An Assessment Of Lake Ecology On The Basis Of The Macrobenthos Multi-Metric Index(MMI) In The Western Region Of Jilin,China

The western region of Jilin Province is located at the northeastern part of China.Large number of lakes are distributed in this region,where is one of five large lake regions within China,supporting both drinking water and agricultural water.The frequent human activities and scarce rainfall in this region have resulted in weaker lake connectivity and enrichment of the pollutants within the lakes.The lake ecosystems in the region have been degraded to varying degrees,thus it is necessary to assess its ecological health.Macrobenthos multi-metric index(MMI)is a mature ecological health assessment method that has been widely used in the lake ecosystem assessment all over the world.However,it has not been well developed for assessing the lake water ecosystem in China.In this study,11 lakes affected by human activities to different degrees were selected as the research objects.A total of 1,259 individual macrobenthos were collected in this study,all of which were identified at the species level,which included 3 phyla,3 classes,6 orders,10 families,and 43 species.They were categorized into three types based on the trophic level.Through the comparison and screening of different biological indicators among different lake types,appropriate indicators were selected to construct the MMI.Four core indicators were selected from 58 candidate indicators to construct the MMI: the total number of taxa,Simpson index,% of Diptera+Mesogastropod,and % of pollution intolerant species.MMI could distinguish lakes that are seriously and slightly disturbed by humans.The results of regression analysis also show that the degree of lake eutrophication caused by human activities has a significant correlation with MMI,can effectively explain the changes in it.MMI can characterize the disturbance and influence of eutrophication on macrobenthos.The results of MMI can also be affected by the land use type and the coverage of aquatic vegetation around the lake,which are important factors affecting the ecological health of the lake.Research on the application of MMI method to assessment of the ecological health of lakes is very rare in Northeast China.This research can provide supplementary information beyond the traditional water environment assessment for the formulation of management strategies.The main research results are as follows:(1)Water quality test results show that all lakes in the study area are in a state of eutrophication.Among them,Sanwang Lake,Zhenzi Lake,Qianzi Lake,Heiyu Lake and Hongzi Lake are the most eutrophications,all of which are highly eutrophication.Nutrition.The rest of the lakes are all in a state of mild eutrophication.(2)The macrobenthos community in the study area is mainly composed of gastropods,oligochaetes and insects.Among them,the gastropod is the first group of macrobenthos in the study area,accounting for 44.16% of the total.(3)Using the constructed MMI model to calculate the MMI value of each lake,the MMI value of the study area is between 0.121 and 0.866.The results showed that2 of the 11 lakes studied were at the level of extremely poor ecological health,4 had poor ecological health,3 had normal ecological health,and only Xinmiao Lake had better ecological health.Etou Lake is the only lake with excellent ecological health.(4)The results of correlation analysis between the MMI value of site(MMIS)and the MMI value of lake(MMIL)and the corresponding comprehensive trophic level index(TLI)value show that MMIS and TLI have a significant correlation(P<0.05),and the significance level is extremely high(R=-0.69);MMIL and TLI are also significant.The correlation of(P<0.05),and its significance level is higher(R=-0.92).The results of linear regression analysis showed that changes in TLI can effectively explain the changes in MMIS and MMIL(linear R2=0.539,P=0.00;linear R2=0.706,P=0.001).It shows that MMI can characterize the interference and impact of eutrophication on macrobenthos.(5)The research results show that in lakes with fine sand and gravel as the main sediments and no aquatic vegetation,the biomass and diversity of macrobenthos are extremely low;where the sediments are mud and aquatic vegetation is lush Among the lakes,macrobenthos have the highest biomass and diversity.It shows that the lake sediment and aquatic vegetation have a positive impact on the survival of macrobenthos.(6)Using MMI to evaluate lake ecological health can be applied to the study area and is better than a single physical and chemical index and biological index evaluation.