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Images: The Great South Channel

The Great South Channel is an undersea canyon between shallower Nantucket Shoals and Georges Bank. A relatively fresh coastal current flows south along the New England coast. In the channel, the coastal current collides with saltier, denser water to form an ocean front. (Amy Caracappa-Qubeck, Woods Hole Oceanographic Institution)

A relatively fresh coastal current carrying tiny marine organisms called copepods flows into the Great South Channel. The current collides with saltier, denser water to form an ocean front. The denser, saltier water sinks beneath the lighter, fresher water. Copepods sinking with the water swim back toward the surface, aggregating in dense patches along the front. (Amy Caracappa-Qubeck, Woods Hole Oceanographic Institution)

The atmosphere has boundaries between warm and cold air called fronts. The oceans have fronts, too, where currents with different temperatures and salinities collide. You can sometimes see the outline of a front by the material that tends to accumulate along it. (David Fratantoni, Woods Hole Oceanographic Institution)

To unravel the circumstances that create rich feeding areas for marine animals, scientists use autonomous underwater gliders. These vehicles “fly” through the ocean, collecting data on water temperature and salinity, currents, copepod clusters, and whale sounds. (Ben Hodges, Woods Hole Oceanographic Institution)

Thick swarms of copepods appear every spring in the Great South Channel, creating a hearty buffet for whales, cod, haddock and basking sharks, which return to feed every year. (Amy Caracappa-Qubeck, Woods Hole Oceanographic Institution)