Billy Causey's email on dissolved oxygen

David Blakeway blakeway at
Mon Aug 28 02:38:57 EDT 2000

Hello coral-listers,
I believe Billy could be right in considering dissolved oxygen depletion to be a 
cause of some coral bleaching and mortality. I attributed bleaching and 
mortality of Acropora and Montipora spp. at some of my PhD sites in the Houtman 
Abrolhos Islands, Western Australia to oxygen depletion. The sites are deep (10 
to 30m) depressions in the reef. DO concentrations below 1 mg/L in some 
instances. Transplanted Acropora branches bleached and died within a week at 
DO's of 2 to 4 mg. Handling controls suffered no (visible) ill effects. I can't 
be sure that oxygen depletion was responsible, as other variables were 
uncontrolled. Water temperature was only 24 deg C though. Is anybody doing any 
controlled field or lab experiments?
I still feel that temperature is critical in many cases. I have a Hydnophora 
pilosa colony in an aquarium that bleaches as soon as water temperature exceeds 
28 deg C, but recovers at lower temperatures. The aquarium has strong 
circulation, so the colony ?should be getting plenty of oxygen.


David Blakeway
Institute for Regional Development
University of Western Australia
Nedlands WA 6907

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