He explains that assumptions about the biological pump the way ocean life circulates carbon – are mostly based on averaging measurements that have been made from ships at intervals widely separated in time. Cost not to mention the environment would have made continuous ship based observations impossible in this case. Luckily one Carbon Explorer float costs only about as much as a single day of ship time.
Return to the Southern Ocean

In 2007 Bishop and Lam who was now at the Woods Hole Oceanographic Institution published measurements from shipboard instruments deployed during SOFeX which suggested that the rosy picture of plankton blooms sending carbon to the deep ocean wasnt so simple after all. Carbon reaching the deep ocean depended partly on particle size and weigh more important there seemed to be much less particulate matter reaching depth where the biomass was highest in plankton blooms.
This paper was criticized on the grounds that it was based on limited shipboard observations says Bishop. So Todd Wood and I turned to the treasure-trove of virtually continuous observations in the records of the Carbon Explorers.

Bishop says these observations point to an important lesson Iron is not the only factor that determines phytoplankton growth in HNLC regions. Light mixing and hungry zooplankton are fundamentally as important as iron.