A Hydrologic-Characterization Approach for Texas Aquatic-Species Studies

Brad Wolaver, Cassandra Cook, Bridget Scanlon, and Michael Young
Bureau of Economic Geology, University of Texas at Austin, University Station, Box X, Austin, Texas 78713–8924

This work describes a generalized approach to characterize hydrologic conditions in support of Texas aquatic biota studies. We describe this framework with application to Texas freshwater mussels, although it may be applied to other aquatic species across the Gulf Coast. Twelve freshwater unionid mussel species found in rivers throughout Texas may be listed as threatened or endangered under the Endangered Species Act (ESA) in the next five or six years. Understanding hydrologic controls on mussel habitat—the goal of this research—is needed to maintain aquatic habitat in the event of an ESA listing. We relate mussel populations to bedrock geology and aquifers, spring locations, and groundwater inflows to streams to assess effects of hydrologic factors on observed distribution of mussel species. Maintaining groundwater-fed streams that flow during extended droughts is critical for future mussel habitat. Spring distribution is assessed relative to mussel sightings to understand if mussels prefer areas of high spring density. Gaining or losing stream segments are evaluated using a base flow index analysis and radon. This work identifies stream reaches most sensitive to droughts and groundwater depletion should the mussels become listed as endangered.

AAPG Search and Discovery Article #90158©2012 GCAGS and GC-SEPM 6nd Annual Convention, Austin, Texas, 21-24 October 2012