At Molasses Reef in the Florida Keys, a patch of approximately 15 Acropora palmata colonies were observed to have numerous ring-shaped lesions, only 2 or 3 smaller colonies were lacking these distinct “rings”. 

Some colonies were more affected than others but consistent patterns such as portion of colony or part of the patch could not be seen. There are several vigorously defended damselfish territories in this patch, in some cases rings were found adjacent to these territories suggesting that a predator would have to be tolerant of damselfish bites. Another patch (0.3 miles away) was surveyed and no such scars were seen. Colonies from this patch were photographed 2 days apart and in some cases, it seemed that some new rings appeared- new rings were the same size and equally distinct suggesting that the difference in “white-ness” is not necessarily a progression (healing or worsening).

Scars that were identical in appearance were photographed by Margaret Miller on one or two A. palmata colonies as well as some Millepora complanata in August 1999 at Pickles Reef (several miles south of Molasses Reef). While surveying this site, some marks were seen on one M. complanata colony, though they were far less distinct than those photographed by Dr. Miller so I could not be sure that they were the same type of scar.

Figure - A Large colony (approx 1m in height) with many ring-shaped scars, note haphazard distribution on colony and uniform size.

Figure - B Close up with scale showing ring diameter approximately 2cm. Note the patch in the lower right appears to be two overlapping “rings” with algal turf in center. This was seen on a few other colonies but was not the typical appearance.

Figure - C Underside of branch showing particularly distinct rings.

Figure - D Topside of a branch showing less distinct but overlapping rings.

Figure - E Rings adjacent to a vigorously defended damselfish territory.

Figure - F Marks on M. complanata.