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Sampling the sea

In August 2008 R/V Oceanus made a transect across part of the eastern Atlantic, from Barbados to Cape Verde. Chief scientist Edward Boyle (MIT) led a research group including Pheobe Lam (assistant scientist) and Stephanie Owens (MIT/WHOI Joint Program student) both of WHOI’s Marine Chemistry and Geochemistry Department. Their object was to map dissolved and particulate iron—an essential nutrient for phytoplankton at the base of ocean food webs. All along the way, researchers tested the water at different depths using an important piece of oceanographic equipment, the CTD rosette. This instrument measures depth, temperature, and conductivity (a proxy for salinity, or salt content) of the water, and collects water samples in the circle of gray bottles, whose lids are held open during descent, then closed upon an electrical signal from the ship.
(Ruifeng Zhang, Massachusetts Institute of Technology)