Now a group of scientists led by Lauren Mullineaux at Americas Woods Hole Oceanographic Institution has described in Science how such transfers could happenand, in the process, discovered something surprising about how surface weather influences the deep ocean, traditionally thought of as an isolated, closed world.
The group was monitoring vents more than 2km beneath the surface in the Pacific Ocean off the coast of Central America when it found that quantities of larva and certain chemicals being emitted both fell sharply during periods of unusually strong deep-sea currents. This is consistent with larva and effluent from the vents being swept away into the open ocean. As a colonisation strategy, dispersal by ocean current would be unreliablewith vent systems so scarce, most of the larva swept out to sea would presumably perishbut plenty of plants on land adopt a similar approach using the wind.
The research offers more than just an insight into the life cycle of subsea gribblies. The powerful deep currents were strongly correlated with the passage of wind-generated mesoscale eddies: swirls of water tens or even hundreds of kilometres across on the ocean surface. The idea that surface winds can influence deep-sea currents is surprising, and it suggests that the atmospheres influence may extend far deeper into the oceans than previously thought. The researchers found that the surface eddiesand presumably, the deep currents as welltended to form between autumn and spring, and were more common during El Nio years. Even in the frigid darkness of the deep ocean it seems there may be weather and seasons of a sort.
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