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 Univerasity

Flesch–Kincaid Reading Grade Level = 7.3

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.
12.11.24

Little butterflies on the prairie

Butterfly on prairie flower.
A Tiger Swallowtail butterfly visiting a prairie flower to drink nectar.

The activities are as follows:

Butterflies are insects with colorful wings. You will often see them in a field, flying from flower to flower. Butterflies eat a sugary food made by flowers, called nectar. In return, the butterflies help the plants make seeds by moving pollen. As they travel from flower to flower, pollen is dropped off. This helps plants reproduce and make seeds. This is called pollination, and butterflies are pollinators. We need pollinators to grow many of the fruits and vegetables that we eat!

Prairies are habitats filled with many types of flowers. The Midwestern United States used to be covered in prairies. Today, most have been replaced by farm fields. Crops like corn and soybeans are commonly planted in the Midwest. Farm fields are important because we need land to grow our food. But this also means there is less food and habitat for butterflies.

Many farmers are concerned with growing our food while still protecting habitat for butterflies and other species. They want to know – how can we grow food for ourselves while still growing flowers for butterflies? A group of scientists in Michigan is working with farmers to think of solutions. The team is made of people from many different backgrounds and work experiences. The members of the team change over time, but typically 8 scientists are working together at a time. They all come together to brainstorm and do their research at the Kellogg Biological Station in Michigan.

Group of researchers ready to go out into field to butterfly survey.
Members of the Haddad Lab, ready to go out for a day of butterfly sampling in the prairie strips!

Prairie strips are a new idea that might help both farmers and the environment. These strips are small areas of prairie that can be added to farm fields. They look like rows of flowers and grasses within a field. They create habitat for many species, like butterflies, birds, ants, and even microscopic fungi and bacteria! Prairie strips may also help our food grow better by providing habitat for pollinators.

To figure out if prairie strips are able to draw in butterflies, the research team needed to collect data. They visited a large experiment that had many different kinds of farm fields. Some of the fields had prairie strips, while others did not. They thought prairie strips would help butterflies by adding habitat for them in farm fields that usually don’t have many flowers. They predicted they would see more butterflies in fields that have prairie strips and fewer in fields without these strips.

To count the butterflies in each type of field, the team went out on sunny spring and summer mornings when butterflies were flying around and eating nectar. They walked along the same paths in the same fields at the same time every week. Each time, they counted all the butterflies they saw within 5 meters. Each walk was 12 minutes long and followed a 150-meter path. They did these counts in 6 farm fields without prairie strips and 6 farm fields with prairie strips. The team counted butterflies like this 20 times over the summer. At the end of the summer, they added up all of the butterflies observed in each field. This number is called butterfly abundance.

Featured scientists: The Haddad Lab from Kellogg Biological Station Long Term Ecological Research Program – KBS LTER

Flesch–Kincaid Reading Grade Level = 7.3

10.24.24

A burning question

Fire crew in a woodland prescribed fire.

The activities are as follows:

Forests in the midwestern U.S. provide many important ecological services. They store carbon dioxide, which helps fight climate change. They also host a variety of plant and animal life. Forests provide spaces for recreation and support local economies through tourism.

Unfortunately, forests face threats. Climate change is causing more severe weather events, such as flooding and droughts. The spread of some parasites and diseases is also increasing as temperatures change. Forest managers are motivated to protect forest health. They can help combat these threats with their knowledge of different management practices.

Ellen and John have studied forest health in Wisconsin for decades. Ellen first became interested in nature while camping and hiking in Minnesota with her family when she was young. John became passionate about nature as a child while walking through the oak-hickory forests on his family farm. They teamed up with foresters from the Wisconsin Department of Natural Resources to examine the impact of prescribed fire as a management tool to increase forest health. A prescribed fire differs from a wildfire in that it is a planned fire that is set on purpose. When the conditions are right, forest managers will assign prescribed fires to specific areas to meet land management objectives. A lot of organization goes into prescribed fires to make sure the fire doesn’t spread or burn too hot.

Fire is part of the natural history of oak forests. They are adapted to recover quickly and they actually can benefit from fire. This is important for land managers who want to encourage the health of oak forests.

Ellen recording plant species diversity in a plot.

Oaks are considered a keystone species. This means they play a major role in maintaining ecosystem functions and the success of other species. There are two main reasons. First, they produce large amounts of acorns, which are food for many types of wildlife. Second, their canopies have more open spaces that allow light to reach the forest floor. Light is an important resource for plants, and smaller plants are limited by the shade of large trees. More light passing through the canopy allows more plants to grow below the oak trees. This increases the variety of species found in oak forests.

Ellen and John wanted to know if there were more plant species in oak forests that had prescribed fires. To answer their question, Ellen and John decided to study a part of the Madison School Forest in southwestern Wisconsin. This oak forest is special because research has been done on the impact of fire for over 75 years. In 1996, the forest was split into 15 units that have been under different management plans. One of the experimental treatments included prescribed fire at different frequencies. For example, the units in the prescribed fire treatment could have been burned every 1 to 4 years. Other units served as a control and were not burned. Comparing the control to plots that had been burned allows managers to see how often oak forests should be burned to increase forest health.

All of the management units were sampled in 1996 when the experiment first began and again in 2002 and 2007. In each sampling year, the number of plant species, or species richness, in the management units was counted. In 2023, Ellen, John, and their team resampled the plots to pick up this experiment where it was left off. This research will guide the best ways to support the health of oak forests and determine how important fire is to maintaining forest biodiversity. If fire is necessary to maintain oak forests, and oaks are a keystone species that support biodiversity, the research team expects to find higher biodiversity in plots where prescribed fire has been used.

Featured scientists: Ellen Damschen (she/her) and John Orrock (he/him) from
University of Wisconsin-Madison. Written by: Amy Workman (she/her)

Flesch–Kincaid Reading Grade Level = 8.8

9.23.24

Did you hear that? Inside the world of fruit fly mating songs

The activities are as follows:

Communication comes in all forms – through sound, smell, sight, touch, or even taste. The purpose of communication is to share some form of message or information to another organism. One form of communication between humans is talking, which is when we make a variety of noises as we speak using language. Just like people, animals make all kinds of noises to communicate with one another.

The tiny fruit flies that live on the ripe banana in your kitchen communicate as well. They use a courtship song when they are ready to mate. The male fly shakes his wings to sing a song to the female fly. The female fly hears the song, her brain processes the sound, and then she responds. Her brain decides whether she likes him or not. She may then try to kick him away or let him get closer.

Emma is a neuroscientist who is really interested in studying how brains are able to understand all kinds of communication. She uses fruit flies to figure out how brains process communication through sounds. Even though the fly brain is very small, they work a lot like human brains, so studying tiny flies singing to each other can help us understand our own brains.

While researching what other scientists had already learned about fly song, Emma read studies that described an interesting behavior called chaining. Chaining is a behavior when males chase and sing to each other. The scientists first observed this behavior when they played a fly song through a speaker for a group of 6 male flies. Emma wanted to see if she could repeat this behavior in her own lab. An important part of science is repeating experiments to make sure the results are accurate and can be achieved again and again. Repeating experiments can also be a way to test that another scientist’s methods work in your lab.

Sound is played through the yellow speaker. Flies are put into the chambers and watched for chaining

There are lots of things in the lab environment that can impact how a fly reacts to a song. Emma wants to pick a few variables to test. The first variable she selected is the volume of the courtship song being played. Emma decided to test different volumes to see how loudly she should play the fly song to get a response.

Since Emma couldn’t ask the flies if they could hear the sounds she played through her speaker, she measured chaining behavior instead. If the flies heard the sound from her recordings, she expected to see more chaining behavior.

Volume isn’t the only variable she can explore though. Imagine you are listening to a song and the singer sings a word you haven’t heard before. Do you think you’d be able to understand the word? The same thing may apply to the flies. Emma wanted to know if flies would react differently if they had been around other flies that sing. To test this, Emma raised some flies alone and others in groups. That way, she could see if being around other flies before the test made the song easier to recognize.

To gather her data, Emma put 6 male flies into a chamber with a clear top. She placed the chamber in front of a speaker. She also set up a camera to take a video of the flies for a minute before the song played and for a minute after the song began. This two-minute video allowed her to compare the flies’ behavior in silence with their behavior when the song plays. Then, Emma watched the video back and counted the number of flies that were chasing each other every 3 seconds. She did this for one whole minute (20 observation points) to get a chaining index for each group of flies.

Featured scientist: Emma Droste (she/her) from North Carolina State University

Flesch–Kincaid Reading Grade Level = 7.2

Students can listen to this audio clip of fly song and think about what these sounds may be communicating. The audio clip was generated by having a mating pair directly over a very sensitive microphone to capture the audio since it is not audible to the human ear.

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

8.28.24

Guppies on the move

Guppies in the lab. Photo Credit: Eva Fischer.

The activities are as follows:

Animal parents often choose where to have their offspring in the place that will give them the best chance at success. They look for places that have plentiful food, low risk of predation, and good climate.

Even though parents pick out these spots, individuals often move away from their birthplace at some point in their lives. Why do animals move away? There are risks that come with moving from one place to another. It can be dangerous to go through unknown places – potentially stumbling into predators or being exposed to diseases. But there can also be benefits to moving, such as discovering a better spot to live as an adult, finding mates, and spreading out to reduce competition.

As someone who loves to travel and has lived in four different countries, Isabela can relate! Isabela likes to see new places, try new foods, and learn new languages. But there can be drawbacks, and occasionally she finds it hard to be in a completely new place. Sometimes people don’t understand her accent, or she can’t understand them. She also misses her family when she is away. Knowing that traveling and moving can have such highs and lows for herself, Isabela wanted to know more about what motivates animals to seek out new places.

To follow her curiosity, Isabela found a graduate advisor who was also interested in animal movement. She joined Sarah’s lab because she had already collected data on the movement of small tropical fish called guppies. Sarah is part of a large collaborative project, where researchers from all over the world come together in Trinidad to study these fish populations.

When Sarah first started collecting data in this system, she wanted to track how far guppies move from one place to the next. She used established protocols from previous work in this system to set up a study. With the help of a team, she captured every fish in two similar streams for replication. Every fish that was caught was marked with a small tattoo so the research team could recognize it if it was found again in the future. She did this same procedure every month for 14 months. Each time she sampled the fish, she recorded the individuals that she found and where they were found.

Isabela used this dataset to ask whether guppies benefit from moving from one place to another. In this study, she focused on one type of benefit: having a higher number of offspring. It is through reproduction that animals are able to pass on their genes, so the more offspring an individual fish has, the more successful it is.

First, Isabela used the existing dataset to find out how far each fish moved: if Fish 1 was captured in Portion A of a stream in February and then in Portion B of the same stream in March, Isabela knew it had to move from A to B. She could use the timepoints to estimate how far each individual had traveled that month.

Second, Isabela used genetics to find out how many offspring each fish had. She looked at genetic markers to determine familial relationships between individuals in each stream. For example, two fish that shared 50% of their genes were probably a parent and an offspring. In this case, the older individual would be marked as the parent. Isabela used the genetic information to build a pedigree, or a chart that documents each generation of a population. That way she could track how many offspring each parent had produced.

She used these data to answer her question on whether there are benefits to traveling more. Isabela also wanted to compare whether the potential benefits of dispersal differed across the sexes. Males have to compete for females in order to mate. Isabela wanted to know if males that moved more were able to mate with more females and have more offspring.

Featured scientists: Isabela Borges (she/her) and Sarah Fitzpatrick (she/her) from the Kellogg Biological Station at Michigan State University.

Flesch–Kincaid Reading Grade Level = 8.3

Additional teacher resources related to this Data Nugget include:

If you or your students are interested in accessing more of the data behind this Data Nugget, you can download the full dataset from Isabella’s research and have students create graphs in Excel, Google Sheets, or using other data visualization software.

If students would like to learn more about Isabela, check out this Exploring with Scientists video from her time at the Kellogg Biological Station.

For more on this system and the research Sarah did in this study system, check out this unit and video on Galactic Polymath:

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.
8.2.24

A plant breeder’s quest to improve perennial grain

Hannah takes notes on the date of flowering in a Kernza® field in Southwest Minnesota.

The activities are as follows:

Kernza® is a new grain crop that is similar to wheat. It can be ground into flour and used in bread, cookies, crackers and more! Unlike wheat, the rest of the plant can be eaten by livestock such as cattle. Another difference is that Kernza® is a perennial, meaning it grows in the ground for multiple years, whereas annual wheat only grows for one year. However, the challenge is that annual wheat makes more grain and is easier to harvest and sell. This means farmers currently prefer growing annual wheat over Kernza®.

One way to address this mismatch between annual and perennial crops is through selective breeding. This is when humans select individual plants with traits that are desirable for a specific reason. This group of individuals are strategically bred together. The breeder’s goal is to shift the traits over generations. Scientists have only been working on breeding Kernza® for the past few decades; in comparison, humans started selecting annual wheat traits over 10,000 years ago! That is a lot of time to get the traits we are looking for.

Kernza® breeders are working on improving the same traits that have already been improved in annual wheat, including larger seed size. Kernza® scientists follow two main steps to breed plants 1) they select the best individuals from the population and 2) they intercross those individuals to create the next generation, or breeding cycle. With each breeding cycle, plant breeders see a slight improvement in the traits they selected.

Breeders can select plants based on phenotypes, genotypes, or both. Historically, plant breeders have selected based on desired phenotypes, or visible traits, only. Modern plant breeding can take advantage of the fact that we can now look at genotypes, or the genetic makeup, of individual plants quickly and at low costs. Scientists can use this information to make quicker breeding improvements, so we don’t have to wait another 10,000 years for high-yielding Kernza®!

A scientist pipettes DNA samples into an agarose gel to separate samples based on genotype using gel electrophoresis.

Hannah is a scientist currently working on Kernza®. Hannah’s passion for plant breeding was ignited during her high school years. She discovered the captivating world of genetics in her AP Biology class. It was then that she first realized the potential for breeding crop plants to make them more productive and viable for human consumption.

Hannah decided to join other scientists who work on Kernza® at the University of Minnesota. Here, scientists have completed four breeding cycles and are about to start the fifth. Hannah wanted to see whether different genetic makeups (genotypes) lead to differences in seed size (phenotypes). Her goal was to look at each plants’ phenotype and genotype for seed size.

To genotype a plant, scientists collect a small piece of leaf tissue, extract the DNA, and send the DNA to a lab for sequencing. This process tells scientists the genetic makeup that ultimately leads to the traits that we see. Specifically, sequencing data identifies nucleotides, or genetic building blocks of each plant’s DNA. Plants have thousands of genes, which are made up of the DNA nucleotides A, T, C, and G.

Sequencing data can be recorded in several ways. One common way is as SNP data, or Single Nucleotide Polymorphism data. You can think of SNP data as the recipe for proteins. In a SNP dataset, each SNP represents a difference in a nucleotide. Similar to using a different ingredient in a recipe, different nucleotides can result in a different phenotype.

By looking at SNP data, plant breeders can identify differences in genotypes that lead to certain phenotypes. Hannah started by evaluating 1,000 Kernza® plants from the first four breeding cycles. Data on phenotypes had already been recorded for these plants. Hannah then collected SNP data to determine their genotypes as well. She was looking for a pattern between genotypes and phenotypes. If she sees that different genotypes have different phenotypes, scientists can then rely on genotypes to select individuals to breed in future breeding cycles.

Featured scientist: Hannah Stoll (she/her) from the University of Minnesota

Flesch–Kincaid Reading Grade Level = 8.9

Additional teacher resources related to this Data Nugget include:

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 released during photosynthesis. As plants photosynthesize, they absorb 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!

Next Page »