Palatability of salt marsh forbs and grasses to the purple marsh crab (Sesarma reticulatum) and the potential for re-vegetation of herbivory-induced salt marsh dieback areas in cape cod (Massachusetts, USA)

Abstract

Intense herbivory by a growing population of intertidal burrowing crabs Sesarma reticulatum (purple marsh crabs) has denuded large areas of salt marsh on Cape Cod (Massachusetts, USA). Spartina alterniflora (smooth cordgrass) and, to a lesser extent, S. patens (salt marsh hay) have been the primary taxa affected while halophytic forb populations of Salicornia spp. (pickleweed), Suaedamaritima (sea-blite), and Limoniumcarolinianum (sea lavender), that normally constitute a relatively low proportion of marsh vegetation, have remained intact. In addition, these forb species appear to be colonizing some of the marsh grass dieback areas. Because the loss of vegetation results in considerable subsidence and erosion, the objective of this study was to (1) confirm whether certain taxa are unpalatable to S. reticulatum and (2) determine whether unpalatable species could be used to re-vegetate dieback areas as an interim measure to control marsh sediment and elevation loss. The results suggest that S. reticulatum prefers Spartina alterniflora over forbs and that one or all of these forb species are good candidates for vegetation restoration in dieback areas.