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Wednesday, May 28, 2008 - 10:00 AM
397
Comparison of bliss rapids snail distribution and densities under two different hydroelectric dam operations
Barry M. Bean, Environmental Affairs, Idaho Power Co., 1221 West Idaho Street, Boise, ID 83702 and Matthew R. Dare, Department of Biology, Boise State University, Department of Biology, Boise, ID 93725.
The Bliss Rapids snail, Taylorconcha serpenticola, was listed as threatened by the USFWS in 1992. The species inhabits free-flowing sections of the Snake River and its springs and tributaries from King Hill to Jerome, Idaho. In this study, we focused on two free-flowing reaches of the Snake River between Hagerman and King Hill, Idaho. Both reaches are downstream of hydroelectric facilities and river flows fluctuate daily in response to electricity demand. Dam operations may impact T. serpenticola populations by periodically desiccating their habitat. Reaches were divided into 50-m sections and 10% were randomly selected and surveyed for T. serpenticola using a 40-cobble-count method. Sites were sampled in 2005 during relatively stable flow conditions resulting from run-of-river dam operations. These sites were revisited in 2007 during highly variable, peak-loading dam operations. Preliminary results suggest that T. serpenticola may have shifted to deeper habitat in 2007, potentially in response to daily river stage fluctuations. We tested correlations between changes in river stage elevation and snail density using a one-dimensional hydrodynamic model.
Web Page: BACI, hydropower, snail