Coral reefs are protected by mucus secreted by their polyps and thus generally resist small, isolated accidents fairly well. In addition, a protective layer of water usually remains between the corals and the surface oil slick. However, repeated pollution incidents can have a serious impact on them, as can large-scale oiling of the surface layer of reefs (the only living part of the reef) caused by the tides and swell. Some of the many species of fish, invertebrates and marine algae which live in coral habitats can be severely impaired even if the coral itself has only suffered mildly.
Sensitivity of intertidal ecosystems
Source: data from O’SULLIVAN A.J., JACQUES T.G. Impact Reference System
Pollution of a mangrove swamp