Size-related effects of physical factors on phytoplankton communities

Sébastien M.J. Portalier (1) , Mehdi Cherif (2) , Lai Zhang (3) , Gregor Fussmann (1) , Michel Loreau (4)

1 Department of Biology [McGill University]
2 Department of Ecology and Environmental Science [Umeå]
3 Umeå University
4 SETE - Station d'écologie théorique et expérimentale

Phytoplankton communities are influenced by light availability. Therefore, one factor promoting phytoplankton species persistence is their ability to stay within the euphotic zone. This ability is determined by the interplay between species mass, buoyancy and dispersion, which are driven by physical factors. In this study, we investigate how these physical factors and light-use efficiency, all correlated with cell size, influence species persistence. Our model shows, first, that species can persist only within a size-dependent range of turbulence strength. The minimal level of turbulence required for persistence increases drastically with cell size, while all species reach similar maximal levels of turbulence. Second, the maximal water column depth allowing persistence is also size-dependent: large cells show a maximal depth at both low and high turbulence strength, while small cells show this pattern only at high turbulence strength. This study emphasizes the importance of the physical medium in ecosystems and its interplay with cell size for phytoplankton dynamics and bloom condition

Mots clés: Turbulence; Light limitation; Critical depth; Phytoplankton bloom

Domaines: Biodiversité et Ecologie; Sciences de l'environnement; Sciences du Vivant [q-bio]

Sébastien M.J. Portalier, Mehdi Cherif, Lai Zhang, Gregor Fussmann, Michel Loreau. Size-related effects of physical factors on phytoplankton communities. Ecological Modelling, 2016, 323, pp.41-50. ⟨10.1016/j.ecolmodel.2015.12.003⟩. ⟨hal-02985694⟩