Tuesday, July 24, 2007

The wood, the trees, the choir invisible

In a note on Ove Hoegh-Guldberg's recent commentary, Charles Sheppard restates with clarity the difference between species extinction and ecological extinction:
I think the media (and some simple scientists it seems!) can’t grasp the difference between species extinction (as in Dodo, Sabre-Tooth Tiger etc) and ecological extinction (as in the system is too broken to work any more). One remaining oak tree in a clear-felled mud-scape is not species extinction of the oak, but the forest doesn't do foresty things any more.

I have recently returned (again) from a very heat stressed region of the coral reef world - Arabian/Persian Gulf - and dived for many hours on once rich reefs. I saw a live coral at intervals of perhaps 20 or 50 metres apart, the rest being dead. That is zero coral cover to the nearest whole number, but it is still not species-extinct. You would need to measure cover to about 0.0001% to register a positive number there. But then, to how many decimal places do we need to measure ‘dead’? Answer: to many, if you are looking to confirm species extinction, but none at all if you want to determine whether you still have a reef.

They don't have reefs any more in the sites I worked, but they do have the odd coral still. The reefs, are as dead as Monty Python’s parrot: eroding, not accreting, bio-deficient, not biodiverse, unproductive not productive, just plain dead, to use a shorthand...
For an earlier comment by Charles Sheppard on Coral Bones see here, and on the dead parrot analogy see here.


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