Global Patterns and Cycles  Differences from place to place
Phytoplankton thrive along coastlines and continental shelves,
along the equator in the Pacific and Atlantic Oceans, and in
high-latitude areas. Winds play a strong role in the
distribution of phytoplankton because they drive currents that
cause deep water, loaded with nutrients, to be pulled up to the
surface.  These upwelling zones, including one along the equator
maintained by the convergence of the easterly trade winds, and
others along the western coasts of several continents, are among
the most productive ocean ecosystems. By contrast, phytoplankton
are scarce in remote ocean gyres due to nutrient limitations.
Map of global chlorophyll concentrations from 2002 to 2010.
Chlorophyll palette.  Phytoplankton are most abundant (yellow,
high chlorophyll) in high latitudes and in upwelling zones along
the equator and near coastlines. They are scarce in remote
oceans (dark blue), where nutrient levels are low. This map
shows the average chlorophyll c