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Tiger salamander. Photo by Erwin and Peggy Bauer/Bruce Coleman

Here Today, Gone Tomorrow

Fed by fall rains, winter snowmelt, and spring showers, seasonal wetlands provide a vital breeding ground—but just once a year. After the annual explosion of plant and animal life, they dry up. Now, just as scientists are grasping the crucial role of these ecological wonders, they are in danger of disappearing—forever.

By Joe Bower

The sun has been down for less than an hour, but already the chorus has reached a fevered pitch. The spring performance features a steady backbeat of frogs' cheeps and American toads' whirs. Northern leopard frogs kick in with baritone croaks, while gray tree frogs trade warbling solos. The collective clamor is deafening, even frightening.

Ah, the songs of love. "These are the mating calls of swarms of anxious males," says Ed Hammer, a biologist with the U.S. Environmental Protection Agency (EPA). He and I are in the shin-deep waters of an oak savanna pond in Chicago's western suburbs, where we're surrounded by love-crazed amphibians. Everywhere our headlamps shine, we see them—hugging bush branches, reeds, and half-submerged sticks—many with their throats ballooning in song. More than once I catch myself feeling like an extra in an Amphibian Attack horror flick—especially when plump toads paddle toward us, undeterred by our lights.

"Their hormone levels are so high," says Hammer. "They're not as aware as they would be."

They're also desperate—time is short. In a few days the mating season will end. By mid-July this pond will be gone. Such is the fragile, fleeting essence of life in a seasonal wetlands.

Also known as vernal pools, prairie potholes, ephemeral wetlands, playas, Carolina bays, mountain bogs, and by a host of other colorful names, seasonal wetlands are among nature's more mysterious and productive ecosystems. Although their waters may be transitional, frogs, toads, salamanders, and many plants have relied on these unique, life-sustaining, and seasonally appearing parcels of real estate for millennia.

Varying in size and shape, the wetlands form in slight land depressions, where they are fed by fall rains, snowmelt, and spring showers, before drying up most summers. Some are mere puddles, just inches deep; others stretch for acres or to depths of a few feet. Most aren't connected to other waterways, at least on the surface, so they're often called isolated wetlands. They can be found from Massachusetts to California.

Yet despite a growing body of research attesting to their ecological importance, seasonal wetlands are often overlooked and underappreciated. After all, says Hammer, "they're not the Grand Tetons or Yosemite."

As part of his duties with the EPA in Chicago, Hammer works with state regulators, biologists, and conservation groups to promote the role these wetlands play. He also devotes personal time to the cause, often leading public tours. Now in his mid-30s, Hammer has appreciated these water bodies since his youth—having chased frogs and toads in the very pond where we're standing. In the mid-1990s, after learning their numbers had diminished dramatically, he resolved to take action. "This habitat wasn't getting much attention," he notes, "even though it is one of the most critical habitats for amphibians in the Midwest and the nation."

Such concern is well founded. "In parts of the United States, seasonal wetlands were once pervasive," says Bruce Kingsbury, a biologist with the Center for Reptile and Amphibian Conservation and Management at Indiana-Purdue University in Fort Wayne. "[In the Midwest] they were the most abundant form of water body." Extensive acreage was covered with them 200 years ago. Today in Illinois, as much as 85 percent of all wetlands have been lost to agriculture and urbanization, says Hammer. Elsewhere, the toll is even higher. "Historically, they're viewed as a nuisance, as breeding sites for mosquitoes, or as a rich [soil] source for farming," Kingsbury says. "Not viewed as important, they were filled in or drained."

As we wade about, dodging menacing toads, Hammer points out globs of salamander-egg masses laid days to weeks earlier. They resemble clumps of seaweed and tapioca hanging off submerged branches. Soon frog and toad-egg sacs will also dot the pond. The larvae that subsequently hatch will have just weeks to metamorphose from aquatic creatures to earth crawlers before the water evaporates and is absorbed.

Every spring, salamanders, toads, and frogs use this spot as a vital breeding ground. At varying times they come by the hundreds from surrounding uplands, leaving their isolated lives behind, and plunge en masse into this pond. The mad rush is triggered by seasonal changes in the amount of daylight, humidity, temperature, and rainfall that scientists haven't yet pinpointed. Once here, the animals climb over one another to copulate and lay eggs.

Amphibians, it seems, come because of what ponds like this lack. "Since they dry out, they don't have fish, which feed on the larvae of frogs and toads," says Hammer. Still, seasonal wetlands are rich food sites for other predators. Blanding's and spotted turtles come to feast on salamander eggs and larvae. Snakes, raccoons, foxes, and skunks eat young amphibians. Other animals, including black bears emerging from hibernation, gorge on plants that sprout early, thanks to the seasonal wetlands' shallow depths, which warm quickly.

A recent U.S. Supreme Court decision has left a gap in the Clean Water Act that puts many biologically diverse and irreplaceable wetlands at risk.

Seasonal wetlands are also crucial stopovers for millions of migrating waterfowl and shorebirds, which feed on the insects, amphibians, water plants, and seeds. In addition, birds use wetland vegetation as cover for resting, breeding, and nesting. Nearly half of North America's dabbling ducks, including mallards, pintails, shovelers, and teals, as well as diving ducks, like the canvasback and redhead, use the Great Plains prairie potholes as their primary breeding ground. According to "Wetlands at Risk: Imperiled Treasures," a recent report by the National Wildlife Federation (NWF), wetlands are essential for the survival of nearly half of all federally threatened and endangered plant and animal species, including whooping cranes, which use the wetlands at various times in their lives.

Seasonal wetlands offer additional creature comforts. Snakes rest in them, protected by the waters. Spotted turtles hibernate in those that collect water in autumn. Other turtles use them as launching pads to nesting sites in upland areas. On the Great Plains, most waterfowl species reproduce in them; crustaceans, like the federally endangered tadpole shrimp, live in them, as do countless insects. Many plants thrive in them as well. California vernal pools support 200 flora species, a third of which aren't found elsewhere, such as the succulent owl's-clover.

Besides habitat, seasonal wetlands provide unheralded benefits for ecosystems. Their ability to hold water helps control runoff and flooding. In addition, their absorption abilities help recharge subsurface aquifers.

Amphibian-friendly seasonal wetlands also need other wetlands nearby. "Healthy populations of many species depend on not just a single wetland but a landscape densely covered by a variety of wetlands," says Raymond Semlitsch, an ecologist at the University of Missouri. This offers the animals options. In drought years more permanent wetlands experience greater amphibian success. Says Hammer, "In a really wet year the critters can breed out across in all the wetlands, which causes their population to explode. It builds up populations to withstand dry years." Access to multiple wetlands also allows individuals to move between wetlands, preventing populations from becoming isolated and inbred.

As scientists start to understand these seasonal wetlands better, they're trying to learn how to restore some of the millions of them that have been paved over and plowed under. One such project involved a wetlands outside Danville, Illinois, that had been filled during the 1930s to build a gravel road. In 1998 the site, located 300 feet from another seasonal wetlands, was excavated. Trees were planted around it. Water returned in the spring. Then the amphibians appeared. "Restoration can be done effectively if the hydrology is there, and if the placement in the landscape mimics natural conditions," says Semlitsch.

Creating wetlands from scratch is a different endeavor, however. Many developers and regulators contend that they can replace wetlands destroyed for malls and subdivisions. The practice, called mitigation, can entail making a wetlands in a new location or replacing a few small ones with single, larger ones. The thinking is that re-created wetlands compensate for those they replace.

"The problem is that these new wetlands are not the same as original ones," says Semlitsch. "They function differently." He and other scientists contend mitigation's artificial wetlands can't replace the natural ones. For example, in one recent study that compared natural wetlands with mitigated ones in central Ohio, researchers at Ohio State University found that spotted salamanders bred in 55 percent of the natural sites but in only 2 percent of the built wetlands. "We're much better at growing a patch of forest than we are at growing a wetland," adds Kingsbury. "We're learning, but there are so many factors we aren't aware of." Indeed, these are complex systems set in conditions that evolved over eons. To exist, they require the perfect mix of soil conditions, hydrology, topography, and placement near other types of wetlands, as well as diverse vegetation. "For a prairie wetland, you want a good mix of native vegetation: sedges, grasses, bushes," says Hammer. "When you have more diverse plants, you have more diverse insects, which represent a better food source. I've seen a lot of wetlands with 50 or 75 different plants that turn into a cattail marsh with maybe a dozen species. [The change] is usually due to human disturbance."

In recent years increased interest in and understanding of these systems by ecologists are changing perceptions and raising awareness of wetlands. No state has done more than Massachusetts, which has passed laws to protect vernal pools, as they're called in the Bay State. As a result of those laws, 30,000 potential vernal pools have been mapped and 2,000 have been shielded from destruction.

Still, despite the growing attention, seasonal wetlands continue to disappear at an alarming rate. And not just temporarily, but permanently. This loss stems partly from a 2001 U.S. Supreme Court decision that effectively removed the protection some wetlands enjoyed under the Clean Water Act. In Solid Waste Agency of Northern Cook County (SWANCC) v. U.S. Army Corps of Engineers, the Court said the government could not withhold a permit to destroy 17 acres of isolated ponds in order to build a landfill just because the ponds provided migratory-bird habitat. A debate has waged since then about the ruling's meaning. Developers, legislators, regulators, and others interpret it to mean waters that are isolated—that is, those linked to other waters only by bird flight rather than by water flow—are excluded from protection. And they have used this opportunity to wipe out wetlands that were once protected. "The decision left a gap in the Clean Water Act that put many biologically diverse and irreplaceable wetlands at risk just because they aren't connected to a river or stream," says Julie Sibbing, a wetlands specialist for the NWF.

The interpretation is erroneous, adds Sibbing, because "if you call these isolated, you're looking at them only two-dimensionally. [But] if you look at them three-dimensionally, most are connected underground to groundwater or streams. It's unfortunate that these issues are decided by legal minds, not biological [ones]."

No one knows how many wetlands have been destroyed since the SWANCC ruling. But efforts are under way to stem the tide. NWF, Audubon, and other environmental groups are pushing to clarify the Clean Water Act so that it applies to all waterways, including isolated ones. Bills have been introduced in Congress to do just that, although they are unlikely to go anywhere soon.

This is especially true in light of guidelines issued by the Bush administration in January in response to SWANCC. The guidelines relinquish some responsibility for the regulation of isolated water bodies that lie entirely within one state and are not connected to other wetlands. Also, EPA field personnel have lost much of their independence, and often must consult superiors in Washington before making decisions.

Environmentalists believe the White House is headed down the wrong track. "Why are we starting this debate over what water and wetlands to protect when the EPA's own data shows that over 40 percent of the water in the United States isn't meeting current water-quality standards," says Bob Perciasepe, Audubon's senior vice-president of public policy and the former administrator of the EPA's water program. "The Bush administration is diverting attention from the real task at hand: improving the quality of our nation's vital water resources," he says. "One would wonder whose interests are really being served."

Meanwhile, Wisconsin, not content to wait for federal action, passed legislation to close the loophole. Other states are considering similar action. Biologists like Hammer continue pushing to call attention to these threatened habitats.

How anyone could not notice them baffles me, as I stand amid an amphibian orgy. All this clamor and commotion must be audible a mile away. Neighbors who come to check it out usually leave with a different opinion of these ponds, says Hammer. "I've brought many people out here, and they're always captivated by what's going on," he says. "I've been coming here for 30 years. It's something that I have to come and see. And it occurs only once a year."