[Coral-List] Question Thermal vs pH shift

John McManus jmcmanus at rsmas.miami.edu
Sat Jan 12 18:13:17 EST 2008


I tend to agree. After some number of decades there may be a predominance of
communities on slowly eroding reef substrates heavily dominated with soft
corals. Soft coral communities exist in many reef areas today, but seem
likely to become increasingly common. Even these may change, as spicule
formation in many soft coral species may suffer. The reduction in 3D
heterogeneity will undoubtedly alter the fish communities and thus the
levels of herbivory, but it is currently difficult to forecast what the net
result will be in terms of algal cover in areas where nutrient loading is
kept below overwhelming levels.  We need to start figuring out what will
result from those changes in terms  of reef composition and resources, and
simulation models are going to have to play a role there. I suspect that the
remaining soft coral communities will be well worth protecting from
eutrophication.

 

In the meantime, I would like to see more experiments with the growth of
heavily aragonite and calcite dependent organisms under increased pH levels.


 

Cheers!

 

 

John

 

John W. McManus, PhD

Director, National Center for Coral Reef Research (NCORE)

Professor, Marine Biology and Fisheries

Coral Reef Ecology and Management Lab (CREM Lab)

Rosenstiel School of Marine and Atmospheric Science (RSMAS)

University of Miami, 4700 Rickenbacker Causeway, Miami, 33149

jmcmanus at rsmas.miami.edu      http://ncore.rsmas.miami.edu

 Phone: 305-421-4814   Fax: 305-421-4910

 

  "If I cannot build it, I do not understand it."

              --Richard Feynman, Nobel Laureate

 

 

 

 

From: kcaldeira at gmail.com [mailto:kcaldeira at gmail.com] On Behalf Of Ken
Caldeira
Sent: Saturday, January 12, 2008 1:16 AM
To: John McManus
Cc: James Cervino PhD.; coral-list at coral.aoml.noaa.gov;
arietta.Venizelos at noaa.gov; konrad Hughen; tyler.volk at nyu.edu; Michael
Robert Rampino
Subject: Re: [Coral-List] Question Thermal vs pH shift

 

John,

In the absence of dramatic reductions in CO2 emissions, the range of
aragonite saturation in  the entire surface ocean will not intersect the
range of aragonite saturation in which coral reefs grew in the
pre-industrial ocean. 

In contrast, areas of ocean will still be found with temperatures in the
range in which coral grew pre-industrially (they will just be closer to the
poles). If temperature were the only issue, we could imagine reefs
establishing themselves poleward of their current range. 

So, while temperature is a threat (perhaps a lethal threat), if temperature
were the only threat their would be some hope for adaptation and migration. 

While corals survive and recover in a fish tank at low pH, their growth
rates are slowed and it is likely that they will be less fit to compete
ecologically, so we may not see acute lethality but rather a weakening that
leads to a loss of ecological competitiveness -- for example, less success
at repopulating an area after disturbance. 

My sense is that temperature is more of a threat to reefs today but if CO2
emissions continue eventually aragonite saturation will become more
important than temperature.

Ken

On Jan 11, 2008 1:29 PM, John McManus <jmcmanus at rsmas.miami.edu> wrote:

The recovery from pH changes is in line with the paper of Fine and Tchernov
"Scleractinian Coral Species Survive
and Recover from Decalcification" SCIENCE VOL 315 30 MARCH 2007, in which
species of Oculina and Madracis corals lost skeletons at high pH and 
regained them upon returning to low pH. They did not test major reef
builders, but the results are astounding anyway.

As for thermal stress, some glimmer of hope lies in the fact that
temperatures that kill a species in one locality may be tolerated by the 
same species elsewhere, whether via coral physiological adaptation or
genetics, or via differences in Symbiodinium. There is also species
substitution (susceptible for tolerant) and natural temperature refugia for 
some species (mesophotic reefs, upwelling areas, etc.). Not to minimize the
immense problems ahead, but the patient does still have a pulse...

Cheers! (at least for the optimists)


John

John W. McManus, PhD 
Director, National Center for Coral Reef Research (NCORE)
Professor, Marine Biology and Fisheries
Coral Reef Ecology and Management Lab (CREM Lab)
Rosenstiel School of Marine and Atmospheric Science (RSMAS)
University of Miami, 4700 Rickenbacker Causeway, Miami, 33149
jmcmanus at rsmas.miami.edu      http://ncore.rsmas.miami.edu 
 Phone: 305-421-4814   Fax: 305-421-4910

 "If I cannot build it, I do not understand it."
             --Richard Feynman, Nobel Laureate




-----Original Message----- 
From: coral-list-bounces at coral.aoml.noaa.gov
[mailto:coral-list-bounces at coral.aoml.noaa.gov] On Behalf Of James Cervino 
PhD.
Sent: Friday, January 11, 2008 9:06 AM
To: coral-list at coral.aoml.noaa.gov
Cc: arietta.Venizelos at noaa.gov ; konrad Hughen; tyler.volk at nyu.edu; Michael
Robert Rampino; kcaldeira at stanford.edu
Subject: [Coral-List] Question Thermal vs pH shift 

Dear Coral Scientists-


A while ago at the MBL when we compared pH shifts vs thermal stress to
investigate what will induce expulsion (bleaching) first I noticed the
following: During every trial exposing corals to thermal stress, heat killed

the corals far faster than pH changes in vitro. I am not saying that acid
like
conditions are not seriously inducing cell impairments in corals or
carbonate
substrates as both arriving at the same conclusion, death for corals. 

With that said, all the data (real time, not models) points to the corals
dying
of heat stroke far before acid like conditions take effect. Are we not
witnessing the death of reefs in real-time due to thermal stress? 

Just a question Cheers, James


*************************************
Dr. James M. Cervino
Pace University & Visiting Scientist
Woods Hole Oceanographic Inst.
Department of Marine Chemistry 
Woods Hole MA.
Cell: 917-620*5287
************************************




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-- 
=============================== 
Ken Caldeira
Department of Global Ecology
Carnegie Institution 
260 Panama Street 
Stanford, CA 94305 USA
+1 650 704 7212; fax: +1 650 462 5968

kcaldeira at stanford.edu

http://globalecology.stanford.edu/DGE/CIWDGE/home/main%20page/caldeira.php 




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