Effects of Introduced Small Wood in a Degraded Stream on Fish Community and Functional Diversity

Though the effects of introduced wood on fishes is widely studied for salmonids in upland coldwater streams, there are few studies on this topic conducted in the Coastal Plain of the southeastern US. This research gap is problematic because the introduction of wood is a critical component of efforts aimed at conserving the threatened fish diversity of the Coastal Plain, but managers lack data on the effects of installed wood on fish communities. Over a nearly 4-year study period, we contrasted the effects of introduced, small, wood bundles on the fish community in a channelized and deeply incised sand-bed Coastal Plain stream with an unmanipulated reference treatment. The central question was whether or not stream reaches with introduced wood had greater taxonomic and functional diversity than unmanipulated reference reaches within the same stream. The introduction of modest amounts of small wood had measurable and biologically significant positive impacts on fish community composition and perhaps functional diversity relative to stream reaches lacking wood. However, species-specific responses varied among treatments, suggesting the design of wood installations has an impact on whether or not management goals are achieved.