Yellow Band Disease Research Articles

Stony Coral Tissue Loss Disease and Other Diseases Affect Adults and Recruits of Major Reef Builders at Different Spatial Scales in the Dominican Republic

Monitoring programs can help understand coral disease dynamics. Here, we present results from a national program in the Dominican Republic (DR) aimed at evaluating coral diseases 3 times a year following a nested spatial design. Prevalence of coral diseases in DR varied from sites to regions, suggesting that disease dynamics can be driven by local processes and/or across larger spatial scales. Three diseases were common: Dark Spot (DSD), Yellow Band (YBD) and Stony Coral Tissue Loss Disease (SCTLD). DSD and YBD were more prevalent across the western coast (north and south), whereas SCTLD was restricted for the study period to the northern coast. SCTLD has become endemic in the northwestern coast, epizootic in the northeastern, and absent in other sites across DR. SCTLD prevalence in the northwest was below 10% across sites, whereas in the northeast it varied from 2.13±3.69% (mean± sd) to 38.7±13.55% in Galeras and from 1.9±0.99% to 38.5±19.8% in Samaná. Over 10 coral species were affected by SCTLD in DR, with Pseudodiploria spp, Dendrogyra cylindrus, Eusmilia fastigiata, Siderastrea siderea, Montastraea cavernosa and Meandrina spp, being the most susceptible. We observed SCTLD affecting recruits and juvenile corals with 5% prevalence on average. Furthermore, we observed Oreaster reticulatus climbing on 1% healthy and 27% SCTLD P. strigosa colonies in Samaná. We conclude that SCTLD is a serious problem in DR, producing rapid loss of coral cover of major reef builders that are locally used for propagation efforts. This monitoring plan will provide future insights to design more effective disease responses.

Coral diseases of mushroom coral (Fungiidae) in Pari Island, Kepulauan Seribu, Jakarta

Coral disease is one of the causes of the decline in the condition of coral reef ecosystems. This study aims to measure coral health based on the abundance and prevalence of coral health categories. The research was conducted in the Pari Island Cluster, Seribu Islands at four stations. The Belt Transect method with 2 × 100 meters was used to calculate coral health and a 30 m Line Intercept Transect (LIT) with three replications to determine substrate cover. The condition of coral reefs can be categorized as moderate to good based on this percentage value. The study results found five genera from the Fungiidae, namely Fungia, Ctenactis, Herpolitha, Heliofungia, and Sandalolitha. The most commonly found genus is the genus Fungia. The health condition of Fungiidae corals in Pari Island is divided into two categories, namely 35% healthy and 65% unhealthy, consisting of changes in tissue color - white (coral bleaching), changes in tissue color - not white (yellow band disease), and compromised health (damage by sedimentation). Yellow band disease is only found in the genus ˆ and is not found in other genera.

Baseline assessment of coral diseases in an environmentally extreme environment of the northern Persian Gulf

The coral diseases are recognized as serious threats to coral reef ecosystems and a major contributor to the reduction of zooxanthellate scleractinian populations worldwide. Quantitative disease surveys can provide important information on the status and trends of coral reef health over the time. In this study, coral disease surveys were carried out during August 2014 and 2015 at designated sites located in the northern Persian Gulf. Seven different diseases affecting eight scleractinian genera were documented: Black Band Disease (BBD), Skeletal Growth Anomaly (SGA), Arabian Yellow Band Disease (AYBD), White Mat Disease (WMD), White Syndrome (WS), Porites Pink Spot (PPS), and Porites Bleached Patches (PBP). Additionally, it should be noted that this is the first report of SGA in Acropora sp. found in the Persian Gulf. The results of this study generated a baseline dataset of various related diseases in the northern Persian Gulf which can be utilized for future studies.

Machine learning on crowd-sourced data to highlight coral disease

Triggered largely by the warming and pollution of oceans, corals are experiencing bleaching and a variety of diseases caused by the spread of bacteria, fungi, and viruses. Identification of bleached/diseased corals enables implementation of measures to halt or retard disease. Benthic cover analysis, a standard metric used in large databases to assess live coral cover, as a standalone measure of reef health is insufficient for identification of coral bleaching/disease. Proposed herein is a solution that couples machine learning with crowd-sourced data – images from government archives, citizen science projects, and personal images collected by tourists – to build a model capable of identifying healthy, bleached, and/or diseased coral. We collected hundreds of images of corals from open source archives, including the National Oceanic and Atmospheric Administration’s records and the XL Catlin Seaview Survey. The image annotation platform Labelbox was used to highlight regions of interest in each of these images and label them as “healthy”, “bleached”, “black band disease”, “dark spot disease”, “white syndrome”, or “yellow band disease”. These annotations were then used to build, train, and validate a Python-based image classification model, adapted from an open-source Mask R-CNN (region-based convolutional neural network) algorithm. Use of the model on a test set of coral images yields over 85% accuracy in distinguishing healthy versus unhealthy coral. This machine learning-based model has the potential to rapidly analyze a large and growing database of images to identify coral bleaching/disease around the world, thereby enabling effective allocation of resources for preservation of our marine ecosystems.

Coral disease at Mansuar Island, Raja Ampat, Indonesia

Coral reef has been facing rapid destruction nowadays. Raja Ampat Islands in Papua has one of the highest coral reef diversities and is located within the Coral Triangle area. The coral condition in Raja Ampat is still categorized as healthy. However, it started to show some of the habitat degrading signs. Coral disease is one of the main causes in coral reef ecosystem decline. This study aims to measure the level of coral disease based on coral disease category prevalence observation at Mansuar Island in Raja Ampat, Papua. The method used in data sampling is by using 5 x 50 m Belt Transect. The results show that as many as 28 coral genera were found from all of the observation sites with Fungia being the most abundant. There are 7 coral health categories, dominated by Tissue Discoloration Non-White. There are 5 coral diseases found namely Yellow Band Disease, White Syndrome, Brown Band Disease, Atramentous Necrosis, and Ulcerative White Spots.

New records of coral diseases in the Persian Gulf

We report first observations of three coral diseases including black band disease on Acropora, a syndrome resembling yellow band disease and red band disease on Porites colonies from depth 5–6 m at Abu-Musa Island after widespread coral bleaching in the northern part of the Persian Gulf in October 2012.

New records of coral diseases in the Persian Gulf

We report first observations of three coral diseases including black band disease on Acropora, a syndrome resembling yellow band disease and red band disease on Porites colonies from depth 5–6 m at Abu-Musa Island after widespread coral bleaching in the northern part of the Persian Gulf in October 2012.

PORIFERAN ABUNDANCE IS NEGATIVELY ASSOCIATED WITH CORAL HEALTH IN THE MESOAMERICAN REEF

Abstract The Mesoamerican Reef is the second largest coral reef in the world and has experienced a 50% loss of coral coverage in recent decades. Due to the high biodiversity of marine life that depend on the Mesoamerican Reef, identifying drivers of coral loss is crucial. This study was designed to assess the relationship between the presence of yellow band disease (YBD) and white plague type-II (WPII) on stony corals with environmental (water depth) and biological stressors (abundance of sponges in close proximity) in the reef surrounding the Bay Islands, Honduras. Both radial and parallel transect survey techniques were used to quantify the abundance of seven sponge species within a one-meter radius of Orbicella species and Montastraea cavernsoa. The strongest predictor of coral health was the abundance of Callyspongia plicifera, followed by Svenzea zeai, in close proximity to diseased coral. A weak, but positive, correlation between poriferan abundance and the presence of disease lesions on coral was observed. However, no significant relationship of disease prevalence with water depth was observed. Additionally, no differences in the prevalence of disease lesions between four species of native stony corals were observed. These findings suggest coral species are equally susceptible to bacterial pathogens, but that close association with poriferans may increase the transmission and persistence of harmful bacteria in coral reef ecosystems.

Testing methods to mitigate Caribbean yellow-band disease on Orbicella faveolata.

Outbreaks of coral diseases continue to reduce global coral populations. In the Caribbean, yellow band is a severe and wide-spread disease that commonly affects corals of the Orbicella spp. complex, significantly impeding coral reproduction, and hindering the natural recovery of Orbicella spp. populations. Caribbean yellow-band disease (CYBD) lesions may be severe, and often result in the complete loss of coral tissue. The slow spread of CYBD, however, provides an opportunity to test methods to mitigate the disease. Here we report the results of in situ experiments, conducted within Buck Island Reef National Monument in St. Croix, USVI, to test the effectiveness of three techniques to minimize disease impact on Orbicella faveolata: (1) shading, (2) aspirating, and (3) chiseling a “firebreak” to isolate the lesion. Neither shading nor aspirating the diseased tissue significantly reduced CYBD tissue loss. However, chiseling reduced the rate and amount of tissue lost by 31%. While 30–40% of the chiseled lesions appeared to be free of disease signs 12–16 months after treatment, success significantly and steadily declined over 23 months, indicating a possible lack of long-term viability of the technique. The results of this study demonstrate that creating a “firebreak” between diseased and healthy-appearing tissue slows the spread of the disease and may prolong the life of O. faveolata colonies. The firebreak method yielded the best results of all the techniques tested, and also required the least amount of effort and resources. However, we do not recommend that this treatment alone be used for long-term disease mitigation. Rather, we propose that modifications of this and other treatment options be sought. The results also highlight the need for extended monitoring of CYBD after any treatment, due to the slow but variable rate and pattern of tissue loss in this disease.

Implications of coral harvest and transplantation on reefs in northwestern Dominica

In June, 2002, the government of Dominica requested assistance in evaluating the coral culture and transplantation activities being undertaken by Oceanographic Institute of Dominica (OID), a coral farm culturing both western Atlantic and Indo-Pacific corals for restoration and commercial sales. We assessed the culture facilities of OID, the condition of reefs, potential impacts of coral collection and benefits of coral transplantation. Coral reefs (9 reefs, 3-20m depth) were characterized by 35 species of scleractinian corals and a live coral cover of 8-35%. Early colonizing, brooders such as Porites astreoides (14.8% of all corals), P. porites (14.8%), Meandrina meandrites (14.7%) and Agaricia agaricites (9.1%) were the most abundant corals, but colonies were mostly small (mean=25cm diameter). Montastraea annularis (complex) was the other dominant taxa (20.8% of all corals) and colonies were larger (mean=70cm). Corals (pooled species) were missing an average of 20% of their tissue, with a mean of 1.4% recent mortality. Coral diseases affected 6.4% of all colonies, with the highest prevalence at Cabrits West (11.0%), Douglas Bay (12.2%) and Coconut Outer reef (20.7%). White plague and yellow band disease were causing the greatest loss of tissue, especially among M. annularis (complex), with localized impacts from corallivores, overgrowth by macroalgae, storm damage and sedimentation. While the reefs appeared to be undergoing substantial decline, restoration efforts by OID were unlikely to promote recovery. No Pacific species were identified at OID restoration sites, yet species chosen for transplantation with highest survival included short-lived brooders (Agaricia and Porites) that were abundant in restoration sites, as well as non-reef builders (Palythoa and Erythropodium) that monopolize substrates and overgrow corals. The species of highest value for restoration (massive broadcast spawners) showed low survivorship and unrestored populations of these species were most affected by biotic stressors and human impacts, all of which need to be addressed to enhance survival of outplants. Problems with culture practices at OID, such as high water temperature, adequate light levels and persistent overgrowth by macroalgae could be addressed through simple modifications. Nevertheless, coral disease and other stressors are of major concern to the most important reef builders, as these species are less amenable to restoration, collection could threaten their survival and losses require decades to centuries to replace.

‘YELLOW SYNDROME’ IN SCLERACTINIAN CORALS THROUGHOUT BINTAN DISTRICT, KEPULAUAN RIAU PROVINCE, INDONESIA

Coral disease surveys were conducted in Bintan, Kepulauan Riau Province. The purpose was to identify the abundance of corals showing signs of Yellow Syndrome (YS) disease and to describe similar pathological signs to that of AYBD throughout Bintan District. Three belt transects (2 m x 50 m in size) were set up to determine the abundance of coral reef attacked by YS disease. Line intercept transects were used to determine the percentage of live corals in the surveyed areas. The survey showed that the YS disease syndrome attacked 8 different genera i.e. Acropora, Montipora, Porites, Pavona, Turbinaria, Favia, Platygyra, and Favites. The highest attack happened at Mapur Island (0.06 kol/m2) on Porites lutea, Turbinaria peltata, T. mesenterina, Acropora bruggemanni, and Pavona frondifera. The survey also indicated that there may have been at least two types of YS i.e. the first type caused by a boring and/or over-growing sponge species and the second type caused by a kind of pathogenic microbe. Regardless the causal agent of YS, the severity of YS attack on coral urged immediate action to be undertaken and should include initial microscopic and histology examinations. Based on this initial microscopic and histology examinations it was found out that YS bears a close resemblance to the Arabian Yellow Band Disease. This study, however, argued that the word “disease” may have been incorrectly used without identifying a specific causal agent.

Some coral diseases track climate oscillations in the Caribbean

Disease outbreaks continue to reduce coral populations worldwide. Understanding coral diseases and their relationships with environmental drivers is necessary to forecast disease outbreaks, and to predict future changes in coral populations. Yet, the temporal dynamics of coral diseases are rarely reported. Here we evaluate trends and periodicities in the records of three common coral diseases (white-band disease, yellow-band disease, and dark-spot syndrome) that were surveyed between 1997 and 2014 at 2082 sites throughout the Caribbean. The relationship between the periodicities of disease prevalence and El Niño Southern Oscillation (ENSO) cycles was examined using cross-wavelet analyses and convergent cross mapping (CCM). The prevalence of the diseases peaked every two to four years, and matched periodicities in ENSO conditions. CCM models suggested that environmental conditions associated with recent ENSO cycles may have influenced the patterns in disease prevalence. We also found no increasing trends in disease prevalence through time. Instead, our work suggests that the prevalence of coral diseases is dynamic and complex. The gradual increase in sea-surface temperature, a consequence of increasing greenhouse gas emissions, progressively raises the modal temperature threshold of each ENSO cycle. These dynamic cycles and the increasing modal temperatures appear to influence the dynamics of coral diseases.

Rapid spread of diseases in Caribbean coral reefs

The variety and frequency of diseased coral reef organisms has increased across the Caribbean during the last 10 years. Black band, white band, white pox, and white plague diseases have become more widespread. Yellow band disease now affects a major portion of Montastrea annularis across the Caribbean. Mortality of Yellow band disease-affected tissues was observed to increase in the southern Caribbean during early 1997 , with affected tissue turning white and dying. During the past two years a major fraction of encristing red calcareous Porolithon algae died across the Caribbean. This disease, also found in the Indian Ocean, lacks the orange band characteristic of Pacific coralline lethal orange disease. A millimeter thick white circular rim is seen between live tissue and dead skeleton. Numerous other emerging diseases have attacked many other organisms in this period, including gorgonians, sponges, and echinoderms. Many of those now known have not yet been described. Generally, most diseases affect one or few species (except white plague and black band diseases); and their spatial and temporal distributions appear unrelated to bleaching, pollution (except black band disease), sedimentation, or grazing. This paper brings together observations made separately by many researchers over a large area and long period; in order to evaluate the geographic and historical distributions of each disease: Photographic images are included which show diagnostic field criteria for recognizing each disease.

Caribbean yellow band disease compromises the activity of catalase and glutathione S-transferase in the reef-building coral Orbicella faveolata exposed to anthracene.

Healthy and diseased corals are threatened by different anthropogenic sources, such as pollution, a problem expected to become more severe in the near future. Despite the fact that coastal pollution and coral diseases might represent a serious threat to coral reef health, there is a paucity of controlled experiments showing whether the response of diseased and healthy corals to xenobiotics differs. In this study, we exposed healthy and Caribbean yellow band disease (CYBD)-affected Orbicella faveolata colonies to 3 sublethal concentrations of anthracene to test if enzymatic responses to this hydrocarbon were compromised in CYBD-affected tissues. For this, a 2-factorial fully orthogonal design was used in a controlled laboratory bioassay, using tissue condition (2 levels: apparently healthy and diseased) and pollutant concentration (4 levels: experimental control, 10, 30 and 100 ppb concentration) as fixed factors. A permutation-based ANOVA (PERMANOVA) was used to test the effects of condition and concentration on the specific activity of 3 enzymatic biomarkers: catalase, glutathione S-transferase, and glutathione peroxidase. We found a significant interaction between the concentration of anthracene and the colony condition for catalase (Pseudo-F = 3.84, df = 3, p < 0.05) and glutathione S-transferase (Pseudo-F = 3.29, df = 3, p < 0.05). Moreover, our results indicated that the enzymatic response to anthracene in CYBD-affected tissues was compromised, as the activity of these enzymes decreased 3- to 4-fold compared to healthy tissues. These results suggest that under a potential scenario of increasing hydrocarbon coastal pollution, colonies of O. faveolata affected with CYBD might become more vulnerable to the deleterious effects of chemical pollution.

RNA-Seq of the Caribbean reef-building coral Orbicella faveolata (Scleractinia-Merulinidae) under bleaching and disease stress expands models of coral innate immunity.

Climate change-driven coral disease outbreaks have led to widespread declines in coral populations. Early work on coral genomics established that corals have a complex innate immune system, and whole-transcriptome gene expression studies have revealed mechanisms by which the coral immune system responds to stress and disease. The present investigation expands bioinformatic data available to study coral molecular physiology through the assembly and annotation of a reference transcriptome of the Caribbean reef-building coral, Orbicella faveolata. Samples were collected during a warm water thermal anomaly, coral bleaching event and Caribbean yellow band disease outbreak in 2010 in Puerto Rico. Multiplex sequencing of RNA on the Illumina GAIIx platform and de novo transcriptome assembly by Trinity produced 70,745,177 raw short-sequence reads and 32,463 O. faveolata transcripts, respectively. The reference transcriptome was annotated with gene ontologies, mapped to KEGG pathways, and a predicted proteome of 20,488 sequences was generated. Protein families and signaling pathways that are essential in the regulation of innate immunity across Phyla were investigated in-depth. Results were used to develop models of evolutionarily conserved Wnt, Notch, Rig-like receptor, Nod-like receptor, and Dicer signaling. O. faveolata is a coral species that has been studied widely under climate-driven stress and disease, and the present investigation provides new data on the genes that putatively regulate its immune system.

Development and application of molecular biomarkers for characterizing Caribbean Yellow Band Disease in Orbicella faveolata.

Molecular stress responses associated with coral diseases represent an under-studied area of cnidarian transcriptome investigations. Caribbean Yellow Band Disease (CYBD) is considered a disease of Symbiodinium within the tissues of the coral host Orbicella faveolata. There is a paucity of diagnostic tools to assist in the early detection and characterization of coral diseases. The validity of a diagnostic test is determined by its ability to distinguish host organisms that have the disease from those that do not. The ability to detect and identify disease-affected tissue before visible signs of the disease are evident would then be a useful diagnostic tool for monitoring and managing disease outbreaks. Representational Difference Analysis (RDA) was utilized to isolate differentially expressed genes in O. faveolata exhibiting CYBD. Preliminary screening of RDA products identified a small number of genes of interest (GOI) which included an early growth response factor and ubiquitin ligase from the coral host as well as cytochrome oxidase from the algal symbiont. To further characterize the specificity of response, quantitative real-time PCR (qPCR) was utilized to compare the expression profiles of these GOIs within diseased tissues (visible lesions), tissues that precede visible lesions by 2–4 cm (transition area), and tissues from healthy-looking colonies with no signs of disease. Results show there are distinctive differences in the expression profiles of these three GOIs within each tissue examined. Collectively, this small suite of GOIs can provide a molecular “finger print” which is capable of differentiating between infected and uninfected colonies on reefs where CYBD is known to occur.

Genetically divergent Symbiodinium sp. display distinct molecular responses to pathogenic Vibrio and thermal stress.

Global climate change and anthropogenic activities are threatening the future survival of coral reef ecosystems. The ability of reef-building zooxanthellate coral to survive these stressors may be determined through fundamental differences within their symbiotic dinoflagellates (Symbiodinium sp.). We define the in vitro apoptotic response of 2 evolutionarily distant Symbiodinium sp., subtypes B2 and C1, to determine the synergistic effects of disease and temperature on cell viability using flow cytometry. The putative yellow band disease (YBD) consortium of Vibrio spp. bacteria and temperature (33°C) had a positive synergistic effect on C1 apoptosis, while B2 displayed increased apoptosis to elevated temperature (29 and 33°C), the Vibrio consortium, and a lone virulent strain of V. alginolyticus, but no synergistic effects. Additionally, heat shock protein 60 expression revealed differential cell-mediated temperature sensitivity between subtypes via western blotting. This result marks the first evidence of Symbiodinium sp. apoptotic variations to YBD pathogens and emphasizes the potential impact of synergistic stress on globally distributed coral-Symbiodinium symbioses.

Patrones a gran escala del reclutamiento de coral en Isla Mona, Puerto Rico: evidencia de una trayectoria transitoria de comunidad después del blanqueamiento y mortalidad coralino masivo

Coral reefs have largely declined across the northeastern Caribbean following the 2005 massive bleaching event. Climate change-related sea surface warming and coral disease outbreaks of a white plague-like syndrome and of yellow band disease (YBD) have caused significant coral decline affecting massive reef building species (i.e., Orbicella annularisspecies complex) which show no apparent signs of recovery through larval sexual recruitment. We addressed coral recruit densities across three spur and groove reef locations along the western shelf of remote Mona Island, Puerto Rico: Punta Capitán (PCA), Pasa de Las Carmelitas (PLC), and Las Carmelitas-South (LCS). Data were collected during November 2012 along 93 haphazard transects across three depth zones (&lt;5m, 5-10m, 10-15m). A total of 32 coral species (9 octocorals, 1 hydrocoral, 22 scleractinians) were documented among the recruit community. Communities had low densities and dominance by short-lived brooder species seven years after the 2005 event. Mean coral recruit density ranged from 1.2 to 10.5/m2 at PCA, 6.3 to 7.2/m2 at LCS, 4.5 to 9.5/m2 at PLC. Differences in coral recruit community structure can be attributed to slight variation in percent macroalgal cover and composition as study sites had nearly similar benthic spatial heterogeneity. Dominance by ephemeral coral species was widespread. Recovery of largely declining massive reef-building species such as theO. annularis species complex was limited or non-existent. The lack of recovery could be the combined result of several mechanisms involving climate change, YBD disease, macroalgae, fishing, urchins and Mona Island’s reefs limited connectivity to other reef systems. There is also for rehabilitation of fish trophic structure, with emphasis in recovering herbivore guilds and depleted populations of D. antillarum. Failing to recognize the importance of ecosystem-based management and resilience rehabilitation may deem remote coral reefs recovery unlikely. Rev. Biol. Trop. 62 (Suppl. 3): 49-64. Epub 2014 September 01.

Coral transcriptome and bacterial community profiles reveal distinct Yellow Band Disease states in Orbicella faveolata.

Coral diseases impact reefs globally. Although we continue to describe diseases, little is known about the etiology or progression of even the most common cases. To examine a spectrum of coral health and determine factors of disease progression we examined Orbicella faveolata exhibiting signs of Yellow Band Disease (YBD), a widespread condition in the Caribbean. We used a novel combined approach to assess three members of the coral holobiont: the coral-host, associated Symbiodinium algae, and bacteria. We profiled three conditions: (1) healthy-appearing colonies (HH), (2) healthy-appearing tissue on diseased colonies (HD), and (3) diseased lesion (DD). Restriction fragment length polymorphism analysis revealed health state-specific diversity in Symbiodinium clade associations. 16S ribosomal RNA gene microarrays (PhyloChips) and O. faveolata complimentary DNA microarrays revealed the bacterial community structure and host transcriptional response, respectively. A distinct bacterial community structure marked each health state. Diseased samples were associated with two to three times more bacterial diversity. HD samples had the highest bacterial richness, which included components associated with HH and DD, as well as additional unique families. The host transcriptome under YBD revealed a reduced cellular expression of defense- and metabolism-related processes, while the neighboring HD condition exhibited an intermediate expression profile. Although HD tissue appeared visibly healthy, the microbial communities and gene expression profiles were distinct. HD should be regarded as an additional (intermediate) state of disease, which is important for understanding the progression of YBD.

Spatial and Temporal Variability of Caribbean Yellow Band Disease Prevalence inOrbicellaspp. off La Parguera, Puerto Rico

The spatial and temporal variability in mean prevalence of Caribbean yellow band disease (CYBD) in the scleractinians Orbicella faveolata and O. franksi was assessed during 2008 and 2009 in reefs off La Parguera, Puerto Rico. All diseased and healthy-looking colonies were counted along each of four band transects (20 m2) in each of 3 depth intervals (3–8; 8–15; > 15 m) in two inner (Pelotas and Enrique) and two mid-shelf (Turrumote and Media Luna) fringing reefs, and two deep bank reefs at the shelf-edge (Weinberg and Old Buoy). Overall, densities of O. faveolata were higher at intermediate depth habitats (0.5 col./m2) while those of O. franksi were higher at deep habitats (1.7 col./m2). In inner-and mid -shelf fringing reefs both O. faveolata and O. franksi showed significantly higher mean CYBD prevalence at intermediate depth habitats (25 ± 24 % and 17 ± 36 %) compared to deeper (13.4 ± 27 % and 5.2 ± 11 %) and shallow habitats (7.9 ± 11 % and 0 %, respectively). Mean CYBD prevalence in O. faveolata and O. franksi were significantly higher (p<0.05, H=31.6; df=2; U=1756; p<0.05) in mid-shelf reefs (28 ± 27 % and 16.3 ± 31 % respectively) compared to shelf-edge reefs (5.3 ± 5.6 % and 1 ± 1.4 %) and to inner-shelf reefs (9.9 ± 20.6 %) only for O. faveolata. There was a significant positive correlation between CYBD prevalence and densities of O. faveolata (Spearman's r = 0.7; p<0.05). In contrast, O. franksi showed a significant but negative correlation (Spearman's r = -0.5; p<0.05). No significant change in mean CYBD prevalence was observed between seasons and years (2008 to 2009) for both species (26.9 ± 24.9 % and 24.1 ± 23.4 % in O. faveolata and 5.4 ± 10.7 % and 5.0 ± 12 % 5.4 ± 10.7 % to 5.0 ± 12 % in O. franksi respectively). Overall, O. faveolata had significantly higher CYBD prevalence compared to O. franksi which indicates that this species is more susceptible to CYBD. Deep habitats with low quality/quantity of light might serve as a refuge from CYBD in both species. The slight decrease over time in the proportion of infected colonies in both species, indicates no new infections, possibly because of lack of more susceptible colonies after 12 years, reduced virulence, an immune response, or any combination of these.