Most models of plankton communities, such as NPZ-type models, ignore the life-cycle (ontogeny) of multicellular zooplankton. Here, we propose a model framework along the Nutrient–Unicellular–Multicellular axis – a “NUM” framework – which incorporates zooplankton ontogeny.
NUM is a mechanistic size- and trait-based model based on traits and trade-offs at the individual level. Key copepod groups, characterized by their adult size and feeding mode, are used as representatives of the multicellular component. The unicellular compartment accounts for auto- mixo- and heterotrophic protists. By approximate analytical solutions and dynamic simulations, in both constant and seasonal environments, we investigate the mechanisms driving size and trophic strategy within the planktonic community. We show that predation by large copepods shapes the dynamics of small/juvenile copepods. We also show that heterotrophic protists and small copepods can compete through intraguild predation. Finally, we discuss how copepods can attenuate the carbon export flux. This conceptually simple, yet realistic framework, opens the possibility to improve end-to-end size-structured models of marine systems and investigate biogeochemical processes.
Serra-Pompei, C., Soudijn, F., Visser, A. W., Kiørboe, T., & Andersen, K. H. (2020). A general size-and trait-based model of plankton communities. Progress in Oceanography, 102473. https://doi.org/10.1016/j.pocean.2020.102473