Effects of shoreline erosion in Galveston Bay, Texas

The shoreline of Trinity Bay and East Galveston Bay, Texas, is eroding at an average annual rate of four feet. Land losses to these coastal properties will continue unless low-cost, effective measures are developed and implemented for shoreline erosion control and wetland habitat enhancement. Once established, smooth cordgrass, Spartina alterniflora Lois, provides an effective means of shoreline erosion protection. The Trinity Bay Soil and Water Conservation District and the Texas A&M University Marine Advisory Service initiated a project in 1985 to study the impacts of shoreline erosion and test cost-effective, vegetative erosion control measures in Galveston Bay, Texas. Smooth cordgrass was transplanted in four sites along the affeted shoreline and adjacent coastal waters for erosion abatement and re-creation of valuable wetland habitats. To date, approximately 1825 meters of shoreline has been vegetatively treated. Turbidity levels were measured during high and low erosion conditions. Sediment accretion was also measured within the study area. Relative abundance of fish species was documented by site during the study. Transplant survival rates varied from 60-70 percent. New shoot development seemed to depend on the care of the transplant stock. More work needs to be done in selecting disease resistant strains of smooth cordgrass and in plant genetics. Turbidity levels were highest during severe erosion conditions during the study. Average sediment accretion as a result of the newly-established stands of cordgrass was 0.14 m in each site. Results of this study indicate that marine organisms readlily utilize the artificially-created smooth cordgrass colonies within the study area. A significant difference in relative abundance of catch was noted between an unvegetated site and a vegetated site (12.7 percent versus 87.3 percent). Predominant species found during both sampling periods were white shrimp, Gulf menhaden, and striped mullet. Technical assistance was provided by the Soil Conversation Service, Texas Agricultural Extension Service, and the Texas A&M University Sea Grant College Program. Funding was provided through grants from The Moody Foundation, The Brown Foundation Inc., and the Texas A&M University Sea Grant College Program.