Coral starving and survival

Jeremy Woodley woodley at
Mon Mar 25 12:35:00 EST 2002

Mike: the work you propose on the stratigraphy of Caribbean hurricane
berms could indeed be informative about the recent history of climate and
hurricanes. When you mention the Hurricane Allen berms on Jamaica, you
might be thinking of the one just west of the Discovery Bay Marine Lab. It
is c. 30m across, 1-2m high, and was built, not just by Allen, but by
centuries of major storms since sea-level stabilised. Allen only added a
new layer of rubble to the seaward slope. While you're at it, if you want
to find when local sea-level stabilized, there's some mangrove peat under
the sand in the back-reef lagoon in front of the Lab!

Of course, Acropora palmata is a major contributor to hurricane berms even
without the hypothesized mortality due to medieval bleaching. That is just
as well for the proposal, since A. palmata may not be particularly prone
to bleach. Ian Sandeman has been investigating the physiology of this.
However, mortality in other corals might provide more ammunition to help
storm waves bring palmata down. Dave Liddell and colleagues reported that
other species made up about 40% of the material contributed to the berm by

Jeremy Woodley

13 South St. West,                      Tel: (905) 627-0393
Dundas,                                 Fax: (905) 627-3966
ON L9H 4C3,                             woodley at
Canada.                                 or jdwoodley at

Centre for Marine Sciences, University of the West Indies (Mona),
Kingston 7, Jamaica.

On Sat, 23 Mar 2002, Mike Risk wrote:

> Hello, and thanks for some interesting postings.
> Without getting into the validity, or lack thereof, of the starvation
> hypothesis: I think you have touched on a key point in mentioning the
> Medieval Warm. The problem is, the data do not exist. They should be
> as indeed should those from the Little ice Age.
> Acropora arose in the Miocene, and quickly spread to become the
> "weed" coral of Late Cenozoic and Modern reefs. It is abundant in fossil
> deposits, virtually always as storm-derived rubble: storm berms, beach
> windrows and the like. These storm deposits can range in elevation from
> metres below where the coral grew to, in the case of the Hurricane Alan
> berms on Jamaica, several metres above present sea level. (This should
> give pause to some who base sea-level estimates on dated Acropora, but it
> doesn't seem to have. I once saw a TV interview with a group who were
> suggesting catastrophically rapid sea level rises at the beginning of the
> Holocene-when they held up the key Acropora sample, and the camera zoomed
> in, one could plainly see it was Cliona-bored on all surfaces, whereas the
> theory was based on it having been found in life position. Yes, a colossal
> scientific blunder-but it got them a paper in Science.)
> If the coral deaths we see now are due to elevated sea surface
> then Yes, you are correct, corals would have died like flies. This event
> would be recorded in storm berms of Acropora rubble, all over (say) the
> Caribbean, at approx. 1000 YBP. These deposits will have been overprinted
> subsequent storms, overgrown by vegetation, and removed by 5-star hotels,
> but enough should remain for dating purposes. Finding berms on one island
> would not be sufficient-one would have to prove the coexistence of
> contemporaneous deposits, basin-wide. Paleotemperatures from these corals
> would nail down SST values. The deposits may very well be there, it's just
> that no one's ever looked systematically.
> A study of this nature would seem to be a natural, given the present slant
> of
>  reefy thinking, but here's why no one's going to do it: Funding agencies
> these days do not fund hypothesis-testing, they fund more-of-the-same. To
> test this hypothesis, one would have to visit (say) a half-dozen different
> locations. At each location, extensive shoreline mapping would have to be
> done to describe the location and extent of storm deposits. From each of
> these, maybe a half-dozen samples would have to be dated. Hundreds of
> months of field work. Maybe a half-million $ for
> testing an hypothesis, with no guaranteed result. Never happen-but it
> should.
> BTW: I do not discount sea-level curves based on Acropora, but I take them
> with a grain of salt. I trust curves based on mangrove peats, Tridacna,
> microatolls.
> ~~~~~~~
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