Geographic variability in the incidence of coral and octocoral diseases in the wider Caribbean

Abstract

Lack of base-line information on the epizootiology and the spatial and temporal variability of most coral diseases/syndromes prevents accurate interpretations of their potential effects on coral reefs. Here, we present quantitative results on the incidence of all diseases/syndromes found in 19 reef sites from six geographic areas across the wider Caribbean. We compare the pathogenesis of the common diseases/syndromes and their variability at geographic scales. Data were collected between August and December of 1999 to avoid seasonal variability. The CARICOMP coral disease protocol was used. All coral and octocoral colonies were counted and checked for diseases/syndromes in up to twelve, 40 m² (20 x 2) band-transects laid over the bottom of at least two reef sites in each geographic locality. Overall, the average incidence of diseases was low at the coral community level (3.02%) and varied significantly (0.40-0.78%) across sites. White Plague-II (WP-II), Yellow Blotch Disease (YBD), Black Band Disease (BBD), and Aspergillosis (ASP) were present in all geographic areas sampled. Aspergillosis showed the highest incidence at both the community (0.60-5.94%) and population (Gorgonia ventalina) level (5.56-30.56%). Thirty eight reef-building coral species were susceptible to at least one disease/syndrome. WP-II affected the highest number of species (32), followed by BBD (16), Dark Spots Disease (DSD) (12), YBD (6) and White Band Disease (WBD) (3). All four Montastraea spp and Colpophyllia natans were each affected by five syndromes. Aspergillosis infected ten species from six genera of octocorals, a significant increase from the 2 susceptible sea fan species reported until now. These results show that even though the incidence rates were low at the community level, the high number of important reef-building species affected, the widespread distribution of most diseases/syndromes, and their wide host breadth present a potential problem for coral reef communities throughout the Caribbean. More frequent epizootic events coupled with current trends in reef degradation might be a lethal combination for the future of these communities. However, before we speculate what the outcome of the current events might be, we need more information and epidemiological models developed with sound quantitative data.