Ocean Currents – Southern Ocean
There is a layer of plant life which lives at the surface of ocean and which the entire ocean ecosystem depends upon. Now this plant life feeds on nutrients and the nutrients routinely sink to the bottom of the ocean. One of the mysteries of science is how do those nutrients get back to the surface of the ocean? I’m Jim Metzner, and this is the Pulse of the Planet.
“We have this layer at the top where the light comes, and then we have the barrier layer, and then we have the deep ocean. And the problem is that we need to bring nutrients back up from the deep ocean through the barrier layer into the surface.”
Jorge Sarmiento is a professor at Princeton University.
“What we found out was that the pathway for a very large fraction of the nutrients to get back up into the barrier layer is actually completely in a different part of the ocean. Itâ€™s that huge band of ocean that circles around the Antarctic called the southern ocean. This is an area where the surface waters are very, very dense. And itâ€™s quite easy for the deep waters, which are also dense, to come all the way to the surface. And so this is a place where all those rich nutrients that have been getting broken down and dissolved again by bacteria, come right up to the surface.
So the nutrients go into the deep waters below the barrier layer everywhere in the world. Then those nutrients are transported towards the south. And around the Antarctic the circulation of the ocean is such that these nutrients are brought up to the surface and then they’re transported towards the north.
This source of nutrients from the southern ocean controls about three-quarters of the oceanic biological productivity outside the southern ocean. So itâ€™s a massive, massive supply of nutrients thatâ€™s absolutely critical to biological productivity in the rest of the world ocean.”
We’ll hear more about the dynamics of the ocean in future programs. Pulse of the Planet is made possible by the National Science Foundation.