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Thursday, June 7, 2007 - 8:45 AM
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Wetland geomorphological linkages to juvenile salmonids and macroinvertebrate communities in headwater streams of the Kenai lowlands, Alaska
Ryan S. King1, Jeffrey A. Back1, Coowe Walker2, Dennis F. Whigham3, and Steve Baird2. (1) Center for Reservoir and Aquatic Systems Research, Department of Biology, Baylor University, One Bear Place #97388, Waco, TX 76798, (2) Kachemak Bay Research Reserve, Alaska Department of Fish and Game, Homer, AK 99603, (3) Smithsonian Environmental Research Center, 647 Contees Wharf Road, Edgewater, MD 21037
Much of the land area of the Kenai lowlands in south-central Alaska is occupied by wetlands. Wetlands in this region vary considerably in their geomorphology. Many of these wetlands exhibit strong hydrological connections to small headwater streams thought to be important habitat for juvenile salmonids. In 2006, we estimated densities of juvenile salmonids and macroinvertebrates in 30 first-order streams in an effort to identify wetland geomorphic settings that may be critical for supporting salmon. Streams were located in watersheds comprised of predominantly 1 of 4 wetland geomorphic classes. Samples were collected within 250-m length reaches, which were further characterized for physical habitat, water chemistry, and riparian vegetation. Juvenile salmonids, particularly Oncorhynchus kisutch (coho salmon) and Salvelinus malma (dolly varden), were present in the majority of stream reaches sampled, including several streams not previously listed as salmon habitat. Densities of salmonids were highly variable among reaches, ranging from just a few to several hundred fish/km. Wetland geomorphic classes were not strong predictors of fish presence or density, but there was considerable uncertainty in these models. However, increasing wetland influence on streams was revealed in macroinvertebrate community structure, which was related to several local and watershed scale variables linked to wetland classes.