Sediment Production via Bioerosion by Cliona Viridis on Grand Cayman Island, B. W. I.

Abstract

The overgrowing, boring sponge Cliona viridis was studied on the Southwest coast of Grand Cayman Island, British West Indies. The surface area covered by the sponge was estimated using transect and quadrat surveys. Between 1 and 8 m depth, the average substrate coverage was 5%. Smaller sponge colonies were usually subcircular and larger colonies more dendritic. This change in shape may aid in exploiting new substrate. The sponge removes between 13.9% and 32.2% of the substrate as it expands laterally and produces an average erosional rate of 0.6 mm yr ⁻¹. Average sediment production rate is 1 kg m ⁻² yr ⁻¹. The chips produced by the sponge comprised only 0.0122% to 1.250% of the bottom sediments. Presumably, the majority of the sponge-produced sediments were transported out by water currents.