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Earthworms jeopardize orchid growth

Friday, March 29th, 2013

by Kristen Minogue

Lumbricus rubellus, a European earthworm that is now one of the most common in the eastern U.S.  More than 10,000 years ago, Pleistocene glaciers wiped out native earthworms. Today virtually all earthworms in the U.S. north of Pennsylvania are invasive. (Holger Casselmann)

Lumbricus rubellus, a European earthworm that is now one of the most common in the eastern U.S. More than 10,000 years ago, Pleistocene glaciers wiped out native earthworms. Today virtually all earthworms in the U.S. north of Pennsylvania are invasive. (Holger Casselmann)

Most gardeners consider the sight of an earthworm writhing in the dirt a good omen. The slimy invertebrates chew up and churn up the soil, making it easier for vegetables and flowers to access nutrients.

But for wild orchids, they’re more of a menace. Earthworms could prevent roughly half a forest’s orchid seeds from even germinating, ecologists from Smithsonian Environmental Research Center and Johns Hopkins University discovered in a study published online this March in Annals of Botany Plants.

The small size of orchid seeds (they are barely the size of dust grains) makes them particularly vulnerable. As earthworms chew up forest litter, they ingest orchid seeds as well. When that happens, two things can keep the seeds from germinating: One, the process of passing through an earthworm’s gut can render them unviable. Or two, if the seeds survive ingestion, they can end up buried so deep that they can’t access the fungi they need to germinate and grow. As a general rule, deeper soils are much less likely to have those fungi.

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Milk before dinosaurs? The evolution of a household beverage

Monday, November 26th, 2012

by Kristen Minogue

Artist’s depiction of the prehistoric synapsid Varanodon agilis (left) under attack from an ancient amphibian. (Wikimedia Commons/Smokeybjb)

Milk—the white, calcium-rich liquid common to mammals and refrigerators across the globe—may have evolved long before the mammals that secrete it. It may have evolved even before dinosaurs. It’s an idea SERC lactation expert Olav Oftedal proposed a decade ago and is now gaining momentum among biologists who study the evolution of what we drink.

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Climate Change Stimulates Growth of Invasive “Super Weed”

Thursday, November 8th, 2012

by Kristen Minogue

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.

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Invaders escape persecution from parasites

Tuesday, February 7th, 2012

by Monaca Noble

Invasion was a godsend for the rough periwinkle snail, which managed to escape its flatworm parasites. (World Register of Marine Species)

Most organisms have several types of parasites associated with them. However, when species are introduced, they may lose some of their natural parasites through the invasion process. Or sometimes, parasites that survive the journey don’t do very well in the new environment. In essence invasion acts as a filter limiting the number of parasites that are transported and introduced. In science this process is called the parasite escape hypothesis.

Take the common cat parasite Toxoplasma gondii. T. gondii‘s complex two-host life cycle makes it difficult for it to adapt to new places. The parasite has two phases, a sexual phase and an asexual phase. The sexual phase can only take place in the cat (primary host), but the asexual phase can occur in several mammal species (secondary host) including cats, mice, humans, and birds. Because the parasite must infect a cat to reproduce and survive, its preferred secondary host is a mouse. If a mouse infected with T. gondii were introduced into an area with no cats, the parasite would not be able to survive.
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Toughest Shellfish in the Sea?

Tuesday, January 24th, 2012

by Kristen Minogue

Blue mussels (Credit: Meriseal)

Some species can survive just about anywhere. Take blue mussels, a group of shellfish whose habitat stretches from the Arctic to the Mediterranean. Over the last several decades, biologists have thrown all kinds of tests at them – heat, cold, saltwater, freshwater, low oxygen. They’ve even tried drying them out. Almost nothing fazes these animals. For invasion scientists trying to figure out how far they could spread, that’s a scary prospect.
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Snowmageddon vs. Caribbean Creep

Monday, January 9th, 2012

by Monaca Noble

SERC's Green Village during Snowmageddon February 2010 (Stephen Sanford)

Remember Snowmageddon 2010, the east coast storms that dumped up to three feet of snow over the mid-Atlantic? The February snowstorm was the largest in the region in nearly 90 years, resulting in the heaviest snowfall on record for Delaware (26.5 inches) and the third heaviest snowfall in Baltimore (24.8 inches). The storm made a big impression on Dr. João Canning-Clode and other scientists at the Smithsonian Environmental Research Center, who began to wonder if the storm, and the December/January cold snap that preceded it, would lead to the deaths and potential disappearance of marine invaders from southern climates.
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How Plants (Occasionally) Escape the Food Chain

Friday, December 23rd, 2011

by Kristen Minogue

Leaf shredded by insects. Credit: Marina LaForgia

It’s a trick worthy of any spy thriller: to elude an enemy, hide among something it won’t notice. Or, to be extra safe, something it finds incredibly disgusting. It turns out the same strategy can work for plants that don’t want to get eaten. Sometimes.

For the last seven months, intern Marina LaForgia has kept tabs on tree saplings in more than a dozen different environments and watched the game of ecological survival play out. As she tracked their progress, she searched for an answer to a deceptively simple question: Is diversity good for plants? When it comes to the food chain, will hungry herbivores pass over tasty plants if they’re surrounded by less palatable ones?
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Why We Like Science

Friday, November 4th, 2011

Above: One perk of student research at SERC. Photo courtesy of the Phytoplankton Lab

It’s impossible to work here without some compulsion to understand the natural world – whether it’s colonial tunicates that bear a creepy resemblance to the Borg or endangered orchids that need microscopic fungi to survive. So when Smithsonian Magazine launched a “Why I Like Science” series on their blog Surprising Science, we took full advantage of the opportunity to share our enthusiasm. Here’s how four staff responded when asked why science is cool.

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Hurricanes, Snakeheads and Dead Zones: What 2011 Weather Meant for the Chesapeake

Wednesday, October 5th, 2011

by Kristen Minogue

Credit: NOAA Photo Library

Let’s face it, the East Coast has had an incredibly bizarre year. In 2011 so far, we’ve seen the coldest January on record, the hottest month on record (July), a hurricane, a tropical storm and an earthquake (we’re not even going to touch the last one – we’ll leave that to our colleagues at Natural History). And to top it off, August and September drenched us with uncharacteristically high rainfall. While SERC tends to focus on the long-term picture rather than brief snapshots, this year has prompted more than a few raised eyebrows among our scientists. What does it mean for the environment? What does it mean for Chesapeake Bay? And can any of it be linked to climate change?

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The Satellite That Could Save the Coasts

Friday, September 16th, 2011

by Kristen Minogue

On a hot afternoon in July, a team of researchers sailing down Chesapeake Bay stumbled across a cluster of striped bass floating in the water. About a dozen of the iridescent black and silver fish bobbed at the surface near the ship’s bow. All of them were dead.

Scientists prepare to measure how light interacts with particles in the Bay. Credit: Carlos DelCastillo

The fish kill came out of a low-oxygen zone near Annapolis, just one symptom of the Bay’s declining health. Overflows of nutrients from farms and cities have fueled massive growths of algae that cut off light and oxygen to the Bay’s lower levels.

“There was a very quiet moment between everybody on the boat,” recalled Vienna Saccomanno, one of the Smithsonian research interns aboard when it was discovered. “You kind of knew what everyone was thinking, feeling empowered to continue with this research and hopefully contribute to prevention of this in our water system.”

The scientists on board weren’t there simply to document the Bay’s many ailments, however. They had joined the 10-day cruise to pave the way for a much larger goal: a geostationary satellite that could provide constant, detailed coverage of coastal health.
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