Microscale heterogeneity in the ocean and its potential impacts on the marine carbon cycle. Microscale heterogeneity in the ocean and its potential impacts on the marine carbon cycle. Phytoplankton-bacterium interactions for example (depicted in the central droplet of seawater) might directly influence biogeochemical cycles, energy transfer to higher trophic levels, sequestration of refractory carbon, and release of climate-active gases. Jean-Baptiste Raina mSystems 2018; doi:10.1128/mSystems.00150-17