Boundaries

This ecoregion stretches from central and southeastern Texas to western Louisiana.

Topography

The topography of the ecoregion is dominated by Coastal Plain formations of lowlands and scarps in the inner zone, and deltaic and alluvial plains toward the coast (Connor & Suttkus 1986).

Freshwater habitats

Wetlands are a dominant feature of this ecoregion, with salinities that range from saline to freshwater. In recent decades they have declined dramatically, particularly freshwater wetlands that have suffered losses greater than 30% (The Nature Conservancy 2002).

Terrestrial habitats

The ecoregion includes primarily piney woods, tallgrass coastal prairie and coastal marshes. Tallgrass coastal prairie was once the primary plant community from southeastern Louisiana to the mouth of the Rio Grande River (Smeins et al. 1991). Today, less than one percent of this original community type remains. An ecotone of eastern pine/hardwood forests is dominant around the Sabine River headwaters and upper Trinity River (Connor & Suttkus 1986).

Description of endemic fishes

There are no known fish endemics in the ecoregion (Connor & Suttkus 1986).

Justification for delineation

Ecoregion boundaries are modified from Abell et al. (2000), which based its units on subregions defined by Maxwell et al. (1995).  Modifications to this ecoregion were made following recommendations from the Endangered Species Committee of the American Fisheries Society. This ecoregion was separated from the East Texas Gulf [140] because of distinct faunal breaks that result from differences in drainage size and physiographic complexity. There are marked differences in richness as one moves east to west across the Gulf Slope region, as well as distinct species clusters at the 80% level among the Nueces-San Antonio drainages (in [139]), Colorado-Brazos drainages (in [140]), and Galveston-Sabine-Calcasieu drainages (in [141]).