Variation in fish assemblages across impoundments of low-head dams in headwater streams of the Qingyi River, China: effects of abiotic factors and native invaders Ling Chu & Wenjian Wang & Ren Zhu & Yunzhi Yan & Yifeng Chen & Lizhu Wang Received: 5 August 2012 /Accepted: 23 January 2014 /Published online: 16 February 2014 # Springer Science+Business Media Dordrecht 2014 Abstract Identifying and explaining the pattern of how stream fish assemblages vary spatially are basic for the conservation and management of fish species diversity. Although low-head dams may facilitate the native inva- sions of generalist fishes to headwater streams, few studies have evaluated the impacts of the native invaders on indigenous fish assemblages. In this study, we col- lected 12 indigenous and 13 native-invasive fish species and measured physical habitats and dam dimensions from 62 impoundments of low-head dams located on headwater streams of the Qingyi River, China. We used linear regression and canonical correspondence analyses to evaluate how habitat and dam variables influenced native-invasive fish assemblages. Our results indicated that invasive fish species richness and abundance were related to elevation and upstream and downstream dam abundances, and their assemblage structures were influ- enced by substrate heterogeneity, dam height, and up- stream and downstream dam abundances. We also used similar analyses to examine how habitat, dam, and in- vasive fish variables affected indigenous fish assem- blages. Our results showed that indigenous fish species richness was correlated with substrate heterogeneity and dam height. However, indigenous fish assemblage structures were not only influenced by dam height, substrate, and downstream dam abundance, but also by invasive fishes. The abundance of one invasive species, Pseudorasbora parva, showed a strong negative influ- ence on indigenous fish assemblages. Our study sug- gests that the combination of changes in abiotic factors and biotic structure and process following dam-building may determine the indigenous fish assemblages in the impoundments of low-head dams within headwater streams. Keywords Anthropogenic perturbation . Native invasion . Assemblage structure . Species diversity . Highland headwaters Introduction Dams have been widely recognized as one of the pri- mary means by which humans alter or modify fluvial ecosystems (Rosenberg et al. 1997; Poff and Hart 2002). Dams may modify water flow and thermal regimes, modify channel morphology, alter habitat condition, and shift the structure and function of biological com- munities in stream systems (Rosenberg et al. 2000; Wang et al. 2011). The degree to which lotic systems are altered depends on the attributes of dams, such as Environ Biol Fish (2015) 98:101–112 DOI 10.1007/s10641-014-0239-6 L. Chu : W. Wang : R. Zhu : Y. Yan (*) College of Life Sciences, Anhui Normal University; Provincial Key Laboratory of Biotic Environment and Ecological Safety in Anhui, Wuhu 241000, China e-mail: yanyunzhi1976@gmail.com Y. Chen Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China L. Wang Institute for Fisheries Research, Michigan Department of Natural Resources and University of Michigan, 212 Museums Annex, Ann Arbor, MI 48109, USA