连江鱼类群落多样性及其与环境因子的关系

Abstract

Twelve dams have been constructed along the Lianjiang River during the last 50 years.The fish community structure in this region was documented by collecting fish and measuring environmental indices at seven representative sites in the Lianjiang River between 2009—2010.A total of 98 species were collected,belonging to 9 orders,20 families,and 75 genera.Among these,Garra pingi hainanensis and Gobiobotia longgibarba meridionalis have not previously been documented in the Lianjiang River.Small species,including Squalidus argentatus,Pelteobagrus fulvidraco,Sarcocheilichthys parvus,Opsariichthys bidens,and Hemiculter lecuisculus dominated the local community.The spatial pattern describing the fish community was analyzed using hierarchical and non-metric multidimensional scaling.The fish community of Lianjiang River separated into three clusters: mid-upriver,mid-downriver,and downriver.GroupⅠwas located in the mid-upriver,a region characterized by large numbers of cavities and gravel,ideal habitat for resident fish.However,migratory fish are unable to reach this section of the river because of dams located further downstream.GroupⅡwas located in the mid-downriver reach,in which habitat was similar to the mid-upriver reach.However,it is possible for some migratory fish to pass the two downstream dams and occupy this section of the river.Group Ⅲ was located in the Feilaixia reservoir,which was characterized by deep water and a lack of cavities and gravel.This region of the river was also occupied by a number of migratory fish species.The fish diversity(H′),species richness(D′),and evenness(J′) at sites S2 and S3 was higher than at the other sites,while the fish diversity(H′) and species richness(D′) were lowest at S1.The relationship between the fish community at each site and environmental factors,including channel width,water depth,velocity,dissolved oxygen,transparency,conductance,pH,total dissolved solids,water temperature,elevation,distance between two dams,and riparian cover was analyzed by canonical correspondence analysis.Fish community structure was correlated with river width,water temperature,height,pH,and the distance between two dams(P0.05).Water temperature was played a large role in determining the distribution of fish species,while and also varied with elevation.The water temperature varied considerably between the upriver and downriver reaches of the Lianjiang River.Clearly,the presence of barriers to migration had a significant influence of the distribution of fish species.The width and the distance between two dams was correlated with the area in which fish could migrate.Water pH is influenced by mining along the Lianjiang River and can have a large effect on the growth and reproduction of fish,Based on a comparison with historical data,the fish species assemblage,distribution,and ecotypes in Lianjiang River have changed significantly.