Towards a mechanistic model of plankton population dynamics

A plankton population model is developed from literature studies with mechanistic descriptions of interactions of individual plankton cells. Interactions considered include diffusion and convection of nutrients to phytoplankton cell surfaces, light capture by phytoplankton pigment assemblages, sinking rates of phytoplankton cells, and encounter rates of predators and prey. Mechanistic formulations are based on individual species characteristics, obtained from measurements in laboratory experiments, and are functions of local fluid properties such as small-scale turbulence and viscosity. Phytoplankton growth is modelled by analogy to chemical kinetics, and is a function of intracellular nutrient and energy reserves. Results from laboratory experiments on single-species populations found in the literature are used to test the applicability of the functional forms for quantifying interactions of populations of common marine plankton species. These functional forms are then used to construct a system of equations describing plankton population dynamics. Simulations of plankton population dynamics at environmental conditions similar to the oceanic mixed layer at Bermuda (32 degrees N, 65 degrees W) and Ocean Weather Station (OWS) 'India' (59 degrees N, 19 degrees W) are performed, and compared to existing models and field data sets.