Gasping for Breath in Hood Canal: Exploring the Dissolved Oxygen Crisis
In this collaborative exercise, students watch a short, online video of Washington State Department of Fish and Wildlife (WSDFW) divers documenting an acute low oxygen event that occurred in Hood Canal during the summer of 2006. They then work in groups to apply their understanding of photosynthesis, respiration, and nutrient cycling to develop hypotheses to explain the event. The instructor then provides additional data and allows the group to revisit their model. In an optional follow-up activity, students generate hypotheses about a water source in their immediate environment and use dissolved oxygen probes and water chemistry kits to test their hypotheses.
Student Learning Outcomes for this Exercise Include:
- Demonstrate an understanding of photosynthesis and respiration by modeling the effects of eutrophication in Hood Canal.
- Interpret primary data to draw conclusions about possible causes of chronic and episodic low oxygen events.
- Apply basic principles of chemistry and physics to model how and why stratification occurs in Hood Canal, and find out what are the biological consequences of this stratification.
Description and Teaching Materials
The Learning ActivitiesPart 1: An Introduction to the Dissolved Oxygen Crisis in Hood Canal.
Students watch a short, five minute video, produced by the WSDFW. The narrated video takes the audience below the surface of the water to witness the unusual behaviors and dying animals associated with acute low oxygen events. This video can be found at: http://wdfw.wa.gov/viewing/guides/diving/habitat.html.
Students then form groups to collaboratively work towards an understanding of these events using a structured worksheet. ("Student Handout 1").
Part 2: Exploring Recent Data Around Dissolved Oxygen in Hood Canal
As written, "Student Handout 1" directs the students to read the recent report " Two mechanisms of low oxygen stress to Hood Canal biota and their associated areas of risk" ("Student Handout 2A"). In this work, Jan Newton provides data on both surface salinity and oxygen levels and clarifies the role that stratification plays in the episodic events in Hood Canal. A list of questions for the students to answer about this work is provided. ("Student Handout 2B").
Part 3: Optional Field Extension 1: Measuring Dissolved Oxygen in Your Watershed
If equipment is available, students may continue their investigation by generating hypotheses to explain how and why dissolved oxygen levels might vary in their own watershed. At North Seattle Community College, Students use Hach dissolved oxygen probes (see http://www.hach.com) coupled with their portable spectrophotometers to measure both dissolved oxygen and a variety of other water quality indicators including phosphate and nitrate. Students then graph the data to look for correlations.
Student Handout 1: Gasping for Breath in Hood Canal- Exploring the Dissolved Oxygen Crisis (Microsoft Word 2007 (.docx) 173kB Oct27 11)
Studnet Handout 2A: Two Mechanisms of Low Oxygen Stress to Hood Canal Biota and Their Associated Areas of Risk (Microsoft Word 2007 (.docx) 214kB Oct27 11)
Student Handout 2B: Gasping for Breath in Hood Canal- Exploring the Dissolved Oxygen Crisis, Part 2 (Microsoft Word 49kB Oct27 11)