Phosphorus is essential for life, but its availability often limits productivity in both terrestrial and aquatic ecosystems (Elser et al., 2007). From tropical rain forests to the open oceans, organ- isms depend on organic phosphorus turnover for their phosphorus nutrition and have evolved complex adaptations that allow them to compete efficiently for this scarce resource (e.g. Lambers et al., 2006; Whitton et al., 2005).