Origins and Effects of Spartina Wrack in a Virginia Salt Marsh

Movements of mats of tidal wrack (dead Spartina alterniflora) and impacts of the wrack were followed in color infrared aerial photographs of a sloping foreshore salt marsh on Wallops Island, Virginia. Tidal wrack may be stranded in high marsh, where it decomposes, or it may be temporarily stranded at lower elevations. The wrack kills underlying Spartina alterniflora in low marsh and in the transition zone from low to high marsh. Wrack is the major cause of devegetated areas within the marsh, but these areas eventually revegetate, and do not evolve into pans. There are substantial short-term reductions in S. alterniflora marsh productivity. Other effects of wrack are discussed.