Australian Institute of Marine Science

Australian Institute of Marine Science

 
 

Copyright ©1996-2008

 

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

 

Skeletal Eroding Band

Skeletal Eroding Band (SEB) is somewhat unique in that it is a disease of hard corals that was first found in the Indo-Pacific26,28 and so far has not been described from the Caribbean5. A sessile protozoan (a folliculinid heterotrich ciliate, Halofolliculina corallasia) that resides in a secreted black sac-like test called a lorica is considered to be the cause of the disease. Clusters of ciliates in lorica form a line between live coral and dead coral giving a strong superficial resemblance to Black Band Disease. However the empty lorica on the white coral skeleton behind the dark band give a dotted appearance to the dead zone and can be used to visually distinguish SEB from BBD26. The disease progresses when the protozoan produces motile larvae asexually. The larvae move ahead of the band onto the living coral tissue, locate a site suitable to take up residence and proceed to secrete a lorica of their own.

Damage to the coral’s skeleton and tissue death come about as a result of a combination of chemicals associated with the production of the new lorica and the physical drilling of the lorica into the coral skeleton29.

On the GBR SEB has been observed to affect 31 species of corals from 6 families with the majority of incidences recorded from Acroporidae, Pocilloporidae, Poritidae and Favidae6. The AIMS LTMP has only been monitoring SEB over the last two years so little can be said on how the prevalence of the disease is changing through time.

However the data set does allow a picture of the current spatial distribution of the disease on the GBR. SCUBA search surveys in 2005 show that SEB is spread throughout the GBR.

Close up view of skeletal eroding band disease.

Image 6. Close up view of skeletal eroding band disease on Acropora sp. hard coral. From the centre the ciliates have started to spread over all adjacent branches of the coral simultaneously and the loricae are clearly visible.
(Photograph from Winkler et al. 2004)
Click here for a larger view

It is most commonly found in the Cooktown/Lizard Island sector of the GBR with another less intense area of activity with smaller numbers of colonies affected in the Swain sector. Of the other reef sectors surveyed SEB proved to be a relatively rare occurrence (Graph 9). It is also apparent that SEB appears to be more common on inner and midshelf reefs rather than outer shelf reefs (Graph 10).

Graph 9. Mean (SE) number of colonies recorded as showing signs of SEB per survey reef for each of the six LTMP survey sectors in 2005. CL = Cooktown/Lizard Island, CA = Cairns, TO = Townsville, WH = Whitsunday, SW = Swain, CB = Capricorn-Bunker.

Graph 10. Mean (SE) number of colonies recorded as showing signs of SEB per shelf position in 2005.

 

 


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

For further information contact
Ian Miller
, AIMS
Telephone: +61 7 4753 4471
Email:
i.miller@aims.gov.au


December 18, 2008