Dr. Amala Mahadevan is a physical oceanographer at Woods Hole Oceanographic Institution. Mahadevan: Ocean currents—particularly, swirling currents known as eddies—can affect plankton in two primary ways. First, they can contribute to their growth by bringing up nutrients from ocean depths to the surface. Mahadevan: Taking dissolved carbon from the surface layer and transporting it to deeper layers of the ocean causes some of the carbon to become sequestered. This, in turn, can decrease the amount of upward mixing of nutrients into the surface ocean.