Scleractinian coral diseases in south Florida: incidence, species susceptibility, and mortality

Abstract

There are limited quantitative data available documenting the natural, or non-epizootic, occurrence of scleractinian coral diseases over multiple years. Individual coral colonies exhibiting black band disease (BBD), white plague (WP), dark spots syndrome (DSS), and white band disease (WBD) were monitored 3 times per year on 5 south Florida reefs over a 2 yr period. Surveys included measurements of coral population composition, coral diversity, disease type, coral species affected, colony size, percent of colony affected, and the number of lesions or active infections per colony. Data on re-infections of the same colonies, multiple infections per colony, disease duration, disease-associated tissue mortality, and coral recruitment are also presented. A total of 674 coral colonies exhibiting coral diseases were tagged and monitored. DSS was the most common syndrome (n = 620 infected colonies), but BBD and WP infections caused the largest amount of coral tissue death. The only disease that exhibited a linear increase in incidence with elevated temperature was BBD. DSS and BBD were the most persistent conditions, and WP infections were comparatively short-lived, with obvious signs of disease typically disappearing after 2 to 3 mo. The only disease that caused total colony death as oppposed to partial mortality during the survey period was WBD. WP and DSS incidence was significantly positively correlated with the relative frequency of the species most commonly affected by each disease at each study site. Of the 61 colonies examined in the recruitment survey, only 5 scleractinian coral recruits were identified. The most commonly recorded colonizer of exposed coral skeleton was filamentous/turf algae, thus indicating the potential for a shift towards algal-dominated reef communities.