MEPS 495:185-191 (2014)  -  DOI: https://doi.org/10.3354/meps10568

ABSTRACT: Sea urchins, important herbivores in marine ecosystems, are strongly impacted by both the direct and indirect effects of predation, and the long-spined sea urchin Diadema antillarum is no exception. Once abundant on Caribbean coral reefs, D. antillarum populations were decimated by disease in the early 1980s, and only where their natural predators have been overfished has D. antillarum recovery been observed. Spiny lobsters (Palinuridae) are predators of sea urchins, and although there are several species of spiny lobster in the Caribbean, only the spotted spiny lobster Panulirus guttatus is restricted to coral reefs where D. antillarum dwells. We investigated the direct and indirect impacts of P. guttatus on D. antillarum mortality, foraging, and behavior in a series of laboratory experiments. We found that P. guttatus prey on D. antillarum, especially small urchins. D. antillarum also consumed significantly less algae in the presence of P. guttatus and fled when exposed to the odor of P. guttatus but apparently not the scent of the Caribbean spiny lobster P. argus. The altered foraging and avoidance behaviors displayed by D. antillarum are strong evidence that predation by P. guttatus has played an important, but underappreciated, role in the evolutionary history of D. antillarum and perhaps its recovery on Caribbean coral reefs.

KEY WORDS: Diadema antillarum · Panulirus guttatus · Florida Keys · Predation · Trait-mediated interactions · Coral reefs