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Evalutation [i.e. Evaluation] of sediment-sensitive biological metrics as biomonitoring tools on varied spatial scales [electronic resource] /

by Owens, Janna Yvonne

Abstract (Summary)
Sediment is one of the principal causes of water-quality impairment in surface waters of the United States. Although biological assessments are useful for characterizing the status of aquatic communities, reasons for impairment cannot be identified without quantifying associated variables physical variables that can be adequately related to biological functions. Our objective was to explore potential relations between fish and benthic macroinvertebrate community structures and variables of sedimentation processes on a watershed and channel-reach scale. Biologic collections and habitat evaluations were conducted using the EPA’s Rapid Bioassessment Protocol over a period of three years (2000-2003) at sites in the upper Cahaba River basin near Birmingham, Alabama. A series of metrics were utilized to examine the status of the aquatic communities. These were compared to water chemistry, habitat conditions, accumulated sediment depths and upstream land usages. To calculate the upstream watershed characteristics, geographic information systems (GIS) and selected data layers were used to construct a cartographic model. This information was used to generate a sedimentation potential index (SPI) value for the watershed upstream of each site, as well as to calculate the coverage of vegetation and impervious surfaces. For reach-scale analysis, rapid geomorphic assessments (RGAs) and identification of the stream channel’s stage of evolution were used to distinguish between geomorphically stable and unstable sites. The channel stability index of hydrologic and geomorphic process variables was also calculated to semi-quantify the channel stabilii ity status. Significant negative correlations were found between the percentage of impervious surfaces in the upstream watershed and pollution-sensitive macroinvertebrate metrics, such as the Hilsenhoff biotic index and the modified percentage of Ephemeroptera, Plecoptera and Trichoptera (EPT). Stable study sites, as classified by the stage of channel evolution, had low embeddedness values ( < 10%) and supported good aquatic communities as determined from a modified EPT metric. Sites with the highest values of the channel stability index, and therefore considered geomorphically unstable, had greater embeddedness values ( > 20%) and a lack of the disturbance-sensitive, crevice spawning fish. Monitoring strategies that link upstream watershed and reach-scale physical variables with the biological community information will be able to detect and characterize aquatic systems more precisely. iii
Bibliographical Information:

Advisor:

School:University of Alabama at Birmingham

School Location:USA - Alabama

Source Type:Master's Thesis

Keywords:water quality biological assessment fishes mayflies caddisflies stoneflies biometry monitoring

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