A satellite captured this nighttime image of bioluminescent marine bacteria just off the coast of Somalia. Image courtesy of Steven Miller and Steven Haddock.
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Glowing Oceans
The satellite images of city lights glowing brightly across the landscape, marking the locations of the world's larger cities at night, have gained much attention but less well known are satellite images of a different sort of light coming from the ocean surface - and it's not man-made.
For years, sailors told stories about glowing seas as far as the eye can see but their accounts were the only evidence of such a phenomenon, that is, until a report from a ship in the Indian Ocean coincided with the passing of a satellite overhead. In 1995, the British vessel S.S. Lima reported such a phenomenon (now termed a milky sea) off the coast of Somalia. A decade later, scientists Steven H.D. Haddock and Steven D. Miller obtained satellite imagery from a satellite involved in the U.S. Defense Meteorological Satellite Program that was particularly sensitive to light. The result was the identification of a bioluminescent event the size of Connecticut from space.
What could be responsible for such a massive area of glowing ocean? Forty billion trillion cells of bioluminescent bacteria called Vibrio harveyi are estimated to be required for a bloom of this magnitude. Once the bacterial population reaches a threshold concentration that allows the accumulation of chemical cues to reach a high enough concentration, bioluminescence may be induced. This is just one hypothesis; many questions remain and there is much to discover about the causes and role of bioluminescence in the marine environment. Now, satellite imagery is another tool scientists can use to learn more.
Citations: Miller, Steven D., Hadock, Steven H. D., Elvidge, Christopher D., Lee, Thomas F. 2005. Detection of a bioluminescent milky sea from space. Proc. Nat. Acad. Sci., 102: 14181 - 14184. http://spie.org/x8854.xml?highlight=x2420 http://www.lifesci.ucsb.edu/~biolum/organism/milkysea.html
- feature story by Karen Breitlow |
