[Coral-List] Excess algal symbionts increase coral susceptibility to bleaching

Wed Nov 28 15:41:23 EST 2012

Dear Coral List,

Reading this correspondence I was reminded of this article by Enric Sala
for National Geographic. Maybe this article about the effects of iron ore
originating from shipwrecks at otherwise "pristine coral reefs" can provide
another clue in determining the effects of iron on coral reefs.

http://newswatch.nationalgeographic.com/2011/09/01/black-reefs-when-the-ship-hits-the-reef/

Bastiaan

On 28 November 2012 21:17, Andrew Baker <abaker at rsmas.miami.edu> wrote:

> My point in picking up on Gene's email about African dust and iron was that
> iron is one of several parameters which seems to influence symbiont
> densities in corals (including light, temperature, nutrients and possibly
> pCO2). In that context, it's interesting to look at whether the increase in
> algal densities influences bleaching susceptibility by exacerbating a
> symbiont density-dependent bleaching cascade.
>
> There are probably many benefits to having more symbionts, as well as
> tradeoffs against having them. Similarly there are probably many impacts of
> iron on corals outside of its (potential) effects on symbiont density. As
> mentioned in previous emails, the bioavailability of iron is also critical
> and also difficult to measure properly. The "black reefs" reported in Kelly
> et al. (2011), and discussed on this list over a year ago, are really
> interesting and unusual places. But equally there are pilings, volcanic
> substrates, and other places where corals appear, at least anecdotally, to
> be doing well. I don’t think these observations invalidate each other; they
> are different corals growing in different situations.
>
> The situation with nutrients is also likely to be complex in a similar kind
> of way, but I think these are all interesting areas of research and we now
> have new molecular assays that make answering these questions much easier
> (In this context I should point out that the metric of symbiont density we
> used in the Nature Climate Change paper, an actin-based symbiont:host cell
> ratio based on Mieog et al. 2009, is different from standard areal metrics
> of symbiont density. Ross and I discussed the differences, and their
> implications, in the paper. It's possible one could get different results
> using different metrics of symbiont density (something we are
> investigating), but you could learn different things from each metric -
> it's
> not that one method is "right" or "wrong".
>
> Best
>
> Andrew
>
> Kelly LW, Barott KL, Dinsdale E, Friedlander AM, Nosrat B, Obura D, Sala E,
> Sandin SA, Smith JE, Vermeij MJA, Williams GJ, Willner D, Rohwer F (2011)
> Black reefs: iron-induced phase shifts on coral reefs. The ISME Journal
> (2012) 6, 638–649; doi:10.1038/ismej.2011.114
> Mieog JC, van Oppen MJH, Berkelmans R, Stam WT, Olsen JL (2009)
> Quantification of algal endosymbionts (Symbiodinium) in coral tissue using
> real-time PCR. Mol Ecol Res 9: 74–82.
>
> ___________________
> Andrew C. Baker, Ph.D.
> Associate Professor, University of Miami
> Pew Fellow in Marine Conservation
>
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>
> -----Original Message-----
> From: coral-list-bounces at coral.aoml.noaa.gov
> [mailto:coral-list-bounces at coral.aoml.noaa.gov] On Behalf Of Szmant, Alina
> Sent: Monday, November 26, 2012 6:44 PM
> To: Delbeek, Charles; coral-list at coral.aoml.noaa.gov
> Subject: Re: [Coral-List] Alga densities and bleaching
>
> FYI, every place I dive where there is metal structure (old ship hulls,
> navigation pilings etc) they are covered with nice looking corals of all
> species.  There is a great example in the Dry Tortugas where there is an
> shallow water old wreck (I can't remember the name now) near the old
> Carnegie Station, that has huge corals growing on it!  These metal
> substrates would make great coral habitat except for the fact that they
> eventually rust, and the corals slough off.  I think the coral larvae like
> the iron-rich substrates..  Iron-rich volcanic rocks seem to have the same
> attraction to coral larvae.
>
> *************************************************************************
> Dr. Alina M. Szmant
> Professor of Marine Biology
> Center for Marine Science and Dept of Biology and Marine Biology University
> of North Carolina Wilmington
> 5600 Marvin Moss Ln
> Wilmington NC 28409 USA
> tel:  910-962-2362  fax: 910-962-2410  cell: 910-200-3913
> http://people.uncw.edu/szmanta
> *******************************************************
>
>
> -----Original Message-----
> From: coral-list-bounces at coral.aoml.noaa.gov
> [mailto:coral-list-bounces at coral.aoml.noaa.gov] On Behalf Of Delbeek,
> Charles
> Sent: Sunday, November 25, 2012 4:04 PM
> To: coral-list at coral.aoml.noaa.gov
> Subject: Re: [Coral-List] Alga densities and bleaching
>
> What are the currents like?
>
> J. Charles Delbeek, M.Sc.
> Assistant Curator, Steinhart Aquarium
> California Academy of Sciences
>
> p 415.379.5303
> f. 415.379.5304
> cdelbeek at calacademy.org
> www.calacademy.org
>
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> -----Original Message-----
> From: coral-list-bounces at coral.aoml.noaa.gov
> [mailto:coral-list-bounces at coral.aoml.noaa.gov] On Behalf Of Rudy Bonn
> Sent: Wednesday, November 21, 2012 9:08 AM
> To: coral-list at coral.aoml.noaa.gov
> Subject: [Coral-List] Alga densities and bleaching
>
> Interesting?  The Key West Marine Park is managed by Reef Relief here in
> Key
> West.  It is a ~48 acre site on the south side of the island and fronts
> Higgs beach, Dog beach, and extends from the duval street pier east to the
> white street pier, (Gene is probably familiar with the area) anyway, years
> ago the county/city put in a new pier at Higgs Beach and left portions of
> the old one behind.  These submerged portions of the old pier are made of
> iron, and there are corals attached to this iron substrate in amazing
> numbers and diversity, and they are all in very good health, I can send
> pictures if you contact me by my email, the water depth is 12 foot max on a
> spring tide, so we know that during the summer months the temp probably
> reaches the upper 80's  these corals show no signs of disease, alga
> overgrowth, bleaching,  like I said in really good health.  Any ideas?  the
> genera we have found include:  montastrea, siderastrea, porites, diploria
> (several sp) meandrina, oculina, among others, all in good health all
> attached to iron,    ideas?
>
> Rudy S Bonn
> Director of Marine Projects
> Reef Relief
> 631 Greene Street
> Key West, FL 33040
> 305-294-3100
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