There is a certain art to the deployment of a crab tow. This brown metal and net contraption, about three feet long and a foot wide, scrapes over the bottom in search of juvenile blue crabs. Fitting three people, two coolers, a selection of buckets and bins and the tow in a 16-foot jon boat is something akin to a giant game of Tetris. Successfully launching and recovering the crab tow without smacking anyone in the face or knocking anything overboard requires practiced choreography and grace.
With a one-two-three, the metal tow hits the water with a splash. After 300 feet, lab tech Paige Roberts gracefully maneuvers the jon boat backwards and forwards to retrieve the tow. Paige captains the jon boat a bit like a fighter pilot—precision is required to coax the unwieldy boat around shoals, patches of sea grass and oblivious jetskiers. Click to continue »
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. Click to continue »
If you take a stroll out along the green grated catwalk that lies several feet above the muddy marsh ground at SERC, the first thing you’ll notice is strange white structures dotting the lush landscape. No, the aliens haven’t landed. These white enclosures make up several experiments at SERC. The goal of each experiment is to determine how a changing climate will affect this valuable marsh habitat, which stores carbon, has high primary productivity, and provides homes for fish, crustaceans, insects,and more.
The SERC marsh. Under each capsule, conditions are set to mimic the CO2 concentration expected in 2100. ( Thomas Mozdzer)
Carbon and Nitrogen: Elements of Growth
Since 1987, SERC scientists have been pumping CO2 into these plastic chambers to simulate the marsh a century from now—a marsh in the grip of climate change. Inside these miniature time capsules, marsh plants grow with 350 parts per million more CO2 than is in the atmosphere today, levels scientists expect to see by the year 2100.As marsh plants grow, they take in CO2 from the air. This carbon can either end up sequestered in the soil or released back into the ecosystem through decomposition. The CO2 addition experiments conducted at SERC are the longest-running in the world.
Besides carbon, marshes also rely on nitrogen, an element necessary for the creation of proteins. Due to runoff from fertilizers, nitrogen levels are also increasing in estuaries like the Cheasapeake Bay. As the concentration of both CO2 and nitrogen increases, scientists at SERC are asking important questions about how the structure of the marsh will be affected, including how it will change the plant communities that will grow there.
European green crabs are eating and marching their way up the west coast.
One of nine marine invertebrates to make the list of the world’s 100 worst invasive species, they’ve had major economic impacts on shellfisheries in New England, including blue mussels, the Virginia oyster (Crassostrea virginica) and Bay scallops. Impacts are mounting on the west coast too, where losses to bivalve fisheries (Pacific littleneck, Japanese littleneck, softshell clams and blue mussels) are projected to reach $20,000-60,000 per year. Ecologically, their impact has been no less severe, as they prey on and compete with other crabs, bivalves, gastropods like snails and slugs, and many other invertebrates.
European Green Crab Carcinus maenas. Green crabs have visited every continent but Antarctica. They’ve colonized parts of the Americas from Alaska to the southern tip of Argentina. (Arthro)
Green crabs are exceptional world travelers, making it from their native region along the European Coast to six major regions of the world, including the Northwest Atlantic (Maryland to Newfoundland), the Northeast Pacific (California to British Columbia), Patagonia, South Africa, Japan and Australia. Their mode of transport may vary, but evidence suggests they’ve been transported with the live-bait trade and in ships’ ballast water.
Green crabs have been on the East Coast of the US for about 200 years, according the NEMESIS database. They made their first appearance near New Jersey in 1817. From there they moved north, reaching the Bay of Fundy, Nova Scotia in 1953, the Gulf of St. Lawrence by 1994, and finally, Placentia Bay, Newfoundland in 2007. Their southward expansion stopped at the Chesapeake Bay; possibly they couldn’t compete with the blue crab (Callinectes sapidus).
(Video: Woolly aphids dancing on a beech tree at the Smithsonian Environmental Research Center. Credit: Tyler Bell/SERC)
Any creature with the word “blight” in its name can hardly escape being labeled a pest. Beech blight aphids are no exception. Like mosquitoes of the tree world, aphids have a vampirical tendency to suck the sap out of trees they colonize, and–while they do not usually kill the entire tree–they can take out some of its smaller branches.
But like all names, pest is a matter of perspective. And aphids have evolved some redeeming qualities as well. Not least is their peculiar ability to dance in the face of danger.
This quirk has earned them a more endearing nickname: the boogie-woogie aphid. Whenever aphids feel threatened, they raise their rear ends and sway, sometimes hundreds or thousands at a time. Up close their abdomens resemble white feather dusters. It’s a defensive dance meant to ward off predators. But in a flip of the natural order, it’s generally the children–not the adults–who do the defending. If larger creatures like moth larvae get too close, young aphid nymphs spin around and sting the predators with the same stylet mouth pieces they use to drain the beech branches.
Honeydew: "aphid poo", excreted after aphids digest tree sap. (Susan Cook-Patton)
Sooty Mold: Fungi that colonize honeydew for its sugar, turning it black. (Kristen Minogue)
And while aphids mean death for small tree branches, for other creatures they give life. After drinking the tree’s sap, aphids excrete it as sweet-smelling honeydew. Ants and other insects flock to it for the nutritious sugar. So do fungi, which rapidly colonize the honeydew and turn it into black sooty mold. Unlike the aphids, the fungi do not penetrate the tree’s surface. Some researchers doubt whether beech blight aphids have any serious effect on the tree’s health, other than producing “vast amounts of aesthetically displeasing sooty mold.” Which would make the name beech blight aphid, though technically accurate, a bit unjust.
As one reader pointed out, “woolly aphid” and “beech blight aphid” do not mean the same thing. “Beech blight aphid” refers to the species Grylloprociphilus imbricator. “Woolly aphid” is a broader name that includes beech blight aphids and other aphids that secrete waxy threads to resemble wool. The video above shows woolly aphids that are probably beech blight aphids.
A white pickup truck prepares to carry Tuck to a nearby farm. Tuck, a bronze heritage turkey, was discovered wandering alone on SERC property last week. His friendliness around people made staff suspect he was an abandoned pet. (Marvin Dorsey)
The following is a true story about how not to break up with a pet. Tuck (left) is a domestic turkey who found himself alone in the woods, presumably abandoned by his keeper and half-starved when SERC security discovered him last Thursday.
It’s not uncommon to hear about pets left on the sides of streets or in vacant houses when their owners, for one reason or another, decide they’re no longer able to keep them. These stories usually involve dogs, cats or the occasional boa constrictor. In their defense, some owners may believe their pets will be able to fend for themselves in the wild. The owner who dropped off Tuck may have been operating under a similar assumption. Unfortunately the assumption is almost always false.
Katrina Lohan packs rubber gloves, Ziploc bags and other field essentials for a science expedition. (Kristy Hill)
Katrina and I leave for Panama City in next week, so we’re gathering supplies and mapping out our game plan. We’re stoked to get this project rolling—beautiful surroundings and mandatory snorkeling in the tropics won’t be such bad work!
The critters we’re looking for grow on coral reefs, mangrove roots, sponges, pilings, sea walls and rocks. Our goal is to collect at least 50 to 60 oysters of three or four different species from three sites along the Caribbean coast. At each site, we’ll take water quality measurements such as salinity, temperature and oxygen content. We’ll take additional notes about the oysters’ habitats, such as their distance from the shore, the depth of the water, their proximity to ports or marinas, etc. We want to obtain as much data (or information) as possible so we can better understand the environment where the oysters and their potential parasites live.
by Katrina Lohan, Smithsonian Environmental Research Center and National Zoo postdoc
Many people cringe when they hear the word “parasite”—not Katrina Lohan and Kristy Hill. Combined, the two of us have spent 12 years conducting research on parasites that infect bivalves (oysters, clams, mussels, etc.), crustaceans (crabs, shrimps, lobsters, etc.), and songbirds. We are both passionate about studying marine parasites and want to better understand how parasitism impacts marine animals. For the next few months, we’ll be searching for these parasites in waters all along the east coast of North America, from Maryland to Panama.
Katrina Lohan (right) and Kristy Hill are preparing to scour the coasts of North America for marine parasites infecting oysters and other shellfish. (Kim Holzer/SERC)
Tom Mozdzer explores a patch of invasive Phragmites in SERC's global change wetland.
Is it better to be a jack of all trades or a master of some? In the plant world, it’s possible to do both–and that could make a huge difference in deciding which plants dominate under climate change. This holds especially true for one: the invasive reed Phragmites australis. Its ability to alter its anatomy enables it to grow well in just about any environment, including one spiked with CO2 and nitrogen, SERC ecologists discovered in a study published Oct. 31.
Plants like this are called “jack-and-master” plants. Typically, the most competitive plants surpass their neighbors through one of two strategies. “Jack-of-all-trades” plants do moderately well under most scenarios. Their competitors will surpass them when conditions are good, but if the environment becomes stressful, the jack of all trades will grow better. “Master-of-some” plants do very well under only a few conditions, so if the environment shifts in their favor, they are certain to emerge victorious. But a few types—the jack-and-master plants—can use both tactics. And the invasive Phragmites is one of them.
Homestead House, called Woodlawn by its first residents in the early 1700s. (SERC)
On the western shore of Chesapeake Bay, less than a mile from the Rhode River, there is an old red house on an abandoned farm. Once, in the 18th century, it belonged to a thriving plantation. The hilled rows of tobacco have vanished, along with the slaves and field hands who planted them. But the scars on the landscape remain. The surrounding earth carries traces of how each of its inhabitants have used it, or abused it.
The house’s first inhabitants in the early 1700s called it Woodlawn. Today it is known simply as the Homestead House. The building and its surrounding farmland now sit within the Smithsonian Environmental Research Center. Instead of slaves and field hands, teams of volunteers are overturning the soil in search of clues about its past.
Archaeologist Jim Gibb began the excavation at SERC earlier in August. His volunteers come for a single afternoon, or several weeks. He isn’t terribly picky about long-term commitments. Gibb welcomes anyone who can handle a shovel and is at least ten years old (and even that rule is flexible). Under his guidance, they are piecing together the story of one household’s legacy on the land.
The team made one of their biggest discoveries just a few weeks into the project, when they uncovered a brick foundation sprinkled with household artifacts. One possibility is that it was a storage shed. Another, that it was someone’s home.
“If someone was living in that in the early 19th century, and we know where the owners were living, then we do the math,” Gibb said. “They have to be labor. And at that point, probably slave labor.”