2002-2003 Science Planning Summary

Biology & Medicine

Dr. Polly Penhale
Program Manager


NSF/OPP 02-28895
Station: Not based at a station
RPSC POC: John Evans
Research Site(s): Marine locations on RV Tangoroa

Viral dynamics and the Southern Ocean iron cycle
Dr. Steven W. Wilhelm
University of Tennessee

Deploying Team Members: Sara M Handy . Steven W Wilhelm
Research Objectives: The bioavailability of iron has been shown to regulate primary production in high-nutrient low-chlorophyll (HNLC) marine environments such as are found in Antarctica. More than 99 percent of dissolved iron in HNLC systems is organically complexed, and these iron-ligand complexes represent (at least indirectly) the pool of iron that is available to marine plankton. However, the character and source of the iron-binding ligands in sea water are unknown.

Recent research has suggested that the activity of naturally occurring viral populations provides enough organically complexed iron to regenerate the concentrations of dissolved iron measured in an HNLC coastal upwelling system in a time frame consistent with the growth of the phytoplankton community. This project’s goal is to participate in the upcoming FeCycle analysis and, in collaboration with scientists from the University of Otago (New Zealand) and the University of Delaware, to determine the rate at which viruses recycle iron back to the marine microbial community.

A 12-day experiment in the vicinity of 46º 30’ S, 178º 30’ E will build on 4 years of research in this region. The overall objective of the project is to collect information that will allow researchers to develop a preliminary model for the cycling of iron in this system in the absence of iron fertilization.

Field Season Overview:
Researchers will sail on the New Zealand research vessel Tangaroa departing from Christchurch, New Zealand.