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From the Field: Mangroves, Salt Marshes and Hungry Insects

Wednesday, September 11th, 2013

by Lily Durkee

Spotted-winged grasshopper, one of two insect herbivores the team tested to see if they would eat mangrove leaves.
(Alex Forde/UMD)

After spending five weeks working indoors as a research intern at the University of Maryland in College Park, walking out into the salt marsh at the Guana Tolemato Matanzas (GTM) Reserve in Florida was a welcome change of scenery. The sky was a crystal clear blue, egrets and herons soared overhead, and crabs scuttled haphazardly on the sand as we waded into the cordgrass, ready for a hard week of field work.

My mentor, Alex Forde, and I were there conducting experiments for his dissertation and for my internship project. This whole summer we had been studying plant resistance to herbivores, so we were excited to document interactions between leaf-eating insects and black mangrove trees (Avicennia germinans) in Northern Florida salt marshes.

Over the past several decades, climate change has allowed black mangroves to move north along the Florida coastline. As a result, they are invading salt marshes and coming into contact with novel herbivores that are not common in mangrove forests further south. Depending on the behavior and food preferences of marsh herbivores, these species may affect how fast mangroves spread into salt marshes and where the trees are able to survive within marsh landscapes. Therefore, we wanted to test (1) whether salt marsh herbivores will eat mangrove leaves when marsh plants are also available, and (2) if salt marsh herbivores show a preference for leaves of different ages or for trees growing in different habitats.

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Posted in Climate Change, Ecology, Invasive Species, Mangrove Tracking: Letters from the Field | 2 Responses »

Trees, Poison Ivy and Climate Change

Monday, August 12th, 2013

By Katie Sinclair

Intern Hope Zabronsky measures the diameter of a tree to see how logging affects biomass regeneration

Summer is almost over, which means intern season is coming to a close. Over 20 interns from universities across the United States have spent their summers here at SERC, studying everything from phytoplankton to Phragmites. Several interns chose to take on the challenge of climate change, exploring how trees will affect rising levels of greenhouse gases.

Mysterious Methane

Although methane emissions worldwide are much lower than CO2 emissions, a little methane goes a long way: Methane is 25 times as powerful a greenhouse gas as CO2. While we have an idea of what the sources of methane are, researchers face difficulties when trying to model methane emissions. The biggest discrepancy is between “top-down” and “bottom-up” models. Top-down approaches use satellite imagery to track the amount of methane in the atmosphere, while bottom-up methods look at the amount of methane emitted from the soil.
The Biogeochemistry Lab wants to see if methane is coming from sources other than the soil. Marsh grasses are known to emit methane, but no research has yet been done on trees. Figuring out if and how much methane is emitted can help determine whether methane projections are accurate. The Biogeochemistry Lab has set up two experimental sites to study methane, and is working on establishing a third.

Intern Kyle King worked on methane emissions this summer. He attached airtight chambers to trees, and measured the gas concentrations at different heights along the tree. He found that trees did emit methane, in some cases more than microbes in the soil. Methane emissions were highest near the roots and less at higher trunk heights. He also found that larger trees emitted much more methane than smaller ones.

The exact mechanism of how trees release methane is not yet understood. Two possibilities are methane diffusing out of the water that is taken in by the plants’ roots, or microbes inside the tree producing methane. But whatever the cause, understanding where methane comes from will be vital when trying to predict the impact of climate change.
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Posted in Climate Change, Ecology, Interns | Comments Off on Trees, Poison Ivy and Climate Change

From the Field: Out of the Mangrove and into the Marsh

Monday, July 22nd, 2013

by Megan Riley

University of South Carolina Ph.D. student; Smithsonian Marine Station visiting scientist

Mangrove tree crabs crowd onto a dwarf red mangrove, in a hybrid mangrove-marsh region. (Megan Riley)

Home for most species largely depends on climate: temperature, light and rainfall. With changes in global climate trends, many plants and animals are expanding their geographic limits poleward. However, not all species in a community respond to these changes in the same way.

Organisms often differ in the type and timing of their responses to environmental changes. Sometimes, animals expand more quickly than the habitats they’re used to. When this happens, these organisms are forced to colonize unfamiliar habitats where they often face numerous challenges, like resource shortages and never-before-seen predators.

So how do these animals alter their behavior, resource use and reproductive strategy to succeed in their new habitats? I aim to explore just that question by studying the range expansion of the mangrove tree crab Aratus pisonii into salt marsh habitats.

Mangrove tree crab Aratus pisonii on a black mangrove tree. (Megan Riley)

Mangrove tree crabs are native to Florida and abundant throughout Floridian mangroves, where they are the dominant herbivores of fresh mangrove leaves. Like mangrove trees, they have slowly begun moving northward. But the crabs are moving faster than the mangroves—and they’ve begun to invade salt marsh territory. They can be found crowding onto isolated dwarf mangroves nestled amidst cord grass, as well as in salt marshes with no mangroves in sight!

How mangroves are taking over marshes

Because mangrove tree crabs in their native habitats rely heavily on mangroves for food and shelter, their habitat shift into salt marshes also causes a diet shift that can impact their growth, survival and reproduction. By focusing on the range expansion of mangrove tree crabs into salt marshes during my time at the Smithsonian Marine Station this summer, I hope to shed light on what exactly is enabling this species and countless others to successfully expand their range into new environments.

Posted in Climate Change, Ecology, Mangrove Tracking: Letters from the Field | 1 Response »

High CO2 Spurs Wetlands to Absorb More Carbon

Tuesday, July 16th, 2013

by Kristen Minogue

“Marsh of the Future.” Bert Drake built these chambers in 1987. Inside half of them, he raised CO2 to roughly 700 parts per million, a level we could reach before the end of the century. (Tom Mozdzer/SERC)

Under spiked carbon dioxide levels, wetland plants can absorb up to 32 percent more carbon than they do today, according to a 19-year study published in Global Change Biology from the Smithsonian Environmental Research Center. With atmospheric carbon dioxide passing 400 parts per million in May, there’s hope that wetlands could help soften the blow of climate change.

But that isn’t the shocking part for plant physiologist Bert Drake. The shocking part is that plants are absorbing the carbon in ways they didn’t expect.

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Posted in Climate Change, Ecology, Publications | 1 Response »

Marsh Rovers: Research at the SERC Marsh

Thursday, June 27th, 2013

By Katie Sinclair

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 treatment, conditions are set to mimic the CO2 concentration expected in 2100. (Credit: Thomas Mozdzer)

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.

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Posted in Climate Change, Ecology, Invasive Species, SERC Sites and Scenes | Comments Off on Marsh Rovers: Research at the SERC Marsh

From the Field: Sleepless Nights and Road Trips

Tuesday, June 25th, 2013

by Cora Johnston

When studying major ecological changes, like the movement of entire species or ecosystems, we often have to sample across large geographic areas. This means lots of road trips!

Taking a moment to reflect after a field day that started at midnight. (Cora Johnston)

Starting nearly two months ago, I began my own road trips along the coast to survey the larval crabs that are washing ashore in swarms. Crabs typically recruit (leave the open ocean as larvae to join adult populations in coastal habitats) in a few brief but frenzied weeks in late spring and early fall. Therefore, I’ve been busy hopping between sites to gather as much data as I can while the crabs are abundant. Unfortunately, this means that my schedule, like the crabs’, depends on moonlight and tides. I’ll wake up around midnight, drive until the wee hours of the morning, and then sample the incoming tides by moonlight until wrapping up and moving to my next site as the sun rises. I then load up a kayak and spend the day paddling around collecting larger crabs (though still far too tiny to eat) from deep in each habitat to compare to the larvae I find riding the currents at night.

I head off on these adventures wielding stacks of audiobooks, a hefty thermos and lots of pre-labeled jars and data sheets that ease the demands on a weary mind. I munch trail mix to battle the exhaustion and swim to soothe the bug bites. After a few weeks on this schedule, even I find it hard to believe that I will get up at midnight the very next week to start all over again. Luckily, what keeps me coming back is what got me out of bed to do these studies in the first place.

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Posted in Climate Change, Ecology, Invasive Species, Mangrove Tracking: Letters from the Field | 2 Responses »

From the Field: Insects Behind the Mangrove Invasion

Thursday, May 30th, 2013

by Mayda Nathan

Many insects visit black mangrove flowers, including bumblebees (left) and Pseudomyrmex ants (right). But which pollinators are the most important? (Mayda Nathan)

Introduced species have a bad—and sometimes well-earned—reputation. Brown tree snakes in Guam, mosquitoes in Hawaii, cheatgrass in the intermountain west, and many more invasive organisms have turned native ecosystems upside-down, changing fundamental ecosystem properties like species diversity, nutrient availability, and the size and shape of food webs. Biologists are hard at work learning how to tell when, where, and how a species becomes a successful invader and driver of ecosystem change. (See a recent post on how tricky this can be.)

But how can we make predictions about invaders that are…native?

In other words, what happens when an organism starts to spread out from its native range into adjacent territory—without hitchhiking along with humans? And why does this happen in the first place?

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Posted in Climate Change, Ecology, Invasive Species, Mangrove Tracking: Letters from the Field | 2 Responses »

Warm enough to snow? Climate Change and Blizzards

Wednesday, March 27th, 2013

by Kristen Minogue

SERC pond on the morning of March 25. The short-lived spring snowstorm dumped up to 6 inches throughout Maryland, but most of it melted within 24 hours. (Kristen Minogue)

If the massive snowstorms that pummeled the northeast this winter—and at least one downpour in spring—seem out of place in a warming world, climate scientists have a message: Don’t fret, it’s just physics.

For several years, scientists have anticipated a future of “less snow, more blizzards” in the winters ahead. The message may sound like a paradox. But for the planet, it boils down to one simple truth: Warm air holds more moisture than cold air.

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Posted in Climate Change, Ecology, Extreme Weather | 1 Response »

From the Field: Farewell, Panama

Friday, December 28th, 2012

by Kristy Hill

The oyster Isognomon sp. in the crevices of a rocky reef at Fort Sherman on the Atlantic coast of Panama. (Kristy Hill)

Yesterday we ventured to the Caribbean coast of Panama, where we had beautiful weather for sampling. Our first stop was near Fort Sherman, a former United States Army base, where we found lots of Isognomon oysters on the subtidal rocks. These oysters are unusual because instead of cementing their shell to a hard surface, they attach themselves to rocks and mangroves with a threadlike structure. We also were able to collect a Crassostrea sp. and a few Ostrea sp. as well.

We then headed to the Smithsonian Tropical Research Institute (STRI) Marine Laboratory in Galeta. We braved the somewhat turbulent waters and snorkeled to collect from the mangroves, despite reports of crocodiles that frequent the area. Oh, the lengths we’ll go to in the name of science.

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Posted in Climate Change, Ecology, Fisheries, Invasive Species, Parasite Hunting, Water Quality | 6 Responses »

From the Field: Punta Chame–Oysters Galore

Thursday, December 27th, 2012

by Katrina Lohan

Katrina Lohan and Kristina Hill sample oysters off the rocks near Punta Chame, on the Pacific side of Panama. (Carmen Schloeder)

Some sampling sites are glamorous. Others are not. Our site near Punta Chame was literally off the side of the road. There were lots of rocks just off the road, and then a sandy bank that led to a stream, which led to the ocean. The rocks were covered in oysters, so it was very easy to get all the oyster samples we needed. We found three different species at that site and were able to collect all the oysters and water samples in about an hour.

Interestingly, there were two locations available for water sampling. One spot was an isolated pond influenced by run-off from the road, where the salinity was only 18 ppt. (The average salinity of the ocean is 35 ppt or parts per thousand). The other spot was more of a stream running from the land into the ocean only a few miles away, and the stream’s salinity was 30 ppt. As the salinity of the water can directly impact the parasites, some of which can only survive in high salinity, I opted to take water samples from both bodies of water so I could compare the differences. I’m hoping to get some really interesting results!

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Life and science at the Smithsonian Environmental Research Center

Climate Change

...now browsing by category

From the Field: Mangroves, Salt Marshes and Hungry Insects

Trees, Poison Ivy and Climate Change

From the Field: Out of the Mangrove and into the Marsh

High CO2 Spurs Wetlands to Absorb More Carbon

Marsh Rovers: Research at the SERC Marsh

From the Field: Sleepless Nights and Road Trips

From the Field: Insects Behind the Mangrove Invasion

Warm enough to snow? Climate Change and Blizzards

From the Field: Farewell, Panama

From the Field: Punta Chame–Oysters Galore