Alabama Snail Returns From the Dead

If you read Smithsonian magazine in August 2009, you would have learned that Alabama is a hotspot for extinctions. As Michelle Nijhuis explained in her story, “The Cahaba: A River of Riches”:

s rivers were dammed for hydropower and transportation over the past century, species began to blink out. The region’s lush rivers—which the eminent biologist and Alabama native E. O. Wilson calls an “aquatic treasure house”—continue to lose species. Alabama now leads the lower 48 in extinctions, due mostly to disappearances among its freshwater fauna: the Coosa River, which runs alongside the Cahaba a few dozen miles to the east, lost 34 species of snails—half its entire inventory—in the 50 years between 1914 and 1964. This is considered by many experts to be the largest recent extinction event of any kind in the United States.

But now there’s a new bit of bright news from the area: A population of wicker ancylid limpets (Rhodacmea filosa), a type of snail that has a cap-shaped shell, has been found in Alabama’s Choccolocco Creek, which feeds into the Coosa River. (The discovery is the subject of a recent paper in PLoS ONE.)

The wicker ancylid was last seen more than 60 years ago and officially declared extinct by the IUCN in 2000. In this new study, researchers collected limpet species from the Green River in Kentucky, the Cahaba River in Alabama and Choccolocco Creek. They then compared their finds with mollusks collected more than 100 years ago and now housed at the University of Michigan Museum of Zoology. The wicker ancylid, they determined, was alive and well in Choccolocco Creek. “Its survival there is somewhat surprising, given the serious episodes of pollution experienced by this watershed,” the scientists write.

“This is very good news,” says the study’s lead author Diarmaid Ó Foighil. “With conservation biology, usually it’s all gloom and doom, but this is one of those rare events where we have something positive to say.”

Michelle noted in her 2009 article:

Snails and mollusks may not inspire us like bald eagles or blue whales or, for that matter, the flashy Cahaba lily. But they form the bedrock of healthy ecosystems, maintaining water quality by eating algae, feeding ducks, fish, crayfish and turtles, and, through their sensitivity to pollution, serving as early indicators of environmental trouble.

The condition of Alabama’s waterways has been improving in recent decades, the scientists note, due to better management and the implementation of anti-pollution policies. And recent surveys have revealed small populations of several species, including the Cahaba pebblesnail, once thought to have been wiped out during the 20th century.

The rediscovery of these species may be a lesson for other parts of the world where rivers are being dammed and destroyed, Ó Foighil says. “The industrialization of freshwater watersheds that happened across the U.S. in the last century is now happening all over the world….Even though we’re now more aware of , when it comes to issues of economic development, freshwater biodiversity almost always loses.”

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Sarah Zielinski is an award-winning science writer and editor. She is a contributing writer in science for Smithsonian.com and blogs at Wild Things, which appears on Science News.