Vulnerability Assessment of Coastal Bend Bays

Freshwater is a scarce resource in the Texas Coastal Bend, and with an ever-increasing demand on freshwater resources, the need for a visualization tool assessing the vulnerability of nekton (fish, shrimp, and crab) in Corpus Christi and Nueces Bays to rising salinities and identifying the occurrence and distribution of these species at various life stages across the bays is essential. The purpose of this project is to identify and map areas of ecological importance and/or vulnerability in the Corpus Christi Bay region based on seasonal salinity modeling, species abundance and distribution (larval through adult), and species-specific salinity tolerances.

Many nekton occurring in coastal waters share a common estuarine-dependent life history strategy characterized by near-shore spawning in the Gulf of Mexico with larvae migrating through tidal inlets into shallow estuarine nursery habitats. Access to high quality habitat and spawning grounds via tidal inlets is essential for reproduction, growth, survival, and maintenance of these populations. Heat maps detailing these ecologically important and vulnerable areas can serve as valuable visualization tools during the consideration of future development to help reduce environmental impacts.

Heat maps, which are graphical representations of data using a matrix of colors, are useful for visualizing attributes of ecosystems. This approach has been used successfully to create a heat map of ecosystem services provided by habitats within the Coastal Bend Bays and Estuaries Program area so that valued ecosystem components could be identified for ecosystem-based management approaches. This project will create new tool and updated charts, leveraging the original map because it already has the habitats and values identified within the region. The following new data would be added as GIS (geographic information system) layers:

1. Salinity model output (for example, wet and dry years obtained from the Texas Water Development Board and used in environmental flow recommendation reports);
2. Larval fish abundance and distributions obtained from Scott Holt’s work at the University of Texas Marine Science Institute;
3. Small adult and juvenile fish and invertebrate abundance and distributions obtained from long-term, fisheries-independent bag seine surveys conducted by the Texas Parks and Wildlife Department; and
4. Additional larval and juvenile fish and invertebrate data as it becomes available.

Available information on species-specific salinity tolerances will be integrated. Though, additional factors such as impingement of biological resources in the intake and degradation of water or sediment quality conditions near the outfall may still have negative effects on species with a high tolerance to increasing salinity conditions.

Final report now available in Downloads section.