Functional diversity promotes phytoplankton resource use efficiency

1.Understanding the relationship between biodiversity and ecosystem functioning (BEF) is a central topic in ecology. Multi‐traits based functional diversity has been proposed to improve mechanistic understanding of the BEF relationship; however, how trait‐based functional diversity affects ecosystem functioning and processes has rarely been addressed in aquatic ecosystems. 2.Here, we examined the causal relationships between three phytoplankton functional diversity indices (FAD2, FDc, FRic) and Shannon diversity index versus resource use efficiency for nitrogen (RUEN), phosphorus (RUEP), and silicate (RUESi), with monthly long‐term datasets from the marine (Western English Channel, 2000 ‐ 2014) and freshwater (Lake Kasumigaura, 1984 ‐ 2012) ecosystems. 3.We employed Convergent Cross Mapping (CCM), a novel method developed for identifying causality for nonlinear dynamical systems; this is in contrast to linear approaches that cannot distinguish causality from correlation. CCM found...