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Book Chapter

Biology and ecology of the Edwards Aquifer

Jean Krejca
Jean Krejca
Zara Environmental LLC, 1707 W. Farm to Market 1626, Manchaca, Texas 78652, USA
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James Reddell
James Reddell
Curator Emeritus of Cave Invertebrates, Biodiversity Collections, The University of Texas at Austin, Lake Austin Center, 3001 Lake Austin Boulevard, Austin, Texas 78703, USA
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Publication history
30 January 201908 May 2019


The Edwards Aquifer supports an important ecosystem with rarely seen faunas that have unique adaptations to a dark and thermally stable environment. We tallied over 60 species of aquifer-adapted (stygobitic) species in the Edwards Aquifer, and 30 more in other Texas aquifers, including snails, flatworms, worms, crustaceans, mites, and beetles. Exploration and research continue, with nine new species described in the last two years. Vertebrate species include Eurycea salamanders and ictalurid catfish, including a blind species (Prietella phreatophila) recorded for the first time in the United States from the Edwards–Trinity Plateau Aquifer in 2016. Contributing to the stygobite diversity are ten state or federally listed species, including the Texas blind salamander (Eurycea rathbuni), which was one of the first species to be listed as endangered by the U.S. Fish and Wildlife Service (USFWS) in 1970. Major springs of the Edwards (Balcones fault zone), Edwards–Trinity Plateau, Trinity, and other aquifers are under constant threat of drying due to aquifer overdraft and climate change. These springs provide habitat for 26 state or federally listed spring-adapted species. Aquifer species in general are known to provide ecosystem services, including water purification, nutrient cycling, and biological indication; however, the function and biology of these species in central Texas have not been studied. Considering the Edwards Aquifer ranks among the top aquifers in the world for number of species, the gaps in understanding remain enormous.

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GSA Memoirs

The Edwards Aquifer: The Past, Present, and Future of a Vital Water Resource

Geological Society of America
ISBN electronic:




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