Drivers of stability in plankton communities: dominance, asynchrony, and averaging effects across temporal, spatial and trophic scales

The origins of ecosystem stability have long intrigued ecologists. Recent theoretical advancements highlight three primary mechanisms driving stability: dominance, asynchrony and averaging. While plant community stability has been extensively studied, our understanding of marine community stability remains limited. Plankton, as key components of marine ecosystems, play vital roles in carbon and nutrient cycling as well as climate regulation. Identifying the drivers of plankton community stability is therefore essential for effective ecosystem management and conservation. Using a biogeochemical model that realistically represents plankton biodiversity, we identified dominance and averaging as the main mechanisms driving plankton community stability. By studying plankton communities across different temporal, spatial and trophic scales, we were able to show that changes in these dimensions can alter the dominant stabilizing mechanism. Stronger stabilization arising from dominance was linked to reduced biomass evenness, while stronger stabilization through averaging was linked to increased biomass evenness. Understanding the mechanisms that underpin the stability of plankton communities is essential to anticipate how marine ecosystems will respond to environmental change and which types of disturbances most threaten plankton communities. If stability is primarily driven by dominance, the system may appear stable but remain highly vulnerable, as its balance relies on a few functional groups. In contrast, when stability arises from temporal asynchrony or the averaging effect among many groups, the community can better buffer environmental fluctuations but becomes more sensitive to biodiversity loss.