Figure 20.6 Global patterns of net primary productivity. (a) Among terrestrial ecosystems, the highest productivity occurs in the tropics, which experience warm temperatures throughout the year and have abundant rainfall. (b) The most productive aquatic ecosystems include the shallow water near the edges of continents and large islands.
Data from http://eoimages.gsfc.nasa.gov/images/news/NasaNews/ReleaseImages/20030917/Image1m.jpg and http://geo.arc.nasa.gov/sge/ecocast/publications/press/globalgarden/earth_observatory_2.htm