[Coral-List] bleaching and acidification

[Paul Muir]

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:
	<2975.129.171.118.2.1234738196.squirrel 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
RSMAS/MBF
Uni. of Miami
4600 Rickenbacker Cswy
Miami,FL 33149
Ph: 305-421-4614
Fax: 305-421-4239
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