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Presented at the NABS Annual meeting, Pittsburgh, Pennsylvania, 2002
in Unionid Ecology
HYDRAULIC ECOLOGY OF FRESHWATER MUSSELS (BIVALVIA:UNIONIDAE) IN STREAMS OF THE COOSA AND TALLAPOOSA RIVER DRAINAGES, ALABAMA, USA.
M.M. Gangloff and J.W. Feminella. Department of Biological Sciences, Auburn University, Auburn, AL 36849
Despite increased investigation in recent years, physical habitat requirements of freshwater mussels remain poorly understood. Historical mussel richness and abundance in the Alabama River Drainage were typically highest in the main channel of the Coosa and Tallapoosa rivers (~65 taxa). However, during the past 100 y impoundments have severely altered fluvial habitat, which has led to extirpation of many endemic mollusks. During the past 3 y we have quantified freshwater mussels and hydraulic habitat features in Coosa and Tallapoosa tributaries. Many species now appear restricted to tributary streams, but mussels in these habitats also are declining. A significant negative relationship was found between mussel abundance and streambed shear stress in Coosa (r = −0.715, p = 0.002) but not in Tallapoosa sites. Abundance and species richness in Coosa tributaries were highest in headwater sites, particularly within the Talladega National Forest. In the Tallapoosa, whereas species richness was higher in larger tributaries, abundance appeared more related to recent hydrologic variability, possibly the result of upstream changes in land use, downstream effects of impoundments, or a combination of these factors. Our data suggest local hydraulics and landscape alteration may have important effects on freshwater mussels in these southeastern drainages.
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