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DEVELOPMENT OF A DISTURBANCE INDEX TO ASSESS THE CONDITION OF AQUATIC ECOSYSTEMS
Citation:
Bryce, S. A. AND M. Bollman. DEVELOPMENT OF A DISTURBANCE INDEX TO ASSESS THE CONDITION OF AQUATIC ECOSYSTEMS. Presented at Conference for Conservation Biology, Duluth, MN, June 28-July 2, 2003.
Description:
An objective of aquatic monitoring is to assess the condition of aquatic habitats and biota. To rationally interpret aquatic condition, we must identify the range of human activities and the risks they pose to aquatic ecosystems. Placing stream reaches and their watersheds on a human disturbance gradient is a prerequisite for distinguishing human disturbance from natural controls in aquatic systems and for interpreting biological response to disturbance. We describe a process that uses readily available sources, such as topographic maps, aerial photographs, and field information, as well as several metrics generated by a Geographic Information System (GIS) to identify and prioritize stream reach and watershed stressors for 31 streams in the Blue Mountains of Oregon, USA. All perceptible human alterations to riparian and upland areas were recorded and ranked, and a scoring system was developed that gave each watershed a discrete score. The resulting disturbance index provides a cost-effective method to directly compare the relative condition of watersheds in similar size classes and ecological regions. It can be used as a measure of condition in multivariate analyses or as an explanatory variable to evaluate the responsiveness of candidate metrics in indices of biotic integrity.