Nitrogen mediates phosphorus uptake

Traditional perspectives on nutrient limitation suggest that a single nutrient (e.g., nitrogen [N] or phosphorus [P]) typically limits the growth of primary producers such as plants, seaweeds, and phytoplankton. More recent work suggests that multiple nutrients (e.g., N and P together) may simultaneously limit growth. For example, one nutrient may be necessary for acquisition of a second nutrient. In a new publication in the journal Oecologia, Valerie Perini and I show that the availability of N affects both the internal concentrations in and uptake of P by intertidal seaweeds, suggesting that P alone cannot support growth and that both N and P are therefore necessary.