Overfishing of top predators along the western Atlantic coastline has led to a trophic cascade in salt marshes, with increases in herbivorous purple marsh crab (Sesarma reticulatum; Say, 1817) abundances in North American estuaries leading to overgrazing of cordgrass (Spartina alterniflora, Loisel.) and shoreline erosion. To evaluate potential physiological limits on the range of S. reticulatum within an estuary, we evaluated survival and physiological tolerance of S. reticulatum from the Ashepoo-Combhee-Edisto (ACE) River Basin in South Carolina, USA, to combinations of salinity (5 and 30 ‰) and pH (pH 6.6, 7.6, and 8.6) challenges, representative of estuarine extremes. Survival, haemolymph ion concentrations, and gill Na+K+ATPase (NKA) and V-type H+-ATPase (VHA) activity were measured after a 48-hr exposure to each experimental condition. Survival was nearly 100 % and osmoregulatory control was maintained across estuarine salinity and pH ranges. Sesarma reticulatum appeared to be robust to all potential combinations of salinity and pH stressors examined in this study, and therefore are likely unrestricted in their fundamental niche based on these stressors throughout an estuary.
Shaughnessy C. A., Anderson E. C., Kasparian M., LaMontagne J. M., & Bystriansky J. S., in press. Survival and osmoregulation of the purple marsh crab (Sesarma reticulatum) at varying salinity and pH. Canadian Journal of Zoology. Article (subscription required).
