[Coral-List] Coral Immortality
David M. Lawrence
dave at fuzzo.com
Wed Mar 16 09:27:12 EDT 2011
First, you have to come up with a relevant definition of immortality. I
doubt the concept of immortality, which applies to individuals, makes
any sense when applied to corals.
Also note this paragraph from the story:
"In many areas of the world, reef degradation is clearly down to human
activities like over-fishing, pollution and rising sea temperatures. In
the Caribbean, 80 per cent of reefs have declined since the mid-1970s
and this is almost certainly down to pollution and over-fishing."
The story also offers an explanation for the growth declines:
"Two main things can slow their growth - lack of sunlight penetrating
the water and lack of space. The shallow and muddy waters of the
inner-shelf of the Great Barrier Reef mean that the space into which
reefs can grow is relatively limited. This means they can pass through
their different evolutionary stage rapidly - young to mature to senile
in only a couple of 1,000 years."
This sounds a hell of a lot more than Liebig's law of the minimum coming
into play than some kind of natural "life span" limit on coral growth.
Which, if that is the case, is no surprise to anyone familiar with
ecological literature.
Dave
On 3/15/2011 1:12 PM, Eugene Shinn wrote:
> Dear Coral-Listers, Here is a stimulating break from the incessant
> job advertisements. See
> <http://planetearth.nerc.ac.uk/news/story.aspx?id=907> It is
> interesting because the vast majority of head corals in the Florida
> Keys suffered mortality over the past 35 years, especially during the
> 1980s at places like once-thriving Carysfort reef where there were
> hundreds in the 200 to 300 year-old range. More than a dozen of the
> living Montastrea sp heads there were cored and their growth rates
> measure and published by Hudson (1981). In addition brain corals also
> perished or are hanging on by a thread (see
> <http://gallery.usgs.gov/videos/334>). It is interesting to note that
> similar head corals grew during the Pleistocene and built the Florida
> keys when sea level was more than 20 ft higher than today.
> Interestingly those heads that built the reef grew no larger than
> those that recently died in the Florida Keys. Why do we not see head
> corals that grew 15 to-20-feet in height (or even 50 ft) back when
> there were no anthropomorphic influences? Does it mean corals are not
> immortal? Could it mean that corals die of old age like all other
> organisms on earth and we just happen to be living at the right time
> to observe the current age class of geriatrics demise? Is that why
> more than 95 percent of what we call the Florida reef tract is less
> than 1 meter thick when it had the past 6 to 7,000 years to grow? I'm
> sure there are those who think today's corals should be immortal but
> why weren't they immortal in the past? Just something to think about!
> Gene
>
> Reference: Hudson, J. H., 1981, Growth rates in Montastraea
> annularis, a record of environmental change in the Key Largo Coral
> Reef Marine Sanctuary, Florida. Bulletin of Marine Science, v. 31,
> pp. 444-459
>
--
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David M. Lawrence | Home: (804) 559-9786
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USA | http: http://fuzzo.com
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