Lesson Plan

Freeing the Elwha (Salmon Nutrient Cycling)

A black bear feasts on a salmon carcass.
© Howie Garber

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Grade Level:
Sixth Grade-Eighth Grade
Subject:
Aquatic Studies, Biodiversity, Biology: Animals, Biology: Plants, Chemistry, Climate, Community, Ecology, Marine Biology, Oceanography, Oceans
Duration:
One Class Period
Group Size:
Up to 36
Setting:
classroom
National/State Standards:
Washington State Standards:
Science
EALR 4: 6-8, LS2B
Reading
EALR 1: Component 1.2, EALR 5: Component 5.2
Writing
EALR 2: Component 2.1, Component 2.2

Overview

Salmon nutrients find their way into terrestrial environments, how is it possible that trees show evidence of having derived nutrition from Salmon?

Background

This lesson focuses on 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.


Materials

  • Lesson 13- Salmon Nutrient Cycling.pptx
  • Food Web Lab.pdf
  • Food Web Quiz.pdf
  • Reflection Journal Pages (Printable Handout)
  • Vocabulary Notes (Printable Handout)


Procedure

Review Essential Question; introduce Guiding Question.

Students should take a few minutes to respond to the first reflection prompts. Discuss their answers and any questions they've generated.
Hand out the Vocabulary Notes. With this lesson you may want to define the words before presenting the PowerPoint Lesson.
Present the PowerPoint Lesson.
Food Web Lab Activity.
Food Web Quiz.
Hand out the second Reflection Journal Page. Give students time for a final reflection the lesson.



Additional Resources

http://newstandardnews.net/content/index.cfm/items/2854
http://chamisa.freeshell.org/food.htm
http://www.wildlifenews.alaska.gov/index.cfm?adfg=wildlife_news.view_article&articles_id=97

For struggling learners:

http://www.snh.org.uk/Salmonintheclassroom/salmon_foodchains.shtml
http://www.scienceisart.com/B_FoodChain/FoodChain.html



Vocabulary

Stable Isotope
Carcass
Marine-derived Nutrients
Nitrogen-15 isotope
Terrestrial
Vertebrate