Lost Cahaba River Snail Has Been Found Once Again
August 9, 2012

Graduate Student Finds Extinct Snail Is Actually Alive

Brett Smith for redOrbit.com - Your Universe Online

A University of Alabama graduate student scored a victory for Mother Nature recently when he came across a snail species previously thought to have been extinct.

The rare happy development regarding biodiversity and conservation occurred when Nathan Whelan, a doctoral student in UA´s department of biological sciences, convinced three of his friends to kayak on Alabama´s Cahaba River in May 2011 in search of the long-lost snail.

“Considering it was the only snail species from the Cahaba that went extinct, it was always interesting to me,” Whelan said. “What would have caused this one species to go extinct and not these others?”

The snail, commonly called the Oblong Rocksnail, has a yellow body less than an inch long and a black band on its head. The species´ signature characteristics include an indentation on the left wall of the shell´s opening, its unique coloring, and microscopic teeth that it uses to scrape algae off of rocks. It had not been collected by biologists in more than 75 years, according to Whelan who detailed his findings and analysis this week in the journal PLoS ONE.

Although the snail has been found alive, its range is currently limited to a small stretch of the Cahaba, a circumstance local conservationists, like those at the Alabama Aquatic Biodiversity Center (AABC), would like to correct.

“Rare aquatic species reintroductions are the primary mission of the AABC, as Alabama has more federally listed animals than any other state,” said Paul Johnson, program supervisor of the center and a co-author of the PLoS ONE paper.

“Most listed animals are snails or mussels, and many remain in one or two locations. Successful reintroduction to formerly occupied habitats reduces the risk of future extinction events.”

Using a hundred-year-old specimen from the collection in the Smithsonian´s National Museum of Natural History as his standard, Whelan used an electron microscope to scan the snail´s teeth, or radulas. He compared these images with those taken of the recently recovered snail.

“The structures were virtually identical,” Whelan said.

Some of the samples collected by Whelan were taken to the AABC, where researchers were able to observe and document how the snails lay their eggs for a potential “artificial propagation and reintroduction” of the species, according to the report.

The biodiversity-related story of the Cahaba is unfortunately a common one. Human activity caused poor water quality and habitat degradation in the river during the last century. These factors drove the Oblong Rocksnail, and other creatures like it to the brink of extinction, the researchers said.

However, a concerted public effort improved the waterway´s health and potentially paved the way for the once extinct snail to bounce back.

“Recovery actions by numerous federal, state and local government agencies and private conservation groups have significantly improved water quality and riverine habitat in the Cahaba River since 1985,” said Johnson.

The modern-day Cahaba River basin supports 121 species of fish, 38 species of mussels and 32 species of snails. The Nature Conservancy has called the Cahaba one of eight “hotspots of aquatic biodiversity” in the U.S. that must be protected.