by Monaca Noble, Kristen Larson, Linda McCann and Ian Davidson
Video: Biologists place pennies underwater to test how well volunteers can spot small invaders
What is the Bioblitz, and why would researcher Linda McCann cash in her dollar bills for hundreds of pennies in preparation for it?
Bioblitzers braved the rain to search for invasive species. (Deborah Mercy)
A Bioblitz is an intensive survey in which trained volunteers head out en masse to catalog species in a specific area. On September 28, volunteers in Ketchikan, Alaska, joined staff from the Smithsonian Environmental Research Center (SERC), San Francisco State and the University of Alaska to search for invasive marine species along Ketchikan’s waterfront. The Marine Invasive Species Bioblitz in Ketchikan had three goals: to engage and teach the public about invasive species, detect newly arriving species that threaten Alaskan coastal waters, and recruit these enthusiastic volunteers for future monitoring efforts.
The goldenrod crab spider (Misumena vatia) blends in almost perfectly with the yellow chamomile flower. (Alvegaspar)
There’s a reason cobwebs make popular Halloween decorations. Spiders rival with snakes, birds and clowns for the most feared creatures in the animal kingdom. But some of nature’s creepiest arachnids don’t build webs at all. They ambush their prey in much more beguiling settings. Like flowers.
That’s a favorite haunt of the crab spider, one of several groups of webless spiders that hunt, instead of trap, their food. The name comes from their four long front legs, which stretch out like claws, and their crab-like method of walking—they’re better at moving sideways and backwards than forwards. But their strategy for capturing prey has earned them another common name: the ambush spiders.
Katrina Lohan and Kristy Hill collect oysters on rocks near Punta Chame, Panama. (Carmen Schloeder)
Katrina Lohan and Kristy Hill have travelled thousands of miles down the Atlantic Coast, from the Chesapeake to the Caribbean. Their goal? Track the range and distribution of parasites in bivalve mollusks that could cause disease. Based on diversity patterns, Hill and Lohan suspect that there are many more protist species in the tropics than have previously been discovered. These parasites could be very similar to the parasites that have caused mass die-offs in Chesapeake oyster beds with diseases like Dermo and MSX.
Close-up of a trematode oyster parasite. These parasites form cysts, and could be similar to the parasites that caused mass die-offs in the Chesapeake.
But there’s one catch: The protists that are parasitizing the bivalves are difficult to identify just by looking at them. Luckily for Lohan and Hill, advances in DNA sequencing can reveal secrets about little-studied and poorly understood organisms. Already famous for helping improve human health, DNA sequencing is proving equally adept at preserving the planet’s health. From the tropics of Panama to the forests of Maryland, the rise in DNA sequencing is opening new realms of possibility for ecologists at the Smithsonian Environmental Research Center and across the world.
7-year-old Cecilia Bowers collects frogs in the SERC forest. (SERC)
It’s 2 o’clock in the afternoon. In the forest beside SERC’s beaver pond, Dylan McDowell and Shelby Ortiz have just finished helping a dozen 7-to-9-year-old students search for frogs and toads. They’re headed to the stream when McDowell runs into a dilemma: Some of the children don’t want to release their frogs.
“It would be really hard to find frogs around where I live,” says Emma Guy, who doesn’t have any parks or forests near her home.
“Did you know a couple years ago, they found a brand new species of frog in New York City?” McDowell asks her. He’s referring to a new species of leopard frog confirmed in 2012, whose known range has Yankee Stadium almost dead center. Closer to home, SERC biologists discovered juvenile eastern spadefoot toads in one of its wetlands this summer—the toad’s first recorded appearance on the SERC landscape. McDowell’s point, at least for the afternoon lesson: Amphibians can appear almost anywhere if you know where to look.
This finding, published Wednesday in Environmental Science & Technology, explains why methylated mercury, a neurotoxin, is produced in areas with no previously identified mercury-methylating bacteria. Methylmercury—the most dangerous form of mercury—damages the brain and immune system and is especially harmful for developing embryos. Certain bacteria transform inorganic mercury from pollution into toxic methylmercury.
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.
Intense fire burns near Crane Flat helibase, close to the Yosemite research plot. (Gus Smith/NPS)
As the Rim Fire burns deeper into Yosemite, park managers are fighting fire with fire—and one of the Smithsonian’s ForestGEO plots was caught in the middle this weekend.
The Yosemite Forest Dynamics Plot sits just north of Yosemite Valley, and south of the wildfire that has already consumed more than 60,000 acres of the national park. It is part of the Smithsonian’s Forest Global Earth Observatory (ForestGEO), a network of 48 plots around the globe that scientists are measuring to understand forest dynamics and climate change. Two of Yosemite’s giant sequoia groves and many large trees also sit near the plot, and managers didn’t want to see the entire forest go up in flames.
These chambers at Kirkpatrick Marsh allow the amount of CO2 and nitrogen to be manipulated, allowing researchers to understand how climate change will affect the growth of Phragmites.
An invasive reed from Europe is conquering marsh habitat throughout the Chesapeake, displacing native marsh grasses and drastically changing the face of the wetlands. Phragmites australis, a “jack and master” plant grows to nearly 10 feet tall and is adept at extracting nutrients from the soil, outcompeting native Phragmites genotypes. Climate change could increase the spread of this invasive plant. But other human activities, such as development, shoreline hardening and agriculture, could also determine the spread and range of Phragmites.
Climate Change Spurs Phragmites Growth
Rachel Hager, who interned with the Biogeochemistry lab, wanted to see if human activities were giving Phragmites even more of a competitive edge. Excess nitrogen from agriculture and industry, as well as increased CO2 levels, could increase Phragmites growth. Working in the Global Change Research Wetland (GCReW), she tracked the growth of Phragmites under conditions that had more CO2 added, more nitrogen added, and both CO2 and nitrogen added. She found that CO2 and nitrogen led to increased Phragmites growth, and plots with both CO2 and nitrogen grew the most.
Increased growth is only part of the story, however. Rachel wanted to see if taller Phragmites would inhibit other plants’ access to light. She analyzed leaf length, number, thickness and canopy cover to see if Phragmites exposed to additional CO2 and nitrogen were better at blocking light from their competitors. She found that Phragmites exposed to more CO2 and nitrogen had more, thicker and longer leaves, but their canopy cover was the same as control Phragmites plots. Thicker, longer leaves could lead to a longer leaf lifespan and more leaf litter, however, which could still block other plant’s access to light. Rachel hopes to see further research done on the amount of light that makes it through a Phragmites canopy. Click to continue »
An illustration depicting bryozoans from Ernst Haekel’s The Art of Nature (photocredit: wikipedia)
All for one and one for all is a motto that bryozoans would take close to heart, if they had hearts, that is. This phylum is made up of 4,000 or so species, almost all of which are colonial. Individuals, called zooids, can’t survive on their own and depend on their fellow colony members to help gather nutrients, get rid of waste, and reproduce. Though sedentary as adults (a few species are able to creep slowly), bryozoans are able to spread through the dispersal of larvae in the water column. If a piece of the colony is broken off, it can survive and form a new colony. Known commonly as “moss animals” most bryozoans live up to the name, resembling robust pond scum. Some species, such as those in the Watersipora genus, form leaf-like, calcareous colonies that can serve as habitat for other animals. Click to continue »
A grass shrimp infected with a trematode parasite (photo: Sara Gonzalez)
While the idea of playing host to something out of the movie Alien is decidedly unpleasant, it’s hard not to marvel at theexquisite grossness of microscopic parasites. Parasites take advantage of their hosts for resources and shelter, but research on parasites suggests that they also can manipulate their hosts’ behavior: Crickets will drown themselves, snails position themselves to be eaten by birds, and some theories suggest that cat-lovers infected with the parasite Toxoplasma gondii become self-destructively reckless. More than half the known species in the world are parasites—making parasitism the most popular lifestyle on Earth.
At the Smithsonian Environmental Research Center (SERC), the Marine Invasions Lab has been tracking parasites in grass shrimp, an incredibly common near shore species. Rates of parasitism are extremely high in grass shrimp, with some years 90 percent of the shrimp caught displaying parasite infection. The most common parasite is a trematode that forms cysts in the tail of the shrimp. Sara Gonzalez, who interned with SERC this summer, wanted to see if parasitized shrimp displayed different predator avoidance behaviors than unparasitized shrimp. Because the trematode only reproduces in birds and mammals, the parasite must find a way to make its way up the food chain. Sara suspected that infected shrimp will change their behavior in a way that makes them more vulnerable to predators like mummichogs. The parasite does not infect the mummichogs directly, but mummichogs are prey for mammals and birds. If a mummichog that has ingested an infected shrimp gets eaten by a bird or mammal, then the parasite will be able to reproduce. Click to continue »