Temporal And Spatial Patterns Of Macrozoobenthos Community In Poyang Lake And Its Connected Waters

Macrobenthos are important groups of aquatic animals,and their species richness determines ecosystem functions to a certain extent,so they play an important role in aquatic ecosystems.However,due to the effect of human activities and natural factors,the habitat of Poyang Lake is seriously degraded,resulting in the decline of fishery resources and loss of biodiversity.Therefore,Systematic investigation of Macrozoobenthos community structure in Poyang Lake and its connected waters from2016 to 2017.The main conclusions are as follows:1.Macrozoobenthos samples in Poyang Lake and its connected waters were identified into 81 species,28 families,9 classes and 3 phylums.The dominant four sampling species are 12 species,14 species,13 species and 15 species respectively,Nephtys oligobranchia,Limnodrilus hoffmeisteri,Bellamya purificata,Bellamya aeruginosa,Rivularia auriculata,Limnoperna lacustris,Corbicula fluminea are the dominant species.2.The mean density and biomass of macrozoobenthos in Poyang Lake and its connected waters were 100.6 ind./m~2 and 65.8 g/m~2,respectively.The density of macrozoobenthos in June was the greatest(142.12 ind./m~2),November was the lowest(61.13 ind./m~2).The biomass of macrozoobenthos in November was the greatest(174.72 g/m~2),June was the lowest(46.46 ind./m~2).The density of macrozoobenthos in Tongjiang channel was the greatest(205.57 ind./m~2),the middle reach of Yangtze River was the lowest(23.02 ind./m~2).The biomass of macrozoobenthos in Xinjiang River was the greatest(267.71 g/m~2),the middle reach of Yangtze River was the lowest(7.79 g/m~2).3.The density and biomass of Gastropoda and Bivalvia in“five rivers”were greater than other sections.The density of Chaironomidae,Oligochaeta and Miscellaneous others in the main lake area of Poyang Lake were greater than other sections,but their biomass in these sections were lower than other sections.4.RDA showed that Mollusca was correlated with dissolved oxygen,pH and salinity;Arthropoda was correlated with velocity,dissolved oxygen and water depth;Annelida was correlated with dissolved oxygen and chlorophyll-a.Therefore,water depth,dissolved oxygen,water velocity and chlorophyll-a significantly affected macrozoobenthos distributions and assemblage structure.5.The NMDS showed that assemblage structure of macrozoobenthos in Poyang Lake and its connected waters were similar in winter.Assemblage structure of macrozoobenthos in spring was divided into two areas,which the first area included Tongjiang channel and main lake area of Poyang Lake;the second area included the middle reach of Yangtze River and“five rivers”.It was divided into two areas in summer and autumn,which the first area included Tongjiang channel,main lake area of Poyang Lake and“five rivers”;the second area included the middle reach of Yangtze River.6.the macrozoobenthos of nine sampling sites in three Shallow-lakes of Poyang Lake Wetland were surveyed in four seasons.31 species macrozoobenthos belonging to three phylum,eighteen families were identified,among them,the number of Mollusca was the greatest species(14)The dominant species were Bellamya purificata,Alocinma longicornis,Parafossarulus anomalospiralis,Pelopia sp.,chironomus sp.,Limnodrilus hoffmeisteri.The annual average density of macrozoobenthos was 63.78ind/m~2,and the average biomass was 70.49 g/m~2.The functional feeding groups had the highest percentage of scrapers and the lowest percentage of shredders,with the highest density and biomass in winter.