PARENT SESSION
Oral Session # 23: Marine Ecology I: Crabs, Coral, and Lobsters.
Presiding: J Wilson
Tuesday, August 5. 8:00 AM to 11:30 AM, SITCC Meeting Room 202.
Interactions between juvenile Caribbean spiny lobsters and Caribbean reef octopuses in the Florida Keys.
Lear, Jennifer*,1, Butler, Mark1, 1 Old Dominion University, Norfolk, Virginia
ABSTRACT- Juvenile Caribbean spiny lobster (Panulirus argus) and the Caribbean reef octopus (Octopus briareus) may simultaneously compete for resources and interact as predator and prey within hard-bottom habitats in the Florida Keys, FL (USA). Lobsters chemically detect the presence of octopuses and avoid shelters from which these cues emanate, thus altering patterns of lobster shelter use. We conducted surveys of juvenile lobsters and octopuses occupying artificial shelters at 18 locations in the Florida Keys during spring 2002 and 2003 and summer 2001, 2002 and 2003. Our findings show that juvenile lobsters do not cohabitate in shelters with octopuses, however there was no correlation between the numbers of octopuses and juvenile lobsters on a site. We then used mesocosm experiments to investigate why the strong behavioral interaction between octopus and lobster is not reflected in local population structure. First, we investigated whether juvenile lobsters reach a size refuge from octopus predation. There was no correlation between octopus weight and the size of juvenile lobsters that they consumed; thus large juveniles were just as readily consumed as small juveniles. Second, we examined the effects of alternative prey, lobster size, the presence of lobster conspecifics, and initial residency on shelter competition between lobsters and octopuses. The presence of alternative prey and conspecifics reduced predation on lobsters and their susceptibility to displacement from a preferred shelter. Although octopuses are effective predators of lobster and can alter their use of dens, the presence of alternative prey and lobster conspecifics mediates predation and shelter use, which may explain why there is no relationship between lobster and octopus abundance in the field.
Key words: Octopus briareus, predation, Panulirus argus, competition