## Lab 5.2 – How do DO levels correlate to seawater temperatures?

Estimated time to complete: 45 minutes
Materials needed: None

In this activity we will add a new data set collected over the same time at the same place, seawater temperature. We will look for patterns in how these two data sets may correlate with each other.

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.

[WIDGET 2]

### Orientation questions

1. What data does the x-axis represent? What does the y-axis represent?
2. What is the range of temperatures experienced in this part of the ocean during this time, lowest to highest?

### Interpretation questions

1. What are some reasons ocean water can be different temperatures? In a general way, where in the ocean do you expect colder water, and where in the ocean do you expect warmer water?
• How does water temperature vary by latitude and why?
• How does water temperature vary by depth and why?
2. The following figure shows us seawater temperature along a transect across the shelf by Endurance Glider #384. The colors represent different temperatures. The seawater temperature data we are examining was collected in approximately 25m of water. According to this profile, what is the expected approximate temperature of seawater off the Oregon coast at 25m? [INSERT FIGURE HERE]
3. According to the figure above, at what approximate depths would we usually find water at the temperature range we see in our minimum temperatures for our 25m study site?
4. How many periods of prolonged low temperatures (more than a day or two) do you see in this data?
5. When the temperatures go from cooler to warmer, do they do so abruptly (over a day or two), or do they do so gradually, changing more slowly over many days?
6. Compare the two interactive graphs. When the water temperatures get lower, the dissolved oxygen levels get (lower/higher).
7. Does DO change at the same pace (rapid or slow) as the seawater temperature?
8. Formulate a hypothesis as to why the seawater is changing temperature and dissolved oxygen content in the pattern observed here. What other sorts of data might be needed to test your hypothesis?

### Assessment questions

Examine these two profiles. The Y axis shows us depth in meters. The X axes show us another variable, with numbers getting bigger left to right. The first graph shows us how temperature changes with depth. Which of the next two shows us how dissolved oxygen is likely to vary with depth, under most circumstances? [INSERT PROFILES HERE]