A reef under siltation stress: Cahuita, Costa Rica

The coral reef at Parque Nacional Cahuita, Costa Rica, shows low live coral coverage and species diversity and large average colony diameters. Amounts of suspended and resuspended particulate matter are very high, and a large amount of terrigenous material is trapped inside massive corals. Coral growth rates are low, and are significantly inversely correlated with sediment resuspension rates. We suggest that deforestation, which increased about 15 years ago, has increased the siltation stress on the reef.

The siltation-specific characteristics of this reef may be used in managing modem reefs, in that the presence and degree of siltation stress may be quickly evaluated by determining the acid-insoluble residues of coral heads, and comparing these with growth rates through time. These characteristics may also be of use in interpreting possible mechanisms for decline and death of reefs in the fossil record.