Functional Roles of Sponges on Coral Reefs

ALTHOUGH a small group of carbonate excavating sponges can dismantle reefs, and some sponges can overgrow corals, it is now known that sponges also substantially benefit coral reefs and associated ecosystems. Sponges benefit reefs by efficiently filtering small (<5um) organic particles from the water column, binding live corals to the reef frame, facilitating regeneration of broken reefs, providing food for spongivores, sheltering juvenile crustaceans such as spiny lobsters, and harboring nitrifying and photosynthesizing microbial symbionts. Sponges uniquely perform many of these functional roles, and possibly others not yet known. However, sponges have not been included in most monitoring programs and assessments due to difficulties in identification and quantification. At the 9th ICRS, it was agreed that greater attention should be focused on sponges and their roles in reef function, particularly in light of recent documentation of rapid losses of sponges from coral reefs and closely associated ecosystems.