Oceanus Magazine
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Images: Where the Food Is in the Sea, and Why

Jessica Benthuysen, who graduated from the MIT/WHOI Joint Program in June 2010, created a mathematical model to better understand what controls upwelling, or vertical movement of water, at the edge of the continental shelf. Upwelling brings nutrients from great depths to surface waters, where they stimulate the growth of phytoplankton that support the oceanic food web. (Photo by Tom Kleindinst, Woods Hole Oceanographic Institution)

Between the shallow, gently sloping continental shelf and the abyss of the deep ocean lies the steep continental slope. The edge between the shelf and the slope is called the shelf break. Phytoplankton, zooplankton, fish, seabirds, whales, and dolphins thrive in the waters above the shelf break, supported by nutrients brought from great depths by upwelling. MIT/WHOI Joint Program student Jessica Benthuysen analyzed how the currents near the shelf break south of Cape Cod control upwelling. (Illustration by Jack Cook, Woods Hole Oceanographic Institution)

A complex system: The currents near the North American shelf break include the large, warm, salty Gulf Stream flowing north and east; warm core rings that bud off the Gulf Stream; the large, cold, relatively fresh shelf current flowing south and west from the Arctic; a narrow, fast, cold jet flowing right along the shelf break; and near-bottom flow across the continental shelf from the coast toward the shelf break. (Illustration by Jack Cook, Woods Hole Oceanographic Institution)