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ECOREGIONAL INFLUENCES ON WATERSHED LAND COVER, WATER QUALITY, AND IN-STREAM BIOLOGY
Citation:
Daniel, F B., T Flum, J M. Lazorchak, AND F H. McCormick. ECOREGIONAL INFLUENCES ON WATERSHED LAND COVER, WATER QUALITY, AND IN-STREAM BIOLOGY. Presented at Society of Environmental Toxicology and Chemistry, Baltimore, MD, November 11-15, 2001.
Impact/Purpose:
This project has three overall goals: 1) To develop efficacious methods for quantitative assessment of riparian resources at a both local and watershed scales; 2) to examine land use elements, at various scales as regulators of both water quality and biological integrity in freshwater streams, and 3) to elucidate the potential of riparian corridors to ameliorate various stressor impacts from the surrounding catchment.
Approach
-FY00 Activities The field sampling conducted in the first year will be repeated for all of the sub-watershed sites in the second year. Using the sub-watershed boundaries determined via the hydrologic models the landscape metrics for each sub-watershed will be developed. Likewise the high resolution land cover data for the riparian corridors will be developed from the digitized aerial photography.
-FY01 Activities The field sampling conducted in the years one and two will be repeated for all of the sub-watershed sites in year three. The field data from all three years will be combined to develop the indices of water quality and biotic integrity for the sub-watersheds. The stream quality and land cover data from the watershed catchment area and the riparian corridor will be correlated using a series of step-wise, multistage, linear regression models. Individual features of stream quality will be related to various riparian land cover parameters and other land use elements in the watershed as a whole. Statistical analysis will be completed.
-FY02 Activities Final reports and manuscripts for submission to the peer reviewed scientific literature will be prepared.
Description:
Omernik's ecoregions were developed to serve as a spatial framework for environmental monitoring and research. We examined the biology and chemistry in 35 headwater streams in the Little Miami River (LMR) of Ohio to determine whethEr there were real differences among three ecoregions. Land cover/land use features for the catchments and riparian corridors were evaluated along with variables related to geomorphology, hydrology, in-stream physical habitat, water chemistry, and fish, macroinvertebrate and periphyton assemblages. Although all of the watersheds in this study are dominated by row crop agriculture, differences in geomorphology, such as slope and soil types, lead to variations in land cover/land use such as relative differences in percent row crop or forest in both the catchments and the riparian corridors. Water quality variables, including nutrients (e.g., nutrients could be changed to total phosphorus, nitrate + nitrite nitrogen, ratio of dissolved organic to dissolved inorganic nitrogen, chloride, and sulfate) were significantly different among the ecoregions. In contrast, there were no significant differences among the ecoregions with respect to in-stream physical habitat measures. Likewise, we found no significant differences in biological indices (e.g., index of biotic integrity, and/or invertebrate community indices) or individual metrics for any taxonomic groups. Thus, the significant physical differences among ecoregions in the LMR did not necessarily translate into quantifiable in-stream biological differences. The absence of correlations between abiotic conditions and land cover/land use with biological assemblages among the ecoregions may be related to the historical degradation of in-stream physical habitat from human alterations.