Influences of low-head dams on the fish assemblages in the headwater streams of the Qingyi watershed, China

Abstract

The influences of low-head dams on the fish assemblages were examined in this study, using fish data collected in six treatment and five reference sites at three low-head dams in the headwater streams of the Qingyi watershed, China. Comparing with those in the reference sites, local habitat variables were significantly altered by low-head dams in the treatment sites, involving wider channel (only in the impoundment area), deeper water and slower flow. Fish species richness varied significantly across seasons, not across site categories, suggesting that these low-head dams did not alter species richness. However, significant decreases in fish abundance and density were observed in the impoundment areas immediately upstream of dams, but not in the plunge areas downstream. Fish assemblage structures kept relative stability across seasons, and their significant difference between-site was only observed between the impoundment areas and the sites far from dams upstream. This variation in assemblage structures was due to the differing relative abundance of some cooccurring species; more lentic but less lotic fish was observed in the impoundment areas. The spatial and temporal patterns of fish assemblages were correlated with local habitat in this study area. Wetted width had negative correlation with fish species richness, abundance and density, respectively. Water temperature also positively affected species richness. In addition, wetted width, water depth, current velocity and substrate were the important habitat variables influencing assemblage structures. Our results suggested that, by modifying local habitat characteristics, low-head dams altered fish abundance and density in the impoundment areas immediately upstream of dam, not in the plunge areas immediately downstream, and thereby influenced fish assemblage structures in these stream segments.

Fish assemblage in the Pearl River Estuary: Spatial‐seasonal variation, environmental influence and trends over the past three decades

“…Many ecosystem functions are modified by dams altered flow regime. Rivers lose the former habitat and landscape traits, and present some variations in current velocity, water temperature, substrate and food‐chain (Domingues & Galvao, ; Yan, Wang, Zhu, Chu, & Chen, ). There are more than 10,000 dams in the Pearl River basin (Tan et al, ), and there are 22 large sluices and 2,550 medium and small sluices in the Pearl River Delta (Li et al, ).…”

Lowhead dams and the downstream dispersal of zebra mussels

“…Lowhead dams in the Neosho also influence spatial patterns of fish assemblages . Porto et al (1999) and Cumming (2004) showed that fish species richness declined immediately upstream from lowhead dams in Lake Ontario streams and Wisconsin streams, respectively, and Yan et al (2012) found lower fish abundances in the impounded areas upstream from lowhead dams in the Qingyi watershed, China. Dean et al (2002) demonstrated consequences of Neosho River lowhead dams on unionid species richness and evenness.…”

Effects of local, river-network and catchment factors on fish assemblages in the headwater streams of the Xin'an basin, China

“…Regretfully, to our knowledge, reports that relate stream fish assemblages to different environmental factors from a riverscape perspective are quite rare in China, where stream fishes are being severely endangered due to many anthropogenic disturbances, such as dam construction, urbanization, agriculture production, industrial release and water pollution (Fu et al 2003;Kang et al 2009;Yan et al 2013). In this study, based on the data collected in 91 sampling sites within first-order through third-order streams of the Xin'an basin, China, we examined the spatial variation in fish species richness and assemblage structures and assessed how fish assemblages related to local habitat, tributary spatial position and land use/cover within this basin.…”