[Coral-List] Mediterranean corals and global warming

Thomas Goreau goreau at bestweb.net
Wed Jan 16 17:04:16 EST 2008

Dear Riccardo,

Your observations are very interesting. Can you please send me pdfs  
of the papers you cite?

The widespread thermal bleaching of Oculina patagonica above  
temperatures of 28 C reported by Yossi Loya and colleagues, and your  
report below, make it clear that even though they are the extreme  
northern range of hermatypes, these corals, just like tropical ones,  
are so close to their upper temperature limit that they can't take  
any more warming. My point was more that the Mediterranean could  
potentially become a habitat for corals not now found there. Mind  
you, I'm not proposing introducing them........

But since the corals we grow on Biorock substrates grow 3-5 times  
faster and had 16-50 times higher survival from bleaching in 1998  
than nearby reefs in the Maldives imply that we should be able to  
keep the Mediterranean corals alive too, under thermal conditions  
that might kill them.

Are you sure that Oculina patagonica is really introduced? I had  
heard claims otherwise, that the introduction had been from the  
Mediterranean to Argentina, where it was named, but forget now who  
told me.

Best wishes,

Thomas J. Goreau, PhD
Global Coral Reef Alliance
37 Pleasant Street, Cambridge MA 02139
goreau at bestweb.net

> Message: 6
> Date: Wed, 16 Jan 2008 19:38:54 +0000
> From: Riccardo Rodolfo-Metalpa
> 	<riccardo.rodolfo-metalpa at plymouth.ac.uk>
> Subject: Re: [Coral-List] Coral range expansion with global warming
> 	(Thomas	Goreau)
> To: "coral-list at coral.aoml.noaa.gov" <coral-list at coral.aoml.noaa.gov>
> Message-ID:
> <6CD19ED93A7A8F4593955A11621242C20618E28E2B at ILS133.uopnet.plymouth.ac. 
> uk>
> Content-Type: text/plain; charset="Windows-1252"
> Dear Pr Goreau,
> I just would like to report a few precisions about the effects of  
> temperature increase on the marginal Mediterranean corals. As you  
> correctly wrote, the average sea surface temperature in the  
> Mediterranean Sea is increasing. Prior to this increase, the  
> temperature ranged from 13 to 24?C due to the marked seasonality -  
> below the optimum for calcification. Therefore, it was not warm  
> enough to build ?real? reefs. However, during the last decade, the  
> average summer temperature reached 25-26?C and remained at this  
> level for several weeks. Furthermore, peaks of 28?C are not unusual  
> and more and more recurrent.
> As a consequence, native coral species such as Cladocora  
> caespitosa, Balanophyllia europaea and the temperate introduced  
> Oculina patagonica are suffering from this temperature increase and  
> show mass mortality events as well as other benthic species.  
> Therefore, without a quick adaptation of these species to high  
> temperatures, this phenomenon can be only harmful and increase the  
> mortality events of shallow water corals in the Mediterranean.
> Paradoxically, in the Middle to Late Pleistocene ages, when the  
> seawater temperatures are thought to have been higher than present,  
> Cladocora caespitosa were very abundant as it has been revealed by  
> the presence of several fossil reefs. In contrast, the present  
> geographical occurrence of C. caespitosa bioherms and true reefs  
> (only few existing in the Adriatic and Aegean seas) in the  
> Mediterranean Sea has decreased with respect to their fossil  
> distribution, suggesting that the current environmental conditions  
> are not favorable to its growth.
> For more details, several papers investigated the effect of  
> increasing temperature on Mediterranean coral species:
> Cerrano C, Bavestrello G, Bianchi CN, Cattaneo-Vietti R, Bava S,  
> Morganti C, Morri C, Picco P, Sara G, Schiaparelli S, Siccardi A,  
> Sponga F (2000). A catastrophic mass-mortality episode of  
> gorgonians and other organisms in the Ligurian Sea (NW  
> Mediterranean), summer 1999. Ecol. Letters 3, 284-293.
> Rodolfo-Metalpa R, Richard C, Allemand D, Ferrier-Pag?s C (2006b)  
> Growth and photosynthesis of two Mediterranean corals Cladocora  
> caespitosa and Oculina patagonica under normal and elevated  
> temperatures. J Exp Biol 209, 4546-4556
> Regards
> Riccardo
> Riccardo Rodolfo-Metalpa PhD
> Marine Biology and Ecology Research Centre
> University of Plymouth
> 6th floor Davy Building
> PL4 8AA, UK
> At 08:45 PM 1/13/2008, Thomas Goreau wrote:
>>> Dear Allen,
>>> I don't have references handy, but here are some leads.
>>> With regard to range expansion:
>>> Mexican researchers have been following northward expansion of  
>>> corals
>>> in the Sea of Cortez for some years, and I hope they can point to
>>> papers on this. Surveys at Sodwana reef in South Africa show that
>>> live coral cover and diversity have been steadily increasing. It
>>> would be most interesting to see if the corals are expanding
>>> northward on Honshu, Japan, and there may be studies on this by
>>> Japanese researchers. Australia should be seeing the same.
>>> In SE Florida the local dive groups I work with there, Cry of the
>>> Water in Broward County, and Reef Rescue in Palm Beach County, are
>>> seeing expansion of the now rare Acropora cervicornis and Acropora
>>> palmata northwards. But they are severely threatened by dredging
>>> projects and algal blooms around the offshore sewage outfalls, which
>>> we have now finally convinced the Governor, after years of appeals,
>>> to shut down.  If we can get these reefs protected (which they are
>>> not now),  clean up the water, and stop the new dredging projects,
>>> which killed almost all the live reefs of the area in the 1960s and
>>> 1970s, we should see significant northward coral expansion since
>>> there is a good supply of coral and fish larvae swept out of the
>>> Caribbean by the Gulf Stream.
>>> Thanks to above average sea surface temperature rise, the
>>> Mediterranean is now warm enough for reef building corals, but the
>>> two local species with zooxanthellae don't build up large
>>> aggregations, and there would be reluctance to introducing non- 
>>> native
>>> species. However, a few million years ago the Mediterranean area was
>>> the global center of coral diversity.
>>> But dreams of coral reef marching poleward, which have been proposed
>>> by some in the past as a benefit of global warming, are probably
>>> fiction. The reason is that the coastal areas of North America,  
>>> Asia,
>>> and Australia that they could expand to are densely populated and  
>>> the
>>> sewage and agricultural nutrients are way too high for coral reefs
>>> even if the temperatures were acceptable.
>>> With regard to the time it takes to form framework coral reef
>>> structures that creates sheltered habitats, as opposed to coral reef
>>> communities that are sparse veneers on non growing coral substrate,
>>> that can take a long time since reefs (as opposed to corals)
>>> typically grow millimeters a year.
>>> Best wishes,
>>> Tom

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