MEPS 345:185-197 (2007) - doi:10.3354/meps06912
Predation in subtropical soft-bottom systems: spiny lobster and molluscs in Florida Bay
Martha S. Nizinski*
ABSTRACT: A 2 yr field experiment conducted in 2 locations in seagrass meadows within Everglades National Park, Florida Bay, tested the hypothesis that variations in physical structure of experimental shelters (casitas) would affect abundance and composition of the predator guild and, in turn, that these predators would then have measurable and commensurate impacts on the nearby benthic community. Experimental structures (casita frame, mesh-roof casita and full-roof casita) were successful in attracting and aggregating predators as hypothesized, with those structures providing more overhead cover attracting significantly more predators. Although many predators, including the numerically dominant spiny lobster Panulirus argus, preyed heavily on or included molluscs in their diets, no significant impacts of predation by spiny lobsters and finfishes on the abundance and species richness of the molluscan assemblage were observed. Regional differences in prey abundance and richness were significant, yet predator effects were similar between locations. Significant location differences in prey abundances, therefore, did not result from differential impacts of prey consumption by casita-associated predators. Predation effects by spiny lobsters and various species of finfishes in Florida Bay were dispersed over time and space and predation was not the primary structuring mechanism for the gastropod and bivalve assemblages in these seagrass and macroalgal habitats. Measurable differences between prey populations in the 2 study locations probably reflect differences in habitat heterogeneity, spatial and temporal variability in predator and prey abundances and distributions, overall high diversity of benthic prey, and ontogenetic shifts in diet and habitat use by predators, all which tend to buffer predatory impacts.
KEY WORDS: Tropics · Soft-bottom systems · Predation · Spiny lobster · Community structure · Florida Bay
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