Disease dynamics of Montipora white syndrome within Kaneohe Bay, Oahu, Hawaii: distribution, seasonality, virulence, and transmissibility.

We report on an investigation of Montipora white syndrome (MWS), which is a coral disease reported from Hawaii, U.S.A., that results in tissue loss. Disease surveys of Montipora capitata within Kaneohe Bay (Oahu) found colonies that were affected by MWS on 9 reefs within 3 regions of Kaneohe Bay (south, central, north). Mean MWS prevalence ranged from 0.02 to 0.87% and average number of MWS cases per survey site ranged from 1 to 28 colonies. MWS prevalence and number of cases were significantly lower in the central region as compared to those in the north and south regions of Kaneohe Bay. There was a positive relationship between host abundance and MWS prevalence, and differences in host abundance between sites explained approximately 27% of the variation in MWS prevalence. Reefs in central Kaneohe Bay had lower M. capitata cover and lower MWS levels. MWS prevalence on reefs was neither significantly different between seasons (spring versus fall) nor among 57 tagged colonies that were monitored through time. MWS is a chronic and progressive disease causing M. capitata colonies to lose an average of 3.1% of live tissue mo(-1). Case fatality rate was 28% after 2 yr but recovery occurred in some colonies (32%). Manipulative experiments showed that the disease is acquired through direct contact. This is the first study to examine the dynamics of MWS within Hawaii, and our findings suggest that MWS has the potential to degrade Hawaii's reefs through time.