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UNDERSTANDING ECOLOGICAL RISK IN RURAL WATERSHEDS THROUGH MEASURMENTS OF STREAM COMMUNITY METABOLISM, NUTRIENT AND SEDIMENT DYNAMICS
Citation:
Morrison**, M A., J SchubauerBerigan, C A. Schultz**, B Daniel, M E. Troyer, AND M. B. Griffith. UNDERSTANDING ECOLOGICAL RISK IN RURAL WATERSHEDS THROUGH MEASURMENTS OF STREAM COMMUNITY METABOLISM, NUTRIENT AND SEDIMENT DYNAMICS. Presented at American Water Resources Assn 2003 Annual Conference, San Diego, CA, 11/3-6/03.
Description:
The goal of this project, and associated research, is to establish thresholds for ecological response to watershed disturbance and to develop tools and insights that will help us manage risks and evaluate best management practice (BMP) effectiveness. Changes in the amount and types of land use in a watershed can result in increased risks from flooding and non-point source pollution. Understanding the ecological response of stream communities to watershed resource use and development, and the accompanying non-point source (NPS) loading of nutrients and sediment, requires better mechanisms that link stream structure and function with watershed land use. The physical structure of stream channels (i.e. geomorphology) provides a baseline for ecological health, but responds differently to levels of disturbance according to landscape variables such as slope and soil type. Sediments dynamics can alter stream structure, affect stream metabolisms and significantly alter patterns of phosphorus binding and availability. Measurement of ecological parameters such as primary production and respiration in streams, across land-use gradients and ecoregions, will help establish useful thresholds for ecological response. Biologically driven cycles are studied because they can affect (and provide an indication of) the form and binding patterns of nutrients and other chemicals in streams. The diurnal pattern of dissolved oxygen concentration, which increases during daylight hours in response to photosynthesis and decreases at night when photosynthesis ceases is one of the fundamental cycles in stream ecology. As part of a larger, ongoing, coordinated study, we are examining these relationships in a selected set of streams in the Little Miami River Watershed, Southwestern Ohio. The study employs YSI 6600 Multi-Parameter Water Quality Monitors to measure dissolved oxygen and ancillary parameters such as pH and temperature at 5 minute intervals for a 72 hour period. By comparing seasonal patterns in stream metabolism with patterns in nutrient (concentration and availability) and sediment (source, nutrient binding and size characteristics) loading, hydrologic and physical habitat (geomorphology) assessment, we hope to develop a better understanding of the mechanisms driving ecological change in stream ecosystems.