Dark Spots Disease - The Offline Version

Discolored spots or markings in the tissue of the massive or lesser starlet corals (Siderastrea siderea and S. radians) have been noted for many years, but not studied. This phenomenon was recently termed a disease by Jaime Garzón-Ferreira and Diego Luis Gil Agudelo, based on increases in the occurrence of these lesions and observations of loss of tissue associated with the spots.

Dark Spots Disease on massive starlet coral, Siderastrea siderea Photo by E. C. Peters.
Appearance	Dark purple to gray or brown patches of discolored tissue, often circular in shape but also occurring in irregular shapes and patterns, are scattered on the surface of the colony (bright purple patches have also been seen on a bleaching colony) or appear adjacent to the sediment/algal margin of a colony. Sediment can accumulate in the centers of these patches, with bare skeleton occasionally seen when the sediment is brushed off.
Cause	Unknown, but currently being studied by scientists.
Distribution	Florida Keys and Caribbean.
Impact	Small areas of tissue loss have been noted on affected colonies. On some colonies of massive starlet coral, a "dimpling" effect is present, in which the tissue and skeleton has continued to build up after the tissue died in a small circular patch, presumably due to sediment accumulations on a dark spot. Affected colonies are now widespread throughout the Caribbean and Florida Keys.