9.20.25

Salmonberries in our future

Picking salmonberries is a cultural tradition for many Alaskans.

The activities are as follows:

In the Yup’ik and Cup’ik Native communities of western Alaska, berry picking is a deeply rooted tradition. Many villages are located more than 500 miles from the nearest road system or grocery store. Fresh fruits and vegetables from other places are flown in by small planes at significant cost. This makes local berries a lifeline for these remote villages.

Salmonberries (also known as cloudberries) are one type of Arctic berry. They are prized for their wonderful taste. Salmonberries are rich in nutrients like vitamin C, antioxidants, and essential minerals. One cup of salmonberries alone can meet a person’s daily vitamin C needs. In addition to humans, these berries provide nutrients to other animals, such as migrating birds, small mammals, and bears.

During berry season, families travel across the land to gather berries, preserve them, and store them for the winter. Families use a vast web of winding rivers to travel by boat to reach their berry picking camps. These western Alaska rivers flow towards the Bering Sea, where freshwater mixes with salty ocean tides.

This mix of saltwater and freshwater shapes the tundra landscape. Tough, salt-tolerant plants, like grasses and sedges, often dominate low-lying areas closest to the sea. Slightly higher ground, just above the reach of the tides, provides a more suitable home for berries. These subtle shifts in water levels play a large role in determining where berries can grow.

Salmonberry ready to be picked.

Ecologists Karen, Katharine, and Joshua are collaborating with Native communities to learn more about how changes in climate are affecting berry plants. They are studying two major changes already observed under climate change – warming and flooding. Over time, warming and flooding combined could change the entire makeup of plant communities. This will affect whether local families are able to continue their traditions and access this valuable food source.

Alaska’s average temperatures are increasing, more so than other parts of the globe. This warming might help some plants by extending the growing season. With more time and sunlight, salmonberries and other plants may actually grow faster.

Climate change is also expected to increase flooding in some areas of coastal Alaska. Storms are already becoming stronger and more frequent, pushing seawater farther inland. Because of this, flooding events are increasing in frequency. Rising sea levels and storm surges may kill salmonberry plants because these plants are not adapted to having their roots submerged in salty water. They used this water to simulate flooding events in the plots. In the end, their experiment had four different types of plots: (1) Control plots with no warming or flooding, (2) plots that were warmed, (3) plots that were flooded, and (4) plots that were both warmed and flooded.

To tease apart the effects of warming and flooding, Karen, Katharine, and Joshua designed a field experiment to simulate climate change. They built clear plastic structures, called open-topped chambers, to trap heat and raise the temperature by about 2°C. These chambers can be thought of as mini time machines, creating small areas that have the expected temperatures of the coming decades. Next, they created flooded plots using brackish, or slightly salty, water that they collected where the fresh river water meets the sea.

They let these treatments run the full growing season. After that time, the team collected data on salmonberry growth. Karen, Katharine, and Joshua measured both the height and biomass of salmonberry plants in all of the plots. These two measures are good estimates of how many berries the plants will produce – the larger the plant, the more berries it can make. They were very precise in their measurements; in a place where food and traditions are tied to the land, every berry matters.

Featured scientists: Karen Beard (she/her) of Utah State University, Katharine Kelsey (she/her) of the University of Colorado Denver and Joshua Leffler (he/him) of South Dakota State University. Written by: Andrea Pokrzywinski (she/her).

Flesch–Kincaid Reading Grade Level = 5.7

7.5.25

Catching fish with sound

Mei next to the research vessel, Endeavor

The activities are as follows:

In our ocean, the connections between the environment and marine organisms are intricate and complex. The watery surroundings connect each level of the food web – including marine mammals, large fish, schooling fish, phytoplankton, and more. Climate change is causing our ocean to become warmer, and organisms are already starting to respond. When ocean waters change, the effects cascade through different levels of the food web. In order to understand how marine organisms, and their interactions, are affected by changing climate, we need accurate measurements that tell us what populations are like today and continue monitoring into the future.
As a biological oceanographer, Mei’s research focuses on organisms in the middle of marine food webs. These are the small schooling fish, like anchovies and herring, that consume other organisms, but are also vulnerable to predation. Growing up in Japan, the ocean was always a part of Mei’s life through hobbies such as swimming, fishing, and also from knowing the cultural importance of eating seafood and learning to prepare for tsunamis. She was first introduced to ocean science through a local fisher who had an oyster farm near her hometown. Since then, she has pursued her career as an oceanographer across three different countries – Japan, Canada, and the United States – both in academia and industry.

Mei now does research as part of a Long-Term Ecological Research project out of Massachusetts. This means that Mei is part of a scientist team working together to study long-term patterns in the ocean.
Looking at data over time allows Mei and others to better identify and understand the consequences of climate change. This information Mei next to the research vessel, Endeavor will help fishers and fisheries managers make decisions and prepare for the future.

Mei testing equipment before a research cruise

In August 2023, Mei went to sea on one of the project’s research cruises. She wanted to take a closer look at one of the fastest-warming ocean areas and richest fisheries in the world – the continental shelf of the Northeast U.S. She boarded a large research ship for 6 days with a team of 14 other scientists who specialize in different areas of oceanographic research. To more accurately collect these data, Mei used sound! Echosounders bounce sound off marine organisms, such as fish. This tool is similar to fish finders that are used by most fishing boats. However, the technology used by Mei is more sensitive and provides more detailed data.
The amount of sound that comes back to the ship after bouncing off fish or anything in the water is called volume backscattering strength, and is measured in decibels (dB). The intensity of what comes back can serve as a measure of fish abundance. If there are more fish, the number becomes larger (less negative).
While the echosounder is operating, other members of the research team measure water temperature and other parameters from the surface to near the bottom. Temperature is measured in degrees Celsius (ºC), and depth is recorded in meters (m). Mei wanted to use these data to give her a snapshot in time of where fish are located.

Featured scientist: Mei Sato (she/her) from Woods Hole Oceanographic Institution and
Northeast U.S. Shelf LTER (NES-LTER)

Flesch–Kincaid Reading Grade Level = 9.8

5.30.25

CO2 and trees, too much of a good thing?

The activities are as follows:

Kristina conducting the tree survey, measuring the size of a tree, which will later be used to calculate the mass of carbon in that tree.

The amount of carbon dioxide (CO2) in the atmosphere has steadily increased since the start of the Industrial Revolution in 1750. This extra CO2 traps heat like a blanket, causing the global climate to warm. The resulting climate change effect is known and widely accepted in science. While scientists are certain that climate change is happening, they still have many questions about its impacts.

For example, scientists today are exploring whether climate change will help or hurt trees and forests. Many scientists think that elevated CO2 in the atmosphere can actually help trees. We can see why in the formula for photosynthesis:

6𝐶𝑂2+6𝐻2𝑂+𝐸𝑛𝑒𝑟𝑔𝑦→𝐶6𝐻12𝑂6 +6𝑂2

Carbon Dioxide + Water + Energy (sunlight) → Glucose + Oxygen

If you add more CO2 to the atmosphere, trees will have more resources for photosynthesis and can make more glucose. Glucose is food for the trees. Trees can use their glucose for growth, using it to make wood. However, trees sometimes have to put glucose towards other things. Just like us, plants break down glucose for energy through cellular respiration:

C6𝐻12𝑂6 +62→ 6𝐶𝑂2+6𝐻2𝑂+𝐸𝑛𝑒𝑟𝑔𝑦
Glucose + Oxygen → Carbon Dioxide + Water + Energy (ATP)

Two large trees stand in the experimental plot after a survey. The tree to the right has been banded to measure its growth.

Trees need energy for everyday functioning, or to respond to stress. Under climate change, trees might experience more stress. Stress for trees might increase if summer temperatures get too hot, or they don’t have enough water. More stress means more respiration and less growth. Or, even worse, the trees could die. Dead trees can’t photosynthesize, and they also decompose, which releases CO2 into the atmosphere
as microbes break down wood and other materials.

Kristina and Luca are scientists looking at the effects of climate change on trees. They wanted to test whether climate change was benefitting or hurting trees. They set out to find some data that would allow them to test these alternative hypotheses.

A dead ash tree stands in the experimental plot after a survey. The carbon in this tree
will return to the atmosphere through decomposition.

Kristina runs a tree census in a forest at the Smithsonian Conservation Biology Center in Virginia. Since 2008, she and many other scientists have surveyed every tree in their 26-hectare plot. Every five years, they count up how many trees are alive, how much they’ve grown, and how many have died. Luca joined Kristina’s lab in 2022. He and Kristina worked together with many other scientists to collect and process data on tree growth and mortality in 2023.

They used this growth and mortality data for individual trees to calculate levels of carbon gained and lost by the whole forest. The amount of carbon used for growth across the whole forest was measured as the mass of carbon gained. They also calculated the weight of the trees that died, which was measured as the mass of carbon lost. Both of these measurements were calculated in megagrams (Mg, that’s one million grams) of carbon (C) per hectare (ha) of forest per year (yr), or (MgC/ha/yr). The difference between these
two values is the change in carbon. This value gives the balance between carbon gained and lost. A positive value means there is more carbon being taken in by the forest than lost, and a negative value means that more carbon is being lost back to the atmosphere.

Featured scientists: Kristina J. Anderson-Teixeira (she/her) & Luca Morreale (he/him) at Smithsonian’s National Zoo & Conservation Biology Institute. Written by Ryan Helcoski

Flesch–Kincaid Reading Grade Level = 7.8

1.20.25

Microbes facing tough times

Jennifer sampling soil before the shelters were set up. Here you can see the control (left) and carbon addition (right) plots.

The activities are as follows:

As the climate changes, Michigan is expected to experience more drought. Droughts are periods of low rainfall when water becomes limiting to organisms. This is a challenge for our agricultural food system. Farmers in Michigan will be planting crops into conditions that make it harder for corn, soybean, and wheat to grow and survive.

Scientists are looking into how crop interactions with other organisms may help. Microbes are microscopic organisms that live in soils everywhere. Some microbes can help crops get through time times. These beneficial microbes are called mutualists. They give plants nutrients and water in exchange for carbon from the plant. Microbes use the carbon they get from plants as food. If plants are stressed and don’t have any carbon to give, microbes get carbon from dead plant material in the soil.

Jennifer is a biologist studying the role of microbes in agriculture. She has always been interested in a career that would help people. As a student, Jennifer thought she would have a career in politics. Along the way, she learned that a career in science is a great way to study questions that may lead to solutions for the challenges we are facing today. Jennifer was drawn to the Kellogg Biological Station, where she joined a team of scientists studying the impacts of climate change and drought on agriculture.

Jennifer and other scientists set out to test ways that we can give mutualists in the soil a boost. She thought, perhaps if we were to give microbes more food, they would be less stressed during a drought and would be able to help out crops growing in these stressful conditions.

To test this idea, Jennifer needed to test how well microbes were doing under different carbon and drought conditions. First, she set up treatments in soybean fields to manipulate the amount of carbon in the soil. She set up control plots where she left the soil alone. She also set up carbon treatment plots where dead plant litter was added to the soil to increase the carbon available to microbes.

Next, Jennifer manipulated the availability of water in her plots to test the microbes under stress. To do this, she set up her plots under shelters that kept out rain. The shelters had sprinklers, which were automated to add specific amounts of water to the plots. This design allowed Jennifer to control the watering schedule for each plot. One shelter treatment was a control, where water was added to the plots every week. This is similar to the schedules of local farmers who add water through irrigation. The other shelter treatment was drought, where plots received no water for six weeks. This experiment was replicated 4 times, meaning there were 4 shelters on the control watering schedule and 4 shelters that were under drought conditions.

A view of one of the shelters used in Jennifer’s experiment.

Finally, Jennifer had to measure how the microbes were doing in each treatment. She did this by measuring their enzyme activity. Enzyme activity is a measure of how active the microbes are. The higher the enzyme activity, the happier the microbes are. To measure this, Jennifer collected soil samples from each plot throughout the growing season and took them to the lab to measure enzyme levels in the soil samples. These enzymes are made by microbes when they are active. She then calculated the mean of all her samples for each treatment combination.

Jennifer predicted two things. First, if drought is harmful to microbes, then she would expect to see lower enzyme activity in the drought treatment compared to the irrigated treatment. Second, if adding carbon to the soil is a way to help microbes overcome the challenge of drought, she expected higher enzyme activity in the plots with plant litter added compared to the control treatment. Both of these taken together would indicate that drought is stressful for microbes, but we can help them out by adding resources like plant litter to soils.

Featured scientist: Jennifer Jones (she/her) from the Kellogg Biological Station Long Term Ecological Research Site. Written with Melissa Frost and Liz Schultheis.

Flesch–Kincaid Reading Grade Level = 8.2

Additional teacher resources related to this Data Nugget:

To introduce this Data Nuggets activity, students can watch a talk by Jennifer when she made a classroom visit to share her background and research interests. This video is a great way to introduce students to scientist role models and learn more about what a career in science looks like, as well as get an introduction to the themes in the research.

There is also a video of Jennifer and her scientist colleague, Grant Falvo, out in the field talking about their research under the rainout shelters.

For more information about the rainout shelter experiment, students can watch this short video featuring Jennifer Jones and another scientist on the team, Grant Falvo:

These data are part of the Kellogg Biological Station Long Term Ecological Research Program (KBS LTER). To learn more about the KBS LTER, visit their website.

1.9.25

Do you feel the urban heat?

Attaching a heat sensor to a street sign in Miami to monitor urban temperatures.

The activities are as follows:

Record-breaking temperatures climb higher every year, and Florida is no exception. In Florida, the impact of climate change is felt mostly during the hurricane season. Storms are becoming more violent and show up earlier in the season. These extreme temperatures and weather events affect living organisms of all types, including humans. Outdoor workers, the elderly, and all people who lack adequate housing are susceptible to temperature changes in the environment.

Heat sensor ready to be put out into the city.

Irvin teaches science at a high school in Miami, Florida. On his way to work, he listens to a local radio station to catch up on the news. One day the radio hosts were talking about an increase in homelessness in Miami and other cities. They also brought up the record heat that the U.S. was experiencing and how this may affect those without homes. This conversation on the radio made Irvin think. He reflected on the impact that such high heat could have on individuals who sleep without air conditioning.

This inspired Irvin to learn more about what could be done to mitigate the impact of climate change in his city. Irvin joined a program that invites teachers to work in scientists’ labs in the summer to gain research experience. Irvin was matched with Tiffany, a scientist interested in how urban heat can change based on structures like concrete buildings, urban dwellings, and unshaded places. Irvin took this opportunity to explore how high temperatures in Miami affect the daily lives of people living there. First, Irvin started looking into how temperatures are reported in Miami. He learned that there was just a single sensor stationed at the nearby airport. The heat and humidity readings from this one sensor are used by local officials to alert the entire city about dangerous heat levels. Alerts are issued when the heat index reaches 108 degrees Fahrenheit or higher. Heat index is a value that represents how the body feels temperature when humidity is factored in. With these alerts, people can take action by spending less time outside.

Teachers visiting the mangroves in Miami on a record heat day.

Irvin realized that no matter how reliable the sensor at the airport is, there is likely a larger range of temperatures within the city. He wanted to know whether the temperatures at the airport were similar to the heat felt at places where people spend time outside.

Tiffany’s research team had already started to collect temperature data in urban places where they hadn’t been recorded before. Since 2018, her lab placed hundreds of small heat sensors around the city. The sensors go out for 3 months and then the team collects them, records their data, and places them back out into new areas of the city.

Irvin wanted to compare areas that varied in coverage from the sun. He focused on sites where people gathered and spent long periods of time outside – bus stops. Some of the sites he chose had shade from trees, some had a roof providing partial sun cover, and other sites were totally exposed with no shade. Irvin took photos of each bus stop and used them to classify all sites as either full coverage, partial coverage, or no coverage. He used data from the airport as a control comparison to his bus stop sites.

Featured scientists: Irvin E. Arce (he/him) and Tiffany Troxler (she/her) from Florida International University

Flesch–Kincaid Reading Grade Level = 9.6

12.20.24

Does the heat turn caterpillars into cannibals?

Kale in the lab setting up an experiment with fall armyworms.

The activities are as follows:

Around the world, temperatures are rising from climate change. This is a hot topic for scientists because warmer temperatures could make diseases spread a lot faster. Many diseases spread by the foods we eat. With warmer temperatures, metabolisms increase, and organisms need to eat more food to survive. This increases the risk of eating something that will get them sick.

When Kale started graduate school, they joined a lab that studies how climate change affects the spread of disease in fall armyworms, a type of caterpillar. Fall armyworms are an agricultural pest known for destroying corn, soybeans, and other crops worldwide. In the summer, they move into fields and rapidly chow down on crops. It’s often reported by farmers that it seems as though fall armyworms can remove all the leaves from a cornfield overnight! Believe it or not, their huge appetite leads them to another food source – they will even turn into cannibals and eat each other!

Once Kale started graduate school, they became interested in how cannibalism can increase disease spread in warmer temperatures. Fall armyworms can get infected with a special type of virus called a baculovirus. Baculoviruses are a group of viruses that infect insects, especially caterpillars. They are highly specialized, meaning that each baculovirus usually only infects one species.

A fall armyworm that has been liquified due to a baculovirus infection.

If a fall armyworm eats a fellow fall armyworm that is infected, it can be deadly. In fact, the disease causes their body to completely liquify into a puddle of pure virus! This baculovirus is so effective that farmers even use it to help control infestations in their fields. Since this specific baculovirus only infects fall armyworms, it is safe to use on crops without worrying about effects on humans or other living things.

To study how cannibalism can affect disease spread, Kale designed a set of experiments. They thought that when temperatures are higher, the larvae’s metabolism would increase and make them hungrier caterpillars. Increased appetite could then lead to more cannibalism. As a result, more larvae would be eating others that are infected, further spreading the deadly baculovirus.

To test these ideas, Kale set up small Petri dishes and placed one big fall armyworm in each dish as the focus of each trial. Kale added a piece of insect food and a smaller fall armyworm to each dish. This way, the larger caterpillars had the option of eating the insect food, cannibalizing its smaller friend, or munching on both.

To see if temperature had an impact, Kale set up three treatments at low, medium (ideal), and high temperatures. They assigned 40 Petri dishes to each temperature. To test changes in disease transmission, half of the smaller caterpillars were infected with baculovirus, and half remained uninfected.

Kale predicted that fall armyworms at higher temperatures would cannibalize more because they need more food to keep up with an increased metabolism. They also predicted that fall armyworms that eat an infected caterpillar would be more likely to become infected at higher temperatures.

Featured scientists: Kale Rougeau from Louisiana State University

Flesch–Kincaid Reading Grade Level = 10.2

Additional teacher resources related to this Data Nugget include:

You can also watch a time-lapse video of Kale in the lab to get a glimpse of their work. Follow along as they check fall armyworm cadaver samples for baculovirus infection using a microscope
Kale also provided a video of baculovirus lysing, where occlusion bodies that encapsulate the virus are dissolved, confirming the presence of infection in the fall armyworm sample.
  • Read more about Kale’s hobby of participating and training for dog competitions on the Beyond the Bench blog.
  • More about fall armyworms here and here.
9.23.24

Too hot to help? Friendship in a changing climate

This coral has lost its algae partners, causing it to be bleached. (Photo by Coffroth Lab)

The activities are as follows:

When given emergency instructions on a flight, you’re told to put on your own oxygen mask before assisting others. This is because if you run out of oxygen, you won’t be able to help others. Turning to nature, this same idea may be true when we look at relationships between two species.

Coral and certain types of algae form a mutualism where both species benefit from the partnership. Coral provides a safe home for algae, and algae make food for coral through photosynthesis. However, climate change is causing warmer ocean temperatures that stress the relationship. If the water gets too hot for algae, they can’t make food for the coral anymore. To survive, the algae must help themselves before they can help the coral.

Casey is a biologist interested in studying the changing coral-algae mutualism. He wants to know whether different individuals of the same algae species do better than others in warming waters. Individuals of the same species can have different traits. For example, each human person belongs to the same species, but each of us has different traits. This is largely because of our genetic composition for these traits, or genotypes. Casey set out to test if different algae genotypes were capable of being better mutualists under warm temperatures. If he could identify these genotypes, then maybe that could help protect coral in the future.

Casey gets a sample of algae from a flask in his lab. (Photo by David J. Hawkins)

Casey and his graduate student, Richard, set up experiments to test algae genotypes to see how well they performed at different temperatures. Casey and Richard grew five different genotypes of the same algae species in the lab. They used a pipette to transfer 10,000 cells of each genotype and placed them in flasks at two different temperatures. The lower temperature treatment is one where corals and their algae are usually happy: 26 degrees Celsius. The higher temperature treatment is where coral’s relationship with algae starts to break down: 30 degrees Celsius. At that temperature, many corals lose their algae entirely, in a process called coral bleaching.

Casey and Richard measured two things – the total amount of photosynthesis and the total amount of respiration happening in each flask. They did this by tracking what happened to oxygen over time. When there is a lot of photosynthesis, oxygen goes up, and when there is a lot of respiration, oxygen goes down. Two conditions are best for the mutualism. First, a lot of photosynthesis means the algae produced more food that they can share with coral. Second, less respiration means the algae used less of the food for themselves and have more to share with the coral. In summary, when the algae is stressed it does less photosynthesis and more respiration, making it a worse trading partner for coral. The best algae partner is the genotype that can photosynthesize the most and respire the least. The net food available is how much of the food made through photosynthesis is available after subtracting the food used by respiration.

Featured scientists: Casey terHorst (he/him) and Richard Rachman (he/him)

from California State University Northridge

Flesch–Kincaid Reading Grade Level = 8.9

Additional teacher resources related to this Data Nugget

8.24.24

Do urchins flip out in hot water?

Erin in the urchin lab at UC-Santa Barbara.

The Reading Level 1 activities are as follows:

The Reading Level 3 activities are as follows:

Teacher Resources:

Imagine you are a sea urchin. You’re a marine animal that attaches to hard surfaces for stability. You are covered in spikes to protect you from predators. You eat giant kelp – a type of seaweed. You prefer temperate water, typically between 5 to 16°C. But you’ve noticed that some days the ocean around you feels too hot. 

These periods of unusual warming in the ocean are called marine heatwaves. During marine heatwaves, water gets 2-3 degrees hotter than normal. That might not sound like much, but for an urchin, it is a lot. The ocean’s temperature is normally very consistent, so urchins are used to a small range of temperatures. Urchins are cold-blooded. This means they can’t control their own body temperature and rely on the water around them. Whatever temperature the ocean water is, they are too!

Erin is a scientist who studies how environmental changes, like temperature, affect organisms. Erin first got excited about urchins when she interned with a research lab. When she started graduate school, she learned more about their biology and started to ask questions about how urchins would react to marine heatwaves. Hot water can speed up animals’ metabolisms, making them move and eat more. However, warmer temperatures can also cause stress, potentially causing urchins to be clumsier and confused.

Erin getting ready to scuba dive to look for urchins off the California coast.

One summer, two science teachers, Emily and Traci, came to California to work in the same lab as Erin. Emily and Traci wanted to do science research so they can share their experience with their students.  As a team, they decided to test whether marine heat waves could be stressing urchins by looking at a simple behavior that they could easily measure. Healthy urchins have a righting instinct to flip over to orient themselves “the right way” using their sticky tube feet.

The research team predicted that urchins would be slower to right themselves in warmer temperatures. However, they also thought the response could depend on the temperature the urchins were used to living in. If the urchins had been acclimated to higher temperatures, they might not be as strongly affected by the heatwaves.

Together, Erin, Emily, and Traci took 20 urchins into her lab and split them into 2 groups. Ten were kept at 15°C, the ocean’s normal temperature in summer. The other ten were kept at 18°C, a marine heatwave temperature. They let the urchins acclimate to these temperatures for 2 weeks. They tested how long it took each urchin to right itself after being flipped over. They did this at three temperatures for each urchin: 15°C (normal ocean), 18°C (heatwave), and 21°C (extreme heatwave). They worked together to test the urchins three times at each temperature to get three replicates. Then they calculated the average of each urchin’s responses.

Featured scientists: Erin de Leon Sanchez (she/her) from University of California – Santa Barbara, Emily Chittick (she/her), and Traci Kennedy (she/her) from Milwaukee Public Schools.

Flesch–Kincaid Reading Grade Level = The Content Level 3 activity has a score of 7.9 ; the Level 1 has a score of 5.9

Additional teacher resources related to this Data Nugget include:

  • Here is a video of a parrotfish finding and eating an urchin. Show this video to emphasize how important it is for urchins to be able to right themselves!
Video of a trial where the researchers flipped over an urchin and timed how long it took the urchin to flip back over.
Watch how sea urchins use items from their environment to cover themselves.
8.1.24

Poop, poop, goose!

Cackling Goose next to a pile of goose poop, or feces
Cackling Goose next to a pile of goose poop, or feces. Photo by Andrea Pokrzywinski.

The activities are as follows:

Each spring, millions of birds return to the Yukon-Kuskokwim Delta. This delta is where two of the largest rivers in Alaska empty into the Bering Sea. It is also one of the world’s most significant habitats for geese to breed and raise their young. 

With all these geese coming together in one area, they create quite a mess – they drop tons of poop onto the soil. So much poop in fact, that scientists wonder whether poop from this area in Alaska could have a global impact! Climate change is a worldwide environmental issue that is caused by too many greenhouse gasses being released into our atmosphere. Typically, we think of humans as the cause of this greenhouse gas release, but other animals can contribute as well. 

When poop falls onto the soil it is decomposed by bacteria. Bacteria release methane (CH4), a potent greenhouse gas. The more geese there are, the more poop they will produce and the more food there will be for soil bacteria. By increasing the amount of greenhouse gasses that are released by soil bacteria, geese might actually indirectly contribute to global climate change.

Trisha is an ecosystem ecologist who scoops goose poop for research projects. Her research is looking into whether animals, other than humans, can change the carbon cycle. Trisha teamed up with Bonnie, a fellow ecosystem ecologist. Bonnie studies how matter moves between the living parts of the environment, such as plants and animals, and the nonliving parts. She is especially interested in how bacteria in the soil play a role in the carbon cycle.

Together, the team designed a three-year project to figure out the effects of goose poop on the carbon cycle. Each summer, a large team of researchers spend 90 days camping on remote sites near the Yukon-Kuskokwim Delta. The team scooped up poop from nearby goose habitats to use in their experiments. They set up six control plots where they added no poop and six treatment plots where they added poop. From these twelve plots, the team measured methane emissions from the soil. Methane was measured as methane flux in micromoles, or µM. These data helped them determine how ecosystems respond to geese by measuring whether goose poop affects methane production by soil bacteria.  

Featured scientists: Trisha Atwood of Utah State University and Bonnie Waring of Imperial College. Written by Andrea Pokrzywinski.

Flesch–Kincaid Reading Grade Level = 8.7

Additional teacher resources related to this Data Nugget include:

7.17.24

Sink or source? How grazing geese impact the carbon cycle

Tricia (left) installing carbon dioxide plots in the field.

The activities are as follows:

“If it wasn’t for the geese, you and I would not be here today because our ancestors would not have made it. When long, hard winters emptied people’s food caches early, starvation loomed. Return of geese in April saved us.” – Chuck Hunt, born and raised on the Yukon-Kuskokwim Delta

Spring geese are an essential food source for subsistence communities like Chevak, Alaska. Elders in western Alaska Native communities have observed a decrease in geese returning to their villages over time. These changes affect the local communities and could also affect the local ecosystem.

One way geese change their environment is by eating grass. In the Yukon-Kuskokwim Delta in western Alaska, birds from every continent on Earth migrate to this sub-Arctic habitat to lay their eggs and raise their young. Once they arrive, geese eat a ton of grass. They graze only in specific areas, called grazing lawns, leaving the rest of the vegetation alone.

When geese graze on wetland plants, they remove plant matter, potentially decreasing the amount of carbon dioxide, or CO2, that is absorbed during photosynthesis. As plants photosynthesize, they take CO2 from the atmosphere and turn it into glucose (a sugar) and oxygen. Gross primary production is the total amount of energy that plants capture from sunlight to grow and live before they use up some of that energy for themselves. Plants can slow climate change by removing CO2 from the atmosphere and turning it into plant matter, like leaves and roots.

A scientist mimics geese grazing by clipping the grass.

Trisha is a scientist who became interested in ways that animals can affect the carbon cycle through their interactions with the environment. She wondered whether fewer geese returning to western Alaska could have global consequences that extend beyond remote communities. She thought that if geese ate enough grass, they may limit photosynthesis. This is important because it could change whether this ecosystem is a carbon sink or a carbon source. An ecosystem is called a carbon sink if it absorbs more CO2 through photosynthesis than it releases through respiration. Alternatively, an ecosystem can be a carbon source if more CO2 is released than absorbed. We want ecosystems to be carbon sinks because then they keep CO2 out of the atmosphere, where it contributes to global warming.

To test her idea, Trisha teamed up with fellow scientists Bonnie, Karen, and Jaron to take a closer look at how grazing grass influences whether the Y-K Delta ecosystem is releasing or absorbing CO2. To do their experiment they had to get creative. They considered getting a lot of geese, bringing them to an ungrazed area, and letting them chow down. However, it’s hard to capture geese and get them to graze exactly where you want. So instead, the research team simulated the effects of geese by cutting the grass to mimic nibbling and then gently vacuuming the pieces of grass to remove them.

The “Carbon and Geese” scientist team.

The team set up six different experimental areas. Inside each area were two plots: one that was left ungrazed, and the other which was artificially grazed. The research team then used a piece of equipment called a LI-COR to measure the quantity of CO2 in the air above each plot. They recorded the CO2 levels during the day and night. The comparison from day to night is one way to look at gross primary production and respiration in a system. At night, when there is no light, plants can’t photosynthesize, so the detected CO2 will be from respiration. The levels during the day represent a combination of CO2 absorption by plants and release from respiration.

To assess whether the ecosystem is a carbon sink or source, we need to determine the difference between respiration and gross primary production, or net ecosystem exchange (NEE). A negative NEE means the ecosystem absorbs more CO2 than it emits. A positive NEE means the ecosystem is releasing more CO2 than it is absorbing. In this way, scientists classify an ecosystem as either a carbon sink that is storing carbon or a carbon source that is releasing carbon into the atmosphere.

Featured scientists: Trisha Atwood, Karen Beard, and Jaron Adkins from Utah State University and Bonnie Waring from Imperial College. Written by Andrea Pokrzywinski.

Flesch–Kincaid Reading Grade Level: 8.9

Additional teacher resources related to this Data Nugget:

Check out this website created by teacher Andrea who participated in the research and wrote this Data Nugget. You will find additional lesson plans, videos, slides, and articles to use in the classroom!

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