Coral Diseases on the Great Barrier Reef
Patterns of distribution and changes in abundance
of Hard Coral Disease

Black Band Disease

Black Band Disease (BBD) is characterised by a black-band (usually 5-30mm wide) separating living coral tissue from the recently exposed white coral skeleton⁷. BBD was first described from the Caribbean in the early 1970’s¹², and first recorded on the GBR in 1992⁹. BBD has been described on 45 coral species in 8 families in the wider Indo-Pacific⁵ and locally from 21 species in five families on Lizard Island on the GBR¹³. The black-band is actually a consortium of microorganisms dominated by Phormidium corallyticum (a gliding filamentous cyanobacteria), but also including heterotrophic bacteria, other types of bacteria (including sulphide-oxidising Beggiatoa and sulphate-reducing Desulfovibrio) and fungus¹⁴.

While the causative agent was originally considered to be Phormidium corallyticum15 more recent studies have thrown some doubt on the true nature of the infection. For instance rDNA analysis of bacterial mats from different locations has indicated a lack of concordance in cyanobacteria inhabiting the mat with up to three unidentified taxa of cyanobacteria and P. corallyticum, the putative causative agent, not detected in some cases16,17,18. There have also been distinct differences, in the cyanobacterial taxa inhabiting the black-band, found between Caribbean and Indo-Pacific corals18. Though the process of infection may not be well understood once the consortium is established production of the lethal gas H2S by Desulfovibrio is considered responsible for the ongoing mortality of the coral tissue and the spread of the consortium across the coral colony. On the GBR BBD remains relatively rare (Graph 1) with less than one colony exhibiting signs of the disease (recorded on average) on any reef surveyed using SCUBA as part of the LTMP. It is also apparent that the disease occurs throughout the entire reef complex and often exists at low levels on apparently healthy reefs (Graph 2). The data also indicate that BBD tends to occur more often on inner and midshelf reefs than outer shelf reefs (Graph 3). Using presence absence data collected during broadscale surveys we can also gain some idea of where BBD occurs around the reef perimeter.

Image 2 Photograph showing the characteristic sign of Black Band Disease on a Pachyseris sp. hard coral colony. Photograph AIMS LTMP Click here for a larger view Image 3 Photomicrograph of the consortium found in a Black Band taken from an Acropora sp. hard coral on  the GBR. The arrow points to the filamentous cyanobacterium Phormidium corallyticum that is an important inhabitant of the band. Photograph courtesy Leigh Owens JCU Click here for a larger view

Graph 1. Mean (SE) number of colonies recorded as showing signs of BBD per survey reef from 1999 to 2005.

Graph 2. Mean (SE) number of colonies recorded as showing signs of BBD per survey reef for each of the six LTMP survey sectors (includes all surveys from 1999-2005). CL = Cooktown/Lizard Island, CA = Cairns, TO = Townsville, WH = Whitsunday, SW = Swain, CB = Capricorn-Bunker.

Graph 3. Mean (SE) number of colonies recorded as showing signs of BBD per shelf position (includes all surveys from 1999-2005).

Graph 4. Presence absence data recorded during manta tow surveys. BBD is more commonly found on the back and first flank of reefs surveyed. (Pearson Chi-square P = 0.009).

 CONTENTS
   Introduction | Black Band Disease | White Syndrome | Skeletal Eroding Band
  Brown Band | Skeletal tumours | Atramentous necrosis
  Porites Pinking | Vibrio Induced Bleaching
  References | Content navigation