Salmon Nutrient Cycling
- Grade Level:
- Middle School: Sixth Grade through Eighth Grade
This activity helps students learn how marine-derived nutrients from salmon carcasses find their way into terrestrial environments and how scientists can track these marine-derived nutrients to analyze their importance to ecosystems today, as well as reconstructing past ecosystem processes. Terrestrial vertebrates such as mammals and birds, as well as, insects consume salmon carcasses and then release those nutrients onto land, either by dragging the carcasses or defecating onto the forest. These nutrients then enter the soil, where they are taken up by plant roots. Once entering plant tissue, they are consumed by herbivores. Salmon nutrients have been found in every living organism investigated and up to seven miles from the stream of origin. Scientists use stable isotope N15 to track marine-derived nutrients, because this isotope is more common in marine environments than freshwater ones. Analyzing sediment layers of lakes for this isotope, scientists can reconstruct ancient salmon abundance and can make inferences to historic climate and ecological processes.
- Stable Isotope: An isotope which does not spontaneously undergo radioactive decay
- Carcass: The dead body of an animal,
- Marine-derived Nutrients: Nutrients acquired by an anadromous fish and deposited in a freshwater or terrestrial ecosystem when that fish dies.
- Nitrogen-15 isotope: A stable, non-radioactive, rare isotope of Nitrogen containing 8 neutrons instead of 7. It is more common in marine environments that freshwater or terrestrial habitats. Thus, its elevated presence outside of a marine environment is an indication that nutrients are marine-derived
- Terrestrial: Of or relating to the earth or its inhabitants
- Vertebrate: an animal with a backbone, such as a fish, amphibian, reptile, bird, or mammal.
For struggling learners: