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Apr 10, 2007 |
Science Diary: Healthy Ocean- Blue Desert
Why is the ocean sometimes green, instead of blue? Music Why is the ocean like a desert and why isnt it always blue? Welcome to Pulse of the Planets Science Diaries, a glimpse of the world of science from the inside. Were with conservationist Carl Safina, aboard a research vessel off the coast of Central America. Hes talking with research scientist Lisa Ballance about why the water around their boat is green, and why that makes this region such a hot spot for marine life. Lisa Balance: Theres so much water in this gigantic surface current that it ends up essentially forming what they call a cyclonic gyre. Which basically means a ring of water thats moving counterclockwise, which causes a vacuum in the middle, and it causes the subsurface waters to move to the surface. And so, what you see is this cold water that typically is high in nutrients, and chlorophyll respond to it, so it has high chlorophyll content. Thats what causes the greenness of the water, and its very distinct. You can see it from satellites quite easily. Carl Safina: Right, and that chlorophyll youre talking about is actually single celled plants that are green, using the deep nutrients. Lisa Balance:Yeah, thats correct, and the reason the rest of the tropics are classically blue tropical water is blue is because of a lack of chlorophyll. Theres plenty of sunlight, clearly, in the tropics, but theres not enough other nutrients that photosynthetic organisms need to grow. So, the water is clear blue. Carl Safina:Because theres really nothing living in it. Its actually a desert. The big, open ocean is generally a desert. Lisa Balance: Exactly. You can check out Carl Safinas blog on pulseplanet.com. Pulse of the Planets Science Diaries are made possible by the National Science Foundation. Im Jim Metzner. Music ANIMALS,Oceans,Conservation,Ecology,Water Scientist: Carl Safina |
