Just received a newsletter from the Nature Conservancy of Alabama with some
depressing news.

The southeastern United States has the world's most diverse freshwater
mollusks (and also crayfishes). Unfortunately, that diversity has declined
precipitously in the last 50 years. According to Jim Godwin, the Mobile
River basin (including the Alabama, Tombigbee, Coosa, and Cahaba Rivers) had
118 species of snails, of which 110 (93 percent) are endemic. The Coosa
River alone had 60 species. However, 30 of the Coosa species are now extinct
due to impoundment of rivers behind hydroelectric dams. Even the
free-flowing Cahaba River has only 27 species of mussels now, compared to 50
in 1938.

None of these extinctions is attributed to overcollection, but rather to
alteration of habitats. Of course, collection of endangered species is
illegal -- and 213 (72 percent) of the 297 freshwater mollusk species of the
U.S. and Canada are "endangered, threatened, or of special concern."
Collecting them now that their populations are in decline might drive some
species into extinction.

What is the situation with land snails in the eastern U.S.? How many species
are in decline?

Andrew K. Rindsberg
Geological Survey of Alabama