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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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Methylmercury Microbes More Widespread Than Realized

Thursday, September 12th, 2013
New places scientists discovered can contain the microbes--Archaea and Bacteria--that create the dangerous neurotoxin methylmercury. (SERC & ORNL)

New places scientists discovered can contain the microbes–Archaea and Bacteria–that create the dangerous neurotoxin methylmercury. (SERC & ORNL)

Microbes that live in rice paddies, northern peat lands and beyond are among the several types of bacteria researchers at the Smithsonian Environmental Research Center and Oak Ridge National Laboratory have just learned can generate highly toxic methylmercury.

This finding, published Wednesday in Environmental Science & Technology, explains why methylated mercury, a neurotoxin, is produced in areas with no previously identified mercury-methylating bacteria. Methylmercury—the most dangerous form of mercury—damages the brain and immune system and is especially harmful for developing embryos. Certain bacteria transform inorganic mercury from pollution into toxic methylmercury.

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Franken Phrag: Tales of a Super Invader

Thursday, August 29th, 2013

By Katie Sinclair

These chambers at Kirkpatrick marsh allow the amount of CO2 and nitrogen to be manipulated, allowing researchers to understand how climate change will affect the growth of Phragmites.

These chambers at Kirkpatrick Marsh allow the amount of CO2 and nitrogen to be manipulated, allowing researchers to understand how climate change will affect the growth of Phragmites.

An invasive reed from Europe is conquering marsh habitat throughout the Chesapeake, displacing native marsh grasses and drastically changing the face of the wetlands. Phragmites australis, a “jack and master” plant  grows to nearly 10 feet tall and is adept at extracting nutrients from the soil, outcompeting native Phragmites genotypes. Climate change could increase the spread of this invasive plant. But other human activities, such as development, shoreline hardening and agriculture, could also determine the spread and range of Phragmites.

Climate Change Spurs Phragmites Growth

Rachel Hager, who interned with the Biogeochemistry lab, wanted to see if human activities were giving Phragmites even more of a competitive edge. Excess nitrogen from agriculture and industry, as well as increased CO2 levels, could increase Phragmites growth. Working in the Global Change Research Wetland (GCReW), she tracked the growth of  Phragmites under conditions that had more CO2 added, more nitrogen added, and both CO2 and nitrogen added.  She found that CO2 and nitrogen led to increased Phragmites growth, and plots with both CO2 and nitrogen grew the most.

Increased growth is only part of the story, however. Rachel wanted to see if taller Phragmites would inhibit other plants’ access to light. She analyzed leaf length, number, thickness and canopy cover to see if Phragmites exposed to additional CO2 and nitrogen were better at blocking light from their competitors. She found that Phragmites exposed to more CO2 and nitrogen had more, thicker and longer leaves, but their canopy cover was the same as control Phragmites plots. Thicker, longer leaves could lead to a longer leaf lifespan and more leaf litter, however, which could still block other plant’s access to light. Rachel hopes to see further research done on the amount of light that makes it through a Phragmites canopy.
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Sonar Reveals Underwater World

Friday, August 16th, 2013

By Katie Sinclair

A short DIDSON clip of a cownose ray swimming near the SERC dock

One of the biggest challenges of studying life in the Chesapeake Bay is poor visibility. In the water, you literally can’t see your hand in front of your face. So how do you see what’s going on under the water? Sampling with nets can give us a pretty good picture, but if you want to observe what’s happening at a specific moment you need to use another approach.

The Fish and Invertebrate Ecology Lab is using Dual-frequency Identification Sonar (DIDSON) to see what their eyes can’t. The DIDSON uses sound to sketch a picture of the environment much like a fish-finder or depth-finder on a boat. When sound hits an object in the water or the bottom, it bounces back. The result is video footage that can be downloaded and later analyzed. The resolution of the image is pretty impressive, considering it’s the product of sound waves. Many species can be identified by their distinct shapes and movement patterns, and their sizes can be estimated. DIDSON was first developed for the military to locate enemy swimmers , but is now being used as a handy tool by anyone who needs to see in murky waters.

River Herring

A still of a river herring (center) swimming past DIDSON

A still of a river herring (center) swimming past DIDSON

The Fish and Invertebrate Lab started using DIDSON with the goal of better understanding the size of river herring populations in Chesapeake Bay. Funded jointly by the National Fish and Wildlife Foundation and the Smithsonian Institution, the project aims to generate accurate population counts of river herring in the Choptank and Nanticoke Rivers. Once a species that supported a major fishery on the Atlantic coast, river herring (actually two species known as alewife and blueback herring) have declined dramatically over the past 10 years. In order to figure out the best way to conserve and manage these populations, the first step is to figure out how many herring are out there. The murky waters and large run sizes make it nearly impossible to get an accurate visual count. Other methods, such as electrofishing and looking at icthyoplankton (fish eggs and larvae) can potentially work as counting methods, but first it must be established how accurate they really are. By deploying the DIDSON during the spring herring runs, footage of the runs can be recorded and the number of fish counted. DIDSON also allows fish to be recorded for several months straight without requiring someone to be out in the field sampling all day and night.
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DNA Barcodes Identify Chesapeake Species

Friday, July 19th, 2013

By Katie Sinclair

Researchers on a jon boat in the middle of the Patuxent River were very excited to find a rainwater killifish in their crab tow. While not the juvenile crabs that the scientists were looking for, the inch-long rainwater killifish was an intriguing find: It was yet another species that could be “barcoded.”

(stock photo)

(stock photo)

Barcoding is another technique to answer the age-old question of what exactly lives in the Chesapeake Bay. By using trawls, seines and a fish weir, researchers at the Smithsonian Environmental Research Center (SERC) have a pretty good idea of what swims in our rivers and bays. But new DNA technology could give an even clearer picture on what species are present, as well as their role in the estuarine ecosystem.
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