Coloured Pigments and Coral Bleaching?

[Simon Dunn]

Just as another comment to this is that the level of tissue degradation
resulting in bleaching may account for the level of MAA's / GFP's
remaining
and hence host pigmentation. Localization of GFP's can be concentrated
within the endoderm such as with Goniopora sp. so with the degradation
of
the endoderm and release of zooxanthellae during environmental stress
there
may be little or no MAA's / GFP's remaining resulting in a more
'whitened'
appearance. However some species have MAA's / GFP's concentrated within
the
ectoderm such as Discosoma sp., hence when bleaching occurs they may
retain
the MAA / GFP pigmentation after the zooxanthellae density is reduced.
Obviously different levels of stress, whether solar or thermal may
result
in different proportions of zoox and MAA's/GFPs and also host
pigmentation
may not be purely associated with GFPs. If anyone has any information
regarding non-GFP host pigmentation I would also be very interested.

At 16:48 28/05/02 +0100, you wrote:
>>===== Original Message From "Mike Matz" <matz at whitney.ufl.edu> =====
>Good question! I myself saw a case when the animal was bleached, but
>retained red fluorescent coloration. This was not on the reef, though -
this
>was a specimen of corallimorph shipped over from Vietnam, on aquarium
>business. The bleaching was apparently a consequence of some stress
>conditions during shipping. By the way, that guy recovered nicely after
>that - regained brown coloration in a week or so in aquarium. It is from
>this specimen we cloned the first red-emitting GFP-like protein. The funny
>thing is - if the specimen was not bleached upon arrival, we would probably
>overlook the red fluorescence of the host tissue, it becomes really
>inconspicious as soon as the brown color is back.
>
>The fact that corals go completely white upon bleaching on reefs, with no
>host-tissue colors remaining, might be a consequence of much worse stress
>than my aquarium corallimorph suffered. But still, this completeness of
>bleaching does seem weird to me. The dissapearance of host pigments might
be
>linked to zooxanthellae loss, but just as well, it might not. I am not
aware
>of any reports that would address this.
>
>Please share your opinions.
>
>Mike
>
>-----
>Mikhail V. Matz, Ph.D.
>
>Whitney Laboratory
>University of Florida
>9505 Ocean Shore blvd
>St Augustine FL 32080-8610, USA
>phone +1 904 461 4025
>fax +1 904 461 4008
>
>
>
>----- Original Message -----
>From: "Rupert Ormond" <rupert.ormond at millport.gla.ac.uk>
>To: <coral-list at coral.aoml.noaa.gov>
>Sent: Tuesday, May 28, 2002 5:48 AM
>Subject: Coloured Pigments and Coral Bleaching?
>
>
>> Dear Coral Listers
>>
>> I would be grateful if any of the coral physiologists involved in
>bleaching
>> work could offer any details on a question that's been put to me a couple
>> of times.
>>
>> The colourful pigments (blues, pinks etc.) that are charateristic of many
>> shallow water corals (Acropora etc.) are, as I understand it, located in
>> the coral tissue itself.  Whereas the pigments present in the
>zooxanthellae
>> are more or less brown in colour.  If coral bleaching (due to elevated
>> SSTs) is principally the result of expulsion or loss of zooxanthellae,
>then
>> why do the corals go completely white.  i.e. what happens to the more
>> colourful coral pigments? Are they damaged as well but independently by
>> temperature induced failure of protective systems?
>>
>> sincerely,
>>
>> Rupert Ormond
>>
>>
>>
>>
>> Dr. Rupert Ormond
>> Director,
>> University Marine Biological Station Millport,
>> Isle of Cumbrae,
>> SCOTLAND
>> UK  KA28 0EG
>>
>> email: rupert.ormond at millport.gla.ac.uk
>> tel: (44)-01475-530581
>> fax: (44)-01475-530601
>> web: http://www.gla.ac.uk/Acad/Marine/
>>
>>
>>
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>
>
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>
Simon R Dunn
School of Biological Sciences
University of Liverpool
Life Sciences Building
Crown Street            Tel: 0151 794-4373
Liverpool               Fax: 0151 794-4393
L69 7ZB                 Email: sidunn at liv.ac.uk
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