PARENT SESSION
Poster Session #27: Salt Marshes.
Wednesday, August 8, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall
130
Spartina alterniflora dieback in a southwestern Louisiana salt marsh.
Edwards, Keith1, Proffitt, Edward2, Travis, Steven2, 1 2
ABSTRACT- Dieback in large patches of Spartina alterniflora was noticed across the Louisiana coast in May 2000. The dieback area increased during the summer and fall: >1000 km2 of salt marsh were affected. We are studying one salt marsh experiencing dieback at the Sabine National Wildlife Refuge in southwestern Louisiana. Live shoot densities differed significantly between affected vs. healthy zones in the dieback marsh (0 and 150 shoots/m2, respectively), as well as from the marsh edge into the interior (230 and 0 shoots/m2, respectively). Shoot densities in the healthy zone were similar to pre-dieback densities (1996-97) in the same marsh and to shoot densities in a nearby non-dieback marsh. Genetic diversity in the marsh was determined in 1998, prior to the dieback event. These data will be compared to those of dieback "survivors" in spring 2001. A preliminary transplant experiment was initiated in September 2000 to determine the feasibility of this method in restoring dieback areas; little natural re-growth or colonization has occurred in dieback marshes. The dead plants quickly decompose, leaving mud flat patches, which can quickly erode away. Initial results are promising, with 50-80% survivorship of the transplants in different zones in the dieback marsh. An extended transplant study is planned, using additional genetically-typed clones of S. alterniflora in other dieback marshes.
KEY WORDS: Spartina alterniflora, Marsh dieback, Restoration, Genetic diversity