Although no diseases of European maerl or other coralline algal species are known, Littler & Littler (1995) recently discovered a potentially serious threat to coralline algae in the Pacific. A bacterial pathogen of coralline algae was initially observed during June 1993 and by 1995 occurred in South Pacific reefs that span a geographical range of at least 6000 km. The occurrence of the coralline algal pathogen at Great Astrolabe Reef sites (Fiji) increased from 0% in 1992 to 100% in 1993, which indicates that the pathogen may be in an early stage of virulence and dispersal. Because of the important role played by coralline algae in reef building, this pathogen, designated coralline lethal orange disease (CLOD), has the potential to greatly influence coral reef ecology and reef-building processes. If such a disease were to occur in temperate maerl beds, the effects could be devastating. We suggest that the possibility of disease should be borne in mind during monitoring programmes. Increased stress levels due, for example, to elevated sea temperatures, might increase the susceptibility of corallines to disease.

Next Section                     References