Mathematical Modeling of Phytoplankton Community Structures As Affected by Biological and Physical Processes

Abstract:

Phytoplankton are microorganisms that play the primary role in oxygen supply and food production for nearly all life in the ocean. Phytoplankton ecosystems are shaped by key factors that enable growth and production, some of which include light and nutrient availability. A systematic understanding of how these factors affect phytoplankton ecosystems are the focus of this study. In order to form a robust understanding of phytoplankton ecosystems, we develop a simple mathematical model to study the effects of light, nutrients, and competition on phytoplankton community structure at Western Mediterranean fronts. With a suitable choice of nutrient- and light- dependent growth rates, mortality, and diffusive mixing, the model produces a depth-differentiation of phytoplankton communities that resembles observations. The ecological model is then embedded in a three-dimensional flow field to investigate how frontal flow affects phytoplankton community composition. An understanding of the spatio-temporal variability in phytoplankton ecotypes will enable us to study its effect on carbon export in the upper ocean and the climate system.