The Effect of Dispersed Oil on the Calcification Rate of the Reef-Building Coral Diploria Strigosa

Hermatypic corals represent environmentally and economically important components of the reef ecosystem. Oil spills and clean-up operations in reef areas are potential sources of pollution impact. This paper presents an evaluation of the calcification rate of specimens of the reef-building coral Diploria strigosa in response to 24 hour treatments of chemically dispersed oil at concentrations of 20 ppm. The concentrations and durations were chosen to represent a scenario of a short-term oil spill treated with dispersant passing over a coral reef.

Calcification rates were determined by the buoyant weight technique at several day intervals for up to 29 days following treatment. Results from laboratory experiments (Winter and Summer) conducted in a flow-through seawater system indicate that treated corals, both in comparison to untreated controls as well as to their pretreatment rates, experienced no depression in calcification.

In contrast, a possible short-term enhancement of calcification for the treated corals was observed.