Uncertainty Analysis of Phytoplankton Dynamics in Coastal Waters

There is an increasing concern about the interactions between phytoplankton and coastal ecosystems, especially on the negative effects from coastal eutrophication and phyto-plankton blooms. As the key indicator of the coastal ecosystem, phytoplankton plays an important role in the whole impact-effect chain. Primary production by phytoplankton forms the basic link in the food-chain. A lot of effort has been paid to the investigation of phytoplankton dynamics on the basis of literature surveys, field observations, and model predictions, providing a better understanding of the coastal ecosystem. In this thesis, the significance of phytoplankton is stressed and no discussion is given to zooplankton. matter, wind profiles, and tidal currents. In chapter 2, factor analysis is developed to characterize the contributions of the environmental variables to the phytoplankton biomass (in terms of chlorophyll a), determined by the 10-year's historical record from 2000 through 2009 in the case study of the Frisian Inlet. In this thesis we focus on three elements of phytoplankton dynamics: phytoplankton growth, phytoplankton biomass, and phytoplankton blooms. Based on the specific properties of the case zones, the Frisian Inlet and the Jiangsu coast, different focuses are taken. Field measurement of phytoplankton dynamics is expensive, thus we use mathematical models as the useful and convenient tool to perform the investigation. The BLOOM II model and the phytoplankton model are introduced to investigate the annual variation of the phytoplankton biomass in coastal waters (chapter 3, chapter 4, and chapter 5). The reliability of the parameter estimation largely determines the confidence of the model output. The estimate function of the phytoplankton growth rate is controlled by the variables of temperature, light intensity and nutrients, separately or comprehensively. The phytoplankton needs light to grow through the photosynthesis process, whereas the light intensity is attenuated due to the absorption by chlorophyll a, salinity, organic matter, turbid water, and background extinction. Phytoplankton consumes nutrients, in turn, phytoplankton releases nutrients back to the water bodies ii Summary iii through its death and the subsequent decay. In this research the growth rate is estimated with the effects of light intensity and ambient water temperature. The loss rate and the grazing rate are simplified as constants in the models, but actually are varied with the environmental variables. Moreover, the role of the vertical mixing process on the phytoplankton is significant, controlling the vertical distributions of the phytoplankton biomass and affecting the availability of light intensity and nutrients. Although a …