Re: NANFA-- Louisiana sinking and other thoughts

Todd Crail (
Mon, 3 Mar 2003 23:04:47 -0500

> 3. What effect would rising sea levels have on short term and long term
> biodiversity of fish? If there is significant warming, then there would
> be a reduction in salinity due to retreating polar ice and glaciers.
> Someone recently said that Red fish have successfully colonized fresh
> or estuarian waters. Would we expect to see more of that? Would a
> reintegration of teleosts occur resulting in completely new distributions?

I'm up for some speculation, and a great thought, I'd like to join in on it.
:) Given that I am no expert on the subject, but have read quite a bit on
adaptation, historical events of crash, divergence and adaptive radiation...
(read: this is not the gospel truth in any way ;)

My quick answer would be yes and then no, and topped with some "You'd need
to live to a thousand to see anything significant". :)

Yes, in that you would see species making their very best efforts to survive
given any change in conditions. Short term it would be redistribution.
Those who have the ability to make the changes more gracefully will carry
on. Those who do not, pass on into the extinction record. I wouldn't
speculate on who would take over where... Maybe estuarine species expanding
a wider range due to the extensive shallows created... Maybe marine species
just expand with the shoreline progress inland. There's really no way to
predict that.

No, in that I don't think it will be much of a "redistribution" for very
long. I seriously doubt that you will have a mass of the current species as
they appear today in the same form over a period of time. I feel that they
would be at first, of a divergent genotype, if not even more so, a unique
species, and certainly so in the future. It would be interesting to compare
DNA of landlocked Salmon in the Great Lakes with their native range "look
alikes" or a population of Striped Bass in a Tennessee or Arizona reservoir
with fish up East in the sea. I doubt they'd come out the same... Even
after the 50 or so years they've had different conditions long enough, I
would think, to make some difference somewhere. The situations are
different, the competition is different, everything is different... And
different, historically, produces different genes. And so that isn't really
a redistribution. That's speciation.

The timeframe, I think speaks for itself :)

Your salinity comment has me wondering and my interest peaked, and I'm gonna
hit the books this week to see if there's already a defined answer. I
vaguely recall that the dilution will not be significant enough, nor quick
enough to cause a mass extinction, and would create the short term
redistribution, long term speciation. Due to the way temperature affects
salinity, I again, vaguely recall reading that as the oceans balance out
their new climatology, that there isn't that great a percentage change. May
need to go pick up an oceanography book for that one tho...

But in the sprit of speculation... I'm concerned that any slight change will
modify hermatypic reef building by coral in such a way that the dominant
reefs and obligate inhabitants are gonna go the way of the Dodo. They're
already in trouble for a variety of reasons. It would be sad, but
interesting, to observe how those species would adapt. Guess we'll have to
save that one for the Meerkat's species line to answer, no? :)

So anyway... There's my 2 cents... Thanks for the inspiring thoughts :)

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