End of summer coral bleaching.

[Ray Berkelmans]

Hello Shaker! (and C-listers)

They breed corals tough where you come from! But obviously still not tough
enough...
Your observations about increasing bleaching while temperatures cool are
very interesting. These sound remarkably like the observations we made at
Hardy Reef on the GBR (offshore) in early 1998. Temperatures peaked at
29.9°C (av. daily) on 23-24 Feb, but bleaching was not observed until 13
March (18 days later), well after temperatures had cooled. Bleaching was
only mild, suggesting that the bleaching threshold was only exceeded by a
relatively small amount (& probably for a short duration). Observations
about the state of the corals were made every day by a biologist (Jackie
Shields) aboard a tourist vessel. To me these observations suggest that
there may be a delay in the onset of bleaching (at least visible symptoms of
bleaching) following stress. Observations of bleaching and temperatures at
other sites indicate that this delay is considerably reduced (or absent)
when stress temperatures are exceeded by a large amount. These field
observations are consistent with the delayed bleaching response I reported
in Coral Reefs (18:219-228) following experimentally induced temperature
stress. Does any one else have similar observations?

Ray Berkelmans
AIMS
PMB 3
Townsville Q4810
Ph 47534268

 -----Original Message-----
From: 	owner-coral-list at coral.aoml.noaa.gov
[mailto:owner-coral-list at coral.aoml.noaa.gov]  On Behalf Of Shaker Alhazeem
Sent:	Wednesday, 20 September 2000 9:18 PM
To:	Coral List
Subject:	End of summer coral bleaching.

Dear Coral-Listers,

Kuwait is experiencing a major coral bleaching event now. Bleaching is
occurring in excess of about 80% in some areas.  The phenomenon is
recent having started within the last week. This is the end of the hot
season so temperature had fluctuated last week, so temperature shock
most likely was the effect on corals. The water temperature was around
32°C on the time of observing coral bleaching.
About three weeks ago I have visited Kubbar island coral reef in Kuwait
in August 12th 2000. I have found there was about 10% bleached coral
colonies and water temperature was 35°C.  But this visit last weekend
the coral was bleached about 80% and water temperature around 32°C in
September 14th 2000. But Quro coral reef had showed about 40% coral
bleaching only, that could be for the reason it is less stressed coral
around in Quro, as it is farther away from the coast so less human
impact. Last week we had sudden drop in the temperature and it came back
up after that week, which could be the real cause of the coral bleaching
is temperature shock.

With Best Wishes,

Shaker Alhazeem

Research Associate
Mariculture and Fisheries Dept.
Kuwait Institute for Scientific Research
P.O. Box : 1638
22017 Salmiya - Kuwait
Fax : (965) 5711293
Email: shazeem at safat.kisr.edu.kw