A river continuum analysis of relationships between bioassessment, land use, and macroinvertebrate assemblages

Sustainable management of stream systems and the development of bioassessment standards are important for the preservation of natural habitats. Maintaining biodiversity in the face of encroaching human disturbance has received much attention in recent years. Bioassessment of habitats is becoming commonplace for many state and federal agencies. This research attempts to answer two questions based on this observation. First, there are currently numerous bioassessment protocols available for use. Recent research has shown no significant difference in aquatic assessment results based on expensive, labor-intensive, quantitative sampling versus more cost-efficient, less defined, qualitative methods. This verifies these findings on a linear river continuum using a macroinvertebrate functional feeding group (FFG) approach. Second, this research utilizes GIS software to account for the effect anthropogenic land uses within the surrounding landscape have on in-stream habitat conditions and their ability to predict macroinvertebrate assemblages iii depending on spatial scale. Macroinvertebrates and water quality data representing thirteen sites along the 106-mile Little Miami River in southwestern Ohio were evaluated by collecting six quantitative (Hess sampler) and six qualitative macroinvertebrate samples from riffle/run habitats in June/July 2006 and 2007. Four ecosystem attributes were calculated based on FFG quantities: autotrophy/heterotrophy, fine particulate organic matter/coarse particulate organic matter, suspended fine particulate organic matter/benthic fine particulate organic matter, and substrate stability. Functional feeding group ratios confirmed the quality of the selected reference site. All four FFG ratios verified similar trends between collection methods within each year. Ratios also showed similar trends between years, with the exception of the autotrophy/heterotrophy ratio. This suggests rapid, qualitative methods are equally proficient in characterizing macroinvertebrate assemblage as quantitative methods. Five spatial scales were used, ranging from entire catchment to immediate riparian corridor, to compare macroinvertebrate indices to land use practices. In most cases, indices were related to percent forested land use and in all cases, the local spatial scale showed the strongest correlation. This suggests even small scale efforts to improve riparian zones can benefit impact recovery and mitigation efforts of waterway