Click on “Download PDF” for the PDF version or on the title for the HTML version.

If you are not an ASABE member or if your employer has not arranged for access to the full-text, Click here for options.

Assessing stream assemblages in systems that were historically designed and managed without regard for ecological criteria will serve as a benchmark for restoration potential in highly modified watersheds. The challenge for modern management is to identify the best measures of sustainability and manage to those objectives in state and national water quality/quantity programs. Our objectives in this study were to: (1) Evaluate the factors associated with the formation of bankfull features in modified streams; and (2) Measure how spatial position within the watershed and habitat availability affects the structure and organization of aquatic communities. At 30 sites within a modified central Ohio watershed we collected data on fish, macroinvertebrates, instream habitat, geomorphology, hydrology, and spatial location. Key ecological drivers for macroinvertebrate communities in modified central Ohio headwater systems primarily related to stream size and gradient. Key ecological drivers for fish communities in these systems are quality of in-stream habitat (i.e., the presence of riffles, pools, and diverse substrates); however, proximity to a larger receiving system, stream size, and presence of water year-round also were important. Larger sites tended to support more aquatic biota and more diverse assemblages either as primary habitat or as conduits to travel or take refuge between higher quality upstream or downstream locations. Our dataset had low variability between sites, which affected multivariate analyses. We contend that strategies to improve water quality, aquatic biology, and ecology will have a higher likelihood of success if in-stream processes and stream geomorphology are considered in national assessment standards.