Lab 5.1 – What trends or patterns can you observe in dissolved oxygen levels in the ocean at this location?

Estimated time to complete: 45 minutes
Materials needed: None

In this activity we will examine OOI data concerning the amount of dissolved oxygen (DO) in the seawater over a few weeks a few kilometers away from the area where the Oregon Department of Fish and Wildlife filmed the dying crabs in the crab pot.

Use the graph to answer the following questions. When you hover over a data point, a box will pop us with more information. You can turn zoom and out of areas of the graph using the slider bar.


Orientation questions

  1. What data does the x-axis represent? What does the y-axis represent?
  2. Why is DO an important data set for making interpretations about life in the ocean?
  3. Most organisms need a DO level of 2 mg/L or above to be able to live. Below this level, we consider conditions to be “hypoxic”, and if DO falls to 0 mg/L, conditions are “anoxic”. Click the “next” button to bring up a line that marks 2 mg/L, the threshold for hypoxic conditions. Characterize conditions on the seafloor over the weeks that this data was collected. Was hypoxia common, rare, or non-existent during this time?

Interpretation questions

  1. What is the absolute lowest oxygen level you can find? When did it happen?
  2. How many longer-term (longer than one or two days) hypoxic events happened during the interval covered by this data??
  3. Was there any trend in the general oxygen levels during the hypoxic events through this time interval?
  4. Was there any trend in the general oxygen levels during the times when conditions were not hypoxic/anoxic?
  5. What are some ways ocean water becomes oxygenated?
  6. Would these processes operate in the same way in all parts of the ocean? What are some differences you might see with depth?
  7. The following figure shows us DO along a transect across the Oregon shelf by Endurance Glider #384. The colors represent levels of dissolved oxygen. Does this real-word data support your hypotheses in the previous questions? [INSERT DO PROFILE HERE]

Assessment questions

  1. An area in the ocean 400 meters below the surface has a DO level of 8 mg/L. What is the best explanation for this?
    • This is to be expected, due to the natural stratification of the ocean.
    • This must be a place where shallow water is downwelling into the deep ocean.
    • This must be an area of high productivity due to photosynthesis.