[Coral-List] Question Thermal vs pH shift
John McManus
jmcmanus at rsmas.miami.edu
Sun Jan 13 19:38:02 EST 2008
Point well taken. I too have seen soft corals bleach (along with giant
clams).
However, in my optimism, I see a far earlier accommodation or adaptation to
heat problems than to acidity problems. Both Symbiodinium symbiosis and
active calcification are the results of long-term evolutionary processes,
and so there is always some ultimate hope for evolution to get around both
heat and acid problems via improved mechanisms. The evolutionary flexibility
associated with calcification can be found in the recent report of a
calcite-based (instead of the usual aragonite-based) coral in the fossil
record. However, it seems possible that Symbiodinium substitution and
perhaps genetic evolution will work successfully in periods of many decades,
where evolving improved active calcification mechanisms could take centuries
(assuming more drastic ecological dominance shifts permit the corals to
survive that long). A little further speculation gives me hope that some
low-lying soft corals will be able to survive with reduced densities of
spicules. I'm hoping someone will turn the speculations into hypotheses and
do the appropriate experiments.
For any grad students out there looking for thesis projects -- these types
of CO2 enrichment experiments would be quite helpful.
Note that though nature gives me optimism, I get far less from political
will. Certainly we must do everything we can to reduce CO2 emissions, lest
they result in far worse problems than we currently foresee. However, the
best case scenarios have that happening over decades, and we already seem to
have enough of a CO2 load in the atmosphere to keep the stresses increasing
for a considerable time to come. Thus, I am struggling to figure out what
ecosystems we will see over the next century where once large hard corals
once stood. I'm sure they will be fascinating, beautiful, highly diverse,
and even of considerable resource value -- and they will include many that
will sit on the thicker of the calcified reef structures that are still
going to be there slowly eroding away for centuries to come. But, they
aren't likely to be what many of us remember from our youth.
Cheers!
John
-----Original Message-----
From: Douglas Fenner [mailto:dfenner at blueskynet.as]
Sent: Sunday, January 13, 2008 4:54 PM
To: John McManus; 'Ken Caldeira'
Cc: coral-list at coral.aoml.noaa.gov; arietta.Venizelos at noaa.gov; 'konrad
Hughen'; tyler.volk at nyu.edu; 'Michael Robert Rampino'; Katharina Fabricius
Subject: Re: [Coral-List] Question Thermal vs pH shift
Keep in mind that many soft corals and gorgonia are zooxanthellate and
bleach and die in high temperatures just like zooxanthellate hard corals.
Zooxanthellate soft corals tend to be the dull colored ones out in the
light, and azooxanthellate soft corals tend to be the ones with bright
colors found in shaded locations. The book on Soft Corals of the
Indo-Pacific by Fabricius and Alderslade has pictures of bleached soft
corals - they seem to melt away as they die. After a mass bleaching event
you can often find rounded pillow-shaped formations which are the spiculite
bases of soft corals that were killed. Some of the larger soft corals may
be a hundred years old or more, so the large colonies are unlikely to be
quickly replaced after bleaching. So if high temperatures kill things
before CO2, many soft corals will die out along with the hard corals, and
they will no longer contribute to building the reef. In some places there
contribution may be significant.
-Doug
----- Original Message -----
From: "John McManus" <jmcmanus at rsmas.miami.edu>
To: "'Ken Caldeira'" <kcaldeira at stanford.edu>
Cc: <coral-list at coral.aoml.noaa.gov>; <arietta.Venizelos at noaa.gov>; "'konrad
Hughen'" <khughen at whoi.edu>; <tyler.volk at nyu.edu>; "'Michael Robert
Rampino'" <mrr1 at nyu.edu>
Sent: Saturday, January 12, 2008 12:13 PM
Subject: Re: [Coral-List] Question Thermal vs pH shift
>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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