Tuesday, May 27, 2008
302

Qualitative survey of native mussels (Mollusca: Unionidae) in austin, Texas: Composition and distributions in 29 small watersheds

Heather A. Perry, Mateo Scoggins, and Tom Ennis. Watershed Protection and Development Review Department, City of Austin, 505 Barton Springs Rd., 11th Floor, Austin, TX 78767

Freshwater mussels (Mollusca: Unionidae) are a poorly understood class of invertebrates, but recently interest in them has peaked due to their susceptibility to in-stream pollution and stressors.  Of the nearly 300 species that are native to North America, 19 are extinct, 62 are federally listed as either endangered or threatened, and 130 are considered in need of conservation status. Freshwater mussels inhabit a variety of water-body types ranging from large rivers to ponds.  This study focused on 29 small watersheds within the city limits of Austin, Texas, documenting distribution and habitat of 9 mussel species at a relatively small spatial scale. Stable habitats tended to have larger, more diverse populations and while some species were more tolerant to a variety of conditions, others had very narrow condition preferences.  The most limiting substrate types were deep shifting sand and soft, deep silt; however heavy boulder and cobble substrates were often poorly populated.  The most densely populated areas were a heterogeneous mix of silt, sand, gravel, and cobble.  Species varied with flow conditions, which ranged from no-flow backwater and wetland areas to rapidly flowing riffle and run habitat.


Web Page: unionidae, freshwater mussels, streams

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