Analysis of elemental ratios (stoichiometry) in food webs may provide fundamental information on the uptake, allocation and sequestration of carbon (C) and key nutrient minerals like phosphorus (P) and nitrogen (N) from the cellular level to ecosystems. In sum, these processes will also play a major role for the global cycling of these elements. The relative abundance of key nutrient minerals like phosphorus (P) and nitrogen (N) is not only instrumental to primary production, also secondary production (grazers) may be directly limited by the relative abundance of P and N. And when C:N or C:P ratios are high in primary producers, an increasing share of C will be in excess, relative to the grazers’ demands. This will have implications not only for energy transfer in food webs, but also community composition and system stability. It will also be a major determinant of CO2-uptake at the base of the food-web to yield at the top. The project has consisted of 22 scientists who have analyzed these aspects in cells and ecosystems, covering topics from the role of P for cellular RNA and growth rate to large-scale ecosystem analysis and models. The work has addressed from three points of departure: continued work with existing data, projects and publication, analysis of large datasets from various databases and theoretical works and models.