Teaching Nutrient Cycling and Climate Change Concepts Using Excretion Experiments with Common Fish

Many high school students learn about nutrient cycling during biology, environmental science, and agriculture classes. These lessons often focus on soil and plants, and nutrient cycling is usually taught independently from climate change. Scientists know that animals, including fish, can have strong effects on nutrient cycling (i.e., nitrogen and phosphorus) in ecosystems. Additionally, research has shown that nitrogen and phosphorus excretion rates of animals increase with water temperatures. We worked with high school students to design and conduct nutrient excretion experiments using common fish (zebrafish) to explore the impact of climate change on nutrient cycling. This allowed students to have hands-on laboratory experience. In 2021, we worked with students participating in a residential summer program in Georgia. Meanwhile, in 2022, students enrolled in the local high school visited the university campus on two occasions to participate in the experiments, and we once again worked with students in Georgia. Students from all three groups showed an increased understanding of the role of animals in nutrient cycling and ways climate change may impact these processes, despite variable results from the excretion experiments. Students also showed increased understanding of science processes and were more likely to feel like part of the science community. We believe that these experiments can be done in high school classrooms to expand students' understanding of the scientific process, nutrient cycling, and climate change.