Gupta and his colleagues report their findings this week in the Proceedings of the National Academy of Sciences.
“As our paper shows, getting the carbon distribution right is not straightforward, and depends on understanding the role of eddies and other fine-scale motions in the ocean.” “There’s a lot of uncertainty about how the carbon cycle of the ocean will evolve as climate continues to change, ” says Mukund Gupta, a postdoc at Caltech who led the study as a graduate student at MIT. While climate models tend to project a decline in the ocean’s ability to sequester carbon over the coming decades, this “nutrient relay” could help sustain carbon storage over the subtropical oceans. Their replenishing effect, which the researchers call a “nutrient relay,” helps maintain populations of phytoplankton, which play a central role in the ocean’s ability to sequester carbon from the atmosphere. Ocean eddies, the team found, appear to be an important source of nutrients in subtropical gyres. These eddies pull nutrients in from high-nutrient equatorial regions and push them into the center of a gyre, where the nutrients are then taken up by other currents and pumped to the surface to feed phytoplankton. Now, MIT researchers have found that phytoplankton may receive deliveries of nutrients from outside the gyres, and that the delivery vehicle is in the form of eddies - much smaller currents that swirl at the edges of a gyre. How, then, were the microbes able to thrive? At the surface, these massive currents appear to host healthy populations of phytoplankton - microbes that feed the rest of the ocean food chain and are responsible for sucking up a significant portion of the atmosphere’s carbon dioxide.īut judging from what scientists know about the dynamics of gyres, they estimated the currents themselves wouldn’t be able to maintain enough nutrients to sustain the phytoplankton they were seeing. These gyres are slow-moving whirlpools that circulate within massive basins around the world, gathering up nutrients, organisms, and sometimes trash, as the currents rotate from coast to coast.įor years, oceanographers have puzzled over conflicting observations within subtropical gyres. Subtropical gyres are enormous rotating ocean currents that generate sustained circulations in the Earth’s subtropical regions just to the north and south of the equator.
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