[Coral-List] Cold Water Bleaching

[Gene Shinn]

Dear Zoe, Thanks for the observation of cold water bleaching. In the 
Paper by Hudson et al., (  Hudson, J. H., Shinn, E. A., Halley, R. 
B., and Lidz, B., 1976, Sclerochronology--a tool for interpreting 
past environments: Geology, v. 4, p. 361-364 ) it was noted that 
there was a distinct stress band that formed in 1942 in M. annularis 
at Hens and Chickens reef off Key Largo, Florida. In fact the same 
stress band was later found in many other M. annularis heads 
throughout the Keys. Hudson  therefore concluded it was a cold water 
stress band because it looked like the stress band created by the 
freeze of 1969/70 that killed most of the 200-year-old heads at Hens 
and Chickens. That cold spell also decimated tropical fish in the 
Keys. At the time he did that research no warm water bleaching event 
had occurred and thus no one knew what record a bleaching event 
preserved in the coral skeleton.  When we did finally did get to see 
the recorded stress bands produced by bleaching in the 1980s it 
looked just like stress band made in 1942. That seemed logical since 
that was during a period of world wide warming. However, I  recently 
had some Carbon and Oxygen isotope measurements done on the the 
banding formed before, during, and after 1942, to see if it would 
confirm a warming event. The data did not confirm a warm water 
bleaching event.  Hudson's original interpretation therefore was 
likely correct. It also confirmed my mothers observation that the 
winter of 1942 in Key West was so cold that people tore up and burned 
wooden sidewalks to keep warm. Gene

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>    1. cold water bleaching (Zoe Richards)
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>----------------------------------------------------------------------
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>Message: 1
>Date: Fri, 16 May 2008 10:01:59 +1000 (EST)
>From: Zoe Richards <zoe.richards at jcu.edu.au>
>Subject: [Coral-List] cold water bleaching
>To: coral-list at coral.aoml.noaa.gov
>Message-ID: <20080516100159.BRJ83806 at mirapoint-ms1.jcu.edu.au>
>Content-Type: text/plain; charset=us-ascii
>
>Hi Alan and coral-listers,
>I find the concept of cold-water bleaching very interesting.
>I observed what appeared to be cold-water bleaching at Orpheus 
>Island on the Great Barrier Reef in August (Winter) of 2005. 
>Preceding this observation was two weeks of very strong SE trade 
>winds that brought cold southerly waters far north along the East 
>Australian coastline - these conditions also caused a large amount 
>of coastal erosion along the northern beaches of Townsville.   I 
>observed bleaching in three bays (little Pioneer, Pioneer and 
>Cattle) and it appeared only shallow water (<5m) Acropora species 
>(e.g. A. millepora) were affected. When I returned 2 months later 
>there were no apparent signs of the bleaching event - so it was my 
>impression at the time that the corals recovered.
>Hope this adds to the global picture of cold-water bleaching events 
>and inspires people to incorporate cold-water bleaching in future 
>bleaching experiments.
>
>Cheers Zoe Richards
>
>James Cook University
>zoe.richards at jcu.edu.au
>
>
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>End of Coral-List Digest, Vol 59, Issue 15
>******************************************


-- 


No Rocks, No Water, No Ecosystem (EAS)
------------------------------------ -----------------------------------
E. A. Shinn, Courtesy Professor
University of South Florida
Marine Science Center (room 204)
140 Seventh Avenue South
St. Petersburg, FL 33701
<eshinn at marine.usf.edu>
Tel 727 553-1158---------------------------------- 
-----------------------------------