The Clan of the Cavesnail

Tom Aley spent a fortune and more than 30 years of his life defending a creature no bigger than a grain of sand. Beautiful madness or crazy vision?

Across the rock footbridge, he steps carefully off the trail and squats by the streambank, swirling his finger through the black water, stirring clouds of silt. Then he stares at a flat rock in the streambed, and rests, just for a second, his wet finger on its surface.

On top, at least, its gray is plain and smooth -- unspeckled -- offering no sign of what he's seeking, no proof of the faith that's sustained him for 35 years. The faith that the near-invisible matters as much as we do.

He stares a while longer. "Maybe they're here," he says finally, rising to his feet.

Jennifer Silverberg
Tom Aley and his wife, Cathy, deep in the underground home of the cavesnail
Jennifer Silverberg
Tom Aley and his wife, Cathy, deep in the underground home of the cavesnail

"And maybe they're not."

Through the '70s, Tom and Cathy watched the cavesnails with proprietary delight. The first survey had indicated a population of about 15,000. Every year, the Aleys checked the cavesnails' water and monitored their numbers.

Every year, the numbers fell.

The population of none of the other species in the cave was decreasing -- except a larger aquatic snail that lived near the entrance. Was some sort of snail disease rampant? Was there a new snail predator?

Nothing checked out.

In the '80s, as the cavesnail's count continued to fall, the Aleys began to wonder whether ammonia and nitrate loads from livestock feedlots were cutting into the cave's dissolved oxygen levels or chemicals from highway maintenance and spills were seeping into the water system. Possible, but not probable, because the other pollution-sensitive organisms in the cave were thriving.

Then the Aleys started thinking about the nine square miles of land that drained into the cave. Much of it had been overgrazed, and with no vegetation to hold the soil in place, more and more silt was entering the cave water.

Cavesnails hate silt.

Back in 1974, a visiting scientist had noted that the snails preferred the clear parts of the stream. The animals' instinct was perfectly logical: Silt would coat their fragile shells and weigh them down, clogging their gills and food filters and roadblocking their hunting expeditions. It could also suffocate their babies and impede whatever undisclosed intimacies allowed them to reproduce in the first place.

Was silt the culprit? Aley caught himself wishing he could talk to the little specks, ask what was causing the problem, ask what he could do to fix it.

Grain-sized, translucent blind snails aren't big on conversation.

Instead, Tom and Cathy proceeded as scientists, fusing her biological knowledge with his hydrogeological expertise. He'd started conducting groundwater tracings in 1970, staining spores of Lycopodium, a genus of mosses, with fluorescent red, green and peach dyes and injecting them into creeks and sinkholes.

Down below, he sank fiberglass-mesh packets of charcoal into underground streams. At regular intervals he'd pull them up, analyze the results in his lab and see how many color-coded spores the water had carried to that location.

He found water dripping from stalactities that had made its way down from the surface, through 100 feet of bedrock, in less than a week. After one crashing thunderstorm, water from a bridge miles away showed up in the cave in 24 hours.

The Aleys knew the cave's recharge area; they knew how the water -- and the silt -- seeped into the cave through sinkholes and crevices or percolated through gravelly soils and stream bottoms. They'd mapped, as tightly as possible, the underground maze, and they knew how fast its water traveled.

They'd done what they could in the dark.

But if they wanted to save the barely visible, one-of-a-kind Antrobia culveri, they'd have to climb up to the earth's sunbaked surface and fix damage any fool could see.

Aley pulls his forest-green Mitsubishi Montero off the road at the crest of a hill.

"Everything the other side of that road is what we bought," he says, gesturing grandly to take in vast curves of toast-brown pasture. "On the left side, we bought 1,350 acres. On the right, the land belongs to one of the people who work for us."

Aley slides the vehicle back onto the road and drives a half-mile. "Now, all the stuff on the right is ours," he says. "All told, we've bought more than 2,500 acres -- which means I'm looking at early retirement at 77."

The Aleys saw the first "For Sale" sign, stuck in a barren patch at the edge of 120 acres, back in 1990. They looked at each other.

"Can we do it?" asked Cathy.

Tom shrugged.

Without being sure, they made an offer. Since then, they've spent $1.4 million buying some of the worst land around. They now own one-fourth of the cave's recharge area.

They've also acquired a heavy debt, because they didn't have $1.4 million.

Periodically, they fly off to the rainforests of Indonesia, the salmon fisheries of southeast Alaska or the glowworm caves of New Zealand to work for hard cash. There are fringe benefits -- such as slicking on a wetsuit and going blackwater rafting beneath a sky of glowworms -- but the main point is the consulting fee, which they carry back to safeguard their cave.

The irony is complete: Aley has done exactly what he set out to do when he was young and brash and filled with his own importance. He has made himself a name, won international fame and a unique place in science.

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