CHAPTER 3
The South’s Incredible Biodiversity Is Threatened and Endangered
The word cavern does not convey any idea of this immense space; words of human tongue are inadequate to describe the discoveries of him who ventures into the deep abysses of earth.
—Jules Verne, Tales of Daring Voyages and Discoveries
Cave City, Kentucky — It took Muir four quick-footed days to reach Mammoth Cave. It took me four meandering hours as I tootled along in my Subaru trying to imagine what Muir saw a century and a half earlier. It wasn’t easy.
Muir “escaped to the woods” beyond Elizabethtown and into the “magnificent flowing hill scenery.” He spoke admiringly of “gangs of woodmen engaged in felling and hewing the grand oaks for market.” He passed through Munfordville, the scene of a Civil War skirmish along the Green River won by Confederate troops five years earlier. At Horse Cave, Muir took a ten-mile detour west to Mammoth Cave. “I was surprised to find it in so complete naturalness,” he wrote before trashing the “paltry artificial gardens” surrounding the main hotel.
Muir didn’t stay long. He didn’t even go underground to witness the awe-inspiring caverns and cathedrals of limestone that stretch for miles in every subterranean direction. Mammoth would soon become one of the nation’s top tourist spots, joining the Grand Canyon and Niagara Falls while attracting visitors from all over the world. But the “father of the national parks” didn’t have time for what’s now known as Mammoth Cave National Park.
Muir, uncharacteristically, was acting more like a typical American tourist than a soulful naturalist. Americans have long had a schizophrenic relationship with the natural world. They ooh and aah over the beauty of a mountain range, sandy seashore, or underground cavern. Yet they like to tart up their natural experiences with “artificial” attractions and all the auto-accessible amenities that can be squeezed in. It’s as if they expect to be bored by wilderness so they stock up on sensory-numbing entertainment before, or after, their visit.
The fun starts in Munfordville along the same Dixie Highway where “Kentucky’s Stonehenge,” a pint-sized, ersatz replica of the prehistoric English masterpiece, awaits. Just down the road, in Cave City, the Wigwam Village motel and its fifteen concrete teepees arrayed in a half-circle entice travelers keen on a night of Instagram memories. No shortage of good times awaits the traveler on the run-up to Mammoth’s main entrance: Dinosaur World; Raven’s Cross Haunted Village; Big Mike’s Rock Shop; and the Kentucky Action Park (with miniature golf, zip line, trampolines, and bumper cars).
Visitors have explored Mammoth Cave for millennia. Native Americans mined six miles of the cave as long ago as five thousand years, according to archaeological discoveries teased from gourds, cloth, pottery, and petroglyphs. A much-disputed legend has it that a hunter named John Houchins shot at a black bear along the Green River at the turn of the nineteenth century. Houchins missed, but he found an entrance to the cave. It wasn’t long until the caverns were being mined by slaves for the saltpeter needed to make gunpowder. It was another slave, Stephen Bishop, bought in nearby Glasgow, whose explorations turned the central Kentucky cave into an international sensation. Bishop crossed the Bottomless Pit by ladder bridge with lantern firmly affixed between jaws to discover Echo River, Roaring River, and Mammoth Dome, which he labeled “a grand, gloomy, and peculiar place.” By 1850, stage coaches from Lexington and steamboats from Bowling Green were delivering thousands of tourists annually to the ever-growing network of caverns. Tourism, abetted by the railroad and the automobile, proved profitable, and acrimonious. Owners of nearby caves—Colossal, Long, Crystal, Great Onyx—weren’t above warning travelers that Mammoth was flooded and closed when neither was true.
Mammoth began losing its charm by the turn of the twentieth century and visitation soon dropped by two-thirds. Maintenance suffered, the buildings grew worn, and the privately held grounds were denuded of timber and wildlife. War and the Depression didn’t help, though legions of Civilian Conservation Corps workers built new roads, cabins, trails, and an elevator to the cave’s Snowball Room. For years conservationists had clamored for national parks east of the Mississippi River. Finally, in 1926, President Calvin Coolidge signed legislation creating Mammoth National Park, contingent upon donation of the land to the federal government. It took fifteen years, and the wholesale removal of hundreds of families, farmhouses, barns, churches, and schools, but Mammoth joined Shenandoah and the Great Smoky as the South’s first national parks.
Kentucky, and the rest of the South that Muir crossed, is a geomorphologist’s dream. A half-dozen very different geographic regions run from central Kentucky to coastal Florida. Muir first crossed the Bluegrass and Knobs regions of rolling hills, hardwood forests, and lush meadows leading to the Cumberland Plateau. Next up were the Appalachian Mountains of Tennessee and North Carolina with their six-thousand-foot peaks and mix of deciduous and coniferous forests. He descended through the ridge-and-valley region of Georgia into the Piedmont of lazy rivers, pine trees, and cotton fields. Muir crossed the coastal plain and its near-impenetrable swamps and longleaf pine stands. The Atlantic and Gulf coasts, with their marshes, estuaries, and beaches, offered the rambling man the most resplendent repositories of flora and fauna. No other thousand-mile walk in the United States crosses such a richness of habitats.
The South’s natural bounty is owed to many factors. Glaciers halted their southern surge at the Ohio River valley, yet they drove plants and animals farther south across the Appalachians. Once the glaciers receded, the hills, dales, and streams filled with a mix of southern and northern plants fostering “enormous biological diversity,” according to Precious Heritage, a compendium of the nation’s ecology. Abundant rains fuel the biodiversity. Certain southern Appalachian hilltops, for example, receive a rainforest-like ninety inches a year. The Atlantic and Gulf coasts, with a healthy mix of fresh and salt water, produce some of the world’s most fecund breeding grounds for birds, fish, and crustaceans. In fact, the Southeast is one of the world’s hotspots of biodiversity.
Like birds? Well, more than 90 percent of the nation’s bird species live or pass through the region.
What about fish? Nearly two-thirds of all US species of fish live in the Southeast’s streams and estuaries, yet the region comprises only 17 percent of the nation’s land mass. And more than a quarter of the area’s freshwater species are found nowhere else in the world.
Trees and flowers your thing? One of every three plant species nationwide resides in the Southeast, with various ecosystems rivaling the Amazon or the Congo in biodiversity.
Mussels? More than 90 percent of all US freshwater mussel species—and 40 percent of the world’s—inhabit Southeastern rivers and streams.
Crayfish? Almost half of the world’s crawdads, some 250 different species, call the Southeast home.
Salamanders? More types of sallies live here than anywhere else in the world, including the otherworldly and slimy hellbender, which can grow up to two feet long.
Evidence of this biological uniqueness abounds nearby. Look no further than the unheralded Conasauga River. Seventy-six species of fish live in the stream that flows one hundred miles through northwest Georgia and a sliver of Tennessee. That’s more species than the Columbia and Colorado rivers combined, yet its watershed is only one one-hundredth the size of those mighty Western rivers. Three of the Conasauga’s fish are threatened or endangered. Six of the mussels are, too, including the wonderfully named Coosa moccasinshell and Georgia pigtoe. Only the tropics can match that level of bivalve biodiversity.
Then there are the few and fabulous mountain bogs, pint-sized wetlands sandwiched between the hills, pastures, blacktops, and railroad tracks of southern Appalachia. The bogs are home to mountain sweet pitcher plants (endangered), swamp pinks (threatened), and bog turtles (threatened), North America’s smallest terrapin.
And the Green River itself, with 151 species of fish and 71 types of mussels, is the nation’s fourth most biologically diverse river. Forty-three species are endemic—found nowhere else in the world—to the Green, including darters, beetles, crayfish, pseudoscorpions, and the Kentucky cave shrimp.
More than four hundred species of plants and animals are endemic to the southern Appalachians. The Nature Conservancy says no other place in North America is as bountiful.
And few spots around the globe tally as many critters and plants at risk of extinction. The US Fish and Wildlife Service lists 437 threatened or endangered species in the Southeast region. Only the massive Western region, which encompasses tropical Hawaii and Samoa as well as rainy Oregon and Washington, counts more (588). In fact, five of the top ten states (Florida, Alabama, Tennessee, Georgia, and North Carolina) with the most T&E species are in the Southeast. If you add Texas and Virginia, that makes seven of ten.
The South’s biodiversity, though, is under attack, particularly its water-borne bounty. The Environmental Protection Agency reports that more than half of the streams in the southern Appalachians are “in poor biological condition.” The ecological damage done to the Conasauga, Green, Tennessee, Chattahoochee, Savannah, St. Johns, Suwannee, and virtually every other Southern river, is heart-rending. Alabama’s Coosa River, for example, used to be one of the most biologically diverse rivers in the world. It now holds the dubious distinction, according to the World Wildlife Fund, as the North American river with the most freshwater extinctions—thirty-eight—of the twentieth century.
In 2010, the Center for Biological Diversity (CBD) sued the Fish and Wildlife Service demanding that 404 aquatic, riparian, and wetland species in the Southeast be listed as threatened or endangered. “Nowhere is this extinction crisis more apparent than in the southeastern United States, where the combination of an incredibly rich fauna, pervasive threats, and few existing protections are leading to the demise of hundreds of aquatic species,” the petition read. CBD warned that “extinction is looming” for 28 percent of the region’s fishes, 48 percent of its crayfishes, and 70 percent of its mussels.
A year later, the nonprofit and the Service settled the suit with the federal conservation agency pledging to determine whether 374 species need listing. Progress has been slow. Dozens of the proposed species have yet to be fully vetted. A Trump administration hostile to the environment, and in bed with the coal, oil, and gas industries, reworked the landmark Endangered Species Act to make it harder to list plants and animals as threatened or endangered, and easier to remove them. (The Biden administration reversed course.) Fish and Wildlife, during the Trump years, added only twenty-five species to the T&E list. The Obama administration listed 360. It was one gut kick after another to the many dedicated biologists and ecologists at the various federal conservation agencies. CBD said the proposed changes would “crash a bulldozer through the Endangered Species Act’s lifesaving protections for America’s most vulnerable wildlife.” Carl Hiaasen, the acerbically wonderful former columnist for the Miami Herald, wrote that “saving God’s creations from oblivion is a worthy mission unless it means lost revenues for ExxonMobil or Koch Industries.”
Slashed budgets prevent Fish and Wildlife from hiring enough biologists to determine species’ status. And revenue-poor state agencies, which have primary jurisdiction over the critters, prize economic growth over the health of, say, orangenacre muckets. In 2019, the Tennessee Aquarium Conservation Institute tallied public dollars spent on species preservation across the country. While the Southeast region is home to 30 percent of the nation’s T&E species, it receives less than 1 percent of all federal and state moneys spent nationwide trying to save those species.
Unlike Muir, I hunger to explore Mammoth Cave. I plan to spend the weekend camping at Mammoth upon leaving Louisville, but an ice storm bears down and forces the park’s closure. I still manage to hike the Big Hollow Loop Trail, an easy jaunt with a wealth of second-generation oak, hickory, pine, and poplar that harkens Muir’s time. The wind out of the southwest picks up as the sky darkens. I quicken my pace. I recall the passage in Muir’s 1894 book The Mountains of California, where he recounts scaling a Douglas spruce during a windstorm in the Sierra Nevada “and never before did I enjoy so noble an exhilaration of motion.” Me, I just want to finish the hike and ride the ferry across the Green River before the storm ices the roads and closes the park.
I return six months later, after three very nice National Park Service scientists invite me on a tour. I arrive mid-afternoon in time for another short hike and a visit to the park’s museum and visitor center, where there’s no mention of Muir. But I do learn that the United Nations named Mammoth Cave a World Heritage Site in 1981 and, nine years later, an International Biosphere Reserve. I stay in a one-room, paint-peeling, non-air-conditioned cabin without television built by the CCC in the early forties. It’s bliss lying under the fan without electronic distraction, listening to the crickets, and conjuring the days of pre-war tourism. (Not until I return home do I realize that bed bugs come with the government room rate.)
The next morning, I meet with Tim Pinion, the park’s science chief; Rick Olson, Mammoth’s ecologist; and Rick Toomey, a cave specialist who runs the park’s International Center for Science and Learning. Pinion, a marine biologist who used to work for Fish and Wildlife, has been at Mammoth less than a year. Olson, lanky and bespectacled with a white Vandyke, probably knows the park better than anybody. He came to Mammoth in 1973 with the Cave Research Foundation and never left. Toomey, also sporting a Vandyke and glasses, arrived in 1994. He’s a paleontologist turned speleologist.
Tim and I had already hashed out where to observe the park’s wondrous biodiversity. I also want to better understand how outside forces—water, pollution, sprawl, climate—impact the park and its creatures. I’m keen to focus on lesser-known species that live either underground or underwater yet whose stories speak volumes about the South’s environment.
We scratch bats and their oft-told plight off our list, even though millions have succumbed to the deadly disease known as white-nose syndrome. First detected in an upstate New York cave in 2006, the pathogen quickly spread south and west. Seven years later, in Long Cave, the white-colored fungus notched its first Mammoth Cave victim. A “bat blitz” conducted in 2017 showed steep declines in the cave’s northern long-eared, little brown, tri-color, and Indiana bat populations. Rick Toomey calls the carnage “devastating.”
Not enough is known about where the disease came from or how it spreads. Without better science, it’s difficult to ascribe environmental causes and effects to white-nose syndrome. Do cave-goers help spread the disease? Are pesticides or other contaminants responsible for the fungus? Is the pathogen air- or water-borne? Does a warming climate play a role? The uncertainty makes it difficult to draw broad-brush conclusions about Mammoth Cave’s ecological health and, by extension, the region’s. Which is why I decide to focus on other, more illustrative—and weirder—species.
We enter the cave through the Historic Entrance, pass the (not so) Great Bat Room, through the limestone belly of the Mammoth Dome, and into River Hall with its water-warped and escalloped ceiling and walls. Tim, the two Ricks, and I bypass the tourists, skirt behind an off-limits sign and descend even farther into what Ralph Waldo Emerson called “the great hole in the ground in Kentucky.” We cross the Natural Bridge over the Dead Sea, its walkway covered in a muddy film courtesy of recent floods. It’s foggy and chilly like London in winter. A nineteenth-century wooden dinghy, used long ago to ferry tourists along the Dead Sea, magically appears out of the mist.
Finally, at 360 feet below ground, we stop.
“Here,” says Rick the ecologist, “is the River Styx.”
Appropriate. For we have come to see the highly endangered, supremely bizarre, ghost-like Kentucky cave shrimp. Once thought extinct, the shrimp was rediscovered in the 1980s and has, supposedly, increased in population ever since. It is believed to reside in only a handful of low-lying streams and pools in and around Mammoth Cave, but nobody really knows. It is one odd creature. The Fish and Wildlife Service refers to the shrimp as a “nearly transparent decapod crustacean with only rudimentary eyestalks.” But that doesn’t do the shrimpy shrimp justice. An adult is about an inch long, with ten legs and two very long antennae. It molts every forty days or so, sloughing off its entire exoskeleton—antennae, mouth, legs, tail—in one whole piece which itself resembles a wholly intact cave shrimp.
But wait, there’s more. The shrimp deploys its antennae to find, taste, and smell food. Because it doesn’t have any eyes. It’s blind. In fact, it doesn’t need eyes. Because it lives in a cave where the sun never shines.
There’s still more. Cave shrimp are translucent—you can see through them. Whereas I crave their ocean brethren smothered in drawn butter and cocktail sauce, my epicurean ardor will surely wane upon observing a cave shrimp floating in a muddy pool at the bottom of a cavern.
“This is shrimp habitat,” insists paleontologist Rick.
Great. Show me one.
“We’re not likely to find any here,” he allows.
Huh?
“If we had wetsuits, I guarantee that I could show you some,” ecologist Rick chimes in.
We stop at a sandy beach along the river’s edge. Headlamps bounce from shallow water to water-smoothed limestone wall to the ceiling thirty feet up. I feel like I’m on the platform of a darkened, flooded subway tunnel.
The scientists find two eyeless cave beetles and a pigment-free cave crayfish. But no shrimp. They were first discovered at Mammoth Cave in 1901 by a zoologist named William Perry Hay, who promptly sent a dozen to the National Museum of Natural History in Washington where, presumably, they remain today.
If any creature is a prisoner of habitat, it’s the cave shrimp. Only four species of the underground crustacean exist in the US. (One summer day, I tried, unsuccessfully, with a platoon of biologists and spelunkers, to find an Alabama cave shrimp near Huntsville, Alabama.) The Kentucky shrimp is wholly dependent on forces beyond its control for survival. The Green River, which flows above, below, and throughout Mammoth Cave, dictates whether the shrimp lives or dies. A heavy rain raises water levels, moves the shrimp around and creates the pools and slow-flowing streams where they live. The river also brings food in the form of tiny protozoans, insects, fungi, and algae. Without the sun’s amazing photosynthetic qualities, the shrimp must rely on takeout food delivered via upstream (or downstream if flooding backs up the river) currents. Little rain reduces the river’s flow, food sources, and places where the shrimp can live. Drought leads to death.
Though few in number, the oddball shrimp has captured the region’s fancy. A decade ago the minor league Bowling Green baseball team was casting about for a new name. The Bowling Green Cave Shrimp—picture the logo of a cartoonish, sunglasses-wearing crustacean with glove on one pincer and bat in the other—was nudged out by the Bowling Green Hot Rods owing to the nearby city’s love affair with fast cars.
Yet despite the blind shrimp’s favorite-arthropod status, Kentucky has done just about everything imaginable the last two hundred years to kill it. As goes the Green, so goes the shrimp. Revolutionary War veterans staked claims along the river as payment for their service and initiated two centuries’ worth of poor farming practices that fed sediment, poop, and pesticides into the river. Loggers felled the surrounding forests, which removed natural buffers that filtered the water flowing into the Green. The strip-mining of coal, with its acidic by-products and habitat-destroying qualities, proliferated along the river’s banks. Rock quarry runoff doesn’t help. Antiquated treatment plants, and a rural reliance on septic tanks, still send millions of gallons of untreated sewage into the ground and, eventually, the river.
A half-dozen dams, the first built in the 1830s, inhibit the free flow of water, impede migrating fish, trap habitat-nourishing sediments, and alter temperatures and oxygen levels, all to the detriment of the once-pristine Green. Lock and Dam Number Six, about ten miles below Mammoth Cave, kept fish and other critters from freely running the river. It also increased the amount of sediment and siltation, which clouded the water, prevented the growth of vegetation, and destroyed habitat. Fish and Wildlife once listed the dam as “responsible for the decline” of shrimp.
There were other culprits, too. Kentucky is blessed, or cursed, with an abundance of oil and natural gas. Spills once happened regularly, and the porous limestone-and-sinkhole topography offered countless entryways for the toxic fluids to reach the streams that feed the Green River. Brine, the sodium chloride by-product of drilling, was either returned underground or dumped directly into sinkholes. The feds reported in 1988 that the nearby oil and gas industry has “the potential for causing complete extirpation of the cave fauna in an entire groundwater basin.” In 2014, The Nature Conservancy wrote that “this unique freshwater basin is at risk to change dramatically over the next fifty years due to compounding threats of residential, industrial, and commercial demands for water, inputs of excess nutrients, sediment, and contaminants due to ecologically incompatible land-management practices, riparian forest conversion, and potential volatile flood cycles/extended drought periods due to climate change.”
The shrimp achieved endangered species status in 1983, with an estimated five hundred specimens still kicking. Five years later, between six and twelve thousand shrimp floated through Mammoth Cave. Today, maybe five thousand survive. But nobody really knows. It remains a federally endangered species.
The two Ricks, Tim, and I climb out of the cave and into the government-issued Chevy Equinox for the short downhill ride to the ferry crossing, where a team of malacologists, or mussel experts, scour the Green in search of booty. The Park Service had recently halted ferry service to allow the ramps on either side of the river to be extended. The ferry, too often, couldn’t run the river due to low flows. The Endangered Species Act requires federal agencies to save as many threatened or endangered critters as possible whenever a construction project impacts their habitat. The Park Service decided to go a step further by capturing all the mussels near the ferry crossing and relocating them a half mile upstream.
A team of wetsuit-wearing divers disappear into the murky brown water only to reappear moments later with mussels in hand. It’s a sun-dappled May morning with oaks and poplars along the banks wearing bright green suits, and dozens of eastern tiger swallowtails flitting by. Clayton Bey, scuba mask firmly in place and tethered to an oxygen tank floating on an inner tube, emerges from the water and muck to drop a few shells into a mesh bag.
“Look how many I’ve got,” Clayton announces to nobody in particular. He climbs the river bank and, one by one, unloads his treasure. A pink heelsplitter. A kidneyshell. Two mapleleafs. A threeridge. It isn’t a particularly remarkable haul. None of the mussels are threatened or endangered. But Clayton’s work is nonetheless notable on two accounts. He and fellow divers have uncovered and replanted 2,500 mussels in just five days, a surprisingly sizable amount even for one of the most fecund stretches of the Green River. And Clayton is only five years old.
“I reckon he’s the youngest malacologist around,” says Clarissa Lawlis, his mother and a true mussel biologist. She says Clayton knows the names of most mussels, prefers a wetsuit to a swimsuit, and works cheap.
“I pay him in Oreos,” she laughs.
Mussels won’t win an endangered-species popularity contest. The World Wildlife Fund doesn’t mount polychromatic fundraising campaigns devoted to saving the bizarre bivalves. Leonardo DiCaprio isn’t likely to shine his star wattage on orange-footed pimplebacks as he does Sumatran elephants. Mussels, let’s face it, are the eat-your-peas equivalent of species conservation, the invertebrate Everyman of the animal kingdom. Americans really only think about mollusks if they stub their toe on one while swimming, or consider their salubrious qualities before ordering a dozen (preferably with a Muscadet or Sauvignon Blanc).
If only they knew. If only they understood the critical role mussels play not only in a particular aquatic habitat, but in an entire ecosystem’s interplay between water and man. Native Americans, as usual, knew the value of mussels. They’d eat the meaty mollusk and use the shell for tools, utensils, and jewelry. Mussel gatherers supplied the burgeoning button industry in the nineteenth century and, consequently, depleted Southern, Eastern, and Midwestern streams of mollusca. By 1912, two hundred button factories operated nationwide. The purple cat’s paw, beloved for its interior deep purple hue, was nearly adored to extinction. If it weren’t for plastic, the mussel kingdom might’ve collapsed altogether.
Mussels can live one hundred years underwater covered in sand, mud, or gravel. A hinged shell is their identifying feature; yet the variety of shapes, sizes, and colors makes instant classification difficult. They may be yellow, green, brown, black, or purple. They may be bumpy, textured, smooth, or ridged. Like trees, the shells produce annual rings that show their age.
A male mussel is a sex machine capable of impregnating downstream females while stuck in the mud. He shoots his sperm higgledy-piggledy into the water where currents carry it, magically, to a waiting female. She then packages the eggs together into a lure-like contraption on her body and goes fishing. The lures resemble insects and entice passing fish who take the bait which then attaches to their gills. The larvae hang out on the fish for a couple of weeks, fattening up on nutrients before dropping off and beginning life as juvenile mussels.
Mussels’ sex life alone qualifies them for a starring role on Animals Gone Wild. But it’s what they do to the water that’s truly sexy. Mussels are filter feeders: they suck up nutrients, sediments, and contaminants before expelling the cleansed by-products back into the water. Water quality improves to the benefit of other critters as well as humans, who typically rely on expensive water-treatment plants. Some mussels filter ten gallons of water daily. And some football-field-sized riffles are home to tens of thousands of mollusks straining water like sieves do flour.
Mussels fill another critical role too. They’re the early-warning system telling us that something’s wrong with the water. Monte McGregor, Kentucky’s state malacologist, tells me that “there is no other species that reflects what is going on in a river better than mussels.” A surge in dead mussels means something—toxic chemicals, sediment runoff, temperature change—is harming water quality. If the mussels disappear, then other species are likely to disappear also. Rick the ecologist says, “Mussels are like the canaries in the coal mine.” And the canaries are sucking wind.
The Green River isn’t unique in its suffering. Remember the aforementioned, and seemingly abundant, Conasauga River? Sedimentation, pesticides, and runoff from chicken-processing plants plague the river once it leaves the Chattahoochee National Forest. Biologists at the Tennessee Aquarium and the University of Georgia have labeled the Conasauga the seventh most imperiled watershed in the Southeast—out of three hundred watersheds. Maybe one-fourth of its fish and mussels have died in recent years.
Remember the rare bogs of North Carolina with their mountain sweet pitcher plants? They’re fast disappearing, courtesy of logging, stormwater runoff, and new home construction. Five thousand boggy acres once stippled the valley floors of the southwestern Appalachians. Today, five hundred remain.
In Muir’s day, the Green River boasted fifty-eight different types of mussels. Seven species, though, have died off. And another ten species, including the fanshell, snuffbox, and pink mucket that live in Mammoth Cave National Park, are threatened or endangered. Pinion, the two Ricks, and other scientists, in a 2020 report, concluded that “habitat alteration . . . is the primary threat to fish biodiversity in the park.”
It’s the same story with virtually every stream Muir crossed on his trek to the Gulf.
But there is hope. The landmark Clean Water Act reduced pollutants flowing from farms, mines, and oil and gas wells into the Green River. The Clean Air Act reduced carbon dioxide from coal-fired power plants that dropped acid rain into the river. In fact, the nearby Paradise Fossil Plant shut down in 2020. More than one hundred million dollars went into the pockets of farmers upstream of Mammoth Cave to get them to quit farming along the banks of the river and plant trees and grass instead. Even the much-maligned Endangered Species Act forced nearby communities to treat their sewage instead of letting the shrimp-killing effluent reach the Green. Nothing, though, excites Pinion and the two Ricks like the demolition of Lock and Dam Number Six.
A day earlier, on my ride up from Atlanta, I stopped in Brownsville on the national park’s western edge, a small town sandwiched between bends in the river with a courthouse, bank, Family Dollar store, Bertie’s Ice Cream, and funeral home whose parking lot was full. I crossed the high bridge over the Green, turned left at a Mexican restaurant, and followed the two-lane blacktop to the river’s edge. Yellow daisies and purple clover lined the riverbanks. Butterflies danced. A turkey vulture rode the currents high above. The river ran slow, yet steady. Fire rings and Bud Light cans indicated a favorite fishing spot. Something, though, was missing. Two years earlier, Fish and Wildlife demolished the low-head lock and dam that for more than a century had allowed barges to head upstream to asphalt and sandstone quarries. Eight miles of river, up to the Mammoth Cave ferry crossing, resumed its long-thwarted natural flow.
“In the two years since the removal of the dam we’ve had better development of mussel beds in the free-flowing zones,” says Rick the speleologist. “As we improve the Green River, the mussels improve.”
Time will tell. I checked in later with the malacologists working the ferry crossing. They plucked twenty-eight different types of live mussels from the muck. Only two were federally endangered: the fanshell and the sheepnose. Two years earlier, at a dozen sites in Mammoth Cave, a similar number of live mussels and the same two endangered species were found. And, eight years prior to that, nearly identical numbers of live and endangered mussels were found. It was hard to see much improvement.
We hop back in the Chevy and drive to the day’s final stop at New Discovery Cave, which is off-limits to all but Park Service–approved scientists. No signs or trimmed pathways steer visitors to the entrance. Instead, chest-high weeds obscure a concrete blockhouse with a locked steel door. It looks like an air raid bunker and, not surprisingly, was built starting in the 1940s when the Service decided that New Discovery was too delicate for hordes of meaty-palmed, graffiti-scrawling tourists. Inside, beyond yet another steel door and down a series of steep metal steps, are passages covered in delicate gypsum “flowers” and wispy gypsum needles that sway gently as you pass. The caverns wend for miles past soaring stalactites and wall-hugging waterfalls. A flurry of fossils—sharks’ teeth, horn corals, crinoids—cluster in patches along the ceiling. CCC workers left behind leather shoes, oil lamps, and sardine tins as if in a haste to escape something gnarly. The skeletons of bats, possums, and wood rats litter alcoves and complete the otherworldly, spooky tableau.
But it’s a bug that brung us. The cave cricket, a brown, hunch-backed, antenna-wiggling, guano-dribbling, night-crawling insect, represents perhaps the most accurate natural barometer of Mammoth Cave and its animals’ long-term health. They aren’t threatened, endangered, or at risk. But they are early-warning systems, like canaries and mussels, that will determine if other critters survive.
We pass through the steel doors, the steamy sunshine giving way to cool (typically fifty-four-degree) darkness. It takes a minute for my eyes to acclimate to the dim light of a handful of headlamps. Once they do, I realize I’m completely surrounded by thousands of creepy crawlies. My helmet scrapes the cave’s roof. And crickets. My shoulders brush up against moist, guano-covered walls. And crickets.
I notice two red laser beams slicing the darkness. Kurt Helf and Brenda Wells, a Park Service ecologist and biologist, respectively, are counting crickets. They position a laser projector atop a tripod and shoot the beams toward a wall. Kurt holds a Kestrel weather instrument, which gauges the temperature, humidity, and air flow, in one hand, and a camera in the other. He and Brenda count insects in ten-centimeter blocks, data they’ll compare with data taken the previous four years to determine the abundance of crickets in New Discovery. They’re members of the Cumberland Piedmont Inventory and Monitoring Network, studying the well-being of crickets at fifteen Mammoth cave entrances. Kurt cautions that he doesn’t have enough long-term data to determine the crickets’ health. After years of relative decline, though, their numbers seem to have stabilized.
“Populations seem to be increasing the last few years,” says Kurt, who has monitored crickets and other bugs at Mammoth since the mid-nineties. “The last two years, there were lots and lots of cave crickets. This year seems to be a bit down. But there is definitely high site fidelity. The animals, on the whole, are mostly in the same spots all the time. That’s a good thing. It enables us to track any changes in the future.”
Crickets leave caves at night to forage for food. They’re omnivores and scavengers able to eat twice their weight in decaying plants, fungi, and other insects in one sitting. It’s what they do upon returning to their darkened lairs that’s most intriguing. They poop. Their guano, smeared along cave walls and ceilings, feeds other troglophiles (animals that can live inside a cave or out) and troglobites (animals that never leave a cave). A whole host of Mammoth Cave’s creatures—beetles, flies, snails, mites, millipedes, salamanders, spiders, springtails—depend upon cricket crap to survive, more so than ever with the decline of guano-producing bats. If there’s no guano, the animals die. And if they die, so do the fish, crayfish, salamanders, beetles, and other critters that depend upon them. And if they die . . .
“Cave crickets are keystone species,” Kurt says. “If cave cricket populations are doing well, you can infer that organisms that depend upon them are doing well. So it’s more efficient to monitor cave crickets than other species.”
Meanwhile, the two Ricks wander off to explore the cave. I catch up with paleontologist Rick who, headlamp zeroed in on a patch of wall, searches for other cave-obligates.
“Here’s a Carychium stygium” or snail, he announces.
“Here’s a tomocerus springtail.”
“Here are some cave flies.”
“I’ve got more cute snails.”
“Ah, I have a cave millipede.”
He’s in his element, happy as a fly in, well, guano. I ask him why I should care about a bunch of seemingly insignificant bugs that may never see the light of day.
“You’ve heard the analogy of the rivets and the plane?” he says. “If you lose one rivet, it’s okay, the plane can fly. But if you lose all the rivets, the plane crashes and everybody dies.”
Of the crickets, Kurt has written that “there are potential threats to this keystone species that may affect the entire cave community trophic structure.” Translation: Climate change may irreparably mess with the food chain. While warmer weather might allow more time to forage, a concomitant drought could wipe out food sources. So too might huge slugs of rain.
Before leaving I ask Kurt about the crickets’ long-term chances for survival.
He pauses. Then looks straight at me, his headlamp rendering me temporarily blind. “We really can’t say what’s going to happen,” Kurt says.