Macroinvertebrate Community Structure And Health Assessment Based On The Benthic Index Of Biological Integrity In Poyang Lake During Flood Period

Poyang Lake is the largest river-communicating lake in the Yangtze River Basin.Under the influence of monsoon climate and connected water system,it has formed a unique hydrological environment,provided a broad habitat for aquatic organisms,and is an ideal place for fish,migratory birds and macroinvertebrates to reproduce.Since the 21 st century,under the interference of global climate and human activities and many other factors,the relationship between rivers and lakes has changed,drought-flood abrupt alternation events occurring continually.In addition,with the destruction of habitat by large-scale sand mining activities and land-use changes,the survival of aquatic organisms such as macroinvertebrates in the basin is threatened.In July 2016,62 sampling points were set up in outlet channel(region ?),the main Lake(region ?)and the eastern Lake(region ?).According to the community structure and distribution of macroinvertebrates in Poyang Lake at present,the relationship between macroinvertebrates community structure and main influencing factors was analyzed.Based on the current situation of natural and human disturbance,the integrity evaluation system of macroinvertebrates in Poyang Lake was constructed to evaluate the health status of Poyang Lake and provide reference for the protection of biodiversity and ecosystem management of Poyang Lake.The results show that:1.In this study,64 species of macroinvertebrates were collected in Poyang Lake,including 28 types of Arthropoda,26 types of Mollusca and 10 annelids.The dominant species are corbicula fluminea,bellamya aeruginosa and parafossarulus eximius.A total of six kinds functional feeding groups were collected,including 10 species of collector-gathers,18 species of filter-gathers,16 species of scrapers,10 species of shredders,9 species of predators,1 omnivorous animal.2.There were obvious differences of the community structure of macroinvertebrates in different ecological areas.In the number of species: region II(56)> region III(37)> regionI(28).The dominant species are bellamya aeruginosa,corbicula fluminea,limnoperna fortunei,and nereis japonica in region ?.The dominant species are corbicula fluminea,bellamya aeruginosa,parafossarulus eximius in region ?.The dominant species are corbicula fluminea,bellamya aeruginosa,parafossarulus eximius,alocinma longicornis and Anodonta woodiana elliptica in region ?.3.Water quality affected the tolerance of macroinvertebrates,sand mining was responsible for the damage of macroinvertebrates in outlet channel and the middle and north of the main lake.Flooding frequency mainly affected the south of the main lake area,and the eastern Lake is mainly affected by the land-use.According to this,12 reference points were selected under the condition of TP?0.1 and TN?1.5,no obvious sand mining activity,flooding frequency > 50%,and no construction and cultivated land within 1km.4.The final benthic index of B-IBI for Poyang lake were number of total species,Margalef richness index,FBI Biotic index,number of intolerant taxa and relative abundance of scrapers.The B-IBI index of each ecological area of Poyang Lake was obtained by ratio method.The final evaluation results show that17.52%of sampling sites in the Poyang Lake Basin were extremely few interference,27.42% of sites were mild interference,43.55% of sites were moderate interference,and 14.52% of sites were severe interference.By comparing the health status of different ecological areas,we found that the outlet channel was more disturbed than the other two regions.