Lab 8.1 – 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 up with more information. You can zoom in and out of areas of the graph using the slider bar.


Quick Check Questions


Interpretation Questions

  1. Most organisms need a DO concentration of 2 mg/L or above to be able to live. Below this concentration, we consider conditions to be “hypoxic,” and if DO falls to approximately 0 mg/L, conditions are “anoxic.” Click the “Draw 2 mg/L Threshold Line” box beneath the graph to bring up a line that marks 2 mg/L, the threshold for hypoxic conditions. Characterize conditions on the seafloor over the weeks that these data were collected. Was hypoxia common, rare, or non-existent during this time?
  2. How many longer-term (longer than a few hours) hypoxic events happened during the interval covered by these data?
  3. Choose one of the hypoxic events in June. Roughly how long, in days, did DO remain below the hypoxia threshold?

Application Questions

  1. What are some ways ocean water becomes oxygenated? Would these processes operate in the same way in all parts of the ocean? What are some differences you might see with depth?
  2. Make a hypothesis about which parts of the ocean would be well-oxygenated and which parts would not be.
  3. The following figure shows us DO along a transect across the Oregon shelf by Endurance Glider #384, near our study area. The colors represent levels of dissolved oxygen. Do these real-word data support your hypotheses in the previous questions?


Figure 8.1.1. Vertical sections collected by a glider in the Endurance Array (upper panel). Lower panel shows position of the glider color-coded by time.