TECHNIQUES FOR CREATING SALT MARSHES ALONG THE EAST COAST 



Ernest D. Seneca 



Department of Botany and Soil Science 

 North Carolina State University 

 Raleigh, North Carolina 27650 



The information that I present is 

 the result of research conducted by Dr. 

 W. W. Woodhouse, Jr., Dr. S. W. Broome, 

 and me in North Carolina. Suggested ref- 

 erences include Woodhouse (1979) and 

 Woodhouse et al . (1972, 1974, 1976). 

 Our research efforts were supported by 

 the Coastal Engineering Research Center, 

 U.S. Army Corps of Engineers; the Uni- 

 versity of North Carolina Sea Grant Pro- 

 gram; and the North Carolina Coastal Re- 

 search Program. I cannot speak with any 

 authority about marsh creation results 

 from other areas, except in North Caro- 

 lina where we worked with a wide range 

 of environmental conditions. Most of 

 the substrates that we worked with in 

 marsh establishment were sandy. 



Low regularly flooded salt marshes 

 are flooded twice daily along the Atlan- 

 tic coast (along the Gulf coast only 

 once daily) and are dominated by smooth 

 cordgrass, Spartina al terniflora . From 

 Maine to Florida, these marshes vary 

 along a latitudinal gradient of increas- 

 ing temperature and decreasing daylight 

 during the summer. Salt marshes may con- 

 sist of only a narrow fringe seaward 

 from irregularly flooded marsh or shrub 

 communities in the mid-Atlantic region. 

 From Cape Lookout, North Carolina, south- 

 ward through South Carolina and Georgia, 

 these marshes consist of broad expanses 

 of smooth cordgrass. Along the Gulf 

 coast these marshes may again consist of 

 only a narrow fringe such as at Ocean 

 Springs, Mississippi. Near Brownsville, 

 Texas, is found the westernmost popula- 

 tions of smooth cordgrass and here, too, 

 they come in contact with mangrove which 

 dominates tropical coastlines in pro- 

 tected areas. The same species of smooth 

 cordgrass supposedly occurs all along 

 the coast from Maine to Texas, but we 

 should understand that even though the 

 adjacent populations may interbreed, 

 there is considerable variation in mor- 

 phological features and physiological 



responses from north to south. Some of 

 this variation is genetic, and some of 

 it is probably only due to local envi- 

 ronmental conditions. We do not have 

 all the answers concerning the variabil- 

 ity, but we do know that there are local 

 population variations and that in marsh 

 establishment we should be aware of 

 those variations in any material that we 

 transplant very far from the source of 

 the transplants. Planting material 

 should not be used very far from the 

 area where it was obtained. Certainly 

 plants from Maine should not be planted 

 in Georgia. 



We began thinking about marsh crea- 

 tion or marsh initiation in the late 

 summer of 1969, at which time Dr. Wood- 

 house and I went to the Coastal Engi- 

 neering Research Center, U.S. Army Corps 

 of Engineers, in Washington, D.C., and 

 talked with some of their personnel 

 about marsh creation. They seemed in- 

 terested, gave us some seed money, and 

 we started our studies in the fall of 

 1969. At that time there was consider- 

 able open water disposal of dredge mate- 

 rial in North Carolina. North Carolina 

 has about 2,400 km (1,500 mi) of nav- 

 igable channels in its sounds and estu- 

 aries, and the Corps' annual expendi- 

 tures for channel maintenance in 1969 

 were around 2 to 3 million dollars. 



The idea of trying to stabilize the 

 intertidal zone of this dredge material 

 appealed to the Corps because stabiliza- 

 tion could reduce the amount of material 

 finding its way back into the same chan- 

 nels from which it was dredged. In the- 

 ory, it could cut down on channel main- 

 tenance costs. Heretofore, nothing has 

 been done to stabilize this material 

 after it was cast out of the pipeline 

 dredge, and through normal wind and wave 

 action, much of it found its way right 

 back into the same channels from which 

 it was dredged. Although the situation 

 has changed and there is no longer open 



