Q&A: Ian Davidson, Aquatic Inquirer

Posted by KristenM on June 26th, 2017

by Joe Dawson

ICD at Cork Harbor

Ian Davidson in Cork, Ireland (Credit: Ian Davidson)

 Ian Davidson is continuing his work at SERC in a new role: as principal investigator of his own lab. From diving under massive cargo ships to studying an invasive organism ugly enough to be nicknamed ‘rock vomit,’ Ian Davidson looks at how human activities affect marine ecosystems. This includes the methods by which humans transfer marine life around the world (mainly shipping), the effects of coastal development on nearshore environments, and management and policy with regard to marine invasions and organisms.

This is the third of three profiles about the young scientists leading SERC’s newest labs. Edited for clarity and space.

How did you get interested in your area of study?

I grew up in Cobh (pronounced, “Cove”), a small harbor town on the south coast of Ireland, so I had plenty of time in rock pools when I was young. My mother grew up a stone’s throw from the shoreline, right in front of the main shipping channel there, so we were always keeping an eye on the to-and-fro of the port. My dad worked in a shipyard until it closed down too, so I suppose the ingredients were there to pursue a career that heavily featured marine biology and shipping! Click to continue »

 

Q&A: Katrina Lohan, Marine Parasite Hunter

Posted by KristenM on 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

Posted by KristenM on 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

Posted by KristenM on 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 »

 

Predicting the Future of Migrating Mangroves

Posted by KristenM on June 19th, 2017

By Joe Dawson

Gfp-mangrove-tree

A stand of mangrove trees in Florida (Credit: Yinan Chen under CC0/Public Domain license)

With their tall, arching roots reaching down like hands into the water, mangrove trees can look downright creepy. And yet they’re critical species for the environment—and humans—on five different continents: They can create their own islands, provide one-of-a-kind habitats for wetland creatures, and store carbon like mad. They also protect shorelines from storms and tsunamis. Unfortunately, and perhaps unsurprisingly, humans are destroying them at a rate that may doom them within a century.

Aquaculture, urban development, tourism, and agriculture are threatening mangrove habitats around the world. Like many natural ecosystems, they are being cut down and destroyed to make way for human endeavors, and human pollution is taking its toll on their growth at the same time. But even as their total acreage decreases, they’re gaining ground in some places. Climate change is causing mangroves to move beyond their tropical habitats and take over neighboring salt marshes, but not always predictably. In North America and South Africa, they are moving toward the poles, while in Australia they are expanding along an east-west axis. All these disappearances and migrations present a riddle for scientists—but one they will need to solve to prevent habitat loss and prepare for a warmer future. Click to continue »

 

Q&A: Kim La Pierre, Ecosystem Conservation Ecologist

Posted by KristenM on 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

Posted by KristenM on 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

Posted by KristenM on 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 »

 

Alaskan Alders Shape Fates of Wetlands, Streams—And Salmon

Posted by KristenM on May 22nd, 2017

by Joe Dawson

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Dennis Whigham samples horsetail plants in an Alaskan headwater stream. Credit: Ryan King/Baylor University

In Alaska, fish mean serious money. For fishermen, landowners, and the government, learning all they can about the lives of salmon could pay off in future fish harvests. There’s a lot to learn, down to how a single type of tree impacts their habitat.

The story of those habitats and trees, the alders, has been explored by SERC senior scientist Dennis Whigham and colleagues in a new study published May in Science of the Total Environment. The researchers have been studying interactions between watersheds and headwater streams for almost two decades.

Alders are most recognizable for their egg-shaped, serrated leaves. Their bark is used for tanning leather, and their wood to smoke salmon and make Fender guitars. But alders also have an outsized effect on their natural environment, transforming the chemistry and structure of wetlands and streams nearby. Bacteria in alder roots make nitrogen, an important plant nutrient, available in places where it is otherwise scarce. This can send ripple effects through entire ecosystems. In another plot twist, scientists also expect alder trees to expand northward, stirred by warmer temperatures and higher carbon dioxide from climate change. Whigham’s findings highlight the interconnectedness of wetland ecosystems, waterways, and the valuable fish that call Alaska home. Click to continue »

 

Surprising Tree Emissions Show Forests Consume Less Methane Than Thought

Posted by KristenM on 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 »