水文连通性对平原河网鱼类群落结构及功能多样性的影响OA

Hydrological connectivity in river systems is important,affecting the structure,stability and function of aquatic ecosystems.In open plains,the lakes and rivers are often connected by complex,mean-dering waterways and their natural connectivity is frequently altered by artificial channels,sluices,dams,reservoirs and other water control structures.In this study,we investigated the effects of hydrological con-nectivity on fish community structure and functional diversity in a typical plain river-network system us-ing representative water bodies in Hanjiang District,Yangzhou City,and Jiangsu Province.In September 2023,fish resource surveys were conducted at 23 sampling sites in the study area across 10 water bodies,including rivers,rural and urban lakes,and reservoirs.Hydrological connectivity was quantified using the hydrological barrier coefficient and the comprehensive index of biological connectivity.The index of rela-tive importance,species diversity indices and functional diversity indices were used to analyze fish com-munity composition,dominant species,biodiversity patterns and their relationships with hydrological con-nectivity.A total of 38 fish species belonging to 9 families and 6 orders were recorded in the study area,with Cypriniformes being the dominant taxa.The dominant species were Coilia nasus,Hemiculter leucis-culus,Carassius auratus and Culter dabryi.Fish community structure differed significantly among the water bodies(P<0.001).Closed reservoirs showed relatively simple species composition and were mainly characterized by resident and widely tolerant species,whereas lakes and rivers with higher connectivity supported a richer species composition and a more complex community structure.The results of commu-nity ordination and similarity analysis indicated clear spatial differentiation of fish assemblages among water bodies with different degrees of connectivity.There was a significant negative correlation of both the comprehensive index of biological connectivity(P<0.01)and functional richness(P<0.01)with the hydrological barrier coefficient.These results suggest that increased hydrological barriers restrict fish migration,dispersal and reproduction,reduce fish community similarity among water bodies,and diminish occupied functional space.Hydrological connectivity is a key factor in driving fish community differentia-tion and functional diversity in plain river networks.The decline of connectivity caused by water conser-vancy facilities alters species composition and affects the functional structure of fish assemblages.To conserve fish biodiversity and protect the ecological stability of aquatic ecosystems,an integrated manage-ment plan for plain river-network ecosystems should focus on three objectives:maintaining water body connectivity,improving habitat heterogeneity and controlling pollution.