Science Diary: Healthy Ocean- Blue Desert

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Why is the ocean like a desert and why isn’t it always blue? Welcome to Pulse of the Planet’s Science Diaries, a glimpse of the world of science from the inside. We’re with conservationist Carl Safina, aboard a research vessel off the coast of Central America. He’s 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: “There’s 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 that’s 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. That’s what causes the greenness of the water, and it’s very distinct. You can see it from satellites quite easily.”

Carl Safina: “Right, and that chlorophyll you’re talking about is actually single celled plants that are green, using the deep nutrients.”

Lisa Balance:”Yeah, that’s correct, and the reason the rest of the tropics are classically blue tropical water is blue is because of a lack of chlorophyll. There’s plenty of sunlight, clearly, in the tropics, but there’s not enough other nutrients that photosynthetic organisms need to grow. So, the water is clear blue.”

Carl Safina:”Because there’s really nothing living in it. It’s actually a desert. The big, open ocean is generally a desert.”

Lisa Balance: “Exactly.”

You can check out Carl Safina’s blog on pulseplanet.com. Pulse of the Planet’s Science Diaries are made possible by the National Science Foundation. I’m Jim Metzner.

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Science Diary: Healthy Ocean- Blue Desert

Why is the ocean sometimes green, instead of blue?
Air Date:04/10/2007
Scientist:
Transcript:

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Why is the ocean like a desert and why isn't it always blue? Welcome to Pulse of the Planet's Science Diaries, a glimpse of the world of science from the inside. We're with conservationist Carl Safina, aboard a research vessel off the coast of Central America. He's 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: "There's 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 that's 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. That's what causes the greenness of the water, and it's very distinct. You can see it from satellites quite easily."

Carl Safina: "Right, and that chlorophyll you're talking about is actually single celled plants that are green, using the deep nutrients."

Lisa Balance:"Yeah, that's correct, and the reason the rest of the tropics are classically blue tropical water is blue is because of a lack of chlorophyll. There's plenty of sunlight, clearly, in the tropics, but there's not enough other nutrients that photosynthetic organisms need to grow. So, the water is clear blue."

Carl Safina:"Because there's really nothing living in it. It's actually a desert. The big, open ocean is generally a desert."

Lisa Balance: "Exactly."

You can check out Carl Safina's blog on pulseplanet.com. Pulse of the Planet's Science Diaries are made possible by the National Science Foundation. I'm Jim Metzner.

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