[Coral-List] bleaching and acidification

William Allison allison.billiam at gmail.com
Thu Feb 19 08:57:58 EST 2009

Hello Paul,
Of the many reefs I have examined (and surveyed with direct measurements,
video and stills) the length and breadth of Maldives before and after 1998 I
can think of only a few locations featuring large tabulate Acropora colonies
as of 2005. Barring the rare colony that survived in otherwise devastated
reefs, these were generally on reefs that I know enjoyed low mortality in
1998. I did sample a few reefs with numerous large colonies (some of which
acquired local fame because of this) where I could not be sure whether I was
looking at survivors or new growth. In any case these are not representative
of the whole system. In most locations mortality was high, the rate of
successful settlement was low, and growth was not spectacular. There were
exceptions at the level of reefs and even large portions of a few atolls
where either survival was high, or recruitment and growth were accelerated,
or both. Whatever the reasons, these exceptions are intriguing and
potentially informative.

On Mon, Feb 16, 2009 at 7:05 PM, Paul Muir <paul.muir at qm.qld.gov.au> wrote:

> Are there maps of aragonite saturation/ carbonate equilibrium for ocean
> areas? On a trip to the Indian Ocean in 2005 we were quite struck by
> differences in apparent growth rates of Acroporas after the '98
> bleaching event at different locations. In the Maldives growth after
> mass mortality was apparently rapid  (ie new colonies 2- 3m diameter)
> while at a similar latitude in the Seychelles the  maximum colony size
> of  Acroporas was approx 25 cm. We did wonder if these apparent
> differences in growth rates were partly due to differences in aragonite
> saturation since both locations appeared quite similar in terms of being
> oceanic reefs with minimal human impact.
> Dr. Paul Muir
> Museum of Tropical Queensland,
> 78-104 Flinders St,
> Townsville QLD 4810 Australia.
> ph. 07 47 260 642  fax. 07 47 212 093  mob. 0407 117 998
> * if no reply or problems sending try paularwen at gmail.com
> -----Original Message-----
> From: coral-list-bounces at coral.aoml.noaa.gov
> [mailto:coral-list-bounces at coral.aoml.noaa.gov] On Behalf Of Thomas
> Goreau
> Sent: Tuesday, 17 February 2009 3:11 AM
> To: Chris Langdon
> Cc: coral-list coral-list
> Subject: [Coral-List] bleaching and acidification
> Dear Chris,
> I fully agree with what you say below based on lab studies. The Elat
> field data of Silverman et al. clearly showing less net calcium
> carbonate accumulation when waters have higher pCO2 makes this even
> clearer.
> However this small reduction must be contrasted with the fact that
> bleached corals completely stop growing (Goreau & Macfarlane) or
> reproducing (Szmant-Froelich) for at least one year, and it takes a
> couple years to fully recover even if they survive and high temperatures
> don't ever come back.......
> Best wishes,
> Tom
> 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
> 617-864-4226
> goreau at bestweb.net
> http://www.globalcoral.org
> Date: Sun, 15 Feb 2009 17:49:56 -0500 (EST)
> From: "Chris Langdon" <clangdon at rsmas.miami.edu>
> Subject: [Coral-List] Bleaching vs acidification
> To: coral-list at coral.aoml.noaa.gov
> Message-ID:
>        <2975. at webmail.rsmas.miami.edu>
> Content-Type: text/plain;charset=iso-8859-1
> It is very clear that bleaching events have resulted in significant loss
> of live coral cover around the globe.  We know that within the
> environmentally probable range of pH that coral mortality does not
> result.
> However, acidification may play an important role in the amount of
> recovery that is possible between bleaching events which have been
> occurring with a frequency of 3-7 years since 1982. The average
> saturation state of the tropical ocean has dropped from a pre-industrial
> value of
> 4.6
> to a present day value of 3.9-4.0.  This is sufficient to have caused on
> average a 17% decrease in calcification for the twelve or so species
> that have been studied in the lab.  In a world where the balance between
> production and loss of carbonate on many reefs is thought to be close
> and where the replacement rate of new coral colonies on many reefs is
> not keeping up with the rate of mortality a 17% reduction in fitness may
> be significant.  While acidification does not kill corals it does result
> in slower development of coral larvae into juvenile colonies (Albright
> et al.
> 2008) and slower development of juvenile colonies to sexual maturity.
> While bleaching is a very important threat I don't we know enough at
> this time to ignore the possibility that acidification has already
> played a role in the lack of recovery that we are seeing on many reefs.
> Chris Langdon
> Assoc. Professor
> Uni. of Miami
> 4600 Rickenbacker Cswy
> Miami,FL 33149
> Ph: 305-421-4614
> Fax: 305-421-4239
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