To search for a near-extinct snail, tread lightly

An undated photo of a Chittenango ovate amber snail inspecting a new leaf in its terrarium. (Photos: NYTimes)
The Chittenango Creek, which runs north for about 48 twisting kilometers in central New York, has few distinguishing markers: The stream is generally only a couple of feet deep, and the towns it passes through are similarly small and overlooked.اضافة اعلان

One exception is found a couple kilometers from the source of the creek, where the riverbed flattens out and drops 50m over a series of limestone cliffs that are segmented into ledges and still smaller rock shelves. The fractal qualities are magnified by the foaming water that tumbles in thin layers down the cliffs. On some mornings, sunlight from the southeast illuminates the mist, and the whole area glows.

Around this time on a recent Thursday, a dozen people clustered on one side of the falls, along two ledges that were blanketed in snakeroot, yellow jewelweed, spotted Joe-Pye weed and pale swallowwort. Here, in an area about the size of a living room, is the only known habitat of a small, critically endangered invertebrate with a marbled spiral shell: the Chittenango ovate amber snail.

A thousand species of land snail worldwide are known to be at risk of extinction. Most have very specific needs and a limited geological range, so scientists have been studying their populations to understand how changes in the environment could affect biodiversity more broadly. “Land snails are apt to be the real canaries in the coal mine for these sorts of changes,” said Rebecca Rundell, a biologist at the SUNY College of Environmental Science and Forestry.

Rundell is conducting such research on endangered land snails in the Republic of Palau, and similar projects are underway in such far-flung places as Hawaii and Bermuda. But the same issues are at play in her backyard, with the “Chits,” which can only flourish in nearly 100 percent humidity and the shade of deciduous forests. “The conservation status of our local snail is emblematic of what is happening to land snails globally,” she said.

And so Rundell’s team, with volunteers and employees from the New York Department of Environmental Conservation, gathered on the side of the waterfall, their feet and knees planted cautiously but firmly on rocks, and sifted gently through the dirt and roots. Their goal: to figure out how many of these snails remain in the wild without crushing any in the process.

Cody Gilbertson, a biologist in Rundell’s lab who has helped lead research on Chits for the past decade, was up near the top of the falls watching over five mature snails that she had raised in captivity and was preparing to release. “Snailsitting,” she called it.

When survey efforts first started, wild Chits could be found all over the spray zone of the waterfall. But those numbers dropped steadily over the years. A rockslide in 2009 took out a large chunk of the population, and heavy rainfall damaged the habitat periodically. In 2010, the number of wild Chits was around 1,000; in 2015 it was around 400; this year, after five preliminary surveys earlier in the summer, Gilbertson said, “the numbers are quite dismal” — in the double digits.

The day before the survey, Gilbertson sat in a white-walled lab in Syracuse, New York, counting out baby Chits, each smaller than a sesame seed, that speckled the inside of plastic deli containers. Some 150 mature snails and 200 juveniles had been raised in the lab, and one of the babies had seemingly disappeared.

“It’s very tedious,” Gilbertson said, handing the container to Alyssa Whitbread, a researcher who has been helping study Chits since 2017. Using a small, flat-tipped paintbrush, Whitbread started to comb through the leaves that lined the container. “Sometimes they like to hide in cracks that you don’t think to look in,” she said.

A “leaf lasagna” prepared for the terrarium of captive Chittenango ovate amber snails at the SUNY College of Environmental Science and Forestry in Syracuse, New York, on August 26, 2022. 

Chits are born with their shells, which start out pearly white and darken over time. Hard enough to see when alive, they often disintegrate after death. Counting the captive animals — which Whitbread, Gilbertson, and Marlene Goldstein, an undergraduate at SUNY, do each week — often takes hours. But the snail population in this lab and the wild one at the Chittenango Falls are the only two in the world. Lose track of one snail, and you’ve lost track of one of the last Chits on Earth.

Still, existential rumination can go on only so long. “At a certain point, we just have to move on,” Gilbertson said, after Whitbread failed to find the itinerant snail.

Most of Gilbertson’s scientific career has been dedicated to figuring out how to keep a Chit population alive in captivity. An effort in the late 1990s failed, and a decade later, when Gilbertson first collected a handful of adults and brought them into the lab, they refused to eat anything. The animals slowly died, as Gilbertson “frantically grabbed stuff from the falls” to try to feed them, she said.

Then one day, miraculously, a cherry leaf worked.

Maintaining a captive population of Chits can theoretically bolster the existing population of wild snails, serve as a last-ditch defense against their extinction and, perhaps eventually, be the source for a new wild population in a different waterfall spray zone. But Gilbertson and Rundell were painfully aware that the decade-long efforts to reintroduce snails to Chittenango Falls have not offset the wild population’s decline. “Even captive breeding is unlikely to save the day for these snails,” Rundell said.

On that sunny Thursday, the surveyors tried to find as many wild snails as possible in 15 minutes, placing them in Tupperware containers and, later, under a park pavilion, sorting through the animals and inspecting them closely. The snails would be released back into the environment once tiny numbered tags had been super glued to their shells.

A dark spot on the foot of a Chit distinguishes it from what the researchers refer to as Species B — Succinea putris, an invasive land snail that is native to Appalachia and now also lives in the Chits’ habitat and may compete for resources. Little is known about Species B’s interactions.

“I get emails all the time, like, ‘I found a Chit; it’s in my backyard,’ ” Gilbertson said. “And I look, and it’s Species B.”

After an hour of sorting, the team collected five Chits. Two had been caught earlier in the summer; one had been released from the captive population a year ago and had a white tag on its shell; two were new finds. “I’m really happy to see some fresh snails,” Gilbertson said. “It gives me hope.”

She added: “By going into this tiny world, we’re able to see something that we don’t normally see. And I think that in general, people don’t realize that the little guys are just as important for conserving.”

Before departing, a few of the researchers walked back down to the falls to release the snails that had been collected as well as the five snails that Gilbertson had picked out of the captive population for reintroduction. The sun shone directly overhead, and water spilled down the falls like white paint. Every bit of ground was drenched in sunlight and steaming in the heat, except for the living room that harbored the only wild population of Chittenango ovate amber snails in the world. This corner of the Earth was cool, shady and damp — just right.

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