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Bay Blog: groundwater

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.



Jun
29
2017

By the Numbers: 23

In our watershed, a fish that is no more than 10 inches long is a sentinel of climate change. Because brook trout need cold, clean water to survive, their presence in the region’s headwaters is a sign of stream health. As urbanization and other factors have raised the temperature of streams across the region, scientists have documented the disappearance of this sensitive fish. But experts now believe future increases in stream temperature will be less uniform than once thought, marking a shift in our understanding of how climate change could impact the only native trout in the Chesapeake Bay watershed.

The single most important factor in predicting whether brook trout will inhabit an area is water temperature.

According to the Eastern Brook Trout Joint Venture, brook trout began to disappear from the region when early agriculture, timber and textile industries prompted the removal of forests and pollution of streams. Today, urbanization threatens remaining brook trout habitat: paved surfaces push sediment into waterways, while dams and poorly designed culverts isolate brook trout populations from one another. The large, non-native brown trout—which is often stocked in rivers and streams to support fly fishing—has also been found to out-compete brook trout.

However, the single most important factor in predicting whether brook trout will inhabit an area is water temperature. While individual brook trout populations can acclimate to regional water temperatures, brook trout experience stress when stream temperatures reach 20 degrees Celsius and are typically absent when temperatures exceed 23 degrees. Scientific consensus has placed the limits of brook trout survival between 0 and 23 degrees Celsius (about 32 and 73 degrees Fahrenheit).

In Maryland and Virginia, high water temperature has been named the greatest disturbance to brook trout populations. In light of this fact, the National Park Service and U.S. Geological Survey (USGS) have supported efforts to predict how climate change will impact brook trout habitat in two national parks in an attempt to resolve the uncertainties of our changing environment at a scale that would be relevant to natural resource managers.

Field work at Shenandoah National Park has helped researchers realize that future increases in stream temperature will be less uniform than once thought, marking a shift in our understanding of how climate change could impact brook trout habitat. Photo by Ken Lane/Flickr.

Craig Snyder and Nathaniel Hitt are researchers at the USGS Leetown Science Center. Through field work in Shenandoah National Park and statistical modeling and simulation, Snyder and Hitt found that climate change would not affect brook trout habitat in the way previous research has largely assumed. Instead, the localized upwelling of cold groundwater into streams will create a varied pattern of stream temperatures and a patchy distribution of suitable brook trout habitat.

“We’ve learned that you need to account for groundwater to anticipate stream responses to climate change,” Snyder said. “The future will be more complicated—and thermally fragmented—than prior research has recognized.” In other words, as the region experiences more widespread effects of climate change, the temperature-related fragmentation of brook trout habitat will play a bigger role in determining the viability of the region’s brook trout populations.

While accounting for the effects of cold groundwater on stream temperature make Snyder and Hitt’s predictions less pessimistic than some others, all of their scenarios predict habitat loss in Shenandoah National Park. “The general consensus is that a 1.5-degree Celsius increase [in the region’s mean annual air temperature] is unavoidable. The question is, will we hit 5 degrees Celsius? And if so, when?” Under such an increase, “basically all habitat [in the park] becomes unsuitable, regardless of groundwater effects,” Hitt said.

“Our research indicates that stream warming will not proceed in a systematic or spatially uniform way,” said Snyder. “It’s going to more closely resemble a shattering of thermal habitat than a systematic change.”

Brook trout that have responded at an evolutionary level to heat stress could be good candidates for reintroduction to historically occupied habitat. Photo by Dave Herasimtschuk/Freshwaters Illustrated.

Just what this “shattering” of suitable habitat will do to brook trout populations is unclear. While it is likely to diminish brook trout occupancy—or the presence of the fish in a particular area, which is used instead of the more variable abundance to determine the health of brook trout populations—some unknowns remain. For instance: what conditions will brook trout swim through in order to find suitable habitat? How much cold habitat is necessary for a self-sustaining brook trout population to thrive? And can local populations adapt to heat stress over time?

This kind of research could help our partners expand brook trout populations rather than merely holding onto the habitat that currently exists. If scientists find brook trout that have responded at an evolutionary level to heat stress, for example, they could use these populations to reintroduce fish to historically occupied habitat and, in turn, move closer to the Chesapeake Bay Watershed Agreement commitment to increase occupied habitat.

“This species has existed for millions of years,” Hitt said. “They’re survivors. A loss of a cohort in one year has little effect on population dynamics. But three or four back-to-back years of bad recruitment—that’s where the problem is. Our research helps us predict where brook trout populations will be more resilient to coming environmental changes.”

Snyder, Hitt and Zachary Johnson recently used remote sensing data to model the effects of groundwater on stream temperature. Their work showed that landform features and precipitation records can predict where groundwater affects fish habitat, and the results of this work have been mapped by the USGS Eastern Geographic Science Center.

“Our research shows that stream temperature data are valuable not only for understanding current thermal habitat conditions for brook trout, but also for anticipating future changes,” said Johnson. “Our work can help prioritize streams for long-term brook trout conservation.”

Learn more about the Chesapeake Bay Program’s work to restore and sustain brook trout in the region’s headwater streams.

Catherine Krikstan's avatar
About Catherine Krikstan - Catherine Krikstan is a web writer at the Chesapeake Bay Program. She began writing about the watershed as a reporter in Annapolis, Md., where she covered algae blooms and climate change and interviewed hog farmers and watermen. She lives in Washington, D.C.



Aug
04
2016

Study warns of potentially corrosive groundwater in watershed states

Untreated groundwater across the Chesapeake Bay watershed has a high potential of being corrosive, according to a recent study from the U.S. Geological Survey. Left untreated, corrosive groundwater could leach lead and other metals from pipes and plumbing fixtures, potentially contaminating private drinking water supplies.

A recent study from the U.S. Geological Survey mapped the potential for groundwater corrosivity in groundwater wells in all 50 states, from "low" to "very high." (Map courtesy U.S. Geological Survey)

Public water supplies across the country are regulated by the U.S. Environmental Protection Agency (EPA). But private water supplies must be tested and maintained by homeowners. Approximately 44 million people in the U.S. get their drinking water from private wells—including 1.7 million in Virginia and 3 million in Pennsylvania. The study, which assessed 20,000 wells across the country from 1991 to 2015, shows groundwater in Maryland, Delaware and the District of Columbia has a ‘very high’ risk of being corrosive, while groundwater in Pennsylvania, New York, Virginia and West Virginia has a ‘high’ risk.

“This study is a good reminder that prudent, routine testing of the water, including its interaction with the water supply system, is an essential first step so homeowners and their families can confidently drink water from their faucets,” said Stephen Moulton II, assistant chief of operations for the USGS National Water-Quality Assessment Program, in a release.

Corrosive water is not dangerous to drink on its own, and potentially corrosive groundwater does not indicate the presence of lead or other metals in tap water. But corrosive water may react with pipes and other plumbing fixtures, leaching metals such as lead or copper into the water and potentially cause health-related problems. Signs of leaching caused by corrosive water may include bluish-green stains, small leaks in plumbing fixtures or a metallic taste to the water.

The report, “Assessing the Potential Corrosivity of U.S. Groundwater,” can be found online.



Feb
25
2014

Science shows restoration work can improve local water quality

Pollution-reducing practices can improve water quality in the Chesapeake Bay and have already improved the health of local rivers and streams, according to new research from the Chesapeake Bay Program partnership.

In a report released today, several case studies from across the watershed show that so-called “best management practices”—including upgrading wastewater treatment technologies, lowering vehicle and power plant emissions, and reducing runoff from farmland—have lowered nutrients and sediment in local waterways. In other words, the environmental practices supported under the Clean Water Act, the Clean Air Act and the Farm Bill are working.

Excess nutrients and sediment have long impaired local water quality: nitrogen and phosphorous can fuel the growth of algae blooms and lead to low-oxygen “dead zones” that suffocate marine life, while sediment can block sunlight from reaching underwater grasses and suffocate shellfish. Best management practices used in backyards, in cities and on farms can lower the flow of these pollutants into waterways.

Data collected and analyzed by the Bay Program, the University of Maryland Center for Environmental Science (UMCES) and the U.S. Geological Survey (USGS) have traced a number of local improvements in air, land and water to best management practices: a drop in power plant emissions across the mid-Atlantic has led to improvements in nine Appalachian watersheds, upgrades to the District of Columbia's Blue Plains Wastewater Treatment Plant have lowered the discharge of nutrients into the Potomac River and planting cover crops on Eastern Shore farms has lowered the amount of nutrients leaching into the earth and reduced nitrate concentrations in groundwater.

“In New Insights, we find the scientific evidence to support what we’ve said before: we are rebuilding nature’s resilience back into the Chesapeake Bay ecosystem, and the watershed can and will recover when our communities support clean local waters,” said Bay Program Director Nick DiPasquale in a media release.

But scientists have also noted that while we have improved water quality, our progress can be overwhelmed by intensified agriculture and unsustainable development, and our patience can be tested by the “lag-times” that delay the full benefits of restoration work.

“This report shows that long-term efforts to reduce pollution are working, but we need to remain patient and diligent in making sure we are putting the right practices in place at the right locations in Chesapeake Bay watershed,” said UMCES President Donald Boesch in a media release. “Science has and will continue to play a critical role informing us about what is working and what still needs to be done.”

UMCES Vice President for Science Applications Bill Dennison echoed Boesch’s support for patience and persistence, but added a third P to the list: perspiration. “We’ve got to do more to maintain the health of this magnificent Chesapeake Bay,” he said.

“We’ve learned that we can fix the Bay,” Dennison continued. “We can see this progress… and it’s not going to be hopeless. In fact, it’s quite hopeful. This report makes a good case for optimism about the Chesapeake Bay.”

You can view an Executive Summary of the report here. Learn more.



Dec
11
2013

Groundwater withdrawal causing land to sink in lower Chesapeake region

The intensive withdrawal of groundwater is causing land to sink in the lower Chesapeake Bay region, worsening the effects of sea-level rise and increasing the severity of floods along the Delmarva Peninsula and Virginia Coastal Plain.

Image courtesy PhotoSeoul/Flickr

Land subsidence, or the sinking of the land’s surface, is in part a natural phenomenon, occurring as bedrock responds to the melting of an ice sheet that once covered Canada and the northern United States. But according to a new report from the U.S. Geological Survey (USGS), most of the land subsidence in this area is taking place in response to groundwater withdrawal, which could help explain why the region has the highest rates of relative sea-level rise on the Atlantic Coast.

When groundwater is pumped out of the earth, water levels in the area’s underground aquifers decrease. As these water levels decrease, the aquifer system compacts, causing the land above it to sink. In the southern Bay region, land subsidence has been measured at rates of 1.1 to 4.8 millimeters per year—close to the width of five stacked pennies.

Land subsidence can increase flooding, alter wetland and coastal ecosystems, and damage human infrastructure and historical sites. Some areas in Virginia—like the city of Franklin and the counties of Isle of Wight and Southhampton—have already experienced floods as the land around them sinks, and the low-lying Hampton Roads could experience similar episodes soon.

But according to the USGS, a change in water use—from moving groundwater pumping out of high-risk areas to slowing rates of groundwater withdrawal—could slow or mitigate land subsidence and relative sea-level rise.

Learn more.



Nov
12
2013

Ancient seawater found under Chesapeake Bay

The oldest body of seawater ever identified is buried under the Chesapeake Bay.

According to the U.S. Geological Survey (USGS), this recently discovered body of water dates back to the Early Cretaceous period, when wet and dry seasons controlled the climate, tropical jungles dominated the landscape and dinosaurs were becoming more plentiful.

Image courtesy Nicolle Rager-Fuller/National Science Foundation

The water is buried beneath a large meteorite that struck the earth 35 million years ago, throwing debris into the atmosphere and spawning a train of tsunamis that probably reached as far as the Blue Ridge Mountains. The so-called “Chesapeake Bay impact crater” is the largest crater discovered in the United States and helped determine the current shape of the Bay.

Because the water is trapped in place, USGS scientists have been able to estimate its age—100 to 145 million years old—and its salinity—twice as salty as modern seawater.

Acting USGS Associate Director for Water Jerad Bales said in a media release that before this discovery was made, no one realized that the saltier-than-normal groundwater found deep in the Atlantic Coastal Plain “was North Atlantic ocean water that has essentially been in place for 100 million years.”

“We are working directly with seawater that dates far back in earth’s history,” Bales said.

Learn more.



Nov
12
2013

Groundwater pushes nitrogen into Bay, delays effects of restoration

Slow-moving groundwater on the Delmarva Peninsula could push excess nutrients into the Chesapeake Bay even after we have lowered the amount of nitrogen and phosphorous we put onto the land.

Image courtesy yorgak/Flickr

According to new research from the U.S. Geological Survey (USGS), most of Delmarva is affected by the slow movement of nutrients from the land into the water. A USGS model developed to track the movement of nitrogen through the region showed that groundwater—and the pollutants it can contain—takes an average of 20 to 40 years to flow through the peninsula’s porous aquifers into rivers and streams. In some parts of Delmarva, the groundwater that is now flowing into local waterways contains nitrogen linked to fertilizer used three decades ago.

The slow flow of nitrogen-laden groundwater into the Bay could affect efforts to restore the watershed, lengthening the “lag-time” between the adoption of a conservation practice and the effect of that practice on a particular waterway. In other words, it could take days or even decades for today's management actions to produce positive water quality results.

“This new understanding of how groundwater affects water-quality restoration in the Chesapeake Bay will help sharpen our focus as many agencies, organizations and individuals work together to improve conditions for fish and wildlife,” said Lori Caramanian, Department of the Interior Deputy Assistant Secretary for Water and Science, in a media release.

While these findings seem to contradict the value of our restoration work, the study in fact indicates that pollution-reducing practices put in place over the past decade have begun to work. The study also confirms that rigorous steps taken to reduce nutrients on the land will lower the amount of nitrogen loading into streams in the future.

Learn more.



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