James Elser investigates the theory of biological stoichiometry the study of the balance of energy and multiple chemical elements in living systems. He and his international team of collaborators seek to understand how the coupling of carbon, nitrogen and phosphorus shapes the ecology and evolution of living things.  To do so, Elser and colleagues work with a diversity of ecosystems (from lakes and deserts, to hot springs and grasslands), biota (plankton to insects, and pandas to tumors), and approaches (laboratory chemostats, field experiments and mathematical models).  As director of the Flathead Lake Biological Station, this work now heavily features work in mountain lakes in western Montana but also mountain lakes in other regions, such as Qinghai (China) and Patagonia (Argentina).

Elser played a major role in establishing ASU's Sustainable Phosphorus Initiative and is now the lead investigator for an NSF Research Coordination Network on Phosphorus Sustainability. Through these efforts, he seeks to help create a sustainable food system by closing the human P cycle.