Smithsonian Science » Smithsonian Environmental Research Center

Fungi-filled forests are critical if endangered orchids are to thrive

John Barrat — Mon, 23 Jan 2012 17:53:31 +0000

When it comes to conserving the world’s orchids, not all forests are equal. In a paper to be published Jan. 25 in the journal Molecular Ecology, Smithsonian ecologists reveal that an orchid’s fate hinges on two factors: a forest’s age and its fungi.

Roughly 10 percent of all plant species are orchids, making them the largest plant family on Earth. But habitat loss has rendered many threatened or endangered. This is partly due to their intimate relationship with the soil. Orchids depend entirely on microscopic fungi in the early stages of their lives. Without the nutrients orchids obtain by digesting these host fungi, their seeds often will not germinate and baby orchids will not grow. While researchers have known about the orchid-fungus relationship for years, very little is known about what the fungi need to survive.

Image right and below: Flowers (right) and leaves (below) of the orchid Goodyera pubescens, commonly known as the downy rattlesnake orchid, endangered in Florida. (Photos by Melissa McCormick/SERC)

Biologists based at the Smithsonian Environmental Research Center in Edgewater, Md., launched the first study to find out what helps the fungi flourish and what that means for orchids. Led by Melissa McCormick, the researchers looked at three orchid species, all endangered in one or more U.S. states. After planting orchid seeds in dozens of experimental plots, they also added particular host fungi needed by each orchid to half of the plots. Then they followed the fate of the orchids and fungi in six study sites: three in younger forests (50 to 70 years old) and three in older forests (120 to 150 years old).

Image right and below: Leaf (right) and flowers (below) of Tipularia discolor, the cranefly orchid, endangered in New York and Massachusetts, and threatened in Michigan and Florida.

After four years they discovered orchid seeds germinated only where the fungi they needed were abundant—not merely present. In the case of one species, Liparis liliifolia (lily-leaved twayblade), seeds germinated only in plots where the team had added fungi. This suggests that this particular orchid could survive in many places, but the fungi they need do not exist in most areas of the forest.

Meanwhile, the fungi displayed a strong preference for older forests. Soil samples taken from older forest plots had host fungi that were five to 12 times more abundant compared to younger forests, even where the research team had not added them. They were more diverse as well. More mature plots averaged 3.6 different Tulasnella fungi species per soil sample (a group of fungi beneficial to these orchids), while the younger ones averaged only 1.3. Host fungi were also more abundant in plots where rotting wood was added. These host fungi, which are primarily decomposers, may grow better in places where decomposing wood or leaves are plentiful.

All this implies that to save endangered orchids, planting new forests may not be enough. If the forests are not old enough or do not have enough of the right fungi, lost orchids may take decades to return, if they return at all.

“This study, for the first time, ties orchid performance firmly to the abundance of their fungi,” McCormick says. “It reveals the way to determine what conditions host fungi need, so we can support recovery of the fungi needed by threatened and endangered orchids.” –Kristen Minogue

The University of Alaska Fairbanks and Purdue University also contributed to this study. The abstract will be available here: http://onlinelibrary.wiley.com/doi/10.1111/j.1365-294X.2012.05468.x/abstract. To receive a copy of the paper, to speak with McCormick or for more information, contact Kristen Minogue at (443) 482-2325 or (314) 605-4315.

Cold spells spell trouble for warm-weather invasives

John Barrat — Fri, 06 Jan 2012 19:17:44 +0000

Aided by a recent increase in ocean surface water temperatures, new marine invaders from the Caribbean have been observed spreading northward along the southern and mid-Atlantic coasts of the United States. This northern migration of marine species—called the “Caribbean Creep”—is occurring because many of these non-native species can tolerate a broad range of temperatures.

Image left: SERC scientist João Canning Clode observes a green porcelain crab in his laboratory at the Smithsonian Environmental Research Center.

But what happens to these fair-weather travelers during a severe cold snap, such as the one that occurred in January 2010 across much of the southeastern and eastern United States? To investigate, Smithsonian Environmental Research Center scientist João Canning Clode and colleagues at the Environmental Research Center in Edgewater, Md., tested the cold-water tolerances of invasive green porcelain crabs (Petrolisthes armatus) in their laboratory. Crabs were collected in Georgia and brought to the lab where they were subjected to one of three temperature treatments. The first was a control treatment of constant moderate winter temperature. The second was treatment in which the temperature was dropped to mimic the cold snap of January 2010, and the third treatment consisted of the extreme cold temperatures of a severe winter.

Canning-Clode and his colleagues found that most of the crabs in the control treatment survived (83%), but many of the crabs in the second cold treatment (61%) and all of the crabs in the third extreme cold treatment (100%) died. Crabs that survived cold treatment number two were sluggish, possibly making them more susceptible to predation and impacting their ability to feed, the scientists determined.

The scientists determined that prolonged exposure to cold temperatures also may compromise the green porcelain crab’s ability to overcome cumulative cold events, such as the two other record cold snaps that occurred in February and March of 2010.

Image right: A green porcelain crab (Photo by Juan Antonio Baeza)

The loss of more than 60% of their population during each cold period might explain the recent dramatic decline of the green porcelain crab in Georgia in 2010, suggesting that extreme cold spells may limit or prevent the northward spread of this invasive species.

Several climate models used to predict how species will react to climate change in the next 100 years have projected a continued decline of global biodiversity and increased spread of introduced species. Many of these models focus on temperature increases, but few have evaluated the impact of severe weather like cold snaps, Canning-Clode and his colleagues write in a paper on their study recently published at PLoS ONE.

For Canning Clode “the core message of this paper is that yes, climate change is happening, but cold is also part of this change. We believe these periodic cold events will limit the range expansion of Petrolisthes armatus as well as other Caribbean creep species” –Monaca Noble, SERC

Location matters: For invasive aquatic species, it’s better to start upstream

John Barrat — Sun, 25 Sep 2011 14:49:51 +0000

Researchers have found that a species invasion that starts at the upstream edge of its range may have a major advantage over downstream competitors, at least in environments with a strong prevailing direction of water or wind currents.

Scientists from the University of Georgia, University of New Hampshire, Smithsonian Environmental Research Center and University of Vermont studied populations of European green crab, Carcinus maenas. The species was introduced to the East Coast of North America twice, at both the upper and lower edges of its range. Their findings, recently published in the Proceedings of the National Academy of Sciences, may help inform the control of invasive species and the conservation of imperiled native species.

Image right and below: Green crabs

“In New England, they’re worried,” said Jeb Byers, an associate professor at the UGA Odum School of Ecology and one of the paper’s authors. “These green crabs have been doing a number on native shellfish. They eat a lot of clams. And they’re a very cosmopolitan species—they’ve now spread all over, to places as far afield as the West Coast of the U.S. and South Africa.”

The European green crab was first detected in North America in New Jersey in the early 1800s, Byers said. It spread slowly north against the prevailing direction of ocean currents until it reached Halifax, Nova Scotia in 1964. That was the extent of its range along the East Coast until the 1990s, when populations suddenly appeared throughout the Canadian Maritime provinces.

Conservation biologist Joe Roman of the University of Vermont, another of the paper’s authors, determined that these new populations were genetically different from those established earlier. Analysis revealed that unlike the earlier arrivals, they were related to European green crabs found in the Baltic, suggesting a new introduction directly from Europe to Nova Scotia had taken place. Other authors of the paper include James M. Pringle of the University of New Hampshire and April M. H. Blakeslee of the Smithsonian Environmental Research Center.

Understanding how the species spread could offer insights into how to control it.

“Our theory was that the old invasion spread as far as it could upstream before fighting the currents made it impossible to spread farther,” Byers said. “We suspected that the new invaders were successful essentially because of physics. Unlike their predecessors, they didn’t have to fight their way against the current to spread. They just had to disperse their larvae into the water column and let the current carry them south along the coast.”

The second crab invasion established in the Strait of Canso and Bras d’Or Lake in northern Nova Scotia, locations well suited to serve as large population retention zones. These zones anchor the crab population because they are not subject to the strong currents typical of the outer coast.

“If you look at the prevailing ocean currents in the area, you can see that these population retention zones are at the upstream edge of practically the entire distribution of the crabs,” Byers said. “Crab larvae enter the water column from there and drift south.”

Byers and his colleagues genetically sampled crab populations from New York to northern Nova Scotia from 1999 to 2007. They found that the northern crabs were making up a greater share of the crab population at each sampling site as time progressed. “The northern crabs were 20 percent more common within only a few generations,” Byers said.

They also found that areas not previously invaded by southern crabs were susceptible to invasion by northern crabs. “The currents were carrying the crab larvae downstream from the northern populations into areas that the crabs moving under their own power up from the south were unable to colonize,” he said.

The team’s findings could help target efforts to control invasive species and conserve native species in environments influenced by strong water or air currents.–Source: Odum School of Ecology, The University of Georgia

Alaska’s cold waters no barrier to invasive marine species, scientists say

John Barrat — Thu, 11 Aug 2011 10:05:46 +0000

Alaska’s pristine coastline is ripe for an influx of invasive marine species such as the European green crab and the rough periwinkle (an Atlantic sea snail) warns a new study by a team of scientists from the Smithsonian Environmental Research Center. To date only 15 non-native species are known to have established themselves along Alaska’s Pacific coastline—as compared to more than 250 invasive marine species that now call California home—but this could easily change with warming temperatures and increased human activity in this region, the scientists warn.

The idea that the colder temperatures of high-latitude regions act as a natural barrier to invasive species is a misconception.

Image right: The European green crab, Carcinus maenas. (Photo by Hans Hillewaert)

“Environmental conditions along the coastline of Alaska and many other high-latitude areas would not prevent successful invasion of non-native marine species with distributions now restricted to lower latitudes,” the scientists write in a recent paper published in the conservation biogeography journal “Diversity and Distributions.”

The team, which includes Anson Hines, director of the Smithsonian Environmental Research Center; Gregory Ruiz, head of the Center’s Marine Invasions Research Lab, and Portland State University ecologist Catherine de Rivera, base their predictions on a series of niche models they created for four taxonomically diverse marine species: the European green crab (Carcinus maenas), rough periwinkle (Littorina saxatilis), bay barnacle (Amphibalanus improvisus) and the sea squirt (Styela clava).

Image left: Sea squirt, Styela clava. (Photo courtesy Fisheries and Oceans Canada)

Using a wide range of scientific data detailing where each species is presently established around the globe—both in their natural and introduced ranges—the scientists created computer models projecting where else on Earth they might logically thrive. Much of the Pacific coast of Alaska came up as a strong match for each of the species. The geographic range of all four animals received a strong nudge northward in the models when higher temperatures predicted from climate change (a rise of between 1.5 and 7 degrees Celsius) were factored in.

The scientists point out that their study focuses on only four invasive species out of more than two hundred that have become established in the region adjacent to Alaska, from California to British Columbia. If more invasive species do move north into Alaska it will likely come through an increase in the frequency and intensity of introductions, the scientists write—namely on commercial ships and recreational vessels, through aquaculture, and through the live trade of animals as food, pets and bait.

Invasive species ride in the ballast water of oil tankers and some cargo ships. Cruise ships and cargo barges can carry invasive species attached to their hulls.

Image right: The shell of the rough periwinkle, Littorina saxatilis. (Photo Amy Benson, USGS)

Alaska has been spared so far from an influx of invasive species, the scientists say, because the magnitude of shipping and other human-mediated transfer mechanisms has been historically low. In recent years however, vessel traffic has increased considerably along the Alaskan coast. For example, more than 7,000 ships arrived to Alaskan waters in 2004 alone, discharging over 4 million metric tons of ballast water. Shipping and other human activities are projected to increase in this region, especially if climate change brings warmer temperatures.

The probability of invasions in Alaska is likely to increase with global warming even without the help of ballast water introductions, the scientists conclude. “On a global scale, the suitability of Alaskan waters is not unique, as other high-latitude areas also offer environmental match for these species,” the scientists write.

“The ranges of all four species have slowly been moving northward up the coast and they may spread further up the coast by ocean currents,” Catherine de Rivera says.

The article “Potential for high-latitude marine invasions along western North America,” authored by Catherine de Rivera, SERC ecologist Brian Steves, SERC ecologist Paul Fofonoff, Anson Hines and Greg Ruiz, appeared in the journal Diversity and Distributions.

‘Science at the Smithsonian’ gallery: 165 years of scientific achievement

Brian Ireley — Tue, 09 Aug 2011 19:29:59 +0000

On Aug. 10, 1846, U.S. President James K. Polk signed the legislation that established the Smithsonian Institution as a trust administered by a Board of Regents and a Secretary of the Smithsonian. Joseph Henry, the first secretary of the Smithsonian (1846-1878), strove to develop the Smithsonian into the nation’s first major research institute for science. During his tenure, the Smithsonian gained widespread acclaim not only as the country’s foremost scientific research institute but also as a facilitator of international scientific dialogue. Congressionally-mandated programs for the public kept Americans informed about Smithsonian activities.

Image left: Joseph Henry

Spencer Fullerton Baird, the Smithsonian’s second secretary (1878-1887) was an avid naturalist, collector and a pioneer in museum collecting and display. Whereas Henry had envisioned the Smithsonian primarily as a research institute, Baird began to develop the Smithsonian into a national museum. Secretary Baird’s vision coincided with a growing sense of nationalism surrounding the celebration of the U.S. Centennial. By 1878 Congress had formally given responsibility for the U.S. National Museum to the Smithsonian Institution. During the Baird years, the Smithsonian became a showcase for the nation’s history, resources, and treasures.

Since its founding 165 years ago, the Institution has expanded into the world’s largest museum and research complex, with 19 museums, the National Zoo and nine research facilities, including the Smithsonian Astrophysical Observatory, the Smithsonian Tropical Research Institute, the Smithsonian Environmental Research Center and the Smithsonian Museum Conservation Institute.

This slide show highlights a number of historic photographs featuring a few of the many scientific researchers who have played a role in the Smithsonian’s long climb to scientific prominence.

(Click photo to advance)

Get the flash player here: http://www.adobe.com/flashplayer

SERC sedge grass experiment mimics predicted global-change scenario

John Barrat — Mon, 01 Aug 2011 14:19:06 +0000

Ecologists at the Smithsonian Environmental Research Center measure the growth rate of sedge grass in a brackish Chesapeake Bay marsh. Fed a diet rich in CO2 and nitrogen, conditions that mimic the rise of atmospheric CO2 and pollution from farming and wastewater, the sedge has been grown and monitored in test chambers by Smithsonian scientist since 2006 in this global-change experiment. (Photo by John Barrat)

Smithsonian team finds northern snakehead fish in Maryland’s Rhode River

John Barrat — Thu, 28 Jul 2011 09:17:10 +0000

A team of researchers and student summer interns from the Smithsonian Environmental Research Center in Edgewater, Md., discovered a northern snakehead (Channa argus) fish in the Rhode River in mid-July. This is the first report of this invasive species in this area, and may indicate a recent range expansion of the snakehead population.

Image left: The team of researchers and interns from the Smithsonian Enviornmental Research Center display the northern snakehead fish they recently found in the Rhode River.

Native to China, the first northern snakehead in Maryland was reported in 2002 in a Crofton pond, approximately 20 miles east of Washington, D.C. That population was eradicated, but a separate introduction occurred in the Potomac River in 2004, which led to the establishment of the northern snakehead in creeks and upper waterways of the Potomac in Maryland and Virginia.

The snakehead was caught during routine sampling at a long-term study site using a seine net. It represents the only specimen recorded for the Rhode River site in decades of such surveys. The fish was a mature female, 58 cm (23 inches) in length, caught near the headwaters of the Rhode River.

The northern snakehead is typically found in freshwater, although it can tolerate low salinity waters. It was thought that higher salinity at the mouth of the Potomac may act as a natural barrier, serving to limit or reduce the fish’s spread to other tributaries. Due to extremely high levels of spring runoff in Upper Chesapeake Bay this year, salinities in Chesapeake tributaries are at some of their lowest levels in the last 30 years. This has potentially allowed the fish to move out of the Potomac and travel to other rivers via Chesapeake Bay.

Image right: The northern snakehead fish specimen recently found in the Rhode River.

Unlike most fish, the northern snakehead can survive up to four days out of water if kept moist. This ability comes from air chambers above their gills that act as a primitive lung. They are top-level predators with the ability to consume other fish and animals up to one-third of their own body size. Northern snakeheads may cause declines in local fish and other organisms, causing potential changes to the food web.

The fish was caught by a research team of scientists and interns from SERC’s Marine Invasions Research Lab, which studies patterns and effects of biological invasions in coastal marine ecosystems throughout North America. Information on this and other non-native species in Chesapeake Bay can be found at SERC’s website (http://invasions.si.edu/nemesis/chesapeake.html).

Any movement or possession of a live northern snakehead fish is a violation of state law. If you catch a Northern Snakehead, please do not release it. Anglers are asked to kill the fish and contact Maryland or Virginia Departments of Natural Resources.

The small whorled pogonia

John Barrat — Tue, 17 May 2011 16:49:41 +0000

The small-whorled pogonia is a plain, endangered orchid that inhabits the hollows of Virginia, and survives only in collaboration with a particular type of fungus and a particular type of tree. Scientists want to save the orchid, but first they have to find it. Listen to a radio broadcast by WAMU correspondent Sabri Ben-Achour as he tags along on a rescue mission for this flower with Smithsonian Environmental Research Center botanist Melissa McCormick. Click here.

New Mathias Lab at Environmental Research Center will have low environmental impact

John Barrat — Mon, 09 May 2011 12:35:20 +0000

With a $45 million federal appropriation to the Smithsonian Institution, the Smithsonian Environmental Research Center in Edgewater, Md., on the Chesapeake Bay, will start building what is expected to be one of the most energy-efficient laboratories in the country. The expanded and remodeled Mathias Laboratory, named in honor of U.S. Senator Charles “Mac” Mathias Jr. (1922-2010) (R-Md.) will have a low environmental impact on all fronts, from where it gets its power to where it gets its materials. Analysts estimate it will consume at least 37 percent less energy, and emit 37 percent less carbon dioxide, than a similar building that meets baseline LEED certification standards. A groundbreaking ceremony for the new facility took place on Friday, May 6 to mark the beginning of the two-year project.

“The Mathias Laboratory project is a cornerstone of the Smithsonian’s environmental research, education and commitment to sustainability,” explains Smithsonian Secretary Wayne Clough. The Mathias Laboratory will serve as a lasting and living tribute to the legacy of Sen. Mathias, who was a leader in the efforts to restore the Chesapeake Bay.

Besides leaving a less intense carbon footprint, the new building will enhance SERC’s capacity for cutting-edge environmental research on the Chesapeake. SERC scientists specialize in a multitude of disciplines, including global change, terrestrial and marine ecology, invasive species and nutrient pollution. The laboratory is designed to promote cross-disciplinary collaboration for SERC’s research teams.

Totaling 90,000 square feet, the new building will add 69,000 square feet of laboratory, office and support space to 21,000 square feet of remodeled existing space. A two-story atrium will connect the old and new sections and create an area where staff from various departments can share ideas.

“Thia new laboratory represents a renewed long-term commitment by the Smithsonian to world-class environmental research on the Chesapeake Bay estuary and watershed, and on coastal ecosystems around the world,” said SERC Director Anson Hines.

The project will seek gold-level LEED certification by the U.S. Green Building Council, targeting the maximum gold score of 51 credits. The lab already has gained recognition from the national Labs21 program and the Department of Energy’s National Renewable Energy Laboratory, which expressed interest in featuring the Mathias Laboratory as a national model.

The laboratory also will use regional materials to prevent long-distance transportation and use only certified sustainable wood.

Image: Architect’s rendition of the new Mathias Lab, complete with solar panels, rain barrels and reconstructed wetlands. Credit: EwingCole. More images available on request.

Falling trees help invasive wineberry move into deciduous forests in North America

John Barrat — Tue, 03 May 2011 15:29:05 +0000

If a tree falls in the forest does it make a sound? Perhaps, but what happens afterward is of growing concern to scientists studying the invasive plant Rubus phoenicolasius, better known as the wineberry, in the United States.

A recent study in a forest at the Smithsonian Environmental Research Center in Edgewater, Md., has shown that soon after a tree falls, wineberry seedlings pop-up in the gap created by the fallen tree. These opportunistic plants quickly fill-in the gap, taking advantage of the increased light coming through the tree canopy and the fresh soil at the fallen tree’s turned-up roots. Once established on the forest floor wineberry canes rarely die. The rapid growth of the plant is slowed after the canopy closes again. Its canes remain on the shaded forest floor waiting to spread further with the next tree fall.

Image above and left: Wineberries (Rubus phoenicolasius) (Photo above by Eva-Maria Kintzel/Photo left by Rasbak)

Native to Japan, China and Korea the wineberry or wine raspberry was introduced to the United States in 1890. It is now listed as invasive in Maryland, Pennsylvania, Tennessee, Virginia, North Carolina and West Virginia. A vigorous grower, it forms dense thickets of prickly red canes with broad leaves covering large areas and displacing native plants. In the eastern United States it is now common along forest, field, stream and wetland edges and in open woods.

During the experiment conducted by David Gorchov of Miami University ; Dennis Whigham, senior scientist at the Smithsonian Environmental Research Center, and their colleagues, the team learned that a thick layer of leaf litter is a forest’s best defense against wineberry seedlings. Bare soil, such as that found at the turned-up roots of a fallen tree, promotes the sprouting of wineberry seedlings.

The bad news, the researchers write, is “that this invasive will become pervasive even in old stands,” of deciduous forest. “The good news is that the invasion of old stands can be prevented by simple cultural control.” The scientists recommend searching new treefall gap areas in a forest every three years and pulling up any R. phoenicolasius seedlings and young plants that are found there.

A paper “Treefall gaps required for establishment, but not survival, of invasive Rubus phoenicolasius in deciduous forest, Maryland, USA,” appeared in a recent issue of the scientific journal Plant Species Biology.–John Barrat