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The role of flow dependency and water availability in fish assemblage homogenization in tributaries of the C hattahoochee R iver, A labama, USA
Author(s) -
Lawson Katelyn M.,
Johnston Carol E.
Publication year - 2016
Publication title -
ecology of freshwater fish
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 55
eISSN - 1600-0633
pISSN - 0906-6691
DOI - 10.1111/eff.12241
Subject(s) - tributary , habitat , streams , ecology , fluvial , environmental science , homogenization (climate) , fishery , biology , geography , biodiversity , structural basin , computer network , paleontology , cartography , computer science
The availability of water is becoming more variable as flow regime alterations intensify both locally and on a global scale. This pattern has been observed in the tributaries of the central C hattahoochee R iver S ystem as water withdrawal and natural drought have caused flows to diminish. Stream discharge has steadily decreased in the study area by 31% over the last 50 years, and during this time, fish assemblage homogenization has occurred throughout the system. Our primary objective was to assess whether spawning mode and water availability are catalysts for fish assemblage change in tributaries of the C hattahoochee R iver S ystem. We found that species which prefer or have adapted to low flow conditions (e.g. blacktail shiner C yprinella venusta, redbreast sunfish L epomis auritus and blackbanded darter P ercina nigrofasciata) are becoming dominant and replacing historically dominant fluvial specialists. When examining short‐term changes between a dry year (2009) and a wet year (2010), some species preferring higher flows such as the highscale shiner N otropis hypsilepis were detected during the wet year, suggesting that the amount of water is important for the presence of these species in upstream reaches where they were historically abundant. Species that can reproduce successfully in low flow conditions are thriving and expanding their native ranges as more habitat becomes suitable. Species that require higher flows for part of their life cycle, however, appear to be declining from upstream areas as water availability continues to decrease, despite temporary recovery from downstream refugia during wet years.