At 06:27 PM 12/2/99 -0300, you wrote:
>I've heard that Zebra mussels are out-competing indiginous Unionids
>rather badly, leading to local extinctions, expecially in the
>Mississippi system.  Can anybody tell the list which species have been
>hit the hardest, and where, and does anyone know of a speicies that has
>actually gone extinct, or is immanant danger of doing so, because of
>zebra-mussel competion?
>
>A foot of snow enough for you?  (it's plenty for me!!).
>-Ross.
>

Unionids in large impounded rivers and the Great Lakes have been hit
hardest. "Big River" species using these habitats are in the greatest
jeopardy. Many beds in the lower Ohio River are steadily declining in
diversity and density. The Western Basin of Lake Erie once had numerous
unionids, but a survey I participated in last year failed to find a single
living unionid in a week of diving. No species have become extinct because
of zebs... yet. Species already on the verge will probably be lost, like
Plethobasus cicatricosus and P. striatus.




*****************************************
 G Thomas Watters, PhD
 Ohio Biological Survey &
 Aquatic Ecology Laboratory
 Ohio State University
 1315 Kinnear Road
 Columbus, OH 43212 USA
 v: 614-292-6170  f: 614-292-0181
******************************************

"The world is my oyster except for months with an 'R' in them" - Firesign
Theater

"Give a man a fish and you feed him for a day. Teach a man to fish and he
has to buy a license" - GTW

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