Relative Roles of Environmental Conditions and Riverscape Connectivity on Fish Metacommunity Structure

An understanding of how riverscape connectivity influences species assemblages has been identified as critical for effective conservation management and restoration of fish communities in dendritic river networks. This study investigates the relative roles of abiotic conditions and spatial factors in structuring stream fish communities and aims to enhance scientific understanding of these structuring factors by combining existing theory with empirical data. Fish abundance data were acquired via backpack electrofishing in wadeable streams of the Broad River watershed throughout northern South Carolina. Environmental and spatial data were also collected or measured. Non-metric multidimensional scaling and Mantel and partial Mantel tests were used to test specific hypotheses concerning the structuring effects of environmental and spatial factors on fish communities. Generalist and specialist species patterns were compared. Results revealed that environmental conditions have a strong influence on stream fish community structure in the Broad River watershed and suggested that spatial factors are also important, particularly for specialist species. Explicit consideration of riverscape connectivity in future stream fish studies and management activities may further enhance the state of knowledge concerning the structuring agents of fish communities and facilitate their effective management.