17,18 Spatial analyses have linked increasing sea surface temperature with disease prevalence, indicating that climate change could be a driver of the disease. 6 WBD is transmissible via water, direct contact and animal vectors, including sea snails, damsel fish and plankton. 1,11–16 Koch’s postulates (the accepted standard of confirming a causative link between a microbe and a disease) were fulfilled in Puerto Rico, identifying Vibrio charcariae as the main pathogen. 9,10 The etiology of WBD is not fully understood, although microbial analyses and the effectiveness of certain antibiotic treatments indicate that bacterial pathogens are responsible. 4,7,8 Nevertheless, signs of genetic resistance and localized population recoveries have been recorded in the Caribbean, including La Parguera in Puerto Rico. These combined threats resulted in unprecedented mortalities of Acropora populations, as well as long-term ecosystem-wide alterations in reef structure and functioning throughout the Caribbean and a shift from coral- to algal-dominance. 6WBD outbreaks extending from the 1980s to early 2000s coincided with other key threats, including hurricanes, thermal anomalies, and a disease outbreak targeting the key herbivorous sea urchin, Diadema antillarum. 1,3–5 These two types were found to be the same disease after more field observations and lab tests were done. 1,2 Two types of WBD (type I and type II), were originally described for the key reef building Acropora species complex, known commonly as Staghorn ( Acropora cervicornis) and Elkhorn ( Acropora palmata) corals, as well as a hybrid of these two species ( Acropora prolifera). White band disease (WBD) is characterized by a white band of bleached diseased tissue, or tissue-denuded skeleton, that progresses rapidly (0.5 – 2 cm/day) from the base or mid-branches of Acroporid corals. 30 Experiments have also found that re-introducing the herbivorous sea urchin Diadema antillarum can reduce black band disease progression by controlling competitive algae populations that could otherwise compromise coral health. 3,5,29,18,22–28 Researchers have had success halting disease progression by shading diseased corals, as well as by aspirating and then placing clay or epoxy putty over the black band. 3,17–21 BBD kills coral tissues at a rate of around 0.3-1 cm per day, and multiple studies have found disease prevalence or progression to increase with higher water temperatures, increased light, and nutrient enrichment form land-based pollution sources. 10,11,13,16 BBD is transmitted through water and direct contact, with corallivores possibly acting as additional vectors. 3,9,12–16 Research has also identified that microcystin and sulfide produced by the bacterial consortium facilitate the lethality of this disease, possibly impacting the coral’s symbiotic algae. 3,4,7–11 Research has identified Roseofilum reptotaenium as the dominant pathogen, 12 although numerous additional bacteria have been found in association with the BBD bacterial consortium. 6 It is caused by a consortium of a cyanobacteria that includes a sulfide-oxidizing bacteria and a sulfide-reducing bacteria, among others. 3–5 BBD is a highly virulent disease that affects 25 species of hard and soft corals. 1,2 It is characterized by the presence of a black band about 0.5 – 3 cm in width that kills coral tissue as it moves across a colony exposing bare coral skeleton. The devastating impact these diseases have on reef health highlights the importance of our continued efforts to monitor, research, and restore Puerto Rico’s vital coral ecosystems, complemented with educational programs and actions aimed at restoring healthy environmental conditions.īlack band disease (BBD), first recorded in Puerto Rico in 1972, was the first biotic coral disease identified in the Caribbean.
Below you will find descriptions of some of the more prominent coral diseases in Puerto Rico. Despite these challenges, collaborative research efforts across the Caribbean have improved our understanding and identification of various coral diseases. Characterizing the cause of a disease remains a challenge, and disease diagnoses often rely upon visual cues that can vary across time, region, observers, and coral species. temperature stress, contamination) factors. Coral diseases can occur for a number of reasons, from biotic (e.g.
The impact of disease on corals can be detrimental, leading to large-scale losses in coral cover, diversity, reproductivity and overall reef structure. The Caribbean has been described as a coral disease “hot spot.” In Puerto Rico, diseases are one of the leading threats to coral health.
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