Radio Script
2003

Feeding The Bering Sea
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INTRO: The Bering Sea is one of the most productive oceans on earth. Scientists studying the Bering Sea say that's thanks to massive ocean eddies that behave like some sort of oceanic hurricane to bring life-sustaining nutrients up from the abyss. Doug Schneider has more in this week's Arctic Science Journeys Radio.

STORY: Much of the Bering Sea sits atop a broad, shallow shelf that's home to huge populations of fish, shellfish, marine mammals and seabirds. All told, the region is one of the most productive marine ecosystems anywhere on the planet. Phyllis Stabeno is an oceanographer with the Pacific Marine Environmental Laboratory in Seattle, Washington. She says the Bering Sea shelf is rich in nutrients that nourish an abundance of life there.

STABENO: "The deep basin has nutrients, and the top is consumed but the bottom is very nutrient rich. But you have to get the nutrients up on the shelf so that you can feed the phytoplankton so that you can feed everybody else. Each year, during the summer, the nutrients are consumed on the shelf, and so the question is, how do nutrients get back onto the shelf?"

Stabeno says massive pools of swirling ocean, called mesoscale eddies, bring nutrients up from the deep ocean onto the shelf where plankton and fish species live and feed. Her studies of these large eddies are funded by the North Pacific Marine Research program at the University of Alaska Fairbanks.

Stabeno describes these eddies as something akin to hurricanes. They aren't as fast or as violent as hurricanes, but they are big, and they do stir things up.

STABENO: "Hurricanes you think are really fast. These things go around at maybe 80 centimeters per second, which is not terribly fast. But they are huge. And they can last for almost a year. They generally form along the eastern shelf break, where you go from the shallow shelf to the deeper basin. And they slowly drift to the southwest, usually. They are very big features and they are enclosed. The water just goes around in a circle."

These eddies and the nutrients they bring to the shelf also attract whales, fur seals and seabirds. Stabeno says such species are frequently seen feeding along the edge of these eddies.

Scientists can "see" these eddies, not with the eye but through measurements of salinity, temperature and other ocean features across hundreds of miles of ocean. Eddies also produce ever-so-slight changes in the height of the sea. Stabeno says finely tuned satellites can detect this change in sea height and roughly pinpoint their location.

STEBENO: "These things are kind of like cups. You'll have fresher water on the inside of the cup. They reach down some 1,800 meters. These are deep features. As they move across the Bering Sea they take all the water, and everything else that's inside that can't swim by itself moves with it."

Scientists say this mechanism is also chiefly responsible for the transport of tiny newborn fish and crab, called larvae, across vast stretches of open ocean. But are such eddies beneficial to fish and other organisms, or are they potentially harmful? Stabeno says that's the key question she and her colleagues are trying to unravel.

STABENO: "The first thing we are trying to find out is whether these eddies really are rich in nutrients. We have never really studied them carefully. We are just now beginning the work to find out what's different in and around an eddy than where there is no eddy. At the moment we are doing the basic understanding of what's happening in these big features."

This is Arctic Science Journeys Radio, a production of the Alaska Sea Grant Program at the University of Alaska Fairbanks School of Fisheries and Ocean Sciences. I'm Doug Schneider.

Thanks to the North Pacific Marine Research Program for help preparing this script.

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Related websites

North Pacific Marine Research Program

The influence of mesoscale eddies on shelf-slope exchange in the southeastern Bering Sea

NOAA Pacific Marine Environmental Laboratory

NOAA North Pacific Ocean Theme Page

PDF Document

Final Report (Year 2) to North Pacific Marine Research Program: "The Influence of Mesoscale Eddies on Shelf-Slope Exchange in the Southeastern Bering Sea." (PDF, 2.85 MB)

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