[Coral-List] Coral bleaching and light levels
goreau at bestweb.net
Fri Feb 13 10:14:53 EST 2009
> From: Thomas Goreau <goreau at bestweb.net>
> Date: February 13, 2009 10:11:18 AM EST
> To: billraymond10 at yahoo.com
> Subject: Re: [Coral-List] Coral bleaching and ocean acidification
> Dear Bill,
> Absolutely! But it is a secondary factor.
> 20 years ago I did a bunch of experiments in Jamaica with corals in
> tanks at different temperatures and light level combinations.
> Bleaching took place only above a certain temperature, but the more
> light the faster it happened. Peter Glynn did similar experiments in
> Okinawa and reached the same conclusions. The reason I did this was
> our field observations in the first Caribbean bleaching event in
> 1987, where shaded corals were much less bleached, in fact where
> they were shaded by overhangs you could see the shadow, and we've
> seen that everywhere in the Indian Ocean and Pacific since too.
> But the discussion was about bleaching versus acidification, so I
> did not get into secondary factors affecting bleaching. And
> temperature has been rising worldwide whereas light levels are
> basically unchanged because solar radiation variations are so small.
> In fact surface light has been going down for decades because of
> atmospheric pollution, but now starting to rise slowly as
> atmospheric sulfur and nitrogen pollution are controlled.
> Hans Creek is an interesting area, and you may know that I proposed
> it as a coral reef restoration site. I still hope this is possible,
> but it really depends on blocking the marina and golf course. Which
> I guess is still a pending issue. There is a small chance that I may
> get back to BVI later this year.
> Best wishes,
> Thomas J. Goreau, PhD
> President, Global Coral Reef Alliance
> Coordinator, United Nations Commission on Sustainable Development
> Partnership in New Technologies for Small Island Developing States
> 37 Pleasant Street, Cambridge MA 02139
> goreau at bestweb.net
> On Feb 13, 2009, at 9:57 AM, Bill Raymond wrote:
>> Tom Goreau:
>> Don't you consider solar intensity a factor in coral bleaching? In
>> Tortola I found bleached corals in late October, offshore, but
>> mangrove-shaded Siderastreas in warm Hans Creek
>> were not bleached.
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