That's a great question.
What you were probably looking-in-in your youth were relicts from exposed
banks or the "living dead", adult mussels that are making a living, but not
reproducing.
Mussels can be extremely long lived (10 - 100 years) and then the valves
degrade fairly slowly, especially when they get locked up in stream
sediments, and then burst back on the scene with an exceptional discharge
(your "bloom" of winged mussels) that scowered old flood plains that haven't
been accessed since the inception of the dams. I find clubshell like this
all the time in the lower Maumee. So it can take a long while for the
evidence to disappear. It's kind of sad that it has.
So basically... You were looking-in-the final evidence they were ever there
(until the dams come down and banks and mucked up bars etc are exposed)
after habitat homogenization and degredation. Anything fresh was probably
"living dead" that finally knocked off... The rest were sub-fossil relicts.
There are probably still patches of species present, but they will be
species favoring the silts and pool habitat (giant floater, pond papershell,
cylindrical papershell, flat floater, pink and white heelsplitter). I'd
encourage you take a look downstream of dams on bars or shores that
intercept the current in high discharge. There, you'll probably find a lot
of valves of these species. But they won't be the ones you saw in your
youth, with the exception of a few sub-fossil relicts.
However... There are always suprises :) So take pictures!
Todd
The Muddy Maumee Madness, Toledo, OH
Be the change you want to see.
http://www.farmertodd.com
----- Original Message -----
From: "Ben Dattilo" <bdattilo-in-utahwisp.com>
To: <nanfa-l-in-nanfa.org>
Sent: Tuesday, March 21, 2006 10:59 PM
Subject: RE: NANFA-L-- San Francisco Bay Invaders
> I love the last line in this article. I remember visiting a few major
public
> aquaria and speculating that the Japanese tourists were talking about how
> this or that fish would taste . . . after my brother came back from an
> extended visit to Japan, he confirmed those speculations. A very
different
> approach to biology . . .
>
> A more serious note along the same vein, Lately I have been walking along
> the bank of the Ohio River from time to time, and I have noticed almost no
> bivalves of any sort maybe a few Asiatic clams . . . When I was a kid
> 1960's, 70,s) it seemed that there were-in-least three common species of
> native mussel, a few more rare types, and tons of Asiatic clams. Later
(late
> 70's or early 80's), the old native mussels were very rare, but there was
a
> "bloom" of large "winged" mussels that resembled the old mussels in some
> ways, but had a distinctly pink-purple coloration to the nacre. After that
I
> did not see much besides the Asiatic clam, until, a few years ago, I saw
few
> of anything but the Zebra mussel. Now even they are gone. . . .
>
> This strikes me as odd--when I was a kid, we didn't really dare touch the
> water, and I distinctly remember that the water was extremely murky. Now
> the visibility looks much better, and I actually see kids playing in the
> river (not mine), but from that same bank, the bivalve situation appears
to
> be dire, much worse than before. . .a long way from the time they would
load
> barges full of mussels into town to make pearl buttons out of them . . .
>
> Does anyone have a clear picture of what is going on with the mussel
> populations of the Ohio River? Is it all as bad as what I am seeing? I had
> always figured that a lot of damage was done long before I was born, and
> this later decline is a bit perplexing to me . . .If the native mussels
> survived the sewage and the impoundment of the river, why after all of
that
> did they start declining just as the clean water act was taking effect?
>
>
> -----Original Message-----
> From: owner-nanfa-l-in-nanfa.org [owner-nanfa-l-in-nanfa.org] On Behalf
Of
> A F
> Sent: Tuesday, March 21, 2006 7:19 PM
> To: nanfa-l-in-nanfa.org
> Subject: NANFA-L-- San Francisco Bay Invaders
>
> A new ecosystem is forming in SF Bay.
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