Habitat-specific impacts of Hurricane Matthew on a range-expanding species

As range-shifting species colonize new ecosystems, they may experience novel conditions that may alter their ability to mitigate the impacts of periodic disturbances. Here we explore how the impact of Hurricane Matthew on the mangrove tree crab (Aratus pisonii) differed between its historic and colonized habitats. As this species responds to floodwaters by climbing structure, we predicted that structural differences between habitats would generate habitat-dependent impacts. Through field surveys, we found that crabs in the historic mangrove habitat, where tall structure remained unsubmerged, showed no reduction in body size as a result of the hurricane. In contrast, crabs in the colonized saltmarsh ecosystem, where all structure was submerged, exhibited a reduction in body size suggesting that large crabs were disproportionately impacted. Further, crabs found on docks within the saltmarsh exhibited a body size reduction in only one of three sites. Docks are more structurally similar to mangroves and may have provided more microhabitat refuges for large crabs than marsh grasses. Thus, structural differences between habitats appear to have altered the hurricane impact experienced by this species. The ability to mitigate disturbance impacts under novel conditions could contribute to the success of range-shifting species as they colonize new ecosystems.