Modelling match and mismatch processes within plankton communities during spring succession

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Phytoplankton, bacteria, protozoa, and meso-zooplankton exhibit different temperature sensitivities which implies that higher winter water temperatures due to global warming may alter their relative timing during spring development and the strength of interactions. The predicted increase of strong wind events may affect vertical mixing intensities and thus the plankton components directly and indirectly in group-specific ways. It is hypothesized that this effect is stronger in deep than in shallow water bodies. Using mathematical models, this project will investigate resulting match-mismatch processes in the food webs of two ecosystems which differ in respect to the impact of thermal stratification on spring plankton growth. First, mixing and temperature dependent spring development of plankton in large, deep Lake Constance will be modelled based on long-term time series using a zero-dimensional dynamic simulation model. For early spring, it will focus on the interactions between phytoplankton, micro-zooplankton and copepods. Daphnids and other groups are included when they become more relevant in late spring. Second, the temperature effects on the plankton food web of the shallow Kiel Bight, Baltic Sea, will be analysed using a mass-balanced trophic food web model and a modified version of the dynamic simulation model. This work will be based on a cooperative mesocosm experiment proposed under AQUASHIFT and conducted by four other groups of scientists (Sommer, Riebesell/Engel, Jürgens/Hoppe and Weithoff).