Carbon: phosphorus stoichiometry and food chain production

Incident light was manipulated in large plankton towers containing algae, m icrobes, and herbivores. Paradoxically, food chain production was lower wit h greater light energy input. This apparent paradox is resolved by recogniz ing stoichiometric constraints to food chain production. At high light, ele vated algal biomass was achieved mainly by increases in cellular carbon. Co nsumers have a high phosphorus demand for growth, and thus a large excess o f carbon inhibited, rather than stimulated, their growth. These experiments may help us predict the consequences of anthropogenic perturbations in nut rients, carbon, and solar energy. They also may help us to understand the w ide range of consumer biomass and production at a given level of primary pr oductivity in ecosystems.