Effects of chronic oil pollution on a Caribbean coral reef

Sublethal effects of oil pollution on coral reefs may not become manifest except over very long periods of time. Uniform reefs with an Acropora palmata belt (2 m depth) and a Montastrea annularis community (4 m depth) were originally present along the coast near an oil refinery that has been in operation for more than 60 years in Aruba. Quantitative surveys of reef structure, coral cover, and numbers of juvenile corals along 15 km of the coast showed these reef characteristics to vary significantly in relation to the location of the refinery and the very persistent local current direction. The spatial structure of the reef has deteriorated, living coral cover is low, and less juveniles are present in front and downcurrent of the refinery. Some coral species, such as A. palmata and M. annularis, show a large gap in their distribution along the coast but a species such as Diploria strigosa is relatively abundant in the polluted area. The results of chronic oil pollution (such as spills, clean-ups, etc.) are, after 60 years, clearly discernible over a distance of 10 to 15 km along the reef.