It was a noisy spring in the Chesapeake Bay watershed.
Record amounts of snowmelt, combined with generous spring rains, revived countless shallow pools in dry depressions across the landscape. With them came those tiny frogs with operatic lungs: the spring peepers.
Every spring, peepers gather at temporary pools to breed. Their chorus of high-pitched calls ring through the air-a signature sound of the season. But while spring peepers are the noisiest creatures at the pools, they certainly aren't alone.
"That's just what you can hear," said Michael Hayslett, director of Virginia's Vernal Pool Society. "Among all that clamor is a similar volume of activity from other frogs, salamanders and invertebrates, a whole suite of living things that converge on the vernal pool in the spring. It's truly a remarkable phenomenon."
Vernal pools are wetlands that fill with water in the spring and typically dry by fall, although some pools stay wet for a year or more. They exist both in the mountains and on the Coastal Plain, tucked into forests, at the edge of fields and even along roadways.
To the casual observer, vernal pools may look like oversize puddles or a miniature spring flood. They are often smaller than an average farm pond, some with a diameter of 30 feet or less.
Yet despite their modest size-and regular vanishing act-vernal pools are a hotbed of life.
Because they are both shallow and temporary, vernal pools don't host fish. That eliminates a major predator threat to amphibians. Spring peepers; wood frogs; and Eastern spadefoot toads; along with the spotted, marbled and Jefferson salamanders thrive in the fish-free environment of vernal pools, where these and other creatures mate, hatch and transform.
Frogs and salamanders have adapted to this setting in remarkable ways, from the timing of their eggs to their ability to grow legs before the pond they were born in disappears.
Even a tiny crustacean called the fairy shrimp depends on these pools. Fairy shrimp hatch in late winter as the ponds begin to fill, then lay eggs and die as the pool empties. The eggs rest in the dry bed until the cycle begins again.
"Vernal pools are a beautiful little microcosm of how dynamic nature can be," Hayslett said.
They fascinate people of all ages, from children chasing tadpoles to volunteers guarding road crossings as salamanders make their way to nearby pools.
But in terms of conservation, vernal pools get left behind.
"These are small, seasonal systems," Hayslett said. "It's very easy for the general populace to presume that they are not important."
Vernal pools receive no federal protection. Initially, they were covered by the Clean Water Act, which once applied to wetlands with remote ties to navigable waters. But in 2001, the Supreme Court ruled that the Clean Water Act has no jurisdiction over "isolated wetlands," including vernal pools.
"There have been some attempts in Congress to strengthen and expand protection to non-navigable waters, but nothing has really happened yet," said Tim Maret, a biology professor at Shippensburg University who specializes in vernal pools.
State protections vary, depending on wetland policies.
Pennsylvania, Maryland and Virginia each address vernal pools through wetland regulations, but the levels of protection are uneven. Pools can sometimes be disturbed or destroyed. Mitigation is not always required.
"It's a huge concern in Pennsylvania," Maret said. "In Pennsylvania, you need a permit to disturb a vernal pool, but it's not an obstacle. It's just a regulatory step."
Virginia protects the pools but applies no rules to surrounding land use that removes tree canopy or disturbs the soil where eggs and amphibians burrow.
"You clear cut around a vernal pool and it dries out too quickly and everything typically perishes," Hayslett said. "And all of the mamas and papas in the surrounding forest are often destroyed outright by the impact of the equipment."
New York does not address vernal pools in its wetland regulations, but may protect specific pools if they have local importance to threatened or endangered species.
Even when state regulations apply, landowners may not recognize a vernal pool or understand how it functions. As a result, vernal pools have been obliterated by construction and road work, or damaged by surrounding land use.
Betsy Leppo of the Pennsylvania Natural Heritage Program provides free advice to landowners who want to keep vernal pools healthy. Much of her advice focuses on the land around the pool, rather than the pool itself.
"Terrestrial habitat goes out about 1,000 feet beyond the pool," Leppo said. "That captures about 95 percent of the amphibians in the pool. You don't want to be disturbing soil in the spring when they are moving."
Removing forest and other vegetation around the pool is especially harmful. A well-planted buffer protects the pool in the same way a forest buffer protects a stream: It cools the water and filters out pollutants. An exposed pool will dry out too quickly and collect water-borne contaminants.
A combined study from by the U.S. Geological Survey, National Park Service and U.S. Fish and Wildlife Service detected caffeine and more than two dozen pesticides in vernal pools on national parks and refuges, including one in Maryland and one in the District of Columbia. These chemicals can impact water quality as well as the development of sensitive young amphibians.
Leppo suggests keeping as much distance possible between vernal pools and pesticides.
Buffers also provide habitat. When mature frogs and salamanders leave the pond, they move into upland areas for the remainder of the year where they need trees, shrubs and woody debris to survive.
"Keep as much tree canopy and vegetation as possible," Leppo said. "And don't remove every single log that falls down."
Leppo's stewardship program is developing 30 conservation plans for vernal pools, the maximum possible under funding from the U.S. Fish and Wildlife Service and Pennsylvania Department of Conservation and Natural Resources. They have a waiting list and hope to see the program continue.
Several efforts are also under way to map the existence of vernal pools in the Chesapeake region. Aerial photos are unreliable, so success depends on both professional field work and online submissions from citizen scientists.
So far, thousands of vernal pools have been documented in both Pennsylvania and Virginia, but biologists say that's a small fraction of the total.
No mapping program exists for Maryland, although some vernal pools have been documented through the Maryland Biological Stream Survey. The Maryland Water Monitoring Council is exploring the possibility of a broader effort.
The Upper Susquehanna Coalition has captured roughly 500 vernal pools through its mapping program, but most of the pools are those that the group has created or restored.
Watershed coordinator Jim Curatolo said that creating new vernal pools promotes biodiversity in a setting where some vernal pools have vanished for good. But the practice stirs debate. "Building vernal pools is very controversial," Curatolo said. "Builders would love to be able to build a pool so they can fill another one in."
Still, creating vernal pools is a robust part of the coalition's wetlands program. This year, they will install a complex of 72 pools for long-term research by the State University of New York. Most projects take place on private land.
"We have a waiting list of about 140 landowners who would like to have vernal pools built," Curatolo said. "It's more than we have the money to do."
In Virginia, Michael Hayslett encourages broad thinking about defining and protecting vernal pools. Although the classic vernal pool-based on New England definitions-is a shallow, isolated pond in the forest, Hayslett said the situation in the Chesapeake region is "a lot trickier."
"We have a much broader perspective of latitude and longitude. In terms of physical geography, we've got everything from Atlantic beaches up to 6,000 feet in forests," Hayslett said. "This complicates how we categorize wetlands. For me, it means that the vernal pool as a wetland concept gets more flexible and fluid than in other distinctive regions of the country."
As a result, Hayslett said, vernal ponds in the Bay region may stray from the classic definition. They may occur in the bottomland-on floodplains connected to major river systems. They may be fed by groundwater, rather than rain and snow. And they may draw down enough to prevent the presence of fish, but never dry entirely.
"The bottom line is the function of the wetland in accommodating vernal pool species," Hayslett said. "These critters don't read our text books."
Vernal Pool Resources