Publications

...now browsing by category

 

Biodiversity just as powerful as climate change for healthy ecosystems

Wednesday, September 6th, 2017

In the wild, diversity determines ecosystem production as much as climate and nutrients

by Kristen Minogue

Yellow fish swimming around coral reef

A school of grunts explores a shallow reef at Carrie Bow Cay, Belize, one of Smithsonian MarineGEO’s long-term research sites. Biodiversity not only can make sites beautiful, but also can help boost their biomass and make them more productive. (Credit: Ross Whippo/SERC).

Biodiversity is proving to be one of humanity’s best defenses against extreme weather and rising temperatures. In past experiments, diversity has fostered healthier, more productive ecosystems, like shoreline vegetation that guards against hurricanes. However, many experts doubted whether these experiments would hold up in the real world. A Smithsonian and University of Michigan study published in this week’s issue of Nature offers a decisive answer: Biodiversity’s power in the wild does not match that predicted by experiments—it surpasses it, in some cases topping even the effects of climate.

“Biodiversity is not just a pretty face,” said Emmett Duffy, lead author and marine ecologist at the Smithsonian Environmental Research Center in Edgewater, Md. “Protecting it is important for keeping the ecosystems working for us, providing food, absorbing waste and protecting shorelines, which is important right now.”

Click to continue »

Want Biodiversity? Love Your Enemies…Sometimes

Tuesday, August 1st, 2017

by Kristen Minogue

Three separate images of leaf infected by anthracnose, acorn with an insect hole and emerald ash borer.

Signs of three temperate forest enemies, left to right: Anthracnose (SERC), insect hole in an acorn (Jonathan Myers), emerald ash borer (Leah Bauer, USDA Forest Service Northern Research Station, Bugwood.org)

Walk through a forest in Maryland or Missouri, and you’ll probably find yourself surrounded by dozens of different tree species. Walk through a tropical forest in Brazil or Malaysia, and you’ll be surrounded by hundreds—in some forests, over 1,000. What’s behind this colossal difference in diversity? Scientists with the Smithsonian-led ForestGEO network came up with one morbid possibility: It may come down to having the right kind of enemy.

Earlier this summer, in a study in Science, researchers from 24 plots in the forest network from five continents pooled their data and detected a strange pattern: There’s a force at work in the tropics helping rare species thrive, a force that is much weaker in the cooler temperate zone.

Call it a clustering effect. The scientific term is “conspecific negative density dependence,” but it boils down to this: If too many trees of the same species grow in the same spot, they become magnets for enemies that slash their populations. In tropical forests, enemies generally knock them down just enough for new species to fill the gaps, without completely wiping out the first species. The result is a kaleidoscope forest with hundreds of species, many quite rare.

It may seem like a counterintuitive idea, that a lethal enemy could help sustain biodiversity. It can work when this thinning process prevents any one species from dominating.

“Just when a population is ready to take over, it catches a cold,” explained Sean McMahon, a co-author and forest ecologist with the Smithsonian Environmental Research Center (SERC). “And so it gets knocked back.”

Click to continue »

Scientists Turn Up the Heat on Herbivores and Their Food

Friday, July 28th, 2017

By Joe Dawson

14742878797_3fc13bfde0_o

Japanese beetles make a meal of evening primrose leaves (Credit: Dejeanne Doublet/SERC)

Plants can seem pretty boring. They just sit there, after all. Sure, they can be pretty; they can make us sneeze. But what else do they do? A lot, it turns out. They are able to shift their own water and energy resources from leaves to stems to roots and back, grow tall or stay low and bushy, defend themselves through biological warfare, or warn their neighbors of danger. When doors get blocked, plants have ingenious ways of sneaking out through windows.

What, then, will plants do when humans spread a carbon dioxide blanket over the planet, warming it by burning fossil fuels? Research scientist Nate Lemoine of Colorado State University, with John Parker of the Smithsonian Environmental Research Center (SERC) and others, decided to investigate one such relationship with an experiment on the SERC campus in 2013 and 2014. Click to continue »

Time Travel, with Trees

Monday, July 10th, 2017

by Joe Dawson

Looking at the Kirkpatrick Marsh on the Rhode River, a time machine is not the first thing that comes to mind. Tall grasses dominate the landscape, with vertical PVC pipes popping up here and there and octagon-shaped chambers rising out of the wetland every ten paces or so. Take a step off the walkway, and you might lose a shoe. But 5 experiments on the marsh are designed to take sections of the marsh into the 22nd Century, and the marsh has been dubbed the Global Change Research Wetland, or GCReW. The expertise that GCReW scientists have in simulating the future brought National Museum of Natural History scientists here to mirror the past.

Rich Barclay and Scott Wing are paleobotanists at the National Museum of Natural History. Paleobotanists are the ones who stare at leaves in Jurassic Park and say, “Alan, these plants haven’t been seen since the Cretaceous Period,” as everyone else stares at brachiosauruses. Ancient plants are their bread and butter, and for Wing and Barclay, the bread is toasted and the butter melty. They study one of the warmest periods in the last 100 million years, the Paleocene-Eocene Thermal Maximum (PETM). During this period, global temperatures skyrocketed, increasing by 10-15 degrees Fahrenheit. By looking at plants that grew during this time, they hope to learn more about what Earth was like 55 million years ago.

chambersignk

Large growth chambers being built around newly-planted ginkgo trees on the SERC campus (Credit: Rich Barclay)

Barclay, Wing, and colleagues have started an experiment on the Smithsonian Environmental Research Center’s (SERC) campus that grows ginkgo trees in varying carbon dioxide levels. They hope to study these trees and compare them to fossil specimens to learn about the past. Click to continue »

The Tiny Fish Awards!

Wednesday, July 5th, 2017

by Joe Dawson

Goatley&Brandl_Fig1.7

A sample of the diversity present within the cryptobenthic reef fishes. Figure from Goatley and Brandl 2017.

Go snorkeling on a coral reef, and you’ll have a hard time not being impressed by the abundance and variety of the fish there. But the fish most divers see make up less than half of the number (and less than half the species) of fish on the reef. Cryptobenthic reef fishes comprise the other half. These fish are small, usually less than 2 inches in length, and hide in coral habitats, either by appearance or by their behavior. Even scientists have been slow to start searching for them, but cryptobenthics are turning up in about every reef habitat where scientists have bothered to look! In the June 5 issue of Current Biology, SERC Scientist Simon Brandl and colleague Christopher Goatley of the University of New England published a quick guide to cryptobenthic reef fishes. Brandl thinks that these little fishes deserve more recognition, and we agree! Therefore, we’re happy to present these honorees with the following awards.

Coolest Camo

Runners Up: Frogfishes (Family Antennariidae), Scorpionfishes (Family Scorpaenidae)

Anpic_u3

The painted frogfish, Antennarius pictus (Credit: John E. Randall/Hawaii Biological Survey, used under CC BY-NC 3.0)

Weird and tricky, frogfishes have plump, short bodies. They’re often covered in spines or even hair-like appendages and prefer to stay still, waiting and blending in, for prey to swim close enough that they can gulp them. The deep-sea dwelling anglerfish is one famous member of this group.

Scorpionfish are also sit-and-wait predators, using their feathery scales or skin flaps to look like rocks or coral, then pouncing on nearby prey. The most renowned member of this group is the lionfish. Click to continue »

Q&A: Ian Davidson, Aquatic Inquirer

Monday, 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 »

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 »

Predicting the Future of Migrating Mangroves

Monday, 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 »

Alaskan Alders Shape Fates of Wetlands, Streams—And Salmon

Monday, May 22nd, 2017

by Joe Dawson

007

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

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 »