Tag Archives: science

A Sweet Solution to a Sticky Problem

When you’re a biologist at a site named for a legendary environmentalist, you feel a responsibility to do your job with the planet in mind.

Just ask Dr. Susan Adamowicz, Land Management Research and Demonstration Area biologist for the Northeast Region of the Fish and Wildlife Service. Stationed at Rachel Carson National Wildlife Refuge in Maine, she is tasked with finding innovative ways to manage wildlife habitat and takes inspiration from the renowned author.

In 1962’s Silent Spring, Carson, who also worked for the Service, sounded the alarm about pesticides that imperiled wildlife and people alike. She knew that many of the synthetic chemicals used to control unwanted plants and insects were dangerous to more than their targets.

For a healthy environment, Adamowicz seeks other solutions … and hopes she has found one with the help of a University of New Hampshire researcher.

A “Consummate Invasive Species”

Phragmites australis, or common reed, is an aggressive, nonnative marsh grass that pushes out native wetland plants. You’ve probably noticed its tall (up to 18 feet!), feathery, golden stalks in your neighborhood or along the freeway.

Phragmites is plentiful in the high salt marsh of the Great Marsh, the largest continuous stretch of salt marsh in New England. Three thousand acres of the 20,000-acre marsh in eastern Massachusetts lie within Parker River National Wildlife Refuge.

Phragmites changes the structure of the salt marsh, filling natural channels and tidal pools where waterbirds, fish, and invertebrates find food and safety. Many wildlife species find its dense patches impassable, and in the fall, when the stalks die back, stands of the plant turn to tinderboxes primed for wildfire, putting nearby homes and businesses at risk.

Biologists have long searched for effective ways to control Phragmites. It’s a determined adversary, however. Like those birthday candles that re-ignite, just when it seems defeated, it springs back to life.

According to Adamowicz, “Phragmites is the consummate invasive species. If you cut it or burn it, it comes back. If you can flood it for six months, that might kill it, but flooding is not always feasible.”

Phragmites grows along a marsh at Sachuest Point National Wildlife Refuge in Rhode Island. (Credit: Tom Sturm, USFWS)

While restoring natural tidal flow to coastal marshes is the preferred way to fight Phragmites,  replacing culverts, filling ditches, and improving drainage can take a long time. Treating it directly is necessary to keep it in check in the meantime.

Sadly, there’s been no good way to do that. Herbicides work in certain locations but pose a risk to native vegetation and groundwater — certainly not a solution Rachel Carson would embrace.

So Adamowicz teamed up with Dr. David Burdick, research associate professor and interim director of the Jackson Estuarine Laboratory at the University of New Hampshire, to explore innovative ways to control Phragmites. One of the methods they tested was sweet and simple.

Turning the Tables

Burdick had a hunch that sugar, the same kind you put in your coffee, might be Phragmites’ Kryptonite.

Dr. David Burdick takes notes at Parker River National Wildlife Refuge. (Credit: Gregg Moore, UNH)

Each summer, rising air temperatures and increased plant growth stimulate bacteria in salt marsh soils to convert organic matter and oxygen into carbon dioxide, water, and energy — a process called aerobic (“with air”) respiration. The activity quickly uses up soil oxygen, forcing other groups of bacteria to make energy using anaerobic (“without air”) respiration.

One by-product of anaerobic respiration is hydrogen sulfide gas, a potent toxin for plants as well as people. At typical levels, the gas is not deadly to most native plants, but it can be toxic to Phragmites.

Burdick thought increasing bacterial respiration, and therefore hydrogen sulfide levels, could kill the invasive.

“Because Phragmites is a master at getting oxygen to its roots for its own respiration, we could use this strength to kill it,” he mused. “By elevating soil hydrogen sulfide levels, we might stimulate the plant to oxidize the gas into a strong acid that it may not be able to tolerate.”

While he couldn’t control air temperatures, he could increase fuel for the bacteria — using glucose in the form of table sugar.

Pour Some Sugar on It

Burdick and his team first tested their idea in the greenhouse. They soaked Phragmites plants with bay water for three hours every two weeks to mimic the flooding that high-marsh plants get during the extra-high “spring” tides that come with the full and new moons each month.

Some plants (the control) received only the bay water; others got water with table sugar; still others water with extra salt; and the remaining, water with sugar and salt.

In the greenhouse study, plants receiving sugar or sugar-plus-salt (right, top and bottom) showed clear signs of distress within weeks of treatment. (Credit: Gregg Moore, UNH)

Both the sugar and sugar-and-salt treatments showed signs of stress within weeks and eventually died. Only the plants that received plain bay water or bay water with added salt lived.

The sugar-treated plants had very high soil acidity, possibly caused by sulfuric acid, the product of hydrogen sulfide oxidation. This supported Burdick’s theory.

Next, Burdick and Adamowicz headed to Parker River Refuge to set up a field study in the northern part of the Great Marsh. The research was supported by federal funds for Hurricane Sandy recovery and resilience projects.

Following the greenhouse trial, Burdick and his team tested the treatments in the Great Marsh at Parker River National Wildlife Refuge. (Credit: Gregg Moore, UNH)

They isolated individual Phragmites plants and applied the same treatments as in the greenhouse. Sugar and salt were put on the plants every two weeks, after the spring tides flooded the marsh.

The plants that got sugar had far greater mortality than the other treatments, even with uncontrollable environmental factors, such as rain — a clear sign that sugar is not sweet to Phragmites.

Refining the Technique

Adamowicz is pleased with the study results so far and eager to set up more field trials. She’s exploring ways to treat Phragmites with sugar and salt more efficiently and broadly, perhaps using a backpack sprayer to apply corn syrup at more-frequent intervals than every two weeks.

“This is another tool in our toolbox, and it’s nontoxic to wildlife, which is very desirable,” she said. “The more complicated response to Phragmites is ecosystem restoration, but in the meantime, we need a fast-acting tool to help native plants come back and buy time.”

If Rachel Carson were alive today, she would certainly approve of this environmentally sound method — and just might be thinking, “Sweet!”

Radar love: Weather data detects hotspots for migratory birds

Have you ever taken a long road trip covering hundreds or even thousands of miles, during which you were pretty much flying by the seat of your pants navigationally? Let me guess: You were broke, moving, between jobs, between semesters, on a journey of discovery, or all of the above. And if your trip took place in the not-so-distant pre-smartphone era, you were also constantly trying to figure out your next move based on maps, vacancy signs, and billboards promising all-you-can eat anything, though usually not salad.


Migratory birds like yellow warbler need to make many stops to rest and refuel during their annual journeys to wintering grounds as far away as South America. Credit: FWS

Migratory birds that breed in North America embark on a similar journey every fall to reach wintering grounds as far away as South America. Similar in that they are also flying by the seats of their pants, but different in that they are actually flying, are not wearing pants, and face much graver dangers than overindulging at the waffle bar.

Tall buildings, food scarcity, high winds, cats — rife with threats, migration is a stressful time in the life of birds. They suffer higher mortality in this period than in any other phase in their annual life cycles, and that can put a strain on entire populations. It’s critical that birds have safe places to rest and refuel along this perilous journey, and the more we can do to help manage and protect important stopover sites for them, the more likely they will be to reach their destinations.

The first step to protecting the most important stopover sites is to figure out where they are located. I know what you’re thinking: Bird migration road trip


Radars detect birds initiating migratory flights from stopover sites, and provide an estimate of the relative density of birds leaving a given location

Dr. Jeff Buler at the University of Delaware had a better idea. “In the Northeast, nothing provides more comprehensive coverage of the land surface than radar,” he points out. “It detects birds over more than a third of the land area in the Northeast.” 

With support from the U.S. Fish and Wildlife Service and other partners, Buler and his colleagues analyzed seven years of weather surveillance radar data to predict potentially important stopover sites for migratory landbirds in the region. They also conducted surveys for two fall seasons at 48 sites in the Delmarva peninsula and mainland Virginia to corroborate the radar detections with that they observed on the ground.

“We wanted to know: What are birds doing during stopovers, and why are they choosing certain sites over others?” says Buler. Here is what they found out:

Bright lights, bird city

When was the last time you gazed up at the Milky Way galaxy shimmering in the night sky from your front steps? For 70 percent of the population of the United States, it’s been awhile. Light pollution has increased dramatically in the past century, and the Northeast is one of the brightest areas on the entire planet. It’s affecting more than star gazers.

“Birds flying at about 500 meters above the ground can always detect the sky glow of some large city on the horizon,” says Buler. For migratory birds, artificial light is never out of sight, and it appears to be attractive. The study showed that migrant bird density increased with proximity to the brightest areas. Also known as cities.


A composite satellite image of the Northeast and Midwest shows the extent of artificial night light in the region. Credit: NASA

Two other key factors that determine where birds are likely to stop are the distance to the Atlantic coast, and the amount of hardwood forest cover on the landscape. “Migrant density is higher in places where there is more food, but migrants also become concentrated in coastal areas because winds push them out over the ocean, and they need need to retreat back to land,” explains Buler.

Across the landscape, results showed that birds responded positively to the coast, bright lights, hardwood forest, and any combination of those variables, indicating that migrant stopover was extra concentrated in woods of urban and suburban parks near the Atlantic coast.

“We need to recognize the importance of urban parks for migratory birds,” says Buler. For the thousands of individual birds representing hundreds of species that are passing through in the fall, these areas are like oases in the concrete jungle. Enhancing the habitat quality of urban forests for migrants by planting native vegetation that will host more insects and fruit during migration may be the best way to maximize the conservation value of these parks.

He also points out an important demographic detail: The relative intensity of use of urban areas is higher in the fall than in the spring. “Fall is when you see naive birds that are migrating for the first time, and studies show that juveniles have strong orientation to bright lights,” says Buler. “Probably in fall, parks are hosting a lot of young birds.” Which represent future generations of their species.

Between meals

If in the midst of a long road trip, you crashed on the floor of a friend’s studio apartment overlooking a busy intersection, you might be inclined to hit the road first thing the next morning. Especially if it’s that friend with the enormous dog who could use a bath and always seems to want to lick your face. If during that same trip, however, you crashed in the guest room of your grandparents’ quiet country home, and they were eager to cook for you, you’d probably stay until they kicked you out.

The ground surveys that Buler and his colleagues conducted at stopover sites in Virginia, Delaware, and Maryland not only helped them corroborate what they were seeing on the radar, they helped them figure out how long birds stayed at certain stopover sites, and why. As with people, it has a lot to do with the quality and quantity of resources available to help them rest and refuel.

“We could see the whole spectrum of uses across the framework of site types,” said Buler, explaining that the framework ranges from so-called “fire escape” sites that only offer a safe place to land in an emergency, to sites with lots of food and space where birds can comfortably rest and refuel.

“The fire-escape sites – which are typically along the coast and in urban areas — get heavy day-to-day use, but there is a lot of turnover,” he says. “Whereas birds tend to stay longer at sites away from the coast with lots of food.”


Shrubs that fruit in the fall, like American cranberry bush, are an important food source for birds during their seasonal migration. Credit: USDA

But the surveys showed that birds tend to stay the longest at sites in the middle of the resource spectrum. While that may seem counterintuitive to those of us who can’t get enough of grandma’s cooking, it’s consistent with what ornithologists call optimal migration theory. “If food is really good or really poor at a given site, you will only stay for a short time: Either there is nothing to eat, or you get a giant satisfying meal right away,” explains Buler. “At places where there is only a moderate amount of food available, it takes longer to refuel, so birds tend to stay longer.”

The surveys also provided detailed intelligence on what exactly migratory species are eating during their stopovers, and the researchers used that information to model habitat relationships for 14 of the most common species.

“For example, both black-throated blue warblers and American redstarts seem to be more closely associated with Lepidoptera larvae – caterpillars of moths and butterflies — than just insects in general,” says Buler.

Sky’s the limit for use on the ground

The combination of the regional radar data and the survey data equips people involved in conservation at any scale to identify important stopover sites and make management decisions that reflect the needs of specific species, such as ground foragers that feed on insects in the leaf litter.

The radar data capture nearly half of the National Wildlife Refuges in the Northeast, emphasizing their importance as stopover habitat, particularly in properties near the Atlantic Coast.

While the maps are useful for informing management strategies on protected lands — Buler says the data can help identify new priorities as well. “We can see many places with heavy use by migratory birds that are not yet protected.”

When Gwen Brewer of the Maryland Department of Natural Resources looked at the study results, she said, “The Pocomoke River corridor on the Eastern shore just lit up like crazy as a migratory hotspot.”

Pocomoke State Forest - Pocomoke River

The Pocomoke River corridor shows up as a hotspot for migratory birds on the radar. Credit: Maryland DNR

The DNR provided funding to help ground truth the radar data in coastal Maryland and the Delmarva Peninsula through the Resource Assessment Service Power Plant Research Program. Brewer, who is the Science Program Manager for the Wildlife and Heritage Service, said the study can direct her agency to other priority areas where they can use fine-scale data to narrow in on the forest patches that offer the greatest value to migratory birds.

“By showing us what stands out as important in Maryland, the study also helps us understand what our role should be in the big conservation picture,” she said. “It helps us think about the responsibility we have as part of the larger landscape, and that can inform our in-state process for acquisition, easements, and grant proposals.”

The full report, maps, and data depicting predicted bird density during fall migration are now available in the Northeast Stopover Sites for Migratory Landbirds gallery on DataBasin, and you can find a short video that the University of Delaware produced about the artificial light finding here.

We are what we eat: Scientists probe the potential effects of emerging contaminants

When contaminants get into the water system, some people might assume that standard water treatment techniques would make that water free from potential contamination.

The truth is, it is not that simple.

What happens when detergents, flavors, fragrances, hormones, medications, new pesticides, veterinary medicines, and other chemicals make their way into waterways of the Great Lakes Basin? Researchers are exploring these contaminants of emerging concern, or CECs, to help us better understand the potential impacts on wildlife and people.

For example, consider a commonly used over-the-counter pain reliever. Sunlight, temperature, pH or microbial activity will naturally break it down into different smaller compounds. Those smaller compounds, and the medication itself, are collectively termed “contaminants of emerging concern.”

Between the years of 2010 and 2014, our agency, the U.S Geologic Survey, and the Environmental Protection Agency (EPA) set out to characterize emerging contaminants present in Great Lakes Tributaries.  From 2015 to the present investigations have focused on assessing hazards and impacts these contaminants have on fish and wildlife species.

Daniel Gefell, biologist for the USFWS, holding a Bowfin at one of the sampling sites, USFWS.

Daniel Gefell, biologist for the USFWS, holding a Bowfin at one of the sampling sites, USFWS.

Funded by the Great Lakes Restoration Initiative, collaborators sampled water, sediment, and fish populations from a variety of different Great Lakes field sites. In New York, field efforts were primarily focused in the Rochester area and in the North Country in the St. Lawrence river drainage.

The most consistently studied organism is fish, with few studies directed toward the toxic effects in freshwater mussels, freshwater aquatic plants, or other native aquatic species. Four approaches were taken to evaluate fish populations and the effects of emerging contaminants.

1)         Biologists measured over 200 sampling sites and found that many of these emerging contaminants are consistently present in the water and sediment within the Great Lakes Tributaries.  From this information, biologists determined which chemicals are most often detected and at what levels so they could mimic environmental conditions with laboratory studies.

2)         In the same places where CECs were found, wild fish populations were evaluated for indicators of poor health including changes in physical appearance and reproductive health.

Drawing blood from a fish to send in for CEC analysis, USFWS.

Drawing blood from a fish to send in for CEC analysis, USFWS.

3)         Unexposed hatchery raised fish were caged and placed in the same areas where CECs were found and where wild fish were evaluated.  Hatchery fish were used because they were unexposed to CECs before the evaluation.  Biologists then compared hatchery fish to the wild fish to help determine the impacts of CECs on their health.

4)         Biologists looked at previous scientific publications of field and laboratory studies to take advantage of all the information we know about individual chemicals and their effects on fish. Biologists used the lab information to infer hazards to fish due to exposure of CECs.

So far, lab studies are confirming that many of the CECs have negative impacts on fish including mortality, developmental effects, and reduced reproductive capacity. Many studies have also confirmed that some CECs accumulate in fish.

Tumor on the mouth of a bullhead - Photo Credit Jo Ann Banda, USFWS.

Tumor on the mouth of a bullhead – Photo Credit Jo Ann Banda, USFWS.

What does it mean when other animals–or even people–eat those fish?

Not enough information is known yet to say for sure how eating fish living in a CEC rich environment could impact humans, but a study published in 2015 evaluated a large group of northeastern bats to determine if CECs could be found within those bat populations.

Have you ever heard of the phrase “you are what you eat”? That’s essentially what’s happening here.

Northeastern bats have a high metabolism, meaning they have to eat a lot of food! The bats are eating bugs, which may have lived in contaminated environments. In turn, eating a lot of insects could mean they have a higher likelihood of exposure to chemicals in the environment. The bugs are incorporating the contaminants into themselves from eating or living with exposure to these contaminants, and when the bats eat the bugs, the contaminants within the bugs are being incorporated into bat tissues.

The results of the 2015 study showed that CECs could be detected within the bats themselves. The CECs detected most frequently in samples were PBDEs (compounds used in flame retardants), salicylic acid, thiabendazole(a fungicide), and caffeine. Other compounds detected in at least 15% of bat samples were digoxigenin, ibuprofen, warfarin, penicillin V, testosterone, and N,N-diethyl-meta-toluamide (DEET), all of which are commonly used.

How do these contaminants make their way to bats? Well, we have some clues. When we dispose of household or personal items, or apply substances to our properties, they can make their way to streams. Insects accumulate them because they live in those areas, and then the bats feed on the insects.

Many of the CECs we are most concerned about were made to be biologically active in the human body (i.e. medications) and we know they work well because they made it into the marketplace. That information coupled with the fact that we know very little about the broader scope of CECs, besides lab studies, is troubling.

What this means for human health….we don’t know. A large number of people get their drinking water from the Great Lakes. Emerging contaminants have been found in some Great Lakes drinking water supplies.

These are complicated issues that warrant deeper exploration to determine the potential human and environmental health impacts as well as ways to help prevent the continued contamination of our environment.

We live in a world where these types of far-reaching health concerns have become prominent in our day to day lives. It is a stark reminder of the finite resources our world possesses and that the actions we take greatly impact not only our direct health and well-being, but the global health of all who inhabit the earth.