Black Band Disease Research Articles

A novel application of a cryosectioning technique to undecalcified coral specimens

Histological observations represent an important application to directly characterize the structure of tissues and locate host-associated and invasive microorganisms. Histological approaches have been widely employed in studies of the physiology, pathology and ecology of corals. However, the conventional preparation of histological sections requires decalcification of coral samples to remove the hard skeletal structure in a series of acid or EDTA solutions over a weeks’ period, causing potential disturbances in coral structures on prepared slides. In this study, we present an alternative method to prepare thin sections from undecalcified frozen coral tissues, which has been developed for retaining the structural integrity of histological sections including skeleton. Cross sections of normal and diseased (rapid tissue necrosis and black band disease) coral specimens prepared with this method displayed the complete structure of the coral fragments including soft tissues and skeleton structure at microscopic scales, thereby clearly showing the orientation of damaged tissues and associated microorganisms in relation to skeletal structures. This study demonstrates that the present cryosectioning method without the need for decalcification is a highly effective tool for in-depth understanding of coral tissue/skeleton interactions.

Microbial transcriptome profiling of black band disease in a Faviid coral during a seasonal disease peak.

The etiology of black band disease (BBD), a persistent, globally distributed coral disease characterized by a dark microbial mat, is still unclear. A metatranscriptomics approach was used to unravel the roles of the major mat constituents in the disease process. By comparing the transcriptomes of the mat constituents with those of the surface microbiota of diseased and healthy corals, we showed a shift in bacterial composition and function in BBD-affected corals. mRNA reads of Cyanobacteria, Bacteroidetes and Firmicutes phyla were prominent in the BBD mat. Cyanobacterial adenosylhomocysteinase, involved in cyanotoxin production, was the most transcribed gene in the band consortium. Pathogenic and non-pathogenic forms of Vibrio spp., mainly transcribing the thiamine ABC transporter, were abundant and highly active in both the band and surface tissues. Desulfovibrio desulfuricans was the primary producer of sulfide in the band. Members of the Bacilli class expressed high levels of rhodanese, an enzyme responsible for cyanide and sulfide detoxification. These results offer a first look at the varied functions of the microbiota in the disease mat and surrounding coral surface and enabled us to develop an improved functional model for this disease.

Integrated approach to understanding the onset and pathogenesis of black band disease in corals.

Emerging infectious diseases are contributing to global declines in coral reef ecosystems, highlighting a growing need for aetiological knowledge to develop effective management strategies. In this review, we focus on black band disease (BBD), one of the most virulent diseases and the only polymicrobial disease so far known to affect corals. A multipartite microbial consortium dominated by Cyanobacteria, but also including sulfur-cycling bacteria, other bacterial groups and members of the Archaea and Eukarya, forms a sulfide-rich anaerobic mat that migrates across the surface of coral colonies, killing the underlying tissues. The polymicrobial nature of the disease challenges classic aetiological approaches to unravelling disease causation. Here, we synthesize current knowledge on the range of pathogens forming the microbial consortium with recent studies on the transmission, biogeochemistry and environmental drivers of BBD to develop a conceptual model of BBD pathogenesis. The model illustrates how the development of BBD virulence factors is linked to a cascade of microbial community shifts and associated functional roles that progressively develop the microbial consortium from comparatively benign cyanobacterial patches to virulent BBD lesions. This review showcases how an approach that integrates multiple key aspects of the disease provides insights essential to elucidating the aetiology of BBD.

Microbial disease in coral reefs: An ecosystem in transition

Infectious disease outbreaks are considered an important factor for the degradation of coral reefs. Reef-building coral species are susceptible to the influences of black band disease (BBD), characterized by cyanobacteria-dominated microbial mat that migrates rapidly across infected corals, leaving empty coral skeletons behind. We investigate coral-macroalgal phase shift in presence of BBD infection by means of an eco-epidemiological model under the assumption that the transmission of BBD occurs through both contagious and non-contagious pathways. It is observed that in presence of low coral-recruitment rate on algal turf, reduced herbivory and high macroalgal immigration, the system exhibits hysteresis through a saddle-node bifurcation and a transcritical bifurcation. Also, the system undergoes a supercritical Hopf bifurcation followed by a saddle-node bifurcation if BBD-transmission rate crosses certain critical value. We examine the effects of incubation time lag of infectious agents develop in susceptible corals after coming in contact with infected corals and a time lag in the recovery of algal turf in response to grazing of herbivores by performing equilibrium and stability analyses of delay-differential forms of the ODE model. Computer simulations have been carried out to illustrate different analytical results.

Microbiome shifts and the inhibition of quorum sensing by Black Band Disease cyanobacteria.

Disruption of the microbiome often correlates with the appearance of disease symptoms in metaorganisms such as corals. In Black Band Disease (BBD), a polymicrobial disease consortium dominated by the filamentous cyanobacterium Roseofilum reptotaenium displaces members of the epibiotic microbiome. We examined both normal surface microbiomes and BBD consortia on Caribbean corals and found that the microbiomes of healthy corals were dominated by Gammaproteobacteria, in particular Halomonas spp., and were remarkably stable across spatial and temporal scales. In contrast, the microbial community structure in black band consortia was more variable and more diverse. Nevertheless, deep sequencing revealed that members of the disease consortium were present in every sampled surface microbiome of Montastraea, Orbicella and Pseudodiploria corals, regardless of the health status. Within the BBD consortium, we identified lyngbic acid, a cyanobacterial secondary metabolite. It strongly inhibited quorum sensing (QS) in the Vibrio harveyi QS reporters. The effects of lyngbic acid on the QS reporters depended on the presence of the CAI-1 receptor CqsS. Lyngbic acid inhibited luminescence in native coral Vibrio spp. that also possess the CAI-1-mediated QS. The effects of this naturally occurring QS inhibitor on bacterial regulatory networks potentially contribute to the structuring of the interactions within BBD consortia.

Coral population dynamics across consecutive mass mortality events.

Annual coral mortality events due to increased atmospheric heat may occur regularly from the middle of the century and are considered apocalyptic for coral reefs. In the Arabian/Persian Gulf, this situation has already occurred and population dynamics of four widespread corals (Acropora downingi, Porites harrisoni, Dipsastrea pallida, Cyphastrea micropthalma) were examined across the first-ever occurrence of four back-to-back mass mortality events (2009-2012). Mortality was driven by diseases in 2009, bleaching and subsequent diseases in 2010/2011/2012. 2009 reduced P.harrisoni cover and size, the other events increasingly reduced overall cover (2009: -10%; 2010: -20%; 2011: -20%; 2012: -15%) and affected all examined species. Regeneration was only observed after the first disturbance. P.harrisoni and A.downingi severely declined from 2010 due to bleaching and subsequent white syndromes, while D.pallida and P.daedalea declined from 2011 due to bleaching and black-band disease. C.microphthalma cover was not affected. In all species, most large corals were lost while fission due to partial tissue mortality bolstered small size classes. This general shrinkage led to a decrease of coral cover and a dramatic reduction of fecundity. Transition matrices for disturbed and undisturbed conditions were evaluated as Life TableResponse Experiment and showed that C.microphthalma changed the least in size-class dynamics and fecundity, suggesting they were 'winners'. In an ordered 'degradation cascade', impacts decreased from the most common to the least common species, leading to step-wise removal of previously dominant species. A potentially permanent shift from high- to low-coral cover with different coral community and size structure can be expected due to the demographic dynamics resultant from the disturbances. Similarities to degradation of other Caribbean and Pacific reefs are discussed. As comparable environmental conditions and mortality patterns must be expected worldwide, demographic collapse of many other coral populations may soon be widespread.

Changes in the bacterial community associated with black band disease in a Red Sea coral, Favia sp., in relation to disease phases.

Changes of the black band disease (BBD)-associated microbial consortium on the surface of a Favia sp. coral colony were assessed in relation to the different disease phases. A number of highly active bacterial groups changed in numbers as the BBD disease signs changed. These included Gamma- and Epsilonproteobacteria, Bacteroidetes and Firmicutes groups. One cyanobacterium strain, BGP10_4ST (FJ210722), was constantly present in the disease interface and adjacent tissues of the affected corals, regardless of disease phase. The dynamics of the operational taxonomic units (OTUs) of this BBD-specific strain provide a marker regarding the disease phase. The disease's active phase is characterized by a wide dark band progressing along the tissue-skeleton interface and by numerous bacterial OTUs. Cyanobacterial OTUs decreased in numbers as the disease signs waned, perhaps opening a niche for additional microorganisms. Even when black band signs disappeared there was a consistent though low abundance of the BBD-specific cyanobacteria (BGP10_4ST), and the microbial community of the disease-skeleton interface remained surprisingly similar to the original band community. These results provide an indication that the persistence of even low numbers of this BBD-specific cyanobacterium in coral tissues during the non-active (or subclinical) state could facilitate reinitiation of BBD signs during the following summer. This may indicate that this bacterium is major constituent of the disease and that its persistence and ability to infiltrate the coral tissues may act to facilitate the assembly of the other BBD-specific groups of bacteria.

Widespread occurrence of coral diseases in the central Maldives

Coral diseases are one of the most important causes of coral reef decline worldwide. Although they are well investigated in some areas of the Caribbean and the Great Barrier Reef, they have been poorly studied in the Indian Ocean, and particularly in the Maldives, where the presence of coral pathologies has been reported only recently. In order to fill this gap, we investigated the prevalence, local host range and distribution of five coral diseases, namely brown band disease, skeleton eroding band, black band disease (BBD), ulcerative white spot and white syndrome (WS), in the central part of the Maldivian Archipelago, focussing, in particular, on the dominant coral genus Acropora. We estimated an overall disease prevalence of approximately 1.51%. Malè North Atoll was the most affected area; however, coral diseases were present at all study sites. WS was the most widespread disease, whereas BBD affected the highest number of scleractinian genera. We found symptoms of disease on 18 genera belonging to eight families. Acropora was the most affected genus in terms of pathogen diversity. These results provide baseline disease levels for the Maldives and can therefore serve as gauge for monitoring future change.

The Distribution and Abundance of Black Band Disease and White Syndrome in Kepulauan Seribu, Indonesia

Coral diseases that have emerged since the early 1970s have caused significant regional ecological impacts. However, there has been a paucity of research into coral disease in South-East Asia, including Indonesia. This study provides baseline coral disease data in the Kepulauan Seribu Marine National Park. In this study we show a positive correlation between overall coral cover and the dominant reef building coral Montipora spp. and found two main diseases, black band disease (BBD) and WS, were highly prevalent throughout all reefs. Based on spatial location, the highest abundance of BBD (0.08 col./m2) was found at sites nearer (zone 1) to the mainland, whilst for WS (0.05 col./m2) highest abundance was found at middle sites (zone 2). According to the temporal data, the highest abundance of BBD (0.77 col./m2) was found during the transition period (between wet and dry seasons), whereas for WS higher abundance occurred within the dry season (0.07 col./m2). There was a significant difference in disease abundance among seasons which was correlated with increasing temperature and light intensity along with variations in total organic matters, nitrite and phosphate levels. Moreover, the middle sites experienced additional stress from the waste material originating from the mainland.

Insights into Migration and Development of Coral Black Band Disease Based on Fine Structure Analysis

<span>En muchos ecosistemas diversos, que van desde ecosistemas acuáticos hasta los intestinos de mamíferos e implantes médicos, las poblaciones y comunidades de bacterias existen como biopelículas (biofilms). El proceso de desarrollo de las biopelículas ha sido bien estudiado para aquellos producidos por bacterias unicelulares como<em> Pseudomonas aeruginosa</em>, pero se conoce muy poco acerca del desarrollo de biopelículas asociadas con microorganismos filamentosos. La Enfermedad de Banda Negra (EBN) de coral es caracterizada como una comunidad polimicrobiana que forma una biopelícula (lecho), visualmente-dominada por una cianobacteria filamentosa. El lecho migra a través de un huésped de coral vivo, rompiendo completamente el tejido del coral y dejando atrás el esqueleto de coral expuesto. Es la única biopelícula cianobacteriana que migra a través de un sustrato, por lo tanto esto genera preguntas acerca de los mecanismos y las características únicas de este sistema. Fragmentos del coral <em>Montastraea annularis</em>, cinco artificialmente infectados con EBN y dos colectados de una colonia EBN-infectada, fueron usados para abordar estas preguntas mediante exámenes detallados con microscopía electrónica de barrido y de transmisión (MEB y MET). En zonas cercanas a la interfaz de tejido del coral y la banda de la enfermedad madura, se han observado dos tipos de grupos de cianobacterias, uno con orientación aleatoria y otro con una orientación paralela de los filamentos. Este último exhibe la secreción activa de polisacáridos extra-celulares (PEC), mientras que los grupos orientados al azar no lo hicieron. Dentro de la banda de filamentos cianobacterianas bien desarrollados se observó que estaban integradas en PEC y que se presentaban como capas de cianobacteria con orientación paralela. Estas observaciones sugieren que la cianobacteria de EBN se orienta a sí misma y produce PEC en un proceso secuencial durante la migración para formar la matriz complejo de EBN.</span>

Arnfried Antonius, coral diseases, and the AMLC

<span>El estudio de las enfermedades de los corales, los patógenos de los corales y los efectos de estas enfermedades sobre los arrecifes tropicales y subtropicales son actualmente áreas importantes de investigación. El interés en este tema ha crecido continuamente desde el primer informe sobre una enfermedad de coral que se publicó en 1973. El autor de este informe fue Arnfried Antonius y la publicación fue un resumen en el Libro de Programa y Resúmenes de la Décima Reunión de la Asociación de Laboratorios Marinos Isleños del Caribe (conocida ahora como la Asociación de Laboratorios Marinos del Caribe). Desde esta comunicación pionera, Antonius siguió trabajando sobre las enfermedades de los corales en arrecifes alrededor del mundo, a menudo documentando la primera observación de una nueva enfermedad en un nuevo lugar. Cada enfermedad de coral descrita por primera vez por Antonius es actualmente el objeto de investigaciones actuales en lo que se refiere a patógenos, ecología de las enfermedades y los efectos sobre los arrecifes de coral. Muchas de las observaciones en sus trabajos tempranos siguen siendo relevantes en la investigación actual. Este trabajo examinará ciertos aspectos de los estudios tempranos de Antonius sobre las enfermedades de los corales, poniendo de relieve sus contribuciones novedosas que incluyen los primeros experimentos <em>in situ</em> que tenían como objetivo el estudio de la etiología de las enfermedades de los corales y los primeros análisis cuantitativos de la incidencia de las enfermedades de corales y de los patrones de distribución en función de los factores ambientales. Las contribuciones iniciales de Antonius se discuten en términos de las controversias actuales sobre el tema.</span>

Massive hard coral loss after a severe bleaching event in 2010 at Los Roques, Venezuela

<span>Durante las últimas décadas las anomalías térmicas han sido más frecuentes y severas en el Caribe, quedando pocos arrecifes exentos de eventos masivos de blanqueamiento (EMB). En el Parque Nacional Los Roques, Venezuela, un archipiélago poco afectado previamente por EMB, la temperatura del agua a 5m de profundidad alcanzó 30,85°C en septiembre 2010, y fue >29,0°C entre mediados de agosto y la primera semana de noviembre en cuatro arrecifes. El 72% de 563 colonias de escleractinios estaban blanqueadas o pálidas para octubre de 2010, mientras que para febrero 2011, el 46% de las colonias aún estaban afectadas. Para febrero 2011, la cobertura béntica coralina promedio disminuyó de 45 a 31%. Además, los arrecifes mostraron una alta prevalencia (de hasta 16%) de enfermedad de banda negra en Octubre 2010, y de plaga blanca (11%) en Febrero 2011. Como consecuencia, es probable que la mortalidad coralina resulte mayor a la reportada acá. Sin embargo, Los Roques es poco afectado por perturbaciones antropogénicas y cuenta con un alto reclutamiento de corales, lo cual podría contribuir a su recuperación.</span>

Identification and prevalence of coral diseases on three Western Indian Ocean coral reefs.

Coral diseases have caused a substantial decline in the biodiversity and abundance of reef-building corals. To date, more than 30 distinct diseases of scleractinian corals have been reported, which cause progressive tissue loss and/or affect coral growth, reproductive capacity, recruitment, species diversity and the abundance of reef-associated organisms. While coral disease research has increased over the last 4 decades, very little is known about coral diseases in the Western Indian Ocean. Surveys conducted at multiple sites in Reunion, South Africa and Mayotte between August 2010 and June 2012 revealed the presence of 6 main coral diseases: black band disease (BBD), white syndrome (WS), pink line syndrome (PLS), growth anomalies (GA), skeleton eroding band (SEB) and Porites white patch syndrome (PWPS). Overall, disease prevalence was higher in Reunion (7.5 ± 2.2%; mean ± SE) compared to South Africa (3.9 ± 0.8%) and Mayotte (2.7 ± 0.3%). Across locations, Acropora and Porites were the genera most susceptible to disease. Spatial variability was detected in both Reunion and South Africa, with BBD and WS more prevalent on shallow than deep reefs. There was also evidence of seasonality in 2 diseases: the prevalence of BBD and WS was higher in summer than winter. This was the first study to investigate the ecology of coral diseases, providing both qualitative and quantitative data, on Western Indian Ocean reefs, and surveys should be expanded to confirm these patterns.

First record of black band disease in the Hawaiian archipelago: response, outbreak status, virulence, and a method of treatment.

A high number of coral colonies, Montipora spp., with progressive tissue loss were reported from the north shore of Kaua‘i by a member of the Eyes of the Reef volunteer reporting network. The disease has a distinct lesion (semi-circular pattern of tissue loss with an adjacent dark band) that was first observed in Hanalei Bay, Kaua‘i in 2004. The disease, initially termed Montipora banded tissue loss, appeared grossly similar to black band disease (BBD), which affects corals worldwide. Following the initial report, a rapid response was initiated as outlined in Hawai‘i’s rapid response contingency plan to determine outbreak status and investigate the disease. Our study identified the three dominant bacterial constituents indicative of BBD (filamentous cyanobacteria, sulfate-reducing bacteria, sulfide-oxidizing bacteria) in coral disease lesions from Kaua‘i, which provided the first evidence of BBD in the Hawaiian archipelago. A rapid survey at the alleged outbreak site found disease to affect 6-7% of the montiporids, which is higher than a prior prevalence of less than 1% measured on Kaua‘i in 2004, indicative of an epizootic. Tagged colonies with BBD had an average rate of tissue loss of 5.7 cm2/day over a two-month period. Treatment of diseased colonies with a double band of marine epoxy, mixed with chlorine powder, effectively reduced colony mortality. Within two months, treated colonies lost an average of 30% less tissue compared to untreated controls.

Prevalence, Insidence and Progression Black-band Disease on Scleractinian Coral (Montipora spp) in Shallow Water of Pari Islands

Black-band disease (BBD) is a persistent disease that cause the decline of the coral reef ecosystems, which is still slightly recorded in Indonesia, including in Pari Island, Thousand Islands. The objectives of this study were to determine progression, prevalence and incidence BBD on Montipora spp in shallow water of Pari Islands. Coral cover were estimated using line intercept transect (LIT) whereas the prevalence and incidence of BBD were carried out by using belt transect method with 1 m left and right of tape as long 20 m with 3 replications recorded approximately every two months. BBD progression was documented with a digital photograph method, the photograph of affected area of each coral was taken each day for 2 weeks. BBD was found to be spread in the surveyed area. The result show that prevalence and incidence of BBD showed a positive exponential relationship with water temperature. During the observation Both prevalence and incidence increased on May transitional season (wet-dry). The highest prevalence was found at 5,96 percent and whereas the maximum disease progression found at 0,46 cm/day.

Overview of Aquatic Animal Diseases in Andaman and Nicobar Islands

Andaman and Nicobar Islands are pristine in nature and blessed with a variety of species diversity in general as well as aquatic resources in specific. The three facets of aquatic environment namely, freshwater, brackishwater and marine resources are not fully tapped to the potential and therefore have further scope for improvement. At present, only freshwater carp farming is being practiced in the Bay Islands while brackishwater aquaculture and mariculture are the identified areas for development. Diseases are the major constraints for the development in aquaculture sector. The present study reviews the work carried out till date on the disease aspects of aquatic animals. Abdominal dropsy from freshwater fishes, pop-eye disease, trematode and cestode infestations from marine fishes, White Spot Syndrome Virus (WSSV) and luminescent vibriosis from crustaceans and necrotic patches, yellow spot disease, pink line syndrome, white line syndrome, white plague, black band disease, tissue lesion, ring line syndrome and abnormal growth from corals have been reported from Andaman and Nicobar Islands. It is interesting to find that the pathogens like virus, bacteria, fungi and parasites were reported from these aquatic animals in the Island ecosystem. This is in contrast to our perception considering the virgin status of the Island. The scanty information available at present on the aquatic animal diseases itself has listed out all the possible diseases which would serve as a base for further studies in future. Therefore, it is the need of the hour to carry out a systematic study on the aquatic animal diseases of Bay Islands. Early detection of the diseases and rapid response to the identified diseases are critical for the effective management of aquatic animal disease emergencies in the Island ecosystem.

MICROBIAL COMMUNITY OF BLACK BAND DISEASE ON INFECTION, HEALTHY, AND DEAD PART OF SCLERACTINIAN Montipora sp. COLONY AT SERIBU ISLANDS, INDONESIA

It is crucial to understand the microbial community associated with the host when attempting to discern the pathogen responsible for disease outbreaks in scleractinian corals. This study determines changes in the bacterial community associated with Montipora sp. in response to black band disease in Indonesian waters. Healthy, diseased, and dead Montipora sp. (n = 3 for each sample type per location) were collected from three different locations (Pari Island, Pramuka Island, and Peteloran Island). DGGE (Denaturing Gradient Gel Electrophoresis) was carried out to identify the bacterial community associated with each sample type and histological analysis was conducted to identify pathogens associated with specific tissues. Various Desulfovibrio species were found as novelty to be associated with infection samples, including Desulfovibrio desulfuricans, Desulfovibrio magneticus, and Desulfovibrio gigas, Bacillus benzoevorans, Bacillus farraginis in genus which previously associated with pathogenicity in corals. Various bacterial species associated with uninfected corals were lost in diseased and dead samples. Unlike healthy samples, coral tissues such as the epidermis, endodermis, zooxanthellae were not present on dead samples under histological observation. Liberated zooxanthellae and cyanobacteria were found in black band diseased Montipora sp. samples.

Ecology and Physiology of the Pathogenic Cyanobacterium Roseofilum reptotaenium.

Roseofilum reptotaenium is a gliding, filamentous, phycoerythrin-rich cyanobacterium that has been found only in the horizontally migrating, pathogenic microbial mat, black band disease (BBD) on Caribbean corals. R. reptotaenium dominates the BBD mat in terms of biomass and motility, and the filaments form the mat fabric. This cyanobacterium produces the cyanotoxin microcystin, predominately MC-LR, and can tolerate high levels of sulfide produced by sulfate reducing bacteria (SRB) that are also associated with BBD. Laboratory cultures of R. reptotaenium infect coral fragments, suggesting that the cyanobacterium is the primary pathogen of BBD, but since this species cannot grow axenically and Koch’s Postulates cannot be fulfilled, it cannot be proposed as a primary pathogen. However, R. reptotaenium does play several major pathogenic roles in this polymicrobial disease. Here, we provide an overview of the ecology of this coral pathogen and present new information on R. reptotaenium ecophysiology, including roles in the infection process, chemotactic and other motility responses, and the effect of pH on growth and motility. Additionally, we show, using metabolomics, that exposure of the BBD microbial community to the cyanotoxin MC-LR affects community metabolite profiles, in particular those associated with nucleic acid biosynthesis.

Slow progression of black band disease in Goniopora cf. columna colonies may promote its persistence in a coral community

Coral diseases have been little investigated in the Indian Ocean and especially in the Republic of Maldives, where they were firstly observed in 2010. Through repeated monitoring, we observed a peculiar slow progression of Black Band Disease in several large colonies of the reef-building coral Goniopora cf. columna in the Maldivian reefs of Magoodhoo Island (Faafu Atoll). We argue that this may ensure the local persistence of the disease, possibly promoting long-term mortality of other, more susceptible coral species.

Quorum sensing signal production and microbial interactions in a polymicrobial disease of corals and the coral surface mucopolysaccharide layer.

Black band disease (BBD) of corals is a complex polymicrobial disease considered to be a threat to coral reef health, as it can lead to mortality of massive reef-building corals. The BBD community is dominated by gliding, filamentous cyanobacteria with a highly diverse population of heterotrophic bacteria. Microbial interactions such as quorum sensing (QS) and antimicrobial production may be involved in BBD disease pathogenesis. In this study, BBD (whole community) samples, as well as 199 bacterial isolates from BBD, the surface mucopolysaccharide layer (SML) of apparently healthy corals, and SML of apparently healthy areas of BBD-infected corals were screened for the production of acyl homoserine lactones (AHLs) and for autoinducer-2 (AI-2) activity using three bacterial reporter strains. AHLs were detected in all BBD (intact community) samples tested and in cultures of 5.5% of BBD bacterial isolates. Over half of a subset (153) of the isolates were positive for AI-2 activity. AHL-producing isolates were further analyzed using LC-MS/MS to determine AHL chemical structure and the concentration of (S)-4,5-dihydroxy-2,3-pentanedione (DPD), the biosynthetic precursor of AI-2. C6-HSL was the most common AHL variant detected, followed by 3OC4-HSL. In addition to QS assays, 342 growth challenges were conducted among a subset of the isolates, with 27% of isolates eliciting growth inhibition and 2% growth stimulation. 24% of BBD isolates elicited growth inhibition as compared to 26% and 32% of the bacteria from the two SML sources. With one exception, only isolates that exhibited AI-2 activity or produced DPD inhibited growth of test strains. These findings demonstrate for the first time that AHLs are present in an active coral disease. It is possible that AI-2 production among BBD and coral SML bacteria may structure the microbial communities of both a polymicrobial infection and the healthy coral microbiome.