Diversity Of Freshwater Bivalves In Anhui Section Of The Yangtze River Basin

Freshwater bivalves are an important part of the freshwater ecosystem and responsible for material circulation and energy flow.However,bivalves have weak mobility and poor tolerance to the environment.Due to the impact of human activities and global climate change,freshwater bivalves have become one of the most endangered groups of aquatic animals in the world.The Anhui section of the Yangtze River Basin has rich resources of freshwater bivalves.Among them,there are many species endemic to China,and the research value is extremely high.However,the research work on bivalves in this area was very limited,most areas of the area had not conducted scientific investigation,and it was difficult to grasp the full picture of freshwater bivalves in this area and their resource status.Nowadays,freshwater bivalves are facing serious survival threats,and the investigation of bivalves in this area is very important.During 2017-2020,this study used the time search method to conduct freshwater bivalve surveys on 164 sections and sample points in 44 water bodies in 13 water systems in the Anhui region of the Yangtze River Basin during the low water level.This research focused on clarifying the composition,dominant groups,spatial distribution pattern and flora similarity of freshwater bivalves in the region,and explored the impact of environmental factors such as hydrology,sediment types,and sediments on the distribution of freshwater bivalves.And this research provided a basis for the utilization and protection of freshwater bivalve resources in the Anhui section of the Yangtze River Basin.The results of the study are as follows:1.A total of 39 species of freshwater bivalves,17 genera,5 families,2 orders,were recorded in the study area,including Solenaia carinata,a newly recorded species in Anhui Province.And there were 24 species endemic to China and 6 species of China second-level protected wild animal.2.Based on the occurrence rate of species and the Berger-Parker dominance index.The dominant species in the study area at this stage were Sinanodonta woodiana,Nodularia douglasiae,Lamprotula caveata,Corbicula fluminea,and Cristaria plicata.The rare species were Aculamprotula fibrosa,Aculamprotula polysticta,Aculamprotula scripta,Aculamprotula tientsinensis,Aculamprotula tortuosa,Cuneopsis captiata,Lepidodesma aligera,Schistodesmus spinosus,Anemina fluminea,Lamprotula triclava,Lepidodesma aligera,Lamprotula bazini and Novaculina chinensis,among which Lamprotula triclava,Lamprotula bazini,and Aculamprotula scripta were critically endangered in this area.3.Based on the cluster analysis of water system species composition and dominance,the study area was divided into two categories.The Qiupu River system,Huanghu River,Chuhe River system and Datong River are divided into one category,which is characterized by low species diversity and mainly common species.Qingyi River system,Shuiyang River system,Yaodu River system,Jiuhua River,the Wanhe River system,Huangpeng River system,Chaohu Lake system,Caizi Lake system and the main stream of the Yangtze River were divided into one category,and its freshwater bivalves had a high diversity.Among them,the Shuiyang River system,Qingyi River system and Wanhe River system had a variety of rare species and China second-level protected wild animals,which should be protected urgently.4.The species diversity of bivalves in different water bodies was quite different.The total number of species in rivers and lakes in the study area,the number of endemic species in China,the number of rare species,and the number of threatened species were significantly higher than those of reservoirs.Due to specific environmental impacts,the species and numbers of the same type of water bodies were also quite different.5.Different environmental factors had different effects on the composition and distribution of freshwater bivalves.Water system connectivity would seriously affect the species of water system.The species diversity of bivalves with silt and sandy bottoms was higher,and the lowest was stone.Water bodies with large water level changes,slow water velocity,and low water clarity had higher species diversity.Solenaia species prefered hard bottom mud,such as Solenaia oleivora.Within a certain range,the species density increases with the increase in sediment compactness.When the average compactness reached 112PSI/Inches,the average density of Solenaia oleivora can reach 42.4 ind/m~2.There were rich species of freshwater bivalves in the Anhui section of the Yangtze River Basin,with a variety of endangered species.In combination with the protection policy of"A10-year fishing ban in the Yangtze River",the protection of the Shuiyang River,Wanhe River and Qingyi River systems should be strengthened,which is of great significance to the protection of freshwater bivalve resources in China.