PREDATION ON CARIBBEAN SPONGES: THE IMPORTANCE OF CHEMICALDEFENCES

Joseph R. Pawlik
Biological Sciences, UNC-Wilmington, Wilmington, NC 28403-3297, USA.

The conventional view has been that the impact of predation on Caribbeanreef sponges is minimal: generalist predatory fishes are deterred by sponge spicules and chemistry, while the few spongivorous fishes are “smorgasbord”feeders that circumvent chemistry by eating small amounts of many differentsponge species. New data suggest that this traditional view needs to bere-examined. Generalist predatory fishes are deterred by chemistry, butnot by structural elements, toughness or nutritional quality of spongetissue. Spongivorous fishes are not smorgasbord feeders, but instead choseto eat chemically undefended sponge species. Transplantation experimentsreveal that the grazing activity of spongivorous fishes restricts certainsponge species to refugia, including cryptic habitats on the reef and mangroveand grassbed environments, where these fish are absent. Chemical defenceplays an important role in the ecology of sponges on Caribbean reefs.