Kurt, Gary, I knew I could count on you. Thanks also to Tom Watters for an
informative reply. I guess the ball's back in my court.
 
About Muscle Shoals (which is on the Tennessee River in northern Alabama):
The words "mussel" and "muscle" have the same derivation; originally, they
were the same word, spelled differently and given different meanings. The
original meaning in Latin is "little mouse"! In the case of the muscle,
this may represent a fossilized Roman joke: "Here, kids, watch the little
mouse run up and down my arm." In the case of the mussel, I think our
forebears were at a loss for words.
 
Muscle Shoals was a long stretch of the Tennessee River that was broken up
into many channels by limestone bedrock. It was named for the mussels that
formerly lived there in great abundance. The name is a translation of
Cherokee Dagunahi, "mussel place" (daguna = mussel, -hi = place). They also
called it Chustanaluyi, "shoals place". In English, the name was spelled
either as Mussel Shoals or as Muscle Shoals until the U.S. Board on
Geographic Names standardized it as Muscle Shoals in 1892. The standardized
and obsolete spelling has led to a local legend that Muscle Shoals was
named "because you had to use a lot of muscle to push your way through the
shoals." Collector Herbert H. Smith tried hard to reform the spelling in
the early 1900's, partly to publicize the environmental disaster that was
going to happen when the Tennessee River was dammed, but few people
followed his example. The environment has changed from one of rushing water
to one of still water, wiping it out as a desirable habitat for most
species of mussels.
 
The Coosa River is another river in Alabama that runs over limestone (and
dolomite, a similar rock) over much of its course. The river water is
therefore rich in dissolved calcium carbonate, which the mussels need to
build their shells and to keep them from dissolving back into the water.
The Coosa flows into the Alabama River, not the Tennessee, and this river
system has its own huge diversity of mussels and freshwater snails. In its
natural state, the Coosa River consisted of a series of rapids and pools,
and each set of rapids had its own fauna of snails. Thirteen species of
Gyrotoma, the entire genus, were made extinct when virtually the entire
river was dammed, converting it into a series of lakes for the purpose of
power generation. Herbert and Daisy Smith were on the scene in the early
1900's, collecting snails from shoals as the lake water literally rose at
their feet. Imagine how that felt. The last dams were erected in the
1960's, just before the passage of laws that would have protected the
snails. The part of the original fauna that throve in deep pools is doing
very well in the new lakes, but the part that required fast-flowing water
is now restricted to a few tributaries and other areas. Occasionally a
species thought to be extinct, such as the big freshwater snail Tulatoma
magnifica, is found living in some tiny area, but their situation is
precarious. A single chemical spill or other unexpected environmental
change could wipe these diminished species out altogether. So Alabama had
(and still has) extraordinary diversity in its freshwater molluscan fauna,
but it also has the highest rate of extinction among them in the United
States.
 
Abrazo,
Andrew
 
Andrew K. Rindsberg
Geological Survey of Alabama