coral reefs doomed?
hendee at aoml.noaa.gov
Fri Sep 7 08:51:29 EDT 2001
Dear Coral Colleagues,
I know I'll get raked over the coals on this (especially because I don't
have all the literature at my fingertips), but the content and tone of the
news article below is troublesome to me, even though such a tone helps to
gain attention, as well as funding, so that we can more thoroughly study
the problem of coral bleacing and global warming. Of course I respect our
colleague's right to a viewpoint, but when I see this, I can't help but
have these thoughts:
Such a projection gives no "credit" to adapatation and natural selection,
even though such adaptation would have to occur under a relatively short
time span (50 years). I believe Ware et al (1996), among others, have
As Dr. Al Strong and I have discussed, and as alluded to but unfortunately
not expanded upon in the last sentence of the article, if the seas are
warming, then you might expect the zoogeography of corals to expand
(relocate?) into the cooler areas, as long as the substrate, circulation,
light and water quality regimes are conducive. (I would imagine some
coral researchers have modeled these possibilities, and I apologize for
not referencing your work.)
Even though high sea temperatures are the primary cause and indicator of
coral bleaching, that is not the only cause, and no credit is given to the
evidence in the literature (e.g., Lesser 1996, among others) that high UV
is also an agent in coral bleaching. Higher UV, especially in the
tropics, is part of the problem as it relates to the earth's ozone layer.
There is evidence that high sea temperatures that elicited coral bleaching
at some localities in the past did not elicit coral bleaching during
extended cloudy periods (Mumby et al, in press). (Perhaps the cooler areas
mentioned in the above paragraph might also have lower UV?)
There are other causes of coral bleaching (e.g., see Glynn 1993, 1996) and
this manifestation of stress is complex and to my mind public statements
on coral bleaching should emphasize this.
Would an annual update to the ITMEMS statement on coral bleaching
(http://coral.aoml.noaa.gov/bulls/ITMEMS-bleach.html) be helpful for the
public in this regard? It is my opinion that it would, that we should
address the topics above (among others, e.g., coastal effects), and that
it would behoove us to widely circulate the update among the press as a
consensus opinion (if that is possible!).
Just my two cents worth...
Glynn, P. (1993). Coral reef bleaching: ecological perspectives. Coral
Reefs 12, 1-17.
Glynn, P. (1996). Coral reef bleaching: facts, hypotheses and
implications. Global Change Biology 2, 495-509.
Lesser, M.P. (1996). Elevated temperatures and ultraviolet radiation
cause oxidative stress and inhibit photosynthesis in symbiotic
dinoflagellates. Limnol Oceanogr. 41(2): 271-283.
Mumby, P.J., Chisholm, J.R.M., Edwards, A.J., Andrefouet, S. & Jaubert, J.
2001. Cloudy weather may have saved Society Island reef corals during the
1998 ENSO event. Mar Ecol Prog Ser (in press).
Ware, J.R., Fautin, D.G., & Buddemeier, R.W. (1996). Patterns of coral
bleaching: modeling the adaptive bleaching hypothesis. Ecological
Modelling 84, 199-214.
-------- Original Message --------
World coral reefs to die by 2050, scientist warns
By Ed Cropley, Reuters
Thursday, September 06, 2001
GLASGOW, Scotland The world's coral reefs will be dead within 50 years
because of global warming, and there is nothing we can do to save them, a
scientist warned Wednesday.
"It is hard to avoid the conclusion that most coral in most areas will be
lost," Rupert Ormond, a marine biologist from Glasgow University, told a
science conference. "We are looking at a loss which is equivalent to the
tropical rain forests."
Only the coral reefs in nontropical regions such as Egypt stand any chance
of lasting beyond 2050, Ormond said, but even the days of the stunning
marine parks of the Red Sea are numbered as sea temperatures continue to
In the past, reefs have suffered from sediment buildup and the coral-eating
crown-of-thorns starfish, whose numbers have exploded due to the
over-fishing of their predators.
Now the main threat to the delicate structures that harbor some of nature's
most stunning creations comes from warmer seas, which cause coral bleaching.
Microscopic algae that support the coral polyps cannot live in the warmer
water, and the polyps, the tiny creatures who actually create the reefs, die
off within weeks.
Scientists agree the world's oceans are now warming at a rate of between one
and two degrees Celsius every 100 years due to the increased amounts of
greenhouse gases in the atmosphere which trap the sun's rays.
But even if humans stopped pumping out greenhouse gases such as carbon
dioxide tomorrow in a bid to halt the process, it would still be too
save the reefs, Ormond said. "I don't know what can be done, given that
there's a 50-year time lag between trying to limit carbon dioxide levels and
any effect on ocean temperature," he told the conference, held by the
British Association for the Advancement of Science.
The implications stretch far beyond the death of the colorful coral
structures themselves. The weird and wonderful eels and fish which inhabit
the nooks and crannies will become homeless, and many species will die out.
"We are looking at a gradual running down of the whole system. Over time,
the diversity of coral fish will die," Ormond said.
Humankind will also suffer directly as the dead reefs are eroded and
shorelines that have been protected for the last 10,000 years face the wrath
of the oceans without their natural defenses.
In an age of relatively cheap scuba-diving holidays, this also means many
developing countries in the tropics, such as Kenya or those in the
Caribbean, face losing a major source of revenue.
The only cause for optimism was that new coral reefs could start to emerge
in colder waters such as the north Atlantic Ocean and Mediterranean Sea.
Copyright 2001 Reuters
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