Linking Whole Ecosystem Stoichiometry to Individual-level Nutrient Dynamics
The availability of nitrogen (N) and/or phosphorus (P) constrains primary production in most ecosystems worldwide. As a consequence, the fluxes of N and P through ecosystems are tightly linked. Thus, N:P stoichiometry at the level of ecosystems, which results from a complex web of biologically mediated chemical reactions, can be viewed as an integrated measure of nutrient utilization, and can be used to infer constraints on primary production. Understanding how whole ecosystem patterns of N:P emerge from processes occurring at the level of individuals will enable inferences about interactions between organisms and their environments to be made using simple stoichiometric ratios. Additionally, linking individual N and P requirements to whole ecosystem N:P will make it possible to predict how carbon cycling and biodiversity will respond to changing N and P dynamics. We are performing experiments with phytoplankton and developing mathematical models to understand how N and P uptake at the level of individual cells influences the N:P stoichiometry of entire aquatic ecosystems.