Our Concern:

Extensive losses of coastal wetlands in the United States caused by sea-level rise, land subsidence, erosion, and coastal development have increased interest in the creation of salt marshes within estuaries. Smooth cordgrass, Spartina alterniflora, is the species utilized most for salt marsh creation and restoration throughout the Atlantic and Gulf coasts of the U.S., and has been used extensively in Galveston Bay. A recent study of status and trends in the Galveston Bay area (White et al. 1993, GBNEP-31) indicated that there had been a net loss of about 35,000 acres of wetlands and aquatic habitats between 1950 and 1989. About 26,000 acres of this loss was the conversion of emergent marsh to open water due largely to human induced subsidence and to sea-level rise.  

Salt marshes have many valuable functions for the surrounding habitat and the animals living there. Some of their physical functions are: protecting shorelines from erosion, stabilizing deposits of dredged material, dampening flood effects, trapping water-born sediments, and serving as nutrient reservoirs. Some of their biological functions are: acting as tertiary water treatment systems to rid coastal waters of contaminants, serving as nurseries for many juvenile fish and shellfish species, serving as habitat for various wildlife species, and providing plant material for the base of a detritus-based food web. The abundance of coastal marshes has been correlated with fisheries landings (Turner 1977,  Boesch and Turner 1984). Marshes function for aquatic species by providing breeding areas, refuges from predation, and rich feeding grounds (Zimmerman and Minello 1984, Boesch and Turner 1984, Kneib 1984, 1987, Minello and Zimmerman 1991). These studies indicate marshes do this better than the open water habitats.

The establishment of vegetation in itself is generally sufficient to provide the physical functions, but the development of the biological functions of salt marsh is more difficult to assess. The value of created marshes versus that of natural marshes for estuarine animals has been questioned (Cammen 1976, Race and Christie 1982, Broome 1989, Pacific Estuarine Research Laboratory 1990, LaSalle et al. 1991, Minello and Zimmerman 1992, Zedler 1993). Restoration of all salt marsh functions is necessary to prevent habitat creation and restoration activities from having a negative impact on estuarine dependent fisheries populations. For this reason alone, we need to monitor the created marshes and how well they develop the biological functions if we are to assess their equality to natural salt marshes.

Many salt marsh restoration and creation projects have been implemented in the Galveston Bay System during the past 20 years. We have been able to list many that were done to stabilize eroding shoreline and to restore salt marsh (Matthews and Minello, 1994).  Many of these projects were done by volunteers guided by the Galveston Bay Foundation (GBF).  Some were private constructions required by the U.S. Army Corps of Engineers (ACE) as mitigation for permitted alterations of natural salt marshes. One at Atkinson Island was a large demonstration project by ACE that utilized bottom sediments from channel dredging. Implementation of more dredged material containment and utilization projects with marsh creation are currently underway or are in our near future.

Each year more marshes are being built, and yet very little information is available concerning the success of past restoration projects. It is essential that we monitor created marshes and obtain information concerning their success and development through the years. Doing so will help to refine the requirements for successful marsh creation. Please check our bibliography section for literature references to salt marsh restoration and ecology.  Also check the interactive mapping site provided by the Galveston Bay Estuary Program via USGS to see if your created marsh site has been recorded; if it has not been added, please contact us and share your information. It would be greatly appreciated.

We would be delighted to hear from you about salt marsh restoration and creation projects.  Please use our monitoring-mapping utility to see locations, data, and imagery of salt marsh creation sites in Galveston Bay. Any information and pictures you can provide to help complete our inventory would be greatly appreciated.  Please contact Jeff Matthews at NMFS, 409-766-3518.

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