[Coral-List] Fw: Coral reef ecosystems will go extinct from global warming, not most coral species
vzlatarski at yahoo.com
Fri Aug 9 20:17:53 EDT 2013
Please allow me to draw your attention to one more publication dedicated to reef development and coral diversity of geological past showing that the Caribbean reef development was independent of coral diversity over the past 28 million years (*). The abstract finishes this way: "Reef development was unrelated to coral diversity, and the largest reef tracts formed after extinction had reduced diversity by 50%. High diversity is thus not essential for the growth and persistence of coral reefs." These unanticipated results pose a question to reef investigators and managers to chose between stimulating coral diversity or reef development (**). However, these results are only for 28 million years and for one region and we do not know what the rest of geological past and regions will show. In the meantime would be good to harmonize both approaches.
(*) Johnson, K.G., Jackson, J.B.C. & Budd, A.F., 2008. Caribbean Reef Development Was Independent of Coral Diversity over 28 Million Years.Science, 319, 1521-1523.
(**) Zlatarski, V. N., J. L. Stake. 2012. The scleractinian
corals: a perspective. Geologica
Belgica, 15(4): 370-375.
D.Sc. (Biology), Ph.D. (Geology)
131 Fales Rd., Bristol, RI 02809, USA; tel.: +1-401-254-5121
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From: Thomas Goreau <goreau at bestweb.net>
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Cc: "eshinn at marine.usf.edu Shinn" <eshinn at marine.usf.edu>; vassil zlatarski <vzlatarski at yahoo.com>
Sent: Thursday, August 8, 2013 7:25 PM
Subject: Coral reef ecosystems will go extinct from global warming, not most coral species
It seems clear that the popular and most of the scientific discussion about coral reefs fails to distinguish between coral reefs, coral communities, and coral diversity. Coral reefs are growing, wave-breaking structures in which live corals cover most of the bottom. Less than that is a coral community, not a coral reef, but most coral ecologists confuse the two, because they have apparently never seen a real growing reef, only the pitiful dying remnants that we now see in most places.
For nearly 25 years, since we first showed that almost all mass coral bleaching could be accurately predicted in time, space, and severity from the duration and intensity of the period above the one degree C anomaly for the warmest month, we have been careful to point out that coral reef ecosystems are imminently threatened by global warming, not coral species. Most coral species will likely survive as small isolated colonies in marginal habitats, outside the normal range of true reefs in depth or latitude, even if coral reefs as functioning growing ecosystems have vanished. In short we face a mass extinction of ecosystem services that only healthy growing reefs can provide, sand, beaches, shore protection, fisheries habitat, etc, but not necessarily coral biodiversity collapse.
You would think that geologists would be the first to understand that reefs are massive wave resisting frameworks, not isolated little heads in mud substrate, but some former oil company geologists are quick to deny global warming impacts by saying that coral species have been around for hundreds of millions of years, so ipso facto, they are resilient and can take anything, so don't worry, be happy, and inhale that CO2!
Two papers in the latest issue of Science contain, buried between the lines, relevant insight into this conundrum.
R. D. Norris, S. K. Turner, P. M. Hull, & A Ridgwell, 2013, Marine ecosystem responses to Cenozoic global change, Science, 341:492-498 contrasts the effects of coupled carbon and climate models with the geological impacts of the Paleocene-Eocene Thermal Maximum (PETM), when the deep ocean and polar regions warmed up some 10-15 degrees C, due to increased CO2 at about the levels fossil fuel use will cause. It takes of the order of 100,000 years for the geochemical pulse of that elevated CO2 to flush its way out of the system, as measured by deep sea limestone accumulation and ocean carbon 13 content.
They also look at the geological record of large reef ecosystems over the last 65 million years, and show that the PETM was followed by about 15 million years in which no large coral reefs formed, although small coral communities survived. The very hot, vertically stratified ocean waters caused low oxygen, mass anoxia, low pH conditions, dissolution of deep sea carbonates, and shallow carbonate shelves built by plankton and calcareous algae, not coral reefs, with sea levels around 60 m higher than today.
J. L. Blois, P. L. Zarnetske, M. C. Fitzpatrick, & S. Finnegan, 2013, Climate change and the past, present, and future of biotic interaction, Science, 341:499-504 looks at the fossil record over the last 500 million years. The Scleractinian corals, which go back for nearly 250 million years, show no decline in diversity at the PETM, showing that mass extinction of reef ecosystems does not result in mass extinction of coral species.
So the argument that coral species may have been around a long time, has no bearing at all on the stability of coral reef ecosystems, which are much more finely tuned to optimal conditions, and vulnerable to small changes from them.
Thomas J. Goreau, PhD
President, Global Coral Reef Alliance
President, Biorock International Corp.
Coordinator, United Nations Commission on Sustainable Development Small Island Developing States Partnership in New Sustainable Technologies
37 Pleasant Street, Cambridge, MA 02139
goreau at bestweb.net
Tel: (1) 617-864-4226
No one can change the past, everyone can change the future
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