Ecology

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Q&A: Katrina Lohan, Marine Parasite Hunter

Friday, June 23rd, 2017

by Kristen Minogue

Katrina Lohan hiking in a forest

Katrina Lohan in New Zealand’s Abel Tasman National Park. (Credit: Chris Lohan)

Weird truth: There are more parasites on Earth than non-parasites. Katrina Lohan would know, having spent over a decade studying them. After five years with the Smithsonian Environmental Research Center’s Marine Invasions Lab, Lohan is now in charge of launching the center’s new Marine Disease Ecology Lab. In this Q&A, meet some of the weirdest parasites she’s encountered and learn how DNA is helping her unlock their secrets.

This is the second of three profiles about the young scientists heading SERC’s newest labs. Edited for brevity and clarity.

What do you find most fascinating about parasites?

I really like it when stories are complicated. And adding parasites certainly complicates any story. But I’m also intrigued by the David and Goliath aspect of it, that parasites are super small, [often] overlooked, and most people don’t even think about them in terms of what role they play in ecosystems or what they could possibly be doing. Most people would sort of shrug off—oh, they’re probably not really that important.  And yet, they’re extremely important. The more we learn about parasites, the more we realize that they control their hosts. They can actually completely change the behavior of their hosts. Click to continue »

The Environmental Cost of Shoreline Hardening

Wednesday, June 21st, 2017

New study shows hardened shorelines may mean fewer fish and crustaceans. 

by Ryan Greene

A split image with a wooden bulkhead on the left and a rocky riprap revetment on the right.

A new SERC study shows that both bulkheads (left) and riprap revetment (right) are associated with lower abundance of several species of fish and crustaceans in the Chesapeake Bay and the Delaware Coastal Bays. Credit: SERC

For decades, ecologists have suspected that hardened shorelines may impact the abundance fish, crabs, and other aquatic life. But now they have evidence that local effects of shoreline hardening add up to affect entire ecosystems. A new study by scientists at the Smithsonian Environmental Research Center (SERC) shows that more shoreline hardening means fewer fish and crustaceans in our waters.

Given the predictions for the coming years (i.e. rising seas and more of us living on the coast), this finding is a cause for concern. Many people will likely try to protect their land from flooding and erosion by armoring their shorelines with vertical retaining walls (bulkheads) or large rocks (riprap revetment). But as SERC researchers found in their new paper, published in Estuaries and Coasts, the impact of these hardened shorelines adds up.

Lead author and former SERC postdoc Matt Kornis likens shoreline hardening to littering. While each individual bit of trash isn’t a huge problem, the combined effect can be enormous. Kornis, now a biologist for the U.S. Fish & Wildlife Service, says the same is true of shoreline hardening. Each individual bulkhead or riprap revetment may not be catastrophic, but cumulatively they can contribute to shrunken populations of ecologically—and economically—important species like the blue crab.

“Shoreline hardening can cause loss of habitats important for young fish, like wetlands and submerged vegetation,” Kornis says. “That may be one reason we observed low abundance of many species in estuaries with a high proportion of hardened shoreline.” Click to continue »

Humans Are Short and Trees Can’t Talk

Tuesday, June 20th, 2017

That’s why Uzay Sezen carries a crossbow and liquid nitrogen into the forest with him.

by Ryan Greene

Intern Alex Koure (left) and postdoctoral researcher Uzay Sezen (right) are using a crossbow to get leaf samples from hard-to-reach branches. A fishing line attached to the arrows helps them shake down leaves from the canopy. Credit: Ryan Greene/SERC

Intern Alex Koure (left) and postdoctoral researcher Uzay Sezen (right) are using a crossbow to get leaf samples from hard-to-reach branches. A fishing line attached to the arrows helps them shake down leaves from the canopy. Credit: Ryan Greene/SERC

Uzay Sezen is a new postdoc at the Smithsonian Environmental Research Center (SERC), and he’s on the hunt for good data. Literally.

A researcher holds a crossbow and metal container of liquid nitrogen in a forest.

Uzay Sezen with his crossbow and liquid nitrogen in Harvard Forest. Credit: SERC

With senior scientist Sean McMahon and other members of the Quantitative Ecology Lab, Sezen is embarking on a multiyear study which aims to unveil the genetic patterns of tree growth. Their mission: Find out if tree species present at both SERC and Harvard Forest grow in the same way, and whether there are particular genes they express when they grow. Not only will this help us understand how trees respond to day-to-day changes in sunshine, temperature, and rainfall, but it may provide insight into how forests will react (and already are reacting) to global factors like climate change.

Since about 2009, scientists at SERC have been using metal bands called dendrometers to measure how trees grow (within a hundredth of millimeter!) over years, seasons, weeks, and even days. According to SERC technician Jessica Shue, combining these physical measurements with Sezen’s genetic analysis may help reveal what makes some trees in the forest winners and others losers.

“Now that we can look at the genetics, we can look at a much finer scale at what’s causing some trees to be dominant in the canopy, and others of the same species [to be] stuck in the understory,” she says.

How, though, do you ask a tree which genes it’s using?

Click to continue »

Q&A: Kim La Pierre, Ecosystem Conservation Ecologist

Friday, June 16th, 2017

by Kristen Minogue

Close-up of Kim La Pierre in prairie

Kim La Pierre in Konza Prairie, Kansas, home to one of the first Long-Term Ecological Research (LTER) programs. (Credit: Arjun Potter)

Kim La Pierre does big-picture ecology. The newest senior scientist at the Smithsonian Environmental Research Center, La Pierre is leading the center’s Ecosystem Conservation Lab. But while working on large-scale global experiments, she also delves into the microscopic world of bacteria. In this Q&A, discover how bacteria give certain plants an edge, and how she blends the very large and the very small.

This is the first of three profiles about the young scientists heading SERC’s newest labs. Edited for brevity and clarity.

You’ve done a great deal of work with legumes—plants in the bean and pea family. Can you talk about their weird relationship with rhizobial bacteria?

The [legume] plants and bacteria are in a mutualism where the plants fix carbon into sugar and give it to the bacteria, and the bacteria are able to take nitrogen from the atmosphere and give it to the plants. This is a source of nitrogen that no other plants have access to. Most plants have to take [nitrogen] up from the soil. Because of this mutualism, legumes can get nitrogen from another source, and that often makes them very successful in different, especially harsh environments….

It’s interesting to think about the different legume species, and how good they are at enforcing cooperation from the bacteria. Thinking about the bacteria as not only potentially being beneficial, but [also possibly] cheating the system—trying to take carbon from the plants and not give back as much nitrogen, especially under high soil nitrogen conditions. Click to continue »

Five Summer Activities That Can Spread Invasive Species

Thursday, June 15th, 2017
summerinvasives

Fishing, camping, and walking the dog can all have unintended consequences. (Credit: pixabay.com, 1,2,3. Used under Creative Commons CC0 license)

By Joe Dawson

Nothing seems to draw people outside like a beautiful summer weekend. A rain-free Saturday could mean taking the boat out on the water for some fishing or a family camping trip. Conservationists have found, however, that many summer activities carry the risk of spreading invasive species. A species gets the name “invasive” if it is not native to a location and causes environmental and economic damage. Here are five popular activities that can spread invaders–and tips for enjoying them safely: Click to continue »

Slime Nets and Other Invasive Parasites Unmasked, Thanks to DNA

Wednesday, May 31st, 2017

by Kristen Minogue

Zebra mussels in the Great Lakes, lionfish in the Atlantic and pythons in the Everglades: Large creatures like these generally draw the spotlight when talking about ways to combat invasive species. But for every visible invader, there are hundreds more too minuscule to see with the naked eye. These species often slip in unnoticed—and unregulated—in the ballast water of large ships.

“There have been reports of parasites being transmitted in ballast water, but most of those have been things that we can easily see,” said Katrina Lohan, a marine biologist with the Smithsonian Environmental Research Center. “So, the parasites that are hanging off the outside of fish.”

Lohan has made it her mission to track the invisible invaders. Click to continue »

Surprising Tree Emissions Show Forests Consume Less Methane Than Thought

Tuesday, May 9th, 2017

by Ryan Greene

White chambers attached to tree trunks. Multi-colored tubes run from the chambers to a black box in the undergrowth.

Methane flux chambers keep track of how much methane a tree trunk releases or consumes. Credit: Pat Megonigal/SERC

Rainbow-colored tubes snake through the undergrowth. White acrylic chambers sit mounted to tree trunks like giant bleached snails. At first glance, it’s not quite clear what the heck is going on. Cryptic as it may seem, these tubes and chambers are the key to a recent study showing that trees in upland forests are capable of emitting the planet-warming greenhouse gas, methane.

Scientists have long considered upland forests to be methane sinks due to the presence of methane-hungry microbes called methanotrophs in their soils. But new research by Pat Megonigal, an ecosystem ecologist who heads up the Biogeochemistry Lab at the Smithsonian Environmental Research Center (SERC), and Scott Pitz, a graduate student from Johns Hopkins, has shown that when it comes to upland forest methane cycling, soil isn’t the only game in town. Trees and their emissions are part of the equation too.

In a recently published study in New Phytologist, Megonigal and Pitz found that trees in upland forests are actually capable of emitting methane through their trunks. This means that some of the methane absorbed by methanotrophs in the forest soils may be offset by tree emissions.

Why, though, does any of this even matter?

When researchers think about global climate change, they need to think about heat-trapping greenhouse gases like carbon dioxide (CO2) and methane (CH4). Specifically, they’ve got to track these gases to see where they’re coming from (their sources) and where they’re getting stored (their sinks). Carbon dioxide receives much of the spotlight (and rightfully so, given its enormous impact on the global climate), but it’s also critical to keep an eye on methane. Although methane stays in the atmosphere for far less time than carbon dioxide, it’s capable of trapping up to 45 times more heat. In other words, methane is a big deal. If temperate forests are consuming less of it than we thought, as Megonigal and Pitz’s research suggests, that could be a big deal too. Click to continue »

Volunteer Spotlight: Lenore Naranjo

Thursday, January 26th, 2017
Lenore and Dan in the SERC education center.

Lenore Naranjo celebrates 10 years of volunteer, with SERC volunteer coordinator Dan Gustafson. (SERC)

by Sara Richmond, communications volunteer

In 2016, nearly 5,000 students and other visitors learned about the Chesapeake Bay ecosystem firsthand through education programs at the Smithsonian Environmental Research Center (SERC). They ventured on hikes and canoe trips, hauled in fish and invertebrates with seining nets, and studied the anatomy of blue crabs. SERC’s education programs are possible through the help of dozens of volunteers who lead field trips and assist behind the scenes. In the coming months, we’ll highlight the work of some of these volunteers in the SERC newsletter and on our blog.

Lenore Naranjo has been volunteering with SERC for over 13 years. After starting as a volunteer in SERC’s canopy labs, she began working with the education program, leading field study groups that give children a hands-on approach to a variety of marine habitats.

“We set up baskets with oysters, and they stay sitting on the bottom of the river through spring, summer, and fall, where they act as a habitat for fish and small critters,” she explains. During field trips, she pulls the baskets from the river bed and sets them in a tray of water so children can explore the baskets’ contents. “Some kids are very hesitant and don’t want to put their hands in something unfamiliar. But then they watch their friends who aren’t hesitant, and the next thing you know, they’re in there too, pulling out fish and crabs.”

Click to continue »

Natural Gas Trade Opens Door for Invasive Species

Friday, January 20th, 2017

by Kristen Minogue

Two scientists look at water sample on ship.

Marine biologists Kim Holzer (right) and Jenny Carney sample ballast water from a cargo ship in Virginia’s James River.
(Kim Holzer)

The U.S. is on the brink of a natural gas boom—but that could expose its shores to more invasive species, Smithsonian marine biologists report in a new study published this winter.

Over the last decade, U.S. natural gas imports have dropped as the country tapped into its own resources. Now, thanks to new technology that makes it easier to extract and store natural gas, it’s poised to be the world’s third largest exporter of liquefied natural gas by 2020.

“We’ve hit an inflection point,” said Kim Holzer, lead author and biologist at the Smithsonian Environmental Research Center (SERC). Exports haven’t yet reached historical import highs, but they are climbing.

Click to continue »

Ten Reasons We’re Earth Optimists After 2016

Friday, January 13th, 2017
Dawn Miller in forest

Ecologist Dawn Miller surveys trees in a SERC forest. (SERC)

by Kristen Minogue

The Smithsonian has a new resolution for 2017: Earth Optimism. This is the year the Smithsonian is celebrating environmental success stories, and shifting the focus to how we can fight battles to save species and preserve our planet—and win. Despite breaking a wide swath of climate records, 2016 gave us reasons for optimism as well. In our 2016 Year in Review, we’ve pulled out the most encouraging stories and discoveries at the Smithsonian Environmental Research Center from the previous year. Here are the top 10 that make us hopeful about the planet’s future:

Click to continue »