Date: Sun, 26 Dec 1999 17:22:31 CST
From: "Dave Neely" <rheopresbe_at_hotmail.com>
Subject: Re: [Re: NANFA-- Fish Kill in Indiana]
Scott,
>If the kill was the result of toxic materials, is it possible that the
>material could have been dense enough to remain at the bottom of the
>river,despite the churning of the water? Might it thus only effect the
> >bethnic species?
Hmm, interesting thought. Maybe, but I can't think of anything that would
be
dense enough to maintain a layer along the substrate (in a riverine
system!)
toxic enough to wax carp and catfish, and yet not causing any mortality to
other fishes. Even minimal current is usually enough to disrupt any
stratification that might occur, or at least set up internal seiches (waves
on the surface of the denser material) that increase diffusion into the top
water column.
When I took limnology (one of the most boring classes I've ever endured),
we
set up a demonstration tank with a dense sucrose + dye solution on the
bottom, and distilled water on top. By blowing across the surface with a
hairdryer, you can set up internal seiches on the sucrose layer. As you
increase the velocity of the current on top, the boundary layer breaks down
and the sucrose eventually dissolves through the tank.
I'd still put my $0.02 on the hypothesis that it wasn't species-specific...
and that carp and catfish just made up most of the fish fauna in that area
anyway. Another option is this: that the biologist that investigated the
kill had no fish ID skills, other than "if it ain't a bass, and it got
scales, it's a carp; if it ain't got no scales, it's a catfish."
Unfortunately, this isn't as far-fetched as it may sound.
cheers,
Dave
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