PREDATION ON EARLY JUVENILE SPINY LOBSTERS PANULIRUS-ARGUS (LATREILLE) - INFLUENCE OF SIZE AND SHELTER

Juvenile spiny lobsters Panulirus argus (Latreille) from three behaviorally and ecologically distinct ontogenetic groups (algal, 5-15 mm carapace length; transitional, 16-25 mm CL; and post-algal, 26-35 mm CL) were tethered in their characteristic shelters and on open substratum to evaluate size related differences in predation risk. Field experiments performed at two sites near Long Key, Florida Bay nursery habitat indicate that juveniles attain a partial size refuge from a suite of abundant algal lobster predators at about the time they emerge from settling habitat. Algal lobsters experience significantly decreased mortality by sheltering at night, thereby attaining a survival rate comparable to that of larger, older juveniles that forage nocturnally in the open. Diver surveying and limited net sampling revealed an array of lobster predators including octopus, portunid crabs, bonnethead sharks, nurse sharks, sting rays, gray snapper and toadfish, as well as general crustacean predators including bonefish and permit. High relative mortality of the smallest juveniles suggests that predation on the algal and early transitional phases is a potential bottleneck to population recruitment.