Impact of a White Plague-II Outbreak on a Coral Reef in the Archipelago Los Roques National Park, Venezuela

Abstract

During the last quarter of 2000, an outbreak of white plague disease (WPD-II) caused significant coral tissue mortality in several reef building species (Montastraea species complex, Colpophyllia natans and Stephanocoenia intersepta) in a fringing reef along Madrizquí Key, Los Roques National Park,Venezuela. Coral cover and abundance by species, and cover of other substrates (i.e., algae, sand, etc.) were measured using eleven 1 m2 quadrats (divided in 100 areas of 100 cm2 each) separated by two meter intervals along each of the eight, 20 m long transects haphazardly placed between 5-12 m depth. Measurements were taken at the onset of the epizootic event and a year later. The average coral cover and cover of other substrates were compared using a Friedman ANOVA, while changes in relative cover by species were tested using a t-test. C. natans and the Montastraea species complex showed the highest significant (t-student, p < 0.05) loss in live cover, from 12.28% to 8.11% and 38.34% to 34.84%, respectively. Overall, the average live coral cover decreased significantly (Friedman = 581.5, p < 0.05) from 35% in 2000 to 29% in 2001, with a corresponding significant increase in algal and bare substrate cover from 33% to 44%. Similar to other Caribbean areas, the results of this study indicated that outbreaks of WPD-II may cause fast and extended coral tissue mortality, with significant reductions in live coral cover with a corresponding increase in algal cover in a relatively short period of time.