Inter-Research > MEPS > Prepress Abstract

MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps13471

Modelling a simple mechanism for the formation of phytoplankton thin layers using large-eddy simulation: in situ growth

Ashley Brereton*, Yign Noh, Siegfried Raasch

*Corresponding author:

ABSTRACT: A curious behaviour found in the phytoplankton community is the forming of the so-called thin layer, where the biomass can stretch out kilometres in the horizontal but only a couple of metres in the vertical. These layers are typically found at the pycnocline, just below the surface mixed layer. Thin layers are usually attributed to a range of complex environmental and species dependent factors. However, we believe that, given the frequency at which this phenomenon is observed, a simpler mechanism is at play. In this study, it was found that phytoplankton thin layers can be attributed simply to a decreasing light availability with depth, when there is an abundance of nutrients in the euphotic zone and below the mixed layer. This mechanism is ascertained using a number of modelling approaches ranging in complexity, from analytical solutions of a simple 1-D plankton model to a 3-D biophysical model incorporating large-eddy simulation. The conditions which allow thin layers to form in this study are ubiquitous to the coastal ocean and therefore a likely candidate to explain why planktonic thin layers are so frequently observed.