Oceanography major Deana Crouser is doing more than getting her feet wet on the R/V Rachel Carson. She’s helping peer into the future of our oceans.

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With the goal of using her education to help the environment, Deana Crouser landed a summer internship in the lab of University of Washington oceanography professor Julie Keister. There was just one key hurdle to overcome: “I didn’t know the name of one kind of zooplankton. I didn’t even know where they were in the food web,” she says. Now she grasps their immense importance in predicting ocean health.

Crouser switched majors from chemical engineering to oceanography during her junior year at the UW, and her internship with Keister involved 10 days aboard a research vessel called the R/V Carson. Preparing for the trip meant a steep learning curve, but Crouser embraced it.

“There was always something to look forward to,” she says. “I feel like this internship gave me life again.”

A backyard laboratory

Having spent weeks in the lab studying zooplankton samples and research data, Crouser joined Keister and oceanography professor Daniel Grünbaum on the R/V Carson for their trip around Hood Canal. Along with two graduate students and a volunteer, the team gathered samples to learn more about how zooplankton change their behavior in response to environmental conditions.

Part of Puget Sound, Hood Canal is a nearly 70-mile-long glacial fjord whose oxygen content drops in late summer and fall.

“It’s like a mini ocean,” says Keister. “It’s incredibly diverse oceanographically and biologically over small scales, so it’s really easy to study important processes here.”

Zooplankton spend their lives searching for food — usually phytoplankton, the microscopic algae that are the linchpin of all ocean life. Where phytoplankton bloom, so do zooplankton; and where zooplankton thrive, so do larger marine animals, from salmon to orca whales.

What will happen to zooplankton as our oceans continue to warm and absorb human-produced carbon dioxide, growing more acidic and lower in oxygen? And if they adjust their behavior accordingly, what happens to the animals that feed on them?

These are big questions with big ramifications. To help peer into the future, Keister and Grünbaum are starting very, very small.

Lessons from the microscopic
Zooplankton make two mass migrations a day. They surface at night to eat phytoplankton, then head back to deeper, darker water to avoid being seen by predators in the daylight.

On board the R/V Carson, in addition to tracking the movements of large zooplankton populations, Grünbaum, Keister, Crouser and the rest of the team used special cameras to observe individual zooplankton in their natural habitat. The two professors suspect that zooplankton’s behavior in response to changing environmental conditions may be magnified as those changes ripple up through the ecosystem.

“The water in Hood Canal is stratified,” explains Keister, meaning that different depths have widely divergent oxygen and pH levels. “Zooplankton are moving through big differences in conditions as they go up and down.”

Grünbaum gives one example of what these movements can teach us: If significant populations of zooplankton are able to hide in low-oxygen waters to avoid predators, we may see a drop in salmon populations and an uptick in jellyfish — predators that are better suited to those conditions.

Whatever the findings, says Keister, “It could have significant implications for the food web.” This includes where humans harvest animals — and what we’re able to catch.

Oceanography major Deana Crouser assists researchers on the R/V Carson as they cruise around Hood Canal. (University of Washington)
Oceanography major Deana Crouser assists researchers on the R/V Carson as they cruise around Hood Canal. (University of Washington)

The ocean of tomorrow
As she gets ready to graduate in June, Crouser feels optimistic about her place in the future of oceanography. Armed with real-life lab and field research experiences, she’s poised to make an impact in her field. But she also faces the reality that tomorrow’s ocean may be starkly different from what she’s always known.

“There’s a lot at stake when it comes to the ocean,” she says. “It can be sad at times. But schools like this are what give me hope. It’s this research. It’s the UW.”

Learn more about the University of Washington’s research at uw.edu.