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The Strange, Controversial Way Plants Trap CO2

Wednesday, June 11th, 2014

by Kristen Minogue

Swamp Rose Mallow surrounded by blades of Schoenoplectus, a sedge in Drake's marsh experiment. (SERC)

Swamp Rose Mallow with blades of Schoenoplectus americanus, a sedge in Drake’s marsh experiment. (SERC)

Plants are among the world’s best carbon sinks, but there’s a side to the plant-CO2 love affair that’s rarely discussed. When carbon dioxide rises, plants cling to it more, releasing less back into the air—and until recently, scientists couldn’t figure out why. With a new paper published June 11 in Global Change Biology, ecologist Bert Drake believes he finally has the answer.

The process is called respiration, and it’s one of the most overlooked parts of the carbon cycle. Unlike photosynthesis, in which plants absorb carbon dioxide and release oxygen, respiration reverses it. And plants respire constantly. Much of the CO2 plants take from the atmosphere for photosynthesis finds its way back via respiration from plants and soil. Which leaves a major question: How much carbon can the world’s ecosystems store as CO2 rises and climate changes?

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Learning by Digging: Archeology Project Explores Colonial Life

Tuesday, June 10th, 2014

Scientists, students, and volunteers unearth late 17th- and 18th-century objects behind Sellman House

by Sarah Hansen

Volunteers excavate a new pit at the “Shaw’s Folly” site behind Sellman House.

On a sunny June afternoon at the Smithsonian Environmental Research Center, students and volunteers are hard at work in a cornfield behind the Sellman House.  Some shovel soil out of pits.  Others screen it with giant sieves, looking for artifacts.  Still others use trowels to smooth the bottom and sides of the pit, hoping to reveal differences in soil coloration and texture.  This scene will repeat every Monday, Tuesday, and Friday from about 9a.m. to 4 p.m. until June 20.  Guided by Laura Cripps, acting Chair of Social and Cultural Sciences at Howard Community College, and Jim Gibb, head of SERC’s Archaeology Lab, the group is excavating a site that contains objects and building materials that provide a window into 17th- and 18th-century life.

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Arctic Unguarded: Melting Ice Opens Way
for Invaders

Wednesday, May 28th, 2014

by Kristen Minogue

Arctic sea ice (Patrick Kelley/U.S. Coast Guard)

Arctic sea ice (Patrick Kelley/U.S. Coast Guard)


For the first time in roughly 2 million years, melting Arctic sea ice is connecting the north Pacific and north Atlantic oceans. The new sea routes leave both coasts and Arctic waters vulnerable to a large wave of invasive species—a problem the Arctic has largely avoided until now.

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What’s Hurting the Chesapeake’s Underwater Plants?

Monday, May 5th, 2014

by Kristen Minogue

Photo: A flounder in a bed of eelgrass. (NOAA)

A flounder in a bed of eelgrass. Seagrasses and other underwater plants provide food and shelter to many iconic Bay creatures, including blue crabs. (NOAA)

It’s been a difficult century for the submerged flora of Chesapeake Bay.

In the 1930s, wasting disease nearly wiped out the eelgrasses of the North Atlantic. In the ‘50s and ‘60s, they faced onslaughts from invasive grasses like water chestnut and Eurasian milfoil. Finally, in the summer of 1972, Hurricane Agnes pummeled underwater plants to the lowest levels ever reported in the Bay. This April, they received news that, at first glance, seemed positive: Submerged grasses rose 24 percent between 2012 and 2013, according to aerial surveys of the Chesapeake Bay Program.

But those increases were largely limited to a single species: widgeon grass, a plant known for wild fluctuations. At 60,000 acres total, submerged plants still didn’t come near a recent mini-peak in 2002, they’re a far cry from the ultimate goal of 185,000 acres across the Bay. What is holding them back? And—more importantly—how we can we help ensure the latest expansion isn’t just a blip?

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Ancient Native American Compost Still Enriching Forests

Wednesday, April 30th, 2014

by Kristen Minogue

Photo: An open pit exposes a 3200-year-old shell midden. Native Americans used middens as trash piles for oyster shells, animal bones and pottery. (by Torben Rick/Smithsonian)

An open pit exposes a 3200-year-old shell midden. Native Americans used middens as trash piles for oyster shells, animal bones and pottery. (Torben Rick/Smithsonian)

More than 3,000 years ago, Native Americans dined on shellfish from the Chesapeake Bay, and the leftovers from those feasts are still benefiting modern-day forests.

Native Americans inhabited the Chesapeake Bay area more than 13,000 years before the first Europeans dropped anchor. During the Woodland period (3,200 to 400 years ago), they ate eastern oysters and threw the shells, along with animal bones, pottery and other shellfish remains, into trash piles called shell middens. Those piles enriched the soil with nutrients, promoting hot spots of native diversity along the Chesapeake shoreline.

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Diversity Helps Forests Resist Deer

Tuesday, April 8th, 2014

by Kristen Minogue and John Parker

White-tailed deer. (Photo courtesy of John Parker/SERC)

White-tailed deer. (John Parker/SERC)

In deer-populated forests, tastier plants can avoid being eaten if they are surrounded by less appealing plants. But with deer gone, diverse plots become weaker and plants are better off sticking to their own kind.

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The Secret Formula to Feeding 900 Babies

Tuesday, April 1st, 2014

Scientists uncover milk composition of naked mole-rat queens

by Micaela Jemison

Naked mole rats at the National Zoo (by Meghan Murphy)

Naked mole rats at the National Zoo (Meghan Murphy)

Parents normally feel the need to provide well for their kids. For humans, that number of offspring is usually in the single digits, but a naked mole-rat queen can have as many as 900 pups in a lifetime spanning up to 30 years.

Naked mole-rats live their lives entirely underground in Africa, digging tunnels in a perpetual search for plant tubers to eat. These bizarre creatures are unlike nearly every other mammal on earth in that the burdens of reproduction and milk feeding of young are placed solely on a single queen and are not shared among the females of the colony.

While this system may work well for insects like bees where the young are fed by a horde of workers and nurses, scientists were perplexed as to how this system works for a mammal where one mother must produce milk for her very large brood.

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With Fewer Hard Frosts, Tropical Mangroves Push North

Monday, December 30th, 2013

by Kristen Minogue and Heather Dewar

Image: SERC ecologist Kyle Cavanaugh explores a field of white mangroves. (SERC)

SERC ecologist Kyle Cavanaugh explores a field of white mangroves. (SERC)

As mangrove trees lose ground to deforestation and urban sprawl, one development seems to be giving them a boost: climate change. Fewer winter cold snaps have empowered them to conquer new territory around their northern Florida boundary, according to a study of 28 years of satellite data from the Smithsonian Environmental Research Center and the University of Maryland.

An estimated 35 percent of the world’s mangroves have been destroyed since 1980, according to previous research, outstripping tropical rainforests and coral reefs. They are also some of the planet’s most valuable ecosystems. Mangroves protect coastal cities from floods and hurricanes. Their above-ground roots shelter many commercially valuable fisheries, including blue crabs, shrimp and lobsters. And they are phenomenal at burying carbon. The soils of coastal ecosystems like mangroves can store carbon at a rate 50 times higher than tropical rainforests. Scientists have estimated their total ecosystem services value more than $1.6 trillion a year—making the expansion a possible blessing.

“Some people may say this is a good thing, because of the tremendous threats that mangroves face,” said the study’s lead author, Kyle Cavanaugh, a postdoctoral research fellow at the Smithsonian Environmental Research Center in Edgewater, Md. “But this is not taking place in a vacuum. The mangroves are replacing salt marshes, which have important ecosystem functions and food webs of their own.”

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Cracking Down on Mercury

Monday, December 9th, 2013

by Kristen Minogue

Ally Bullock, a technician in SERC's mercury lab, draws pore water samples from Berry's Creek. (SERC)

Ally Bullock, a technician in SERC’s mercury lab, draws pore water samples from Berry’s Creek. (SERC)

It isn’t safe to eat the blue crabs from Berry’s Creek.  American eels and white perch are also off-limits. White catfish are permissible, but only once a year, according to a New Jersey advisory for the Newark Bay Complex, where the creek is located. Crabbing in the 6.5-mile stream is illegal and can carry up to a $3000 fine. Waste from a now-defunct chemical processing plant, combined with more than a century of manufacturing, has made Berry’s Creek and its surrounding wetlands hot spots for mercury pollution.

The Environmental Protection Agency calls places like Berry’s Creek “Superfund sites”—a label for abandoned or neglected sites that became dumping grounds for hazardous waste. Some of the highest levels of mercury contamination in the U.S. exist in Superfund sites. Cynthia Gilmour knows this first-hand. As a microbial ecologist at the Smithsonian Environmental Research Center, she has worked in several.  But short of digging up the polluted sediments and dumping them elsewhere (an expensive and ecologically risky proposition), not many methods exist to get rid of the problem.

“If we use the traditional technologies of removing that and putting it in a landfill, we don’t have a wetland anymore,” says Upal Ghosh, an environmental engineer from the University of Maryland, Baltimore County, who works with Gilmour.

This fall, Gilmour and Ghosh explored a new technique: using charcoal to trap it in the soil.

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Wetlands Can Resist Rising Seas, If We Let Them

Thursday, December 5th, 2013

by Kristen Minogue

Fishing camp along Falgout Canal Bayou, La., where marsh has submerged into open water and remains mostly on canal leaves. (Matt Kirwin/VIMS)

Fishing camp along Falgout Canal Bayou, La., where marsh has submerged into open water and remains mostly on canal leaves. (Matt Kirwin/VIMS)

Left to themselves, coastal wetlands can adapt to sea-level rise. But humans could be sabotaging some of their best defenses, according to a review paper from the Smithsonian Environmental Research Center and the Virginia Institute of Marine Science to be published Thursday, Dec. 5, in Nature.

The threat of disappearing coastlines has alerted many to the dangers of climate change. Wetlands in particular—with their ability to buffer coastal cities from floods and storms, and filter out pollution—offer protections that could be lost in the future. But, say co-authors Matt Kirwan and Patrick Megonigal, higher waters are not the key factor in wetland demise. Thanks to an intricate system of ecosystem feedbacks, wetlands are remarkably good at building up soil to outpace sea-level rise. But this ability has limits. The real issue, the scientists say, is that human structures such as dams and seawalls are disrupting the natural mechanisms that have allowed coastal marshes to survive rising seas since at least the end of the last ice age.

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