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Upper ocean biogeochemistry

Iron regulation of ocean ecosystems
Lead Scientist/Project Manager: Ken Johnson

The goals of this project are to extend our understanding of the roles that iron plays in regulating ecosystem structure, its impacts on biogeochemical cycles and climate. We propose a suite of related projects. We will continue our studies of iron cycling in coastal environments (Johnson et al., 1999), with a focus on the Monterey Bay region. Our major coastal effort in 2000 would be a joint, 2-week cruise with F. Chavez on R/V Western Flyer. The primary purpose of this cruise would be to trace the "natural iron enrichment experiment" that occurs when upwelled water entrains continental shelf sediment. Our main focus on this cruise will be an assessment of the processes that control the transformation of iron in resuspended sediment, which we have found to be the primary iron source for coastal plankton (Johnson et al., 1999), into bioavailable iron. In addition, we will continue to collect and analyze iron samples on R/V Point Lobos survey cruises to assess the natural variability in iron concentration along the continental margin.

Johnson K. S., Chavez F.P. & Friederich G.E. 1999. Continental-shelf sediment as a primary source of iron for coastal phytoplankton. Nature, 398, 697700.