effects of Microcystis aeruginosa on rotifers were influenced by the concentrations of other edible green algae,and the effects varied with the change of temperature.In this study.Comprehensive research results show that in eutrophic water bodies,the community structure and population density of rotifers will be affected by various nutrients,temperature and algae in eutrophic water bodies,and will also be repaired when lakes and rivers are repaired.The impact of the project further changes the community structure of rotifers.The rotifers also monitor thechanges in water quality through changes in the diversity index and respond to water quality indicators.In this study,field experiments and laboratory experiments are conducted to show that the density changes of different feeding rotifers can mark the impact changes of river water quality and water ecosystems.It is also hoped that by simulating eutrophic water bodies,by measuring different temperatures and different food concentrations.The interaction of rotifers on some important life history parameters and life table factors of Brachionus calyciflorus to understand some of its basic biological characteristics and for future research on the effects of various factors on rotifers in the wild environment Pave the way for data and theory.