Type II White-Band Disease

Abstract

Epizootics of type II white-band disease (WBD II) can be confused with type I white-band disease (WBD I) and with bleaching. The only well documented cases of WBD II have been on Acropora cervicornis from the Bahamas, but descriptive reports indicate that it may be widespread. WBD n begins as a bleaching margin which pre­cedes a necrotic margin. The bleachíng margin usually progresses at a faster rate than the necrotic margin and can arrest, allowing the necrotic margin to catch up. In this case, the disease has the appearance of WBD I. Living polyps are found in the bleached zone although recovery has not been observed. A. bacterium, similar to Vibrio charcharia is always isolated from the surface mucapolysaccharide layers (SML) of the bleached zone, but not from the SML of unbleached areas.