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Diving into the Past: Scuba and the Temporal Dimension of Coral Reefs

A variety of sampling techniques afforded by scuba diving have made it possible to study the Holocene history of coral reefs in detail. This paper describes results of three geological techniques and illustrates them with examples from our own work in the Caribbean. First, cores extracted with a hydraulic drill from cemented reef frameworks provided the complete history of a fringing reef off the Caribbean coast of Panama and documented a relict reef stranded by rising sea level off St. Croix. Second, surface samples collected from a coral death-assemblage helped explain the demise of an algal-dominated reef off the southern coast of Barbados. Third, push-cores from un- cemented reefs in the Belizean barrier-reef lagoon and a coastal lagoon in Panama revealed that 3,000 or more years of compositional stasis were followed in recent decades by precipitous turnover events, in which the previously dominant corals were replaced by a different species. Understanding the geo- logical history of coral reefs over the last several thousand years is critical to predicting their response to climate change, alterations in land use, and other natural and anthropogenic perturbations.