Oxygen and sulfide dynamics in a horizontally migrating cyanobacterial mat: Black band disease of corals

Abstract

Black band disease is caused by a horizontally migrating microbial consortium which overgrows and kills reef‐building corals in many areas of the world. The cyanobacterium Phormidium corallyticum, the sulfide‐oxidizing bacterium Beggiatoa sp., fungi, and sulfate‐reducing bacteria dominate the consortium, which is generally several mm to 1 cm in width and ca. 1 mm in thickness. Microelectrode measurements revealed photosynthetically produced O2‐supersaturation in upper layers during day, although conditions at the band‐coral interface were consistently anoxic and, at night, sulfide‐rich. Diel distributions of oxygen and sulfide resembled those from cyanobacterial mats in sulfur springs, intertidal mats and hypersaline lagoons.

Coral and macroalgal exudates vary in neutral sugar composition and differentially enrich reef bacterioplankton lineages

“…The etiologies of marine diseases frequently cannot be determined (Rosenberg et al, 2009). Thus, polymicrobial (Carlton and Richardson, 1995;Cooney et al, 2002) and opportunist pathogens (Harvell et al, 1999) are becoming more important in our understanding of emerging diseases in the marine environment. Our results support the idea that coral-algal phase shifts result in more algal-released DOM and that these labile resources stimulate bacterioplankton growth (potentially causing localized hypoxia) and select for potential opportunistic pathogens, which may directly increase coral disease.…”

Dynamics of seasonal outbreaks of black band disease in an assemblage of Montipora species at Pelorus Island (Great Barrier Reef, Australia)

“…Although an optimal temperature for the ubiquitous BBD Oscillatoria has not been reported thus far, the summer outbreaks of BBD reported here indicate that higher temperatures may also be favourable for this strain. Increased cyanobacterial biomass under higher temperatures may be important in BBD pathogenesis by increasing local cyanotoxin production ) and/or generating dynamic vertical micro-gradients of oxygen and sulphide, which have been implicated in coral tissue degeneration (Carlton & Richardson 1995;Richardson et al 1997).…”

“…A range of micro-organisms have been identified from the characteristic disease band, including cyanobacteria, sulphate-reducing Desulfovibrio bacterial species, sulphide-oxidizing Beggiatoa bacterial species, a marine fungus and other heterotrophic microbes (reviewed in Richardson 2004). These micro-organisms maintain a tightly organized synergistic community that causes host tissue necrosis (Carlton & Richardson 1995;Richardson 2004). Identification of the primary causative agent of BBD has been difficult, although complex microbial associations within the microbial mat suggest that the BBD is a polymicrobial disease.…”

“…High light has been demonstrated to elicit an immediate behavioural response in the microbial community, causing upward migration of Beggiatoa spp. within the cyanobacterium dominated BBD mat and shifting vertical gradients of oxygen and sulphide, which potentially contribute to pathogenesis (Carlton & Richardson 1995;Viehman & Richardson 2002). While these studies suggest that seasonal fluctuations in light intensity may affect the virulence of BBD, the role of annual photoperiod cycles in driving BBD outbreak dynamics has not been previously tested.…”

Successional changes in bacterial communities during the development of black band disease on the reef coral, Montipora hispida

“…Pathogenesis of BBD is currently thought to involve light-associated, vertical microgradients in oxygen and sulfide (Carlton and Richardson, 1995), accompanied by down-migration of the filamentous cyanobacteria when light levels are high (Richardson, 1996;Viehman and Richardson, 2002). Subsequent cyanobacterial penetration of coral tissue (Barneah et al, 2007) suggests that mechanical and/or chemical degeneration of coral tissue is also involved in pathogenicity.…”