Program and Agenda



We explore how phytoplankton are adapted to variable light regimes with a physiological model in which key traits are cell size and nitrogen allocation. The model allows nitrogen to be optimally partitioned between light harvesting, carbon fixation, biosynthesis and photoprotection machinery and predicts growth rate of different size classes. When nitrogen is optimally partitioned to suit a constant light regime, there is high plasticity in the carbon-to-chlorophyll ratio and photosynthesis-irradiance response curves as a function of growth irradiance. When nitrogen is partitioned to suit a dynamic light environment, there is less plasticity in the carbon-to-chlorophyll ratio, and photosynthesis-irradiance response curves never inhibit. Large cells, able to store carbon, buffer variations in irradiance leading to higher average daily growth rates than small cells. Model predictions are consistent with observed traits of diatoms which occur in variable light regimes, and Prochlorococcus which inhabit the relatively stable oligotrophic gyres. Light variability, influenced by the relative amplitude of vertical mixing, selects particular adaptations in resource allocation and storage. We will illustrate selection for these traits in three-dimensional simulations of ocean circulation and ecosystem dynamics.


Talmy, D., Massachusetts Institute of Technology, USA,

Geider, R. J., University of Essex, United Kingdom,

Blackford, J., Plymouth Marine Laboratory, United Kingdom,

Hill, C., Massachusetts Institute of Technology, USA,

Follows, M., Massachusetts Institute of Technology, USA,


Oral presentation

Session #:017
Date: 2/27/2014
Time: 09:00
Location: 313 C

Presentation is given by student: No