Lab 11.5 – OOI Ocean Data Labs

Lab 11.5 – Upwelling: Nutrients from the Deep

Fundamental concept: Ocean pH varies with ocean CO2, which is influenced by both biological and physical processes in upwelling regions.
Estimated time to complete: 20 minutes
Data skills preparation:
Materials needed: None

As we’ve learned, photosynthesis at the ocean’s surface (where there is sufficient sunlight) uses CO2 and nutrients to produce O2 and organic matter. As a result, nutrients are low at the ocean’s surface. At depth, this organic matter is remineralized, or broken down via aerobic respiration. This process – which looks much like the mirror image of photosynthesis – releases CO2 and nutrients at depth.

How, then, do surface waters regain their nutrients? New nutrients can be brought into the system (e.g., via rivers or wind), or nutrients from deeper waters can be recycled within the system. These nutrients from the deep can be brought to the surface via mixing or upwelling. Upwelling occurs anytime surface water diverges – away from other water, or away from a coastline – allowing cooler, nutrient-rich water to rise to the surface. Upwelling areas are some of the most productive areas on our planet, as they lead to the replenishment of limited resources at the sun-lit ocean surface. The Peruvian Anchoveta fishery stock, one of the most productive in the world, is fueled by upwelling along the Peruvian coast. Today’s activity is going to focus on upwelling along the coast of Oregon, and specifically on data collected at the Oregon Shelf Surface Mooring.

Drawing of a coastline showing wind blowing toward the right and creating the upwelling of deeper water

Upwelling by Lichtspiel is in the Public Domain.

Now, let’s explore seasonal patterns in CO2 off the coast of Oregon from July 2020 to August 2021.

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The figures in this widget show three things: 1) the relationship between CO2 concentrations and ocean pH, 2) trends in ocean pH over time, and 3) trends in ocean CO2 over time.

Tips

Select a specific time period to explore that interests you by selecting a range of data in the pH graph (top right). Click to to draw a box over the data points. You can then move the highlighted box to the right or left.

Zoom in and out of the data to look at different time scales that interest you by changing the width of your highlighted box section in the pH graph (top right).

The color denotes the time of year the pH data are from (light purple/pink are from the early part of the record, while blue/dark purple are from the later part.