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Coral
Disease Identification and Information Main | Comparison | Etiology Disease Overview Bleaching caused by a specific bacterial infection (as opposed to a response to environmental stress) occurs when loss of zooxanthellae is due to a toxin produced by the intracellular bacterial pathogen. Bacterial bleaching occurs in the Mediterranean scleractinian coral Oculina patagonica by the Vibrio shilonii pathogen and in the Indian Ocean and in the Red Sea coral Pocillopora damicornis by the Vibrio coralliilyticus pathogen (Ben-Haim et al., 2002, in press) . Initial pathogen attachment to coral is specific to a b-galactose containing receptor in the coral host surface mucopolysaccharide layer. Subsequent invasion of coral host tissue is followed by temperature dependent intracellular growth of bacteria. Production of a heat sensitive toxin results in lysis of the zooxanthellae. Disease signs consist of loss of zooxanthellae, with coral tissue intact, and differs from environmental bleaching in that Vibrio shilonii or Vibrio coralliilyticus are present in the affected tissue. The reservoir is not known. (See Kushmaro et al., 1996, 1998; Ben-Haim et al., 1999, 2002, in press; Banin et al., 2000, 2001, in press.)
Bacterial Bleaching
Bacterial bleaching is caused by a specific bacterial/coral interaction. Specificity includes recognition by the pathogen of host (coral) surface receptors; invasion of coral tissue; multiplication of bacteria in coral tissue; and release of bacterial toxins that cause bleaching.
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