[Coral-List] starvation?

Mark Eakin Mark.Eakin at noaa.gov
Thu Jun 1 09:04:17 EDT 2006

Follow-up to the mass bleaching in the Caribbean has revealed that  
coral death from large scale thermal stress results from a wide range  
of causes.  Some of the corals died very quickly (ca. 1 week).  This  
is probably thermal stress.  Some died within a few weeks.  Lack of  
nutrition from zooxanthellae and loss of reserves probably  
contributed here (starvation).  Some died later, often from disease.

I think when dealing with the press and public, the message that  
thermal stress and bleaching may result in mortality is the important  
message.  The rest is for us to debate.


On May 31, 2006, at 1:06 PM, jmcmanus wrote:

> Most likely we are dealing with two phenomena in severe bleaching  
> events:
> 1. Stresses related to the loss of Symbiodinium
> 2. Thermal stress per se.
> All organisms have upper thermal tolerance limits, set by various
> physiological mechanisms (oxygen uptake, other aspects of metabolism,
> protein and enzyme production, etc.). Many organisms live nearer  
> the upper
> than the lower tolerance limits, which is why it is usually safer to
> transport marine organisms in colder water than they are used to  
> than in
> warmer water. During periods of very warm water, other species on a  
> reef may
> die suddenly, such as mollusks and fish. It may be that coral death  
> that is
> too quick to be explained in terms of starvation may not  
> necessarily be
> related to the loss of the Symbiodinium.
> Cheers!
> John
> John W. McManus, PhD
> Professor, Marine Biology and Fisheries
> Coral Reef Ecology and Management Laboratory (CREM Lab)
> Director, National Center for Coral Reef Research (NCORE)
> Rosenstiel School of Marine and Atmospheric Science
> University of Miami, 33149
> Office: 305-421-4814/4820, Fax: 305-421-4910, Website:  
> www.ncoremiami.org
> 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 Julian  
> Sprung
> Sent: Wednesday, May 31, 2006 10:15 AM
> To: coral-list at coral.aoml.noaa.gov
> Subject: [Coral-List] starvation?
> As a follow up to the post I just sent, I have not yet seen this  
> recent
> paper in Nature and look forward to reading it- My comments about  
> starvation
> are not in any way intended to dismiss the conclusions of the paper.
> I am only commenting on what I believe to be true with regard to  
> temperature
> induced bleaching and mass die off of corals-- that the majority of  
> the die
> off usually occurs in a matter of days, far too quickly to be  
> caused by
> starvation.
> It is an interesting point to compare what can be achieved in an  
> aquarium
> with respect to food inputs as opposed to food supply on reefs. In  
> general
> the live and particulate food supply on reefs is greater than what  
> is the
> norm for most aquariums, but I agree aquariums could achieve higher  
> inputs
> to meet the demands of a particular coral, given the effort of an  
> aquarist
> to make it happen. The idea that some corals might not be able to  
> get enough
> food in the wild if they lack zooxanthellae is new to me- if true,  
> it would
> mean I have to revise my opinion about starvation as being too broad!
> Julian
>> ----------
>> From: 	coral-list-bounces at coral.aoml.noaa.gov on behalf of Andréa
> Grottoli
>> Sent: 	Tuesday, May 30, 2006 3:37 PM
>> To: 	coral-list at coral.aoml.noaa.gov; goreau at bestweb.net
>> Subject: 	[Coral-List] coral bleaching: response to Goreau
>> Dear Tom,
>> I read your contribution on the coral list about
>> coral bleaching with interest.  As the lead
>> author of the recent Nature paper on
>> heterotrophic plasticity in bleached corals, I
>> would like to comment.  You stated:
>> "The recent paper that claims to have discovered "for the first time"
>> that corals eat zooplankton and can survive bleaching better if  
>> fed is
>> not new either. The fact that corals don't get their carbon from
>> zooxanthellae is also very old knowledge, but for decades people have
>> ignored the old literature and have mistaken the net oxygen  
>> balance to
>> assume that corals are also autotrophic in carbon. This recent  
>> error has
>> become dogma, despite being wrong, because nowadays people don't read
>> the literature or ask those who know it. The first radiocarbon tracer
>> experiments, done by Thomas F. Goreau and Nora I. Goreau more than 50
>> years ago showed that very little zooxanthella carbon translocation
>> contributed to coral carbon, and that corals relied on zooplankton  
>> for
>> the vast bulk of their carbon needs. They kept corals completely
>> bleached in the dark for years, feeding them on zooplankton. So  
>> survival
>> of bleached fed corals has been known for over half a century and  
>> is not
>> a "new discovery" at all. Like so much else in the current  
>> literature."
>> I would like to point out that our paper showed
>> that only one species, Montipora capitata,
>> consumed enough zooplankton to meet all of its
>> metabolic demand heterotrophically when
>> bleached.   When healthy, M. capitata met less
>> than 15% of its metabolic demand
>> heterotrophically.  The other two species we
>> studied, Porites compressa and Porites lobata,
>> only met 21-35% of their daily metabolic demand
>> heterotrophically when they were either healthy
>> or bleached.   In all cases, our corals were
>> exposed to naturally occurring zooplankton on the
>> reef.  Thus under natural reef conditions, not
>> all bleached corals can meet all of their
>> metabolic needs heterotrophically.  Under
>> artificially fed conditions (i.e., coral exposed
>> to higher than ambient concentrations of
>> zooplankton or brine shrimp in tanks), things can
>> be quite different.   As you pointed out, the
>> fact that corals do get some fixed carbon from
>> zooplankton has been know for a very long
>> time.  However, the fact that when bleached at
>> least one species can  increase heterotrophic
>> feeding to meet all of its metabolic needs while
>> two others could not, is novel.  Our results
>> suggest that not all species of corals would be >
>> able to meet their metabolic demand when
>> maintained in the dark under natural
>> concentrations and abundance of zooplankton (i.e,
>> P compress and P lobata probably could not get
>> all of their energy needs met heterotrophically
>> when bleached under darkness... but this would
>> need to be specifically tested).   In addition,
>> bleaching induced by keeping corals in the dark
>> is not necessarily the same as
>> temperature-induced bleaching.  The chain of
>> physiological stress responses that occur under
>> high temperature include free radical and stress
>> protein production, making any heterotrophic
>> responses under tempreature-induced bleaching
>> possibly quite different than hetertrophic
>> responses under sustained darkness.
>> Sincerely,
>> Andrea Grottoli
>> *******************************************************
>> Andréa G. Grottoli, Assistant Professor
>> Ohio State University
>> Department of Geological Sciences
>> 125 South Oval Mall
>> Columbus, OH 43210-1398
>> office:  614-292-5782
>> lab: 614-292-7415
>> fax: 614-292-7688
>> email: grottoli.1 at osu.edu
>> web: www.geology.ohio-state.edu/~grottoli
>> Office location: 329 Mendenhall Labs
>> *******************************************************
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C. Mark Eakin, Ph.D.
Coordinator, NOAA Coral Reef Watch
National Oceanic and Atmospheric Administration
Center for Satellite Applications and Research
Satellite Oceanography & Climate Division
e-mail: mark.eakin at noaa.gov
url: coralreefwatch.noaa.gov

E/RA31, SSMC1, Room 5308
1335 East West Hwy
Silver Spring, MD 20910-3226
301-713-2857 x109                   Fax: 301-713-3136

The contents of this message are mine personally and do not  
necessarily reflect any position of the Government or the National  
Oceanic and Atmospheric Administration.

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