Factors Affecting the Rate of Plankton Productivity

Province Percentage of ocean Area (10 km ) Mean productivity (gC/m year) Total productivity (lO gCyear) 

Trace metals can serve as essential nutrients and as toxic substances. For example, cobalt is a component of vitamin B12. This vitamin is essential for nitrogen-fbdng algae. In contrast, copper is toxic to marine phytoplankton at free ion concentrations similar to those found in seawater (Sunda and Guillard, 1976). The possibility that iron availability may limit primary productivity was discussed earUer. 

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