Yellow Band Disease (YBD) is one of the most damaging diseases in Caribbean coral reefs because it affects the major groups of reef building coral species. YBD affects primarily the Montastraea annularis complex (e.g., M. annularis, M. faveolata and M. franksi) in reefs off La Parguera, Southwest, Puerto Rico. The purpose of this study was to document the spatial distribution patterns of YBD in M. faveolata and M. franksi colonies in six reefs off La Parguera insular shelf. Number of disease and healthy colonies of Montastraea sp. were counted along of four band transects (10x2m = 20m²) in each of 3 depth intervals (3-8; 8-12 and > 12m) in each reef site during the winter-spring season of 2008. Spatial distribution patterns were assessed using Lloyd’s index of patchiness. The index of patchiness was calculated for different spatial scales (e.g., 40, 60 and 80m2) per habitat (depth) in each of the six reefs.
Spatial distribution patterns of YBD infected Montastraea sp. resulted in a significant marked clumped pattern (p<0.05) in relation to the entire population as the spatial scale was increased at shallow and intermediate depths (3-8 and 8-12m, respectively) at mid shelf reefs. At shelf edge and inner shelf reefs (at all habitats) YBD infected Montastraea sp. showed no significant differences in patchiness at any spatial scale. Augmented YBD patchiness at mid shelf reefs may be due to an infectious characteristic of the pathogen as it encountered more potential hosts as the spatial scale increased.