SGER: Viral Dynamics and the Southern Ocean Fe-cycle

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The bioavailability of Fe has been shown to regulate primary production in high nutrient low chlorophyll (HNLC) marine environments. More than 99% of dissolved iron in HNLC systems is organically-complexed, and these Fe-ligand complexes represent (at least indirectly) the pool of Fe that is bioavailable to marine plankton. However, the character and source of the Fe-binding ligands in seawater are unknown. Recent research has suggested that the activity of naturally occurring viral populations provides sufficient organically complexed-Fe to regenerate the concentrations of dissolved Fe measured in a HNLC coastal upwelling system in a time frame consistent with the growth of the phytoplankton community. The goal of this SGER proposal is to participate in the upcoming (January February 2003) FeCycle analysis and (in collaboration with scientists from the University of Otago (NZ) and the University of Delaware) to determine the rate at which viruses recycle Fe back to the marine microbial community. A 12-day experiment in the vicinity of 46 degrees 30 degrees S, 178 degrees 30 degrees E will build on 4 years of research in this region. The overall objective of the project is to collect information that will allow for the development of a preliminary model for the cycling of Fe in this system in the absence of Fe fertilization.