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Characterization and Evaluation of Benthic Community Composition and Structure on the Texas Gulf from National Coastal Assessment (NCA) Sampling, 2000-2005

Kim Withers 1, Holly Bellringer 2 and James Simons 2

1 Center for Coastal Studies, Texas A&M University-Corpus Christi, Corpus Christi, Texas
2 Texas Parks and Wildlife Department, Corpus Christi, Texas

The Environmental Protection Agency’s (EPA) National Coastal Assessment Program (NCA) uses a probabilistic design and a common set of survey indicators to assess coastal ecological conditions. Benthic invertebrates are sampled as part of this assessment. In Texas, 50-70 stations were sampled for benthic invertebrates using either a Van Veen grab or PVC coring device during late July or August, 2000-2005. The majority of stations were located in the large estuaries of Sabine Lake, Galveston, Matagorda, Aransas, and Corpus Christi bays and Laguna Madre although a number of smaller bays and coastal lakes were also sampled during some years. In general, annelids, particularly polychaetes dominated abundance and biomass of the benthic faunas in most bay systems. Bivalves were often the next most abundant organisms. Diversity and species richness varied greatly among bays and years. The composition of estuarine faunas appears to be governed by freshwater inflows or the lack thereof, sediment composition, the presence of submerged vegetation, and/or bay size.

We calculated EPA’s standard Index of Biotic Integrity but found that it did not accurately reflect the condition of the bays and estuaries in Texas, particularly as one moves to the more southerly portions of the Texas coast. Thus, we evaluated the level of disturbance (pollution-induced or otherwise) in bays using the Abundance/Biomass Comparison (ABC) method. These results indicate that most bays appeared to be relatively undisturbed. Future work will include research into the development of a more relevant benthic index for the for the south Texas coast.

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