GILCHRIST,S.L.: Resetting the system: Dynamics of hermit crab shell cycling after Hurricane Mitch

An eight-year study at Bailey’s Cay has revealed a dynamic shell cycling system between hermit crabs on the coral reef, in backreef seagrass, and on land. Predators such as octopuses, crabs and fish consume both hermit crabs and gastropods on the reef. Birds, crabs, and flies eat terrestrial hermit crabs and gastropods. Typical shell cycling is from the reef to land with little movement in the opposite direction. Hurricane Mitch hovered near the Cay, scouring the reef with sand, depositing sand in seagrass areas, and submerging the island for 3 days. Comparisons of shell use patterns, population sizes and distributions of hermit crabs and their predators before and after Mitch show consistency in shell types used and remarkable persistence of shells within the system. Predators are of nearly uniform year class as are several species of hermit crabs. Hermit crab visits to artificial and natural predation sites increased in frequency after Mitch though “quality” of shells occupied appeared higher than those used by crabs in previous years.