A Microscopic Bloom from Space

By Phil Plait

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Posted Friday, May 3, 2013, at 8:00 AM

One of the great ironies of space exploration is that by leaving the Earth, we sometimes get a better view of it. It shouldn’t be too surprising; a change of perspective is generally good for context, and since we live on the Earth we only see a small piece of it at any one time.

Getting above the Earth and looking back provides perspective, context, and a large-scale picture that supplements both. It’s not just geology and geography that benefit from this, either; it’s also biology and microbiology. And, if I may, it can also be art.

To wit, a phytoplankton bloom swirls off the coast of France in this lovely shot taken from NASA’s Aqua Earth-observing satellite:

Phytoplankton going forth and multiplying, as seen from space. Click to autotrophenate.
Photo by NASA/GSFC

Phytoplankton are algae, microscopic plants. The name is fairly generic; there are a lot of different kinds of phytoplankton. They live in water all over the planet, and in some places, when the temperature rises and food is plentiful, they undergo explosive reproduction. Called a bloom, the area can be so big it can be seen from space. Obviously.

The color is due to various pigments in the phytoplankton; in this case, blue. I think the greenish milky swirls closer to the coast are from sediments. It can actually be difficult to separate out the two in some images, and in cases like that samples of the water can be physically examined to distinguish them.

I’ve written about various blooms seen from space before (like here, here, here, and here, and yeah, you really want to click those), because they are always incredibly beautiful. I’ve also written that scientists keep an eye on them because these blooms can rob the water of oxygen and nutrients, which affects the ecology of the area, and that they also produce some toxins that can be problematic for other life.

An electron microphotograph of Coccolithus pelagicus, a fairly common coccholithophore.
Photo by Richard Lampitt, Jeremy Young, The Natural History Museum, London, via wikipedia

This prompted an email from Dr. Adrian Burd, a biology oceanographer at the University of Georgia. He noted that toxins released by phytoplankton are generally limited to dinoflagellates—a subpopulation of phytoplankton, and probably not seen in the blooms I’ve posted. Given the color, he thinks it’s more likely these are from coccholithophores, an entirely different kind of phytoplankton.

I’ll note that dinoflagellates sometimes glow when disturbed. I recently took a night kayak excursion in Mosquito Bay on Vieques, an island near Puerto Rico (we were doing a site visit for a possible future Science Getaway), and every time the paddle hit the water the dinoflagellates would glow; it was a surreal and amazing experience. Needle fish plowing through the water left sparks and trails like a meteor underwater. Astonishing.

Dr. Burd also noted that the oxygen depletion sometimes seen with phytoplankton blooms is not from the algae itself, which actually produce oxygen. However, the plankton sink and are consumed by bacteria which do use up the oxygen. So these dead zones are due to the phytoplankton, but only indirectly.

Sometimes I really love my job. I get to look at gorgeous pictures, find the science in them, tell you about it, and then hear from scientists who tell me more. Even if they’re correcting me, I don’t mind—that’s another chance to learn, and a chance to be even more amazed about how all the millions upon millions of pieces of our world fit together. Science, like the world and like life itself, is a tapestry; interconnected and interwoven, with each piece affecting every other piece in some way. From the microscopic to the macroscopic to the truly cosmic, it all holds together to create an astonishing and wondrous whole.