Nathan Whelan wasn’t going to give up. He knew his chances of finding the small creature were minimal, but he was still going to try.



His perseverance paid off last year when he and a few friends went kayaking in the Cahaba River and discovered a freshwater snail that had been declared extinct in 2000.



Historically found in a small stretch of the river, the oblong rocksnail had not been seen since the 1930s, said the 26-year-old University of Alabama doctoral student from Eureka, Mo.



“Being able to hold something that no one has been able to hold for more than 75 years is amazing,” Whelan said. “Usually, news of conservation and biodiversity is not positive. With this rediscovery, maybe I’ll have a chance to be part of a conservation story with a positive ending.”



Whelan, who is studying biology with a focus on conservation evolution of freshwater snails in the southeastern United States, said he did not understand why this snail, the only one in the family, had gone extinct, but other snails had not. He decided to put his knowledge to work.



Knowing the snails had typically been found on shoal habitats, Whelan and his friends looked on different shoals until they found a snail that looked like the oblong rocksnail. Whelan said they were able to distinguish the snail because of its unique shell shape. He later found that the snail also has a different color pattern.



Using a specimen from 1881, Whelan compared the snail’s teeth, which are also unique to the species, with the sample collected in May 2011. It was identical, he said.



“This one floored us, especially given the amount of effort put into monitoring the Cahaba River over the last 10, 15 years. There’s been multiple surveys and no one had seen this animal,” said Paul Johnson, program supervisor of the Alabama Aquatic Biodiversity Center. “But Nathan refused to believe it wasn’t there. Sometimes the guy with the least amount of experience is right.”



Alabama has more listed animals than any other state, the majority being freshwater mollusks, Johnson said. The state has a number of different watersheds, each one supporting unique species, making it a hotspot for freshwater diversity. The Cahaba River basin supports 121 species of fish, 38 species of mussels and 32 species of snails; 12 of these are federally threatened and endangered species, he added.



Poor water quality during the mid-20th century in the Cahaba River probably created such low numbers that the oblong rocksnail may have been overlooked, which would explain why it was thought to be extinct, Johnson said. Once, however, water quality started to improve, the snail was able to reach a detectable level. The next step is conservation, ensuring the snail stays at that level.



Because the snail’s distribution is so small — a range of a couple hundred yards — it is “very susceptible” to being completely wiped out by a large pollution event, Whelan said. The goal now is to start a new population in another area of the river. While this process will take a couple of years, Johnson is fairly certain it will work.



The snail is the latest in a series of species that have been rediscovered in the Mobile River Basin over the last decade. Recovery efforts have not only re-established a species population, but also improved the overall water quality to all Alabama residents, he said.



“There’s some good news to this. Things aren’t as bad as we think,” Johnson said. “But we still need to be vigilant about improving water quality resources in the state.”



Reach Kim Eaton at kim.eaton@tuscaloosanews.com or 205-722-0209.