Church will investigate the linkages between microbial physiology and biogeochemical cycles, targeting the time and space dynamics of specific microbial groups that control transformations of carbon, nitrogen, and phosphorus. By merging rate measurements of organic matter production and consumption with molecular approaches to identify variability in gene expression, he seeks to elucidate how the activities, biomass, and diversity of functionally important groups of organisms contribute to biogeochemical variability in the oceans.