In the ocean, the microenvironment surrounding phytoplankton cells is rich in dissolved organic matter, and bacteria competing for this matter are advantageous if they can perform chemotaxis, the sensing and movement toward a chemical source. Postdocs Steven Smriga and Vicente Fernandez in Professor Stocker’s group revealed this finding in a paper published in the U.S. Proceedings of the National Academy of Sciences (PNAS) on Feb. 9. The study used videomicroscopy to quantify bacterial behaviors around individual diatom cells and incorporate these data into a mathematical model for estimating DOM utilization by bacteria during phytoplankton blooms and other environmental conditions.  “Understanding microscale interactions is key to unraveling biogeochemistry in the ocean, and the hybrid approach we used here represents a blueprint toward the elusive goal of ‘scaling up’ the consequences of microscale interactions,” said Smriga. Read the paper.