Resources Status And Diversity Patterns Of Freshwater Mussels In Dongting Lake

Freshwater mussels have a universal distribution through the lakes,ponds and streams in the world,are one of the most important groups in the freshwater system.With stable living area,freshwater mussels are one of the most imperilled faunal groups globally.They are one of the most imperiled groups in the world.Dongting Lake is the second largest lake in China and one of the two biggest lakes still linked with the Yangtze River.On the basis of massive investigation of the resources of freshwater mussels in Dongting Lake in 2013 and 2015.An analysis of composition,biomass,distribution,population structure,factors affected biodiversity and unionid faunas changes in history were did for the freshwater mussels species.So it may provide a scientific basis for management and protection of freshwater mussels resource.The main conclusion are as follows:1.1142 specimens of freshwater mussels belonging to 34 species,14 genera were collected by a investigation in Dongting Lake.A new record species of Lepidodesma aligera was found in Hunan province.30 species according to 13 genera were recorded in South Dongting lake;19 species according to 9 genera were recorded in East Dongting lake;there recorded the least species:18species,10 genera in West Dongting Lake.9 species of genera Anodonta which numeber is the most were collected.Unio douglasiae was the dominant species in Dongting Lake with the maximum relative abundance of 63.76%.2.The total average biomass was 7.31±6.56 g/m~2 and density of 0.28±0.33ind./m~2.The biomass and density of freshwater mussels in the three lakes were:11.65±6.12 g/m~2 and 0.45±0.43 ind./m~2 in East Dongting Lake,4.97±5.96 g/m~2 and0.18±0.23 ind./m~2 in South Dongting Lake,2.42±3.30 g/m~2 and 0.13±0.13 ind./m~2 in West Dongting Lake.There are significant differences in biomass(p=0.049<0.05),and the same in density(p=0.006<0.01)of three lakes.3.The analysis of distribution showed that different mussels species have great differences on distribution range and occurrence rate.Unio douglasiae was the highest in both distribution range and occurrence rate.Some unionids had a narrow distribution range.As for the population structure,most of species had relatively stable population structure,and few difference between living and death of individual in population structure was found.4.According to the species composition analysis of each sampling site.The largest number of species and highest diversity were occurred in site 21 and 17 in the whole Dongting Lake.These two area of natural fish docks become refuge for some freshwater mussels.5.Historically,46 freshwater mussels belonging to 14 genera were recorded in Dongting Lake.Among them 22 species were occurred in each investigation of different periods.The species richness decreased slightly compared with the first survey in last century.