Southeastern Fishes Council
SFC Abstracts
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Texas Freshwater Fish Assemblages Following Three Decades of Environmental Change
ALLISON A. ANDERSON1CLARK HUBBS2KIRK 0. WINEMILLER1, and ROBERT J. EDWARDS3
1Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, TX 77843;
2Department of Zoology, University of Texas, Austin, TX 78712;
3Department of Biology, University of Texas-Pan American, Edinburg, TX 78539
In 1953, C. Hubbs and colleagues surveyed fishes from a large number of freshwater habitats throughout the state of Texas. Thirty-three years later, he replicated sampling at 129 sites within the Red, Sabine, Neches, Trinity, Brazos, Colorado, Guadalupe, San Antonio, Nueces, and Rio Grande drainages. Great care was taken to reproduce fishing effort, sampling times, and dates at each location. Relative proportional abundances of families showed numerous changes from 1953 to 1986 within the ten basins. Mantel tests comparing family abundances in early (1953) and recent (1986) datasets showed little overall change statewide. Sites in the eastern half of the state that excluded marine species showed less significant positive covariation between early and recent datasets than those in the western Texas. Rank plots of species diversity (H') for the two regions of the state showed a consistent trend of decreased diversity over time in eastern Texas. The analyses reveal reductions in diversity on a local scale but also reveal relative stability in the statewide and regional ichthyofaunas. Despite the encouraging large-scale trends, several Texas fishes have gone extinct and others are threatened as a result of disturbances, including alteration of instream flow, eutrophication, and exotic species introductions.
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