[Coral-List] Has the death of the Great Barrier Reef been greatly, exaggerated??

Brodie, Jon jon.brodie at jcu.edu.au
Wed Oct 26 19:07:45 EDT 2016

The current GBR reefs are indeed only about 10,000 years old max. but actually overlie Pleistocene reefs from the last 500,000 years. So while the Holocene reef may only be metres thick the whole structure may be up to 100m thick of carbonate until the basement rock is reached (depends on shelf position).


-----Original Message-----
From: coral-list-bounces at coral.aoml.noaa.gov [mailto:coral-list-bounces at coral.aoml.noaa.gov] On Behalf Of Eugene Shinn
Sent: Thursday, 27 October 2016 2:23 AM
To: coral-list at coral.aoml.noaa.gov
Subject: [Coral-List] Has the death of the Great Barrier Reef been greatly, exaggerated??

I recall that coring and seismic profiling showed the linear  great barrier reef (like the outer reef in the Florida Keys) is quite thin (only a few meters) and underlain is by terrigenous sediment. Like the Florida reef tract it has only been submerged for between 6 and 7 thousand years (not 25 million years as the article states). The barrier reefs has been in and out of water many times during the past 25 million years and suffered mortality each time it was left high and dry.  The present reef was dry land between 6 and 7 thousand years ago. The thickest coral accumulations are the patch reefs (composed of corals and
Halimeda) that lie in the deeper lagonal area landward of the great barrier reef. Same is true in the Florida Keys. Our USGS Fisher Island group presented a paper  titled /Autopsy of a Dead Reef/ at the annual SEPM meeting in the 1970s. It was about Hens and Chickens reef in the Keys which had suffered near total mortality caused by a cold front during the winter of 1969-70. The time of death was clearly preserved in annual growth bands of both living and dead coral heads. One may wonder if similar periodic paleo cold fronts  kept the linear outer reef in check during the previous 6,000 years. Gene


No Rocks, No Water, No Ecosystem (EAS)
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E. A. Shinn, Courtesy Professor
University of South Florida
College of Marine Science Room 221A
140 Seventh Avenue South
St. Petersburg, FL 33701
<eugeneshinn at mail.usf.edu>
Tel 727 553-1158
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