[Coral-List] Survival of corals without zooxanthellae

[Martin Pêcheux]

Dear all,

Attention, Younge and Nicholls, 1930, 1931a, 1031b, Younge, Younge and Nicholls, 1932.
They have done a fantastic work for this epoch, in particular he cytological part, but
they didn't know all; One must remember always that part of their experiments (starvation
in sealed jars, in darkness with bleaching, in light and low pH and O2) were done in
summer with 30°C ! and "reef flat bleaching".
Historically, it is why it took so long, till the 1970, to recognize the role of symbionts
in autotrophy of the association, as they measure respiration as great as photosynthesis
under these conditions.
There best hypothesis for bleaching is starvation of CO2 (also N, P, not in one week),
fine, isn't it ?
See some synthesis in my quotable Review (see below), in text and bibliographic notes).

See also the Peter Glynn works on refuge population of zooxanthellae in bleached Panama
corals. And remember higher, almost normal Fv/Fm of the 2% remaining zoox of T bleached
corals  (Salih et al., poster at Panama, 1996), also with short term strong T and HIGH pH
in Styllophora (pers. obs.).

"Large forams died when kept in darkness, albeit fed" (John Lee), but as in corals, I
guess it depends on species. One have been kept alive for 77 days, with no growth of
course, as corals with bleaching in the field.(here at contrast to forams).

Cheers,

Dr. Martin Pêcheux
Large Foraminifer Institute
16, rue La Fontaine, 92160 Antony, France
:+33(0)1.40.96.01.99 (4+96=1+99=100) soon a new one
Email: martin-pecheux at wanadoo.fr soon martin.pecheux at free.fr ?

Publications at  www.reefbase.org, Author=Pecheux (without ^), in which
REVIEW ON CORAL REEF BLEACHING, 1997, Atoll Research Bulletin, proof 214p. so with
fundamentals of reefs (accepted so quotable even if unprinted; download see link above)

Write 05 not 2005, reset churches.


RichardPDunne at aol.com a *crit :

> You will find some useful information on this in:
>
> C M Yonge 1931 The effect of starvation in light and in darkness on the
> relationship between corals and zooxanthellae. Scientific Reports of the Great
> Barrier Reef Expedition 1928-29. Vol I no 7. Corals kept in the dark but fed
> lost a high percentage of their zooxanthellae (colourless to the eye) but
> survived until the end of the experiment ( 228 days). Variable according to
> species.
>
> See also:
> C M Yonge and A G Nicholls 1931 The structure, distribution and physiology
> of the zooxanthellae. Scentific Reports of the Great Barrier Reef Expedition
> 1928-29. Vol I no 6. They constructed a light tight box on the reef flat
> through  which the seawater could flow. after 152 days many of the species contained
> very  few zooxanthellae but were otherwise in good condition. Their
> conclusion in this  respect was "without any doubt that individual reef-building corals
> at any rate  can flourish without contained zooxanthellae."
>
> I doubt however that corals ever loose ALL their zooxanthellae - the best
> that Yonge noted was "almost completely absent". And in our own work even a
> reduction of 86% of the seasonal maximum density following severe bleaching  can
> leave 0.026 x 10^7 algae per sq cm of tissue area (260,000). (Brown et  al
> 1999 MEPS 191:53-69).
>
> The evidence seems to point to an ability to survive without zooxanthellae
> if a source of food is available, and presuming the stress which caused the
> zooxanthellae loss does not persist or at least does not have a directly
> deleterious effect on the coral host itself.
>
>
>
> Richard Dunne
>
> Tel: 01833  650059
>
> RichardPDunne at aol.com
>

I think it is important when answering this question, as Josh did, to point out the cause
of the loss of
zooxanthellae. Since high temp was the stimulus in the experiment with P. damicornis, and
it is known that
at elevated temp P. damicornis may die rapidly as a reult of a Vibrio infection, then the
cause of death
cannot specifically be blamed on lack of symbionts unless Vibrio had been ruled out.

I have seen bleached shaded colonies of P. damicornis in aquaria survive great lengths of
time with few if
any zoox's. The same is true for shaded portions of colonies that have zoox's in the upper
illuminated
branches, but that probably doesn't count.

My opinion on the question posed- while it may vary among species or genera, and there may
well be
exceptions, I believe that with sufficient food most corals can survive many months or
indefinitely
without symbionts. This can be demonstrated in temperature controlled flow through
aquariums with no
illumination and high food inputs (the water flushing removes waste and maintains water
chemistry).

While I cannot comment on the effects on growth, the survival is the question posed.

Sincerely,

Julian


-----Original Message-----
From: coral-list-bounces at coral.aoml.noaa.gov on behalf of Joshua Feingold
Sent: Sat 1/8/2005 10:31 AM
To: John P Carlin; coral-list at coral.aoml.noaa.gov
Subject: Re: [Coral-List] How long can corals survive without theirsymbiotic
zooxanthellae?

Hi John,

I did some work on this for my dissertation, and survival is variable
depending on the species and type of stress. Also, it is important to
understand that, nearly invariably, bleached corals possess at least some
zooxanthellae. The population size isn't enough to see pigment in the coral
with the naked eye, but they are there in the tissues, but at very low levels.

One species I investigated, the fungiid Diaseris distorta, could remain
alive in the bleached state for over 2 months and then regain pigmentation.
In contrast, another species, Pocillopora damicornis, was much more
sensitive with mortality occurring in nearly all colonies after 2-3 weeks
in the bleached state. Elevated temperature was the stress in both of these
examples.

Cheers,

Joshua Feingold
Nova Southeastern University Oceanographic Center

At 03:48 PM 1/7/2005 +0000, John P Carlin wrote:
>Hi,
>
>I would like to know if there has been any published work on how long corals
>can survive without their zooxanthellae following a stress event?
>
>Thank you
>
>John Carlin
>Reading University
>England
>

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