Populations of the shallow-water Caribbean elkhorn coral, Acropora palmata, are being decimated by white pox disease, with losses of living cover in the Florida Keys typically in excess of 70%. The rate of tissue loss is rapid, averaging 2.5 cm 2 ⅐day ؊1 , and is greatest during periods of seasonally elevated temperature. In Florida, the spread of white pox fits the contagion model, with nearest neighbors most susceptible to infection. In this report, we identify a common fecal enterobacterium, Serratia marcescens, as the causal agent of white pox. This is the first time, to our knowledge, that a bacterial species associated with the human gut has been shown to be a marine invertebrate pathogen.

Black-band disease affects many species of tropical reef-building corals, but it is unclear what factors contribute to the disease-susceptibility of individual corals or how the disease is transmitted between colonies. Studies have suggested that the ability of black-band disease to infect coral is enhanced by different stressors. We examined the effect of both water temperature and mechanical injury on the ability of this disease to infect the reef coral Montastraea faveolata, and investigated the possibility of an interaction between the 2 stressors. Under laboratory conditions, Phormidium corallyticum was able to successfully invade all injured fragments but no uninjured fragments of M. faveolata, irrespective of temperature regime. We also determined whether the local coral-feeding butterflyfish Chaetodon capistratus was involved in the inter-colony transfer of black-band disease. In aquaria, the presence of C. capistratus increased the rate at which the disease spread from infected to non-infected fragments of M. faveolata. Both corals that were protected from and those that were exposed to fish predation contracted the disease. Hence, either direct oral transmission of the pathogen from colony to colony and/or indirect fecal transmission could be occurring. Variables such as potential stressors and/or disease vectors on a reef could contribute to the patterns of blackband disease observed in the field.

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Abstract. The cyanophyte (Cyanobaclerium) that causes black band disease of Atlantic reef corals is described under the name Phormidium corallyticum, new species (family Oscillatoriaceae), and its generic placement is discussed from the standpoint of the GEITLERian (classical) and Drouet systems. Distinguishing characters include densely interwoven filaments that form a blackish mat and trichomes without significant cell wall constrictions, almost isodiametric cells (4.2 μm mean width, 4.0μm mean length) tapering end cells, and thin (0.1 μm or less) mucilaginous wall coating. Transmission electron microscopy shows typical cyanophyte cell walls, sheath, nucleoplasm, and cytoplasmic inclusions, but an unusual thylakoid of straight, and, as seen in cell cross section, radiating lamellae. The dark coloration is due to a high concentration of phycocyanin and some phycoerythrin. The species is similar to Oscillatoria (=Phormidium) submembranacea, which differs in several morphological features and does not infect coral tissue. It is concluded that Phormidium should be used for this and related species that have external mucilage but not the distinct sheath found in Lyngbya.

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Heterotrophic bacteria associated with the Caribbean sclerosponge, Ceratoporella nicholsoni (Hickson), were found to occur extracellularly and were confined to the mesohyl regions of the sponge tissue. Physiological, metabolic, and morphological attributes of the culturable bacteria associated with the sponge were recorded by using numerical taxonomy methods for the analysis of 158 phenotypic attributes. Morphometric methods were used to determine the proportion of the total sponge-associated bacteria that were culturable by the methods employed, with the results ranging from 3 to 11% of the total bacteria inhabiting the sponge. Approximately 78% of the culturable bacteria clustered into four groups or phena, representing two previously undescribed Vibrio spp., an Aeromonas sp., and a coryneformor actinomycete-like sp. Most of the bacteria were facultative anaerobes, fermenting sucrose and fucose but unusual in an inability to ferment glucose. This study was the first comprehensive study of heterotrophic bacteria associated with a sponge from the Caribbean basin, a region reputed to contain the most prolific sponge populations, with respect to biomass and diversity. The possible significance of these associations is discussed.

The destruction of coral reef habitats has occurred at unprecedented levels during the last three decades. Coral disease and bleaching in the Caribbean and South Florida have caused extensive coral mortality with limited recovery, often coral reefs are being replaced with turf algae. Acroporids were once dominant corals and have diminished to the state where they are being considered as endangered species. Our survey assessed the condition of reef corals throughout South Florida. A probability-based design produced unbiased estimates of the spatial extent of ecological condition, measured as the absence or presence and frequency or prevalence of coral diseases and bleaching intensity over large geographic regions. This approach allowed us to calculate a quantifiable level of uncertainty. Coral condition was estimated for 4100 hectares (ha) (or 41.0 km2) of coral reefs in South Florida, including reefs in the Florida Keys National Marine Sanctuary (FKNMS), New Grounds, Dry Tortugas National Park (DTNP), and Biscayne National Park (BNP). The absence or presence of coral disease, 'causal' coral bleaching, partial bleaching and coral paling were not good indicators of overall coral condition. It was more useful to report the prevalence of anomalies that indicated a compromised condition at both the population and community levels. For example, 79% of the area in South Florida had less than 6% of the coral colonies diseased, whereas only 2.2% (97.15 ha) of the sampled area had a maximum prevalence of 13% diseased coral colonies at any single location. The usefulness of 'causal bleaching' might be more important when considering the prevalence of each of the three different states at a single location. For example, paling was observed over the entire area, whereas bleaching and partial bleaching occurred at 19 and 41% of the area, respectively. An index for coral reef condition might integrate the prevalence and species affected by each bleaching state at individual locations. By establishing these baselines, future surveys can examine changes and trends in the spatial distribution of coral conditions in South Florida and able to score the reefs as to their health status.