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A detailed map of marine microorganisms

Daily, global image of phytoplankton diversity from a high resolution ocean and ecosystem model for October 19, 1999. Colors represent the number of types of phytoplankton.
[Image courtesy of Oliver Jahn, Chris Hill, Stephanie Dutkiewicz, and Mick Follows (MIT) and NASA]

Microscopic organisms are the primary producers in the world's oceans, and their activities influence many of the Earth's processes. Now, a new study shows exactly how some important microscopic marine plants are distributed around the globe.

Andrew Barton and a team of researchers investigated how the numbers of microorganisms in the oceans change—from the equator to the poles. They built a model of marine circulation to predict the movements of phytoplankton populations, and found that these microorganisms have more species located in tropical regions of the globe than near the Earth's poles.

The same trend of having greater numbers of different species near the equator—and fewer species as one heads north or south—is also seen in larger creatures on the land and in the sea, alike.

The new model shows clear patterns of phytoplankton distribution, and indicates that most of the different species of phytoplankton are found in mid-latitude zones. Fewer phytoplankton species—but greater numbers of them—live in the higher latitudes of the world.

This model also indicates "hotspots" of many different species in areas of the globe that are associated with strong currents and rough water. In the future, those hotspots could be explored in more detail to learn about the microorganisms that live there.