Marine eukaryotes such as diatoms and phytoplankton sequester as much as 50 billion tons or gigatons of carbon annually, but very little is known about the tiny microorganisms that primarily make up this group, and their role in the global carbon cycle.
To help answer this question, a team led by DOE JGI collaborator Alexandra Worden of the Monterey Bay Aquarium Research Institute and including DOE JGI’s Susannah Tringe and Tanja Woyke conducted a metagenomic analysis of a particular group of uncultured phytoplankton known as pico-prymnesiophytes. The study was published online July 23, 2010 in the Proceedings of the National Academy of Sciences.
Worden and her colleagues collected DNA samples of the phyto-picoplankton from several areas of the Atlantic, Pacific and Indian Oceans. They then divided the world into five biogeographical regions and the compared surface biomass of picophytoplankton to the known biomass of Prochlorococcus and Synechococcus, both of which had been sequenced at the DOE JGI.
They found that in areas of high latitudes, the pico-prymnesiophytes accounted for up to 60 percent of the picoplankton biomass. In tropical regions however, the picoplankton accounted for only 20 percent of the surface biomass, which, the researchers noted, counters a previous study suggestion the pico-prymnesiophytes have a greater impact on the carbon cycle than does Prochlorococcus in these latitudes.