Biodiversity Of Aquatic Organisms And Ecosystem Health Assessment Of Xiaoxingkai Lake

An ecosystem is a unity of biological and environmental,interaction between biological and environmental processes,and in a relatively stable dynamic equilibrium in a certain period of time.Thus,simply selecting one or more of the methods of physical,chemical or biological monitoring techniques,it is not objective to make a simple assessment of the integrity of a healthy ecosystem,and it is also important to include human activity,So thehealth assessment of ecosystem should also include human,social,economic development and other indicators.In recent years,a series of aquatic ecological problems such as the blooming of blue-green algae,the increase of water pollution and the decrease of biodiversity have been made.Xiaoxingkai Lake and Daxingkai lake connects to each other,the lakes have a certain connection,the water quality and water ecosystem health of Xiaoxingkai Lake has directly threatens to ecological security of Daxingkai Lake,and water ecological security issues related to Sino-Russian relationships.Therefore,it is of great theoretical and practical significance to evaluate the health of Xiaoxingkai Lake aquatic ecosystem and put forward the reasonable control measuresBased on the investigation and analysis of physical and chemical indexes and aquatic biological indicators,this paper constructs the ecosystem health integrity system with physical,chemical and biological integrity as the criterion layer.At the same time,the ecosystem health comprehensive evaluation system was constructed based on the social,economical health index and the lake self health indicators,Few methods were used to assess the statute of the lake ecosystem,including single factor evaluation method,fuzzy comprehensive evaluation method,diversity index method,physical integrity index method,chemical integrity index method,biological integrity index method and comprehensive health evaluation method.The main conclusions are as follows:1.Water quality evaluation based on physical and chemical indexesThe water quality of Xiaoxingkai Lake is the best in spring,followed by winter and summer,and the water quality is the worst in autumn.The seasonal variation of pollution level is consistent with the annual variation.The contribution of pollution is TN> DO> BOD5>CODCr> TP.Single factor evaluation method and fuzzy comprehensive evaluation method show that Xiaoxingkai Lake water quality is class ?,the main cause of pollution is N,P amount exceeded.Jianchang bridge,in the middle of the Muling River,has the highest concentration of pollution,the water quality is class ?.The concentrations of pollution in the middle of the Jixi Bridge,Jidong Bridge and Zhiyi bridge pollution also are higher,water quality is class ?.Most of water pollution is mainly from the middle reaches of the Muling River,the main pollution matters are TN,TP and BOD5,among which the two sites,Jianchang and the Jixi Bridge contribute a lot of the pollution.2.Water quality assessmemt based on the evaluation of aquatic biodiversityTotal of 93 species and their variants of phytoplankton were identified,the most of species belong to Chlorophyta division,and Pyrroptata divison has the least species.Abundance and biomass were highest in the summer and lowest in the winter;23 species of zooplankton were identified,the copepods have the most species,and the cladocerans have the smallest.Abundance were the highest in spring,Abundance and biomass were the lowest in winter,and biomass was highest in summer and lowest in spring.The 25 species of benthic invertebrate were identified,mainly composed of oligosaccharides,aquatic insects and mollusks.Among them,there were the most species were aquatic insects,followed by the animals,and Molluscs were at least;35 species of fish were founded,most of species belongs to Cypriniformes,thorn fish has the least species.The body weight and body length of the main economic fish tend to be miniaturized,the age structure was younger,and the growth was slow.Except Protosalanx only has one age group,the ages of the other species are mainly on to 1 ?3,5 to 6age fish has less proportion.The results showed that the Shannon-wiener biodiversity index(//"),Pielou evenness index(J)index of the phytoplankton,zooplankton and zoobenthos and Margalef species richness(D)index were more consistent,that is,2 #,3 # and 10 # three sampling points pollution is heavier,6 # and 7 # two sampling points pollution is light,the average of the diversity index shows Xiaoxingkai Lake water quality is p-pollution;seasonal distribution,the three diversity index evaluation results are the same,the most serious pollution happened in autumn,followed by summer,spring and winter have the lightest pollution;The results of biodiversity index were consistent.The results showed that the fish species integrity index system and the fish integrity index were the same,and the health status of Xiaoxingkai Lake ecosystem was in normal level.It is not optimistic.3.Water ecosystem health assessment based on integrityThe physical,chemical and biological integrity of Xiaoxingkai Lake were evaluated by the integrity index method.The evaluation results were the same.It can be seen that the natural habitat and community structure of Xiaoxingkai Lake aquatic ecosystem have changed greatly,and even some ecological functions have been lost.Among them,Xiaoxingkai lake physical integrity indicators in the mouth of the inflow rate is relatively good,mainly inlet water is not subject to human control,and the outlet is made of man-made water conservancy project,The outflow of the water can be affected by human factors,so the flow rate of the outlet reduced the overall flow rate;lake stability is relatively poor,the formation of geological,location,climate characteristics and late human disturbance made those relationships;lake area integrity is also relatively good,pond around the lake and lake area reduction has not much impacts on its integrity;chemical integrity of the indicators is relatively low,which mainly due to human activities.The pollution caused by the pollution of the farmland around the Lake and the discharge of domestic sewage have great influence on its chemical integrity.For the biological integrity index,the integrity of the aquatic organisms is generally low,and the diversity is relatively poor,which is mainly related to the lower water temperature and water pollution in this area.4.Water ecosystem health assessment based on comprehensive indicatorsBased on the study of physical and chemical indexes and aquatic biodiversity of Xiaoxingkai Lake,a total of 24 indicators were set up covering five aspects: economic development index,environmental impact index,lake structure index,lake system index and lake self-Comprehensive evaluation system.And the level and the indicators of the evaluation and affirmation criteria was determined by using of AHP.Using the grading index scoring method,step by step weighted to get the ecosystem health comprehensive score,according to the scores to determine the health of the ecosystem.The results show that the evaluation results of the economic development index,the environmental impact index,the lake structure index and the lake system index all shows that the level of ecosystem health is in a normal level.The evaluation results of the lake's own state indicators are micro-morbid,the human,economic and environmental indicators and the lake own health were micro-morbid and general.The final score of the comprehensive evaluation index of the ecosystem of the target layer was 58.6points,and the evaluation result was general.