金沙江下游向家坝库区鱼类群落结构空间格局OA北大核心CSTPCD

In this study,we explored the impacts of cascaded hydropower development on the fish com-munity in the lower Jinsha River.The study was based on an investigation of fish community structure conducted from 2016 to 2018,focusing on species composition,body size,dominant species,ecological groups,and spatial distribution.The investigation,that included seven fish surveys,was conducted using multiple gill nets and cages in the Shaonvping,Suijiang and Huixi sections of the lower,middle and upper streams of Xiangjiaba Reservoir.A total of 59 fish species belonging to 49 genera,16 families and 6 or-ders were collected,among which there were 5 species endemic to the upper Yangtze River and 12 exotic species.There were 39,40 and 30 fish species collected in the Shaonvping,Suijiang and Huixi sections,respectively.The Jaccard index of similarity showed that fish species composition in the three sections were at a medium level.The relative importance index(IRI)showed that Spinibarbus sinensis and Hemiculter leucisclus were the dominant species in the Shaonvping section,H.Leucisclus,Hypophthalmi-chthys molitrix,Pseudobagrus vachelli and Aristichthys nobilis were dominant in the Suijiang section,and P.vachelli,Cyprinus carpio var.specularis,Cyprinus carpio,H.leucisclus,Ctenopharyngodon idellus and Carassius auratus were dominant in the Huixi section.Nonmetric multidimensional scaling(NMDS)showed that fish community structure between the Shaonvping and Huixi sections was more dissimilar with a Bray-Curtis dissimilarity index of 0.59,while the fish community structure between the Suijiang and Shaonvping sections were more similar with a Bray-Curtis dissimilarity index of 0.41.The Bray-Cur-tis dissimilarity index between the Suijiang and Huixi sections was 0.46.Eurytopic species dominated the Xiangjiaba Reservoir,accounting for 57.7%±5.9%of the total species number,65.2%±20.7%in abun-dance and 47.7%±16.1%in total catch weight.The abundance percentages of the eurytopic species were 43.3%in Shaonvping,67.8%in Suijiang and 84.5%in Huixi sections,displaying an increasing trend from the lower to upper streams of the reservoir.Body length and weight ranges were 29-655 mm and 0.1-5 408 g,with mean values(±SD)of(128±65)mm and(70±218)g.Body size of the primary species was significantly different among the three sections of the reservoir,except for C.carpio var.specularis and C.carpio(P<0.05).In conclusion,fish community structure in the lower Jinsha River has changed dra-matically since reservoir impoundment in 2011,and diversity among endemic species has decreased and increased among exotic species.Our results provide a basis for ecological impact assessment of cascaded hydropower projects and fish protection in the lower Jinsha River and information for assessing the effec-tiveness of the"ten-year fishing ban"in the Yangtze River.