Restored Urban Streams as Indicators of Ecosystem Health in the Pacific Northwest
Tracy Collier, Northwest Fisheries Science Center and West Coast Center for Oceans and Human Health
31 Aug 2007
Small urban streams have received considerable attention and have been the subject of many restoration activities, in an attempt to provide increased ecosystem function. Much of the interest arises because of the focus on preserving populations of Pacific salmon, many of which are listed as threatened or endangered under the Endangered Species Act. Coho salmon (Oncorhynchus kisutch) are especially known for using small streams for spawning and juvenile rearing. We have been investigating reports of unusual ‘pre-spawn’ mortality (PSM) in coho salmon returning to restored urban streams in the Puget Sound Basin. In this presentation, we describe the PSM syndrome, report the results of our forensic investigations, and describe the land use characteristics that are most closely associated with this mortality. In addition, we report recent results on developmental defects that appear to be associated with the same type of urban runoff that induces the mortalities in adult fish. Urban streams, despite intense efforts to restore stream and ecosystem function, are still not providing certain critical habitat attributes, but as of yet we do not know what is specifically causing deleterious effects. These studies caution us that there is still much we do not know about how urbanization of our coastal areas affects both freshwater and estuarine ecosystems.