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Effects of multiple dams on the metacommunity structure of stream macroinvertebrates
Dams and floodgates have been established to mitigate flood hazards and to satisfy the growing demand for water resources; however, the excessive presence of dams in river ecosystems causes a series of ecological problems. Most previous studies regarding the effects of dams on aquatic community structure have focused on the impacts of individual dams on river ecosystems on a local scale, whereas few studies have investigated the combined effects of multiple dams at the basin scale. Here, we explored the combined effects of multiple dams on macroinvertebrate metacommunity structure and have quantified these effects using variation partitioning and asymmetric eigenvector map analysis (AEM). We found that the combined effects of multiple dams on macroinvertebrate metacommunity structure are significant, and that the direct impacts of dams that limit dispersal were greater than the indirect effects of changing environmental conditions. We also found that spatial variables at medium and fine scales captured more variation in macroinvertebrate metacommunity structure than broad-scale partitioning. As broad-scale spatial variations are mainly attributed to environmental spatial structuring, and medium- and fine-scale spatial community structures are likely related to neutral processes, it was inferred that the direct impacts of dams were greater than the indirect effects.
MF17159 Accepted 20 September 2017
© CSIRO 2017