by Katie SinclairKatrina 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. 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.
by Kristen MinogueIt’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.
Microbes that live in rice paddies, northern peat lands and beyond are among the several types of bacteria researchers at the Smithsonian Environmental Research Center and Oak Ridge National Laboratory have just learned can generate highly toxic methylmercury.
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.
by Lily DurkeeAfter 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.
by Kristen MinogueAs 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.
By Katie Sinclair
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.
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By Katie Sinclair
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 »
By Katie Sinclair
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.
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By Katie Sinclair
Boats, beavers. . .and bear poop? If you want to see what our campers learned this summer, take this quiz below and see how you measure up!
As store aisles quickly fill up with back to school supplies, SERC’s summer education programs are coming to a close. SERC’s Education Team took a slightly different approach to summer programming this year. Instead of hosting summer camps, they sponsored three “activity weeks” throughout the summer. Each activity week had a specific theme, and was tailored to different age groups. The first of SERC’s activity weeks was “Changing Environments,” designed for students aged 13-15. The week focused on certain case studies that highlighted environmental changes. The students also visited SERC’s weather tower, and went on expeditions in the SERC forest to catch insects and frogs. “Kids Unplugged”, the next week, was made up of students aged 7 to 9. One of the more memorable lessons was when the kids made “scat” out of play-doh in order to better understand the types of birds and mammals that live in the SERC forest. The last activity week, “Junior SERC Scientists” introduced 10-12 years olds to problem solving and the scientific method. They used forensic clues to discover who “killed” a beaver. The kids put their sleuthing skills to the test and found that the murderer was none other than Education Intern Shelby Ortiz!
By Katie Sinclair
A short DIDSON clip of a cownose ray swimming near the SERC dock
One of the biggest challenges of studying life in the Chesapeake Bay is poor visibility. In the water, you literally can’t see your hand in front of your face. So how do you see what’s going on under the water? Sampling with nets can give us a pretty good picture, but if you want to observe what’s happening at a specific moment you need to use another approach.
The Fish and Invertebrate Ecology Lab is using Dual-frequency Identification Sonar (DIDSON) to see what their eyes can’t. The DIDSON uses sound to sketch a picture of the environment much like a fish-finder or depth-finder on a boat. When sound hits an object in the water or the bottom, it bounces back. The result is video footage that can be downloaded and later analyzed. The resolution of the image is pretty impressive, considering it’s the product of sound waves. Many species can be identified by their distinct shapes and movement patterns, and their sizes can be estimated. DIDSON was first developed for the military to locate enemy swimmers , but is now being used as a handy tool by anyone who needs to see in murky waters.
The Fish and Invertebrate Lab started using DIDSON with the goal of better understanding the size of river herring populations in Chesapeake Bay. Funded jointly by the National Fish and Wildlife Foundation and the Smithsonian Institution, the project aims to generate accurate population counts of river herring in the Choptank and Nanticoke Rivers. Once a species that supported a major fishery on the Atlantic coast, river herring (actually two species known as alewife and blueback herring) have declined dramatically over the past 10 years. In order to figure out the best way to conserve and manage these populations, the first step is to figure out how many herring are out there. The murky waters and large run sizes make it nearly impossible to get an accurate visual count. Other methods, such as electrofishing and looking at icthyoplankton (fish eggs and larvae) can potentially work as counting methods, but first it must be established how accurate they really are. By deploying the DIDSON during the spring herring runs, footage of the runs can be recorded and the number of fish counted. DIDSON also allows fish to be recorded for several months straight without requiring someone to be out in the field sampling all day and night.
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