Geukensia demissa, the ribbed mussel, is a mytilid bivalve that inhabits salt marshes along the East Coast of North America. It is an important ecosystem engineer, contributing to salt marsh species diversity and landscape-scale ecosystem processes. In South Carolina, commercial harvest of G. demissa has increased markedly over the past five years. There are currently no species-specific regulations, raising concerns about the sustainability of commercial harvest, especially considering that harvesting practices can be destructive to the salt marsh habitat. The goal of the current study was to characterize G. demissa habitat, demographics, recovery following simulated harvest, and its foundation species role in order to establish ecological characteristics of G. demissa in South Carolina and inform management decisions regarding the commercial harvest of the species. Demographic sampling at commercially harvested and unharvested sites revealed that G. demissa in South Carolina primarily consists of large individuals, with low rates of recruitment. A year-long manipulation experiment revealed that selective harvesting practices mitigated the effect of harvest on metrics of Spartina alterniflora health, but not on G. demissa recruitment. Elevation surveys in salt marshes along the Ashley River were performed to characterize the elevational range of G. demissa, and a model was created using elevation and salinity data to identify G. demissa habitat, with the potential to be applied to estuaries throughout South Carolina. Finally, drop net sampling indicated that G. demissa did not have a foundation species effect on the transient nekton assemblage at the patch scale, in contrast to its role in promoting the abundance and diversity of resident salt marsh invertebrates. The current study offers important ecological information on G. demissa in South Carolina that can be used to support future management decisions associated with the commercial fishery,