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Bay Blog: vernal pools

Jun
29
2017

From the Field: How invasive species could be impacting vital salamander habitat

Within five minutes of entering Corcoran Woods, Susan Lamont is bent over what looks like a large puddle, gently holding a gelatinous mass. The mass is made up of salamander eggs, and what she’s bent over is no puddle, but a vernal pool.

Vernal pools are ephemeral forest ponds, fed by snow, rain or groundwater. They only stay wet for about seven months out of the year, but in that time, they host a wealth of animals. Amphibians like salamanders and frogs lay their eggs in vernal pools, which have fewer predators like fish due to their temporary nature.

Today, Lamont, a biology professor at Anne Arundel Community College, is leading a group of students and volunteers in a survey of vernal pools, looking for egg masses lain by spotted and marbled salamanders. They’re exploring the more than 200-acre Corcoran Environmental Study Area, which lies in Anne Arundel County, Maryland, just west of the Chesapeake Bay.

Anne Arundel Community College student Dominic Ollivierre, right, pulls leaves from a net while surveying a vernal pool with classmates and biology professor Susan Lamont, second from left, at Corcoran Woods, part of Sandy Point State Park in Anne Arundel County, Md., on March 24, 2017. For three years, Lamont has brought her students and volunteers out to survey the woods’ vernal pools.

The southeastern section of Corcoran Woods is dotted with these temporary pools. Lamont breaks the students up into groups and shows them the pools they’ll be surveying. Armed with nets, boots and GPS markers, they begin scouring their pools for evidence of amphibian breeding.

Along with the surveying that her students and volunteers are doing, Lamont is setting traps for adult salamanders to help determine how they use the pools. In the past, she and her students would find adults by looking under rocks and logs. “I want to know how much they’re using the pools,” she says.

Now in her third year of the study, Lamont’s research not only answers her own questions and provides her students with an outdoor learning opportunity, it also serves the Maryland Department of Natural Resources (DNR), which owns Corcoran Woods. They were concerned about the vernal pools and if they were at risk of drying up. “If you’re managing the pools, you have to know what’s happening with them,” says Lamont. “They don’t have the staff to come out and do [the surveying], and it’s easy to get the students—they love it.”

A spotted salamander egg mass develops in a vernal pool at Corcoran Woods. Anne Arundel Community College biology professor Susan Lamont is studying the impact on vernal pools at Corcoran following the removal of invasive plants.

About a half mile away, the northwest corner of the forest tells a different story. There are no vernal pools here, but there is an even more dramatic difference: this corner of the woods, unlike the southeast where Lamont’s students are surveying, is plagued by invasive species.

Much of the land was cleared of invasives last year, treated with herbicides and replanted with native trees. The hope is that the natives will grow large enough to shade the area and help keep invasives out. Until then, it will have to be carefully looked after to prevent regrowth of invasive species.

A slight turn in the trail reveals the vastly altered landscape. A forest of plastic tree tubes blankets the area of what used to be acres of invasive plants like oriental bittersweet, English ivy and multifloral rose. Some original trees still remain, but pale-green tubes stick out like hundreds of hair plugs.

Susan Lamont, a biology professor at Anne Arundel Community College, stands at the edge of a large invasive species removal and tree planting site at Corcoran Woods.

“The red plot was severely infested,” recalls Lamont. “Before they treated it, all you could see were invasives. Vines were over the tops of the trees.” Thick vines still hung from a few of the remaining trees, but hovered about six feet above the ground where they had been severed from their roots.

Along with sunlight, invasive species require a lot of water, and in turn could have lowered the groundwater table. “This is a drier area than the vernal pool area,” Lamont notes. “We’re not sure if it’s drier because [the invasive species] were here, or if that’s why the invasives took over.” If the former is true, it could spell bad news for the vernal pools if the invasive species make their way south east.

Groundwater is generally talked about in terms of drinking water and irrigation, but forest plants and animals need it just as much as humans. In Corcoran Woods, groundwater is vital for feeding the vernal pools that salamanders and other amphibians rely on, but this corner of the woods is much drier and noticeably absent any pools.

That’s where Lamont’s new research comes in. She’s going to put groundwater monitoring wells in the area where the invasives are to see if the removal efforts make the area wetter. She’ll also put some groundwater wells in the vernal pool area to compare water levels within Corcoran Woods.

“[Maryland DNR is] very interested in protecting the pool habitat and restoring the part of the woods that was decimated by invasives,” Lamont says. By measuring the effect of invasive species on groundwater—and, in turn, the vernal pools the salamanders use—Lamont and her students can help DNR support the interconnected ecosystem at Corcoran Woods.

Images by Will Parson

Joan Smedinghoff's avatar
About Joan Smedinghoff - Joan is the Communications Office Staffer at the Chesapeake Bay Program. Originally from Chicago, she was introduced to the Chesapeake Bay region through the streams of central Pennsylvania. She received her Bachelor's in Environmental Studies from Dickinson College in Carlisle, Pa., where she first discovered her passion for storytelling.



Mar
31
2017

Photo of the Week: Spring peepers perform seasonal serenade

A spring peeper’s throat swells as it makes its signature call in a vernal pool at Kings Gap State Park in Thurmont, Pennsylvania, on March 25, 2016. As its name implies, the spring peeper’s “peeping” call is one of the first signs of spring in the Chesapeake region.

Calling the sound a “peep” might make it seem like a small, subdued noise. In actuality, the call has been likened to a car alarm—and when hundreds of frogs sing in a single location, as they often do, the noise can be almost deafening. A high-quality call is extremely important during breeding season, as it influences which mate a female will choose.

In early spring, the arrival of vernal pools spurs peepers to mate. Vernal pools are temporary ponds, fed by snow, rain or groundwater and blanketed in leaves from a healthy forest. They only last for a handful of months each year, but stay wet long enough to host a multitude of breeding frogs, toads and salamanders. Because the pools aren’t directly connected to a waterway, they’re free from the fish that would otherwise prey on amphibian eggs and larvae.

While best-known for their springtime symphonies, spring peepers spend the rest of the year on land. Their dependence on marshy woodlands for habitat makes spring peepers particularly vulnerable to the loss of forests and wetlands. Work by Chesapeake Bay Program partners to conserve land across the watershed provides habitat not only peepers, but other wildlife that live in the region.

Image by Will Parson

Stephanie Smith's avatar
About Stephanie Smith - Stephanie is the Web Content Manager at the Chesapeake Bay Program. A native of the Midwest, she received her Bachelor’s in Professional Writing from Purdue University and Master of Science degree from the University of Michigan. Stephanie’s lifelong love of nature motivates her to explore solutions to environmental problems and teach others what they can do to help.



May
13
2016

Photo of the Week: Warm rains spring salamanders into action

A spotted salamander rests near the edge of a vernal pool in Edgewater, Maryland. Named for their bright yellow spots, these amphibians thrive in the swamps and bottomland forests of the Chesapeake Bay region.

The first warm spring rains prompt the annual migrations of these salamanders, along with wood frogs and other vernal pool breeders—species that depend on these small, seasonal bodies of water to reproduce. Vernal pools are short-lived forest ponds, fed by snow, rain or groundwater. They only stay wet for about seven months, just long enough for a cascade of frogs and salamanders to use them as a home for their developing young.

Areas that house vernal pools are often vulnerable to development, endangering the breeding grounds of critters like the spotted salamander, which will return to the same pool year after year to reproduce. But conserved lands like the Forests Pools Preserve near Carlisle, Pennsylvania, provide an oasis for these ephemeral ponds—and the species that depend on them.

 

Photo by Will Parson

Stephanie Smith's avatar
About Stephanie Smith - Stephanie is the Web Content Manager at the Chesapeake Bay Program. A native of the Midwest, she received her Bachelor’s in Professional Writing from Purdue University and Master of Science degree from the University of Michigan. Stephanie’s lifelong love of nature motivates her to explore solutions to environmental problems and teach others what they can do to help.



Apr
26
2016

Restoration Spotlight: From trash pit to amphibian oasis

Andy Green, right, a volunteer with The Nature Conservancy, spotlights wood frog egg masses in a vernal pool at Forest Pools Preserve in Cumberland County, Pa., on March 25. The 70-acre preserve is home to seven vernal pools supporting an array of amphibians, invertebrates and plants.

In late March, Pennsylvania’s South Mountain was already weeks into spring’s thaw, but a stinging breeze and sinking sun meant jackets and beanies for a group forming under the tall, swaying pines near Kings Gap State Park.

Devin Thomas, almost ten years old, from nearby Carlisle, showed up in shorts and sneakers but came prepared with a headlamp he made using an old pair of underwear and faithfully equipped with enthusiasm for the outdoors.

“He won’t even kill bugs,” said Ray Thomas, Devin’s father—also wearing shorts.

As more people arrived, they took turns dunking their boots in a bucket of soapy disinfectant, used to get rid of harmful microbes, seeds, and any other invasive species. It was a precaution justified by the group’s destination, the vernal pools of Forest Pools Preserve.

Wood frog embryos develop inside eggs at Forest Pools Preserve. Wood frogs will lay their eggs in the sunniest part of a pool, so that the warmer temperature will hasten development.

Vernal pools are ephemeral forest ponds, fed by snow, rain or groundwater, and blanketed in leaves from a healthy forest. They host a wealth of animals and only stay wet for about seven months, which is just long enough for a cascade of frogs and salamanders to use them as a home for their developing young.

You won’t find fish—they would eat all the eggs—but if you get the timing right, you’ll hear the clucking chatter of spawning wood frogs or the car alarm call of camouflaged spring peepers. You might see yellow spotted salamanders wriggling among the leaves, and you might see tiny fairy shrimp, the country cousins of the commercial pet Sea-Monkeys.

If you were visiting the area ten years ago, you would also see piles of trash and hear the sound of broken glass underfoot.

“I guess back in the olden days you would see these depressions in the forest, and before we had trash pickup I think that’s where a lot of people would just put their trash,” said Molly Anderson, a volunteer program manager with The Nature Conservancy. “You’d walk and you’d just hear ‘crunch crunch.’”

The Conservancy purchased the preserve’s 70 acres in 2007, and for three years it held volunteer trash cleanups and monitored the vernal pools there. A Conservancy scientist started noticing that some of the pools weren’t holding water long enough for the young amphibians to develop.

Several theories arose. One was that growing development, with people drilling wells, had lowered the water table below the groundwater-fed pools. Another was that it might be just be a naturally drier period than normal.

“I also heard that maybe the clay liner that was holding the water, that it was popped by all the trash that was laying in it,” Anderson said.

In 2010, with grants received by the Western Pennsylvania Conservancy, The Nature Conservancy held a workshop to restore some of the ailing pools. Volunteers Mike Bertram and Kathy King, a local married couple, were instrumental volunteers overseeing the effort, and nearby Dickinson Township provided equipment, Anderson said.

The work involved raking away leaves, setting aside mosses and other plants, using heavy machinery to remove layers of soil and carefully replacing everything above a synthetic liner placed in the depression. A season’s worth of leaf litter was the finishing touch.

“The restoration took place in the beginning of August, and we came back in the fall of the same year and it was hard to tell that anything was done there,” Anderson said.

In the years since, the restored pools hold water when the pools that weren’t restored are drying up, Anderson said. Now Forest Pools Preserve serves not only as critical habitat but as a means to raise awareness.

“One of the things that we’re concerned about is that because vernal pools are really small and kind of unnoticeable, they’re not protected really under any kind of laws protecting water,” Anderson said.

Anderson said the Conservancy is trying to educate local governments about the importance of vernal pools and address issues raised by landowners, such as the threat of mosquitos. Aiding the effort, the Pennsylvania Natural Heritage Program has a vernal pool landowner incentive program and an online registry.

“In a really healthy vernal pool, you’ll have a lot of different predators on mosquito larvae that would keep the mosquito numbers in check,” Anderson said.

A younger member of the group holds a spring peeper at the edge of a vernal pool in Kings Gap State Park.

Conservancy volunteer Andy Green helps monitor the pools and led the walk that the Thomas family attended. A retired doctor who grew up in Carlisle, Green managed remnant prairie and stormwater programs in Illinois before returning to Pennsylvania. He lives just down the road from Forest Pools Preserve.

“It’s interesting, there are none of these pools in the North Mountain, or many of these mountain ridges north of here,” Green said. “This is essentially a South Mountain phenomenon.”

Bringing the group to a pool fed by groundwater, Green pointed out the telltale masses of wood frog eggs. Wood frogs love a 40-degree night with rain, he said. The eggs were a sign that the frogs had already found a break in the cold weather, came, and left before anyone could spot them.

“They fooled everybody,” Green said.

A spring peeper’s throat swells as it makes its signature call.

Fairy shrimp swim through a vernal pool. Their eggs can survive dry periods up to a decade or more before hatching.

A spotted salamander is held at a vernal pool at Kings Gap State Park in Cumberland County, adjacent to Forest Pools Preserve.

Smaller in number were masses of eggs belonging to Jefferson and spotted salamanders, attached to sticks where the male of the species first places a sperm packet, or spermatophore.

As the adults listened to Green, the younger members of the group dispersed once they learned that they could find salamanders underneath rocks. They became the most avid explorers of the night, flipping rocks and logs, finding tiny red-backed salamanders, and replacing them as they were—at Green’s urging—before moving on to crouch low and face the water’s surface at each pool.

At the site of another pool, Green was dismayed to find nothing but a depression full of leaves. Under some of the leaves were wood frog egg masses, still moist, but the pool protecting them had dried up, and without a rain the eggs would dry up as well.

Green led the group to a final stop just over the boundary with Kings Gap State Park, which the Conservancy acquired in 1973 and transferred to the state. The sound of spring peepers became louder and louder as the group approached a pool, until the chorus seemed to be coming from every direction at once.

One of the adults held a spotted salamander she had found near the pool, showing it to the admiring group and periodically wetting her hands in the pool to keep the salamander’s skin moist—just another measure to keep the vernal pool community healthy.

The peeper’s call that had been so piercing faded quickly as the group left the low-lying bowl holding the pool, giving way to the crunching of leaves and excited recounting of what the group had just seen.

 

To view more photos, visit the Chesapeake Bay Program’s Flickr page

Photos and text by Will Parson

Will Parson's avatar
About Will Parson - Will is the Multimedia Specialist for the Chesapeake Bay Program. A native of Bakersfield, California, he acquired an interest in photojournalism while studying ecology and evolution at University of California, San Diego. He pursued stories about water and culture as a graduate student at Ohio University's School of Visual Communication, and as an intern at several newspapers in New England before landing in Maryland.



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