A novel method to simulate the 3D chlorophyll distribution in marine oligotrophic waters

A 3D advection-diffusion-reaction model is proposed to investigate the abundance of phytoplankton in a difficult-to-access ecosystem such as the Gulf of Sirte (southern Mediterranean Sea) characterized by oligotrophic waters. The model exploits experimentally measured environmental variables to reproduce the dynamics of four populations that dominate phytoplankton community in the studied area: Synechococcus, Prochlorococcus HL, Prochlorococcus LL and picoeukaryotes. The theoretical results obtained for phytoplankton abundances are converted into chl-a and Dvchl-a concentrations, and the simulated vertical chlorophyll profiles are compared to the corresponding experimentally acquired data during the MedSudMed-08 oceanographic survey. Non parametric tests showed that the 3D model successfully simulates the spatial distribution of chlorophyll in most of the Gulf of Sirte. Statistical analysis indicates that about 80% of the simulated chlorophyll vertical profiles are not significantly different from the experimental data. This model is also a useful tool to predict chlorophyll distributions in hard-to-access areas, where experimental data cannot be collected. Moreover, the model could be used to predict the effects of global warming on phytoplankton dynamics and primary production in marine ecosystems.