Seaflow Search for Prochlorococcus

Left: Older Darwin model of global ocean microbiome showing no drop-off of Prochlorococcus populations in arctic regions.Right: New Darwin model, updated to show interactions between heterotrophic bacteria and shared grazer, which prevents Prochlorococcus habitat extending poleward. Research ships traveling from Hawaii into the north Pacific Ocean have measured quantities of tiny organisms in the water called Prochlorococcus using an instrument called SeaFlow. These organisms are phytoplankton that, like plants, turn carbon dioxide into oxygen. Prochlorococcus is both the smallest and most abundant photosynthesizing organism on the planet. Scientists observed a falloff in the quantity of these organisms as the ships moved northward; however, the falloff did not happen where the water cooled as the scientists expected. This was a bit of a mystery. The scientists hypothesized that the drop off was actually due to competition with other tiny organisms like copiotrophic bacteria and their shared predator Paraphysomonas_sp, a type of zooplankton. They coded this hypothesis into an existing computational model of the oceans called Darwin. Sure enough, in the new version of the computational model that included the predator-prey relationship, the drop off occurred in the same place as the real-world measurements. This model can be used to understand how carbon is absorbed from the atmosphere over all of the world's oceans. This demonstrates the power of scientific research that combines observed data and model data. Related pages