Water Quality

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Oyster Disease Thrives in Nightly Dead Zones

Wednesday, February 11th, 2015

by Kristen Minogue

Image: Slides of oysters suffering different Dermo intensities as the parasite multiplies, from healthy (left) to severely infected (right). (Credit: SERC Marine Ecology Lab)

Slides of oysters suffering different Dermo intensities as the parasite multiplies, from healthy (left) to severely infected (right). (SERC Marine Ecology Lab)

In shallow waters around the world, where nutrient pollution runs high, oxygen levels can plummet to nearly zero at night. Oysters living in these zones are far more likely to pick up the lethal Dermo disease, a team of scientists from the Smithsonian Environmental Research Center discovered in a new study published Wednesday.

Oxygen loss in the shallows is a global phenomenon, but it is not nearly as well known as the dead zones of the deep. Unlike deep-water dead zones, which can persist for months, oxygen in shallow waters swings in day-night cycles, called diel-cycling hypoxia. In nature it works like this: When algae photosynthesize during the day, they release oxygen into the water. But at night, when photosynthesis stops, plants and animals continue to respire and take oxygen from the water, causing dissolved oxygen to drop. Nutrient pollution, because it fuels massive algal blooms, can make the cycle even more drastic. The resulting lack of oxygen can cripple the oysters’ ability to fight off the parasite Perkinsus marinus that causes Dermo and slowly takes over their bodies.

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Oysters and the Chesapeake’s Jellyfish Wars

Tuesday, September 30th, 2014

Image: Jellyfish Chrysaora quinquecirrha (Credit: Lori Davias)

Jellyfish Chrysaora quinquecirrha (Lori Davias)

by Kristen Minogue

Every summer, the food web in Chesapeake Bay gets jostled around as two plankton-eating predators jockey for power: comb jellies and jellyfish. Most smaller species don’t have a stake in the battle—both predators eat zooplankton and fish eggs, after all. But for young oyster larvae, the victor could make the difference between being protected civilians or collateral damage.

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Urban kids, urban waterways: Citizen science improves lives and environment

Thursday, August 21st, 2014

By Sarah Hansen

Tony Thomas (left) supervises while Donovan Eason (center) and DaWayne Walker run a chemical test on a water sample.

Tony Thomas (left), education program coordinator at the Anacostia Community Museum, supervises while students Donovan Eason (center) and DaWayne Walker run a chemical test on a water sample.

“Is the net like a Spongebob jellyfish net?” student Cristal Sandoval asked.  Alison Cawood, citizen science coordinator at the Smithsonian Environmental Research Center (SERC), used another analogy to explain: “It’s like a bowl with holes in it for pasta.”  Light bulbs came on around the room and a knowing, “Oh,” escaped the lips of at least a dozen students.

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Marshes: Pollution Sponges of the Future

Thursday, August 21st, 2014

by Melissa Pastore, biology graduate student at Villanova University

Image: Melissa Pastore in a marsh near Delaware Bay. (Credit: Lori Sutter)

Melissa Pastore in a marsh near Delaware Bay.
(Lori Sutter)

What if we could create a giant sponge capable of soaking up nitrogen pollution? It turns out that the Chesapeake Bay, which has experienced a rapid increase in nitrogen pollution from municipal and agricultural sources over the last few decades, already contains a natural version of this sponge: marshes fringing the Bay. But global change—and the nitrogen pollution itself—could change how this natural sponge operates.

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Using Computer Models to Help Rescue Bay’s Underwater Flora

Thursday, July 17th, 2014

By Sarah Hansen

SERC intern Bridget Smith, immersed in a sea of environmental data.

SERC intern Bridget Smith, immersed in a sea of environmental data. (SERC)

Underwater plants like sea grasses provide habitat and feeding areas for a wide range of aquatic life.  They also help filter the water and put the brakes on erosion.   But in Chesapeake Bay, the coverage of underwater plants, or submerged aquatic vegetation (SAV), has been low for decades, and restoration attempts have had mixed results.  That’s why this summer, Smithsonian Environmental Research Center intern Bridget Smith is grappling with 28 years of data to explore which of a host of factors affects SAV in the Bay and how.

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How much could streamside forests reduce nitrogen pollution in the Bay?

Monday, June 23rd, 2014

by Sarah Hansen


A buffer on the Chester River in Queen Anne’s County, MD protects the river from nitrogen pollution. (USDA)

Nitrogen pollution in the Chesapeake Bay became a serious concern in the mid-20th century after the advent of nitrogen-rich chemical fertilizers. Bay restoration efforts have reduced nitrogen pollution somewhat, but achieving healthy nitrogen levels in the Bay is still a long way off. Croplands remain an important source of the nitrogen that pollutes Chesapeake Bay.

Don Weller, senior scientist at the Smithsonian Environmental Research Center, and his colleague Matthew Baker, associate professor of geography and environmental systems at the University of Maryland, Baltimore County, report in a new study that just over half the nitrogen from croplands might never reach the Bay—if all crop fields were protected by streamside forests and wetlands.

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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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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 a mid-Atlantic Superfund site. (SERC)

There are places in the U.S. so polluted, eating fish or crabs from their waters isn’t just unhealthy—it can be illegal. The Environmental Protection Agency calls sites like that “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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Q&A: The Heart of the Ocean

Tuesday, November 12th, 2013
Before joining MarineGEO, Emmett Duffy did research in waters from Australia to Siberia. (Photo: College of William and Mary)

Before joining MarineGEO, Emmett Duffy did research in waters from Australia to Siberia. (Photo: College of William and Mary)

by Kristen Minogue

It’s “the largest, coolest marine biological project on Earth”, according to its new director, Emmett Duffy. On Sept. 16 Duffy came on board the Tennenbaum Marine Observatories Network, a.k.a. MarineGEO–the Smithsonian’s global network to monitor the oceans. So far it has five stations tracking the ocean’s chemistry and biology, from SERC in Maryland to STRI in Panama. They plan to add at least 10 more in the next decade. Now, after two  months on the job, Duffy shares his vision in this edited Q&A.

What’s the main purpose of MarineGEO?

The overall goal really is a very ambitious one. In my mind, it’s to understand what’s at the heart of how marine ecosystems work…and that is biodiversity. The living web from microbes to large predators that are responsible for ecosystem processes like fish production and habitat creation. So basically what we want to do is map marine biodiversity and what it’s doing across the globe.

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Hunt for a Missing Nutrient: Part II

Wednesday, July 24th, 2013

By Katie Sinclair

Alyssa and Carey begin their search for key nutrients in a stream in the Choptank Watershed.

Alyssa and Carey begin their search for key nutrients in a stream in the Choptank Watershed.

The nutrient lab is still plagued by the mystery of the missing nitrogen. More nitrogen enters the watershed than exits it, and the question remains: Why?

How much nitrogen makes it to the bay can have huge impacts on the water quality and bay health. The Choptank watershed, in a farm-heavy area, has much lower levels of nitrogen in stream water than expected. As farmers add fertilizer to their crops, some nitrogen gets taken up by the plants, and the rest washes away into the watershed , eventually reaching the Chesapeake Bay. Of the nitrogen that is added as fertilizer, only 20 to 30 percent of it is accounted for.

In a narrow, slow-moving stream in the Choptank watershed, fondly nicknamed “Pizza Branch” (due to its proximity to a lone pizza joint puzzlingly located in this predominantly farming area), researchers working under Tom Jordan, Principal investigator of the nutrient lab at SERC, are using different methods to help determine what’s happening to the nitrogen. The project is a joint effort between SERC and Tom Fisher’s lab at the Horn Point Laboratory of the University of Maryland.

Researchers brave high heat, humidity, and voracious mosquitoes to take water samples, a process that can take all day. While taking water from a stream may seem like a straightforward undertaking, the true complexity comes through in the lab, where analysis of microscopic dissolved compounds can reveal the secrets of a watershed.

“It’s a fun challenge to go all over a stream and take samples and bring them back to the lab, to discover things you can’t see with your eyes,” said Jordan.
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