Author(s): Kei Nukazawa; Kodai Shirasaka; Yoshihiro Suzuki
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Abstract: Alteration of natural flow regime by reservoir dams may impair aquatic habitats of stream organisms. Although earlier researches have primarily aimed to assess this phenomenon at broader scales such as global and continental, spatial and seasonal heterogeneity of other biotic and abiotic factors (e. g., climate) obscures their findings. This study aims at understanding variation in fishes, invertebrates and algae along a gradient of flow regulation in a mesoscale catchment. We compiled biological and dam outflow data observed from 2006 to 2015in the Mimi River catchment situated in southern Japan. Indicators of hydrological alteration were computed using the outflow data and synthesized using principal component analysis. We found that flow regimes between the strongly and moderately regulated streams were clearly discriminated by the first principal component. When the annual flow varies at a higher rate, the fish diversity increased while fish abundance decreased.
Year: 2018