John Casey, Simons Postdoctoral Fellow working with the Follows group, is a microbial oceanographer interested in the many roles microbes play in regulating elemental cycles and the transduction of energy in the marine ecosystem. Combining field observations, laboratory experiments, theoretical and computational models, he is working to build toward a mechanistic understanding of microbial life in the oceans. New theory is needed to bridge the gap from high-frequency cellular-scale processes to those of the larger marine ecosystem, but a fundamental understanding of the time and space scales over which microbes processes information is lacking. John is motivated to understand the objectives of cellular scale processes, how those objectives are influenced by communication between higher tiers of biological organization, and how they are imprinted in the genetic code. With Mick Follows and collaborators within the CBIOMES initiative (cbiomes.org), John is designing detailed models of microbial metabolism and physiology and using these models to simulate microbial community dynamics in the marine environment.