Coral reef sponges: Do predatory fishes affect their distribution?

Abstract

The predatory activities of fishes are thought to have little impact on the distribution and abundance of sponges on Caribbean coral reefs. To test this premise, 15 species of sponges were transplanted from mangrove and grassbed habitats, where spongivorous fishes are rare, to shallow patch reefs, where spongivorous fishes are common. Twelve of these 15 sponge species could also be found in cryptic locations, but not in conspicuous locations, on nearby reefs. After 3 d, there was significant loss of wet mass of uncaged sponges versus caged sponges for nine sponge species because of consumption by spongivores, primarily angelfishes. A mean of >50% of the sponge tissue was consumed for seven species: Chondrilla nucula, Chondrosia collectrix, Geodia gibberosa, Halichondria sp., Halichondria melanodocia, Myriastra kalitetilla, and Tedania ignis. These results, in addition to other recent data on the chemical defenses of Caribbean reef sponges against generalist predatory fishes, suggest that predation plays an important role in structuring the reef sponge community and that predation limits the distribution of some Caribbean sponges.