The spatial and temporal dynamics of coral diseases in Dominica, West Indies

This study involved a detailed documentation of individually tagged, diseased coral colonies at five reef sites in Dominica, West Indies from 2000 to 2002. At each reef site, survey areas were selected, and a pivoting line search pattern was used to identify and tag all scleractinian coral colonies exhibiting white plague (WP), black band disease (BBD), and dark spots syndrome (DSS) in March, June, and August of 3 yrs. There was an overall trend towards increasing disease incidence, but DSS was the only coral syndrome/disease that exhibited a significant increase among years. Conversely, the amount of disease-related tissue mortality (measured in August of each survey year) decreased each year. Coral diseases resulted in over 8 m² of coral tissue death during the 3 yr survey period, and 80% of this mortality was attributed to WP infections. The coral species affected by diseases varied in each year, thereby highlighting the need for multi-annual surveys to assess the long-term effects and management of coral diseases. WP and DSS incidence was significantly correlated to the relative frequency of the species most commonly affected by each disease/syndrome, and coral diseases predominantly affected the larger colonies of four susceptible species: Siderastrea siderea (Ellis and Solander, 1786), Montastraea faveolata (Ellis and Solander, 1786), Dichocoenia stokesi (Milne, Edwards and Haime, 1848), and Colpophyllia natans (Houttuyn, 1772). DSS progression rates on individual colonies were low (< 0.4 mm d⁻¹ ), and both BBD and WP progression rates were lower than those documented in other published studies. However, the progression of WP on affected colonies increased with warmer water temperatures. DSS and BBD infections were relatively persistent on individual colonies throughout the yearly surveys, while WP was the most short-lived of the three diseases/syndromes. The re-infection rate of affected colonies between survey years was approximately 25%. Scleractinian coral recruitment rates onto coral skeleton exposed by diseases were low, and the comparatively high occurrence of bioeroders and algae may have contributed to the overall degradation of reef structure or caused a shift toward reef communities dominated by algae.