Global biogeochemical impacts of phytoplankton: a trait‐based perspective

TLDR

Phytoplankton drive about half of global primary productivity and, through functional groups defined by distinct traits, influence nitrogen, phosphorus, and silica cycles, so shifts in community structure can reshape elemental cycling from local to global scales. This review examines how trait‑based differences among phytoplankton functional groups shape biogeochemical cycles and models these links, while assessing how global environmental change may alter community composition and consequently elemental cycling. The authors synthesize trait‑based traits of phytoplankton functional groups, model their biogeochemical impacts, and evaluate the influence of global environmental change on community structure and elemental cycling. Focusing on response and effect traits clarifies how phytoplankton community structure drives biogeochemistry, and uncovering trait trade‑offs improves predictive models for anticipating global change impacts. Synthesis.

Abstract

Summary Phytoplankton are key players in the global carbon cycle, contributing about half of global primary productivity. Within the phytoplankton, functional groups (characterized by distinct traits) have impacts on other major biogeochemical cycles, such as nitrogen, phosphorus and silica. Changes in phytoplankton community structure, resulting from the unique environmental sensitivities of these groups, may significantly alter elemental cycling from local to global scales. We review key traits that distinguish major phytoplankton functional groups, how they affect biogeochemistry and how the links between community structure and biogeochemical cycles are modelled. Finally, we explore how global environmental change will affect phytoplankton communities, from the traits of individual species to the relative abundance of functional groups, and how that, in turn, may alter biogeochemical cycles. Synthesis . We can increase our mechanistic understanding of the links between the community structure of primary producers and biogeochemistry by focusing on traits determining functional group responses to the environment (response traits) and their biogeochemical functions (effect traits). Identifying trade‐offs including allometric and phylogenetic constraints among traits will help parameterize predictive biogeochemical models, enhancing our ability to anticipate the consequences of global change.