RHODES*, S.; GILCHRIST, S.L.; HENDERSON, M.: Role of Algal Refugia in Hermit Crab Populations of Bailey’s Cay Reef, Roatan, Honduras

Hermit crabs are found commonly in the reef, backreef, and seagrass areas of Bailey’s Cay. In the backreef, patches of sand have stands of algae available to hermit crabs as refugia. Preliminary studies revealed that hermit crabs occupy Penicillus, Avrainvilla, and Halimeda along with gastropods. Crabs were densest in algae found in shallow water (approximately 1 meter), becoming sparse in deeper algae (greater than 2 meters). Shell types and sizes of hermit crabs found in algae were noted. To examine how crabs associated with the algal resource, both hermit crabs and gastropods collected from algae were marked. Samples of gastropods and hermit crabs were collected from algae and from surrounding backreef and seagrass areas for several days. Hermit crabs originally marked in Penicillus moved rarely while those found on Halimeda moved regularly. A final experiment on shell recruitment by crabs occupying algae revealed that hermit crabs do move from algae to acquire new shells, but few of those with new shells return to the algae.