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Wetlands of Galveston Bay

Wetlands in the Lower Galveston Bay watershed play several key ecological roles in protecting and maintaining the health and productivity of the estuary. There are two major categories of wetlands around Galveston Bay:

(1) Fringing or estuarine wetlands, are tidal in nature, with saltwater from the ocean mixing with freshwater rivers flowing off the land. They are situated along the edge of Galveston Bay and are intermediate between the aquatic habitats of the bay and the terrestrial habitats that surround it.

(2) Freshwater wetlands are palustrine, or non-tidal, in nature and do not have flowing water. They lie inland from the bay and may be embedded in coastal prairie, riparian corridors, or forest habitat complexes.

Wetlands are important elements of many biological processes that support the bay ecosystem. Hydrologically, fringing marsh and freshwater wetlands are valuable filtering zones for polluted runoff, protecting the bay from excessive organic and sediment loadings from the land. Freshwater wetlands also serve as flood control areas that release rainfall runoff slowly compared to the rapid discharge from man made drainage systems. Finally, well-established, vegetated wetlands also provide a buffer between high-energy water and land, pre¬venting or reducing shoreline erosion.

Among the most important of wetland functions is their role in providing habitat for many species of plants, fish, birds, and other wildlife. All of Galveston Bay’s principal commercial and recreational fishery species rely on estuarine wetlands during at least some part of their life cycle. The wetland edge is a particularly important habitat for white and brown shrimp (Whaley and Minello 2002). Other marsh dwelling species include blue crab, red drum, spotted seatrout, Southern flounder and Gulf menhaden. In the same way, wetlands are important nurseries to hundreds of non-commercial species that comprise a large part of the bay food web. Bird species, such as snowy egrets, great egrets, roseate spoonbills, tri-colored herons, black-crowned night herons and great blue herons use marsh as feeding habitat.

Trends in Wetland Distribution

Understanding where wetlands are located and how their area has changed over time is critical if these important habitats are to be effectively protected and restored. Studies to classify and assess wetlands are a priority nationally and in the Galveston Bay system. Numerous analyses to quantify wetland acreage have been performed to determine the change in areal coverage of wetland habitats in the Galveston Bay system (White et al. 1993; Pulich and Hinson 1996; White et al. 2004 ; Jacob and Lopez 2005; NOAA 2006; Webb 2006; Lester and Gonzalez 2008). While the studies often use different methodologies or look at slightly different areas all of the studies indicate some gains and numerous losses in the different classes of wetlands over the years. Go to the estuarine or freshwater wetlands pages to see the status and trends in wetlands distribution over the years.

Causes of Wetlands Loss

Wetlands have been declining in the Galveston Bay system since the 1990s at a rate of about 0.3 percent per year. Causes for wetland loss in this watershed include relative sea level rise; land use conversion for agricultural, urban, industrial, and transportation purposes; dredge and fill activities; and isolation projects (Moulton et al. 1997).  Additionally, invasion by exotic species such as Chinese tallow is a threat to native wetlands.

Restoration and Creation

The Galveston Bay Plan identifies the loss or degradation of aquatic habitats as the greatest priority problem in the Lower Galveston Bay watershed and sets a goal of increasing wetland area and restoring the quality of wetland habitats. Specifically this goal calls for the creation or restoration of 5,000 acres of freshwater marsh and 8,600 acres of estuarine emergent marsh.

Preservation

Wetland preservation efforts deliberately work to save natural wetlands that still exist in the Lower Galveston Bay watershed. Over the past twenty years, more wetland restoration projects have been funded and completed in the Lower Galveston Bay watershed than wetland preservation projects. While wetland restoration and wetland preservation projects are valid uses for public funding and both are needed in the Lower Galveston Bay watershed, we now know that unlike estuarine wetlands (most of which are subject to the Section 10/404 permitting process), freshwater wetlands continue to be lost at a greater rate than they are being restored or preserved. For this reason, a greater number of wetland preservation projects should be implemented to maintain the ecological integrity of the Lower Galveston Bay watershed in the coming decades.

 

Literature Cited

Jacob, J. S. and R. Lopez. 2005. Freshwater, Non-tidal Wetland Loss Lower Galveston Bay Watershed 1992-2002: A Rapid Assessment Method Using GIS and Aerial Photography. Webster, TX: 73.

Lester, L. J. and L. A. Gonzalez. 2008. Galveston Bay Status and Trends Final Report. Houston, TX, Texas Commission on Environmental Quality, Galveston Bay Estuary Program: 83.

Moulton, D. W., T. E. Dahl and D. M. Dall. 1997. Texas coastal wetlands status and trends, mid-1950s to early 1990s. Albuquerque, New Mexico, United States Department of the Interior, Fish and Wildlife Service, Southwestern Region: 32 pp.

Moulton, D. W. and J. S. Jacob. 2000. Texas coastal wetlands guidebook. Bryan, Texas, Texas Sea Grant College Program: 66 pp.

NOAA. 2006. "Gulf Coast Land Cover." Web PageNational Oceanic and Atmospheric Administration (NOAA), Coastal Services Center, Coastal Change Analysis Program (C-CAP), from http://www.csc.noaa.gov/crs/lca/gulfcoast.html.

Pulich, W. M., Jr. and J. Hinson. 1996. Coastal studies technical report No. 1: development of geographic information system data sets on coastal wetlands and land cover. Austin, Texas, Texas Parks and Wildlife Department.

Whaley, S. D. and T. J. Minello. 2002. "The distribution of benthic infauna of a Texas salt marsh in relation to the marsh edge." Wetlands 22(4): 753-766.

Webb, J. W. 2006. Galveston Bay: Estuarine and marine habitat change analysis. Webster, Texas, Final report for the Texas Commission on Environmental Quality, Galveston Bay Estuary Program: 41 pp.

White, W. A. and J. G. Paine. 1992. Wetland plant communities, Galveston Bay System. Webster, Texas, Galveston Bay National Estuary Program Publication GBNEP-16.

White, W. A., T. A. Tremblay, R. L. Waldinger and T. R. Calnan. 2004 Status and trends of wetland and aquatic habitats on barrier islands, upper Texas coast, Galveston and Christmas Bays. Final report. , Texas General Land Office and NOAA under GLO Contract No. 03-057.

White, W. A., T. A. Tremblay, E. G. Wermund and L. R. Handley. 1993. Trends and status of wetland and aquatic habitats in the Galveston Bay system, Texas. Webster, Texas, Galveston Bay National Estuary Program Publication GBNEP-31.

 

 

 

Galveston Bay Wetland Change Data for 1996, 2001, and 2005 (NOAA CCAP)
 

 

LULC Map of Lower Galveston Bay Watershed

MAP OF HABITATS AND DEVELOPED LANDS IN THE LOWER GALVESTON BAY WATERSHED. DATA SOURCE COASTAL CHANGE ANALYSIS PROGRAM LAND USE/LAND COVER DATA (NOAA 2006).
Map of habitats and developed lands in the Lower Galveston Bay watershed. Data source Coastal Change Analysis Program land use/land cover data (NOAA 2006).

 

  
 

 

 

HOMES IN THE BROWNWOOD SUBDIVISION OF BAYTOWN WERE PERMANENTLY INUNDATED BY BAY WATERS DUE TO SUBSIDENCE. IMAGE COURTESY THERON SAGE
Homes in the Brownwood subdivision of Baytown were permanently inundated by bay waters due to subsidence. Image courtesy Theron Sage

  

 

 

Project Brays
The constructed wetland at Mason Park on Brays Bayou.  Image courtesy of Texas Agrilife Extension, photographer Milt Gray.
The constructed wetland at Mason Park on Brays Bayou.  Image courtesy of Texas Agrilife Extension, photographer Milt Gray.

 

 

 

Galveston Bay Invasive Species Field Guide: Chinese Tallow
Leaves and flowers of the Chinese tallow tree. Photo courtesy of Ted Bodner, Southern Weed Science Society, www.forestryimages.org; Image Number 0016032.
Leaves and flowers of the Chinese tallow tree. Photo courtesy of Ted Bodner, Southern Weed Science Society, www.forestryimages.org; Image Number 0016032.

 

 


Check out the Maps page for more Galveston Bay spatial data
 

 
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