Sabine Wollrab
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Dipl.biol. Sabine Wollrab
Aquatic Ecology
Department Biology II
Großhaderner Str. 2
82152 Martinsried-Planegg
Germany
Tel. ++49-(0)89-2180-74-213
Fax ++49-(0)89-2180-74-211
E-Mail: wollrab@biologie.uni-muenchen.de
My PhD thesis
Influence of nutrient supply and foraging behavior and life history of copepods on the dynamics of a widespread pelagic food web module
The size structure of plankton communities strongly influences functional properties of pelagic ecosystems such as nutrient fluxes, primary and export production, and energy transfer up the food chain. In many marine and freshwater systems copepods play a key role in these processes and may act as a 'switch' between alternative food chains.
We theoretically investigate the dynamics of a widespread planktonic food web, the pentagon module. It consists of five components, a limiting nutrient (nitrogen) at the bottom of the food web, two competing algae (small picoplankton and larger diatoms), a ciliate that only preys on picoplankton, and a crustacean top consumer (copepod), that preys on ciliates and diatoms. In this food web a food chain of odd length (nutrient-diatom-copepod) is connected with a food chain of even length (nutrient-picoplankton-ciliate-copepod). Because of this special architecture the food web shows patterns of decrease and increase of the food web members with nutrient enrichment that cannot be understood intuitively.
So far we theoretically investigated the influence of certain parameters on the dynamics of the food web and we compared the pentagon module with other related food web architectures. Furthermore we will investigate how the dynamics of the pentagon module are influenced by (i) food choice behaviour of copepods (e.g. switching), (ii) the supply with limiting nutrients (nitrogen and silicon), (iii) variation in the carbon to nutrient stoichiometry of phytoplankton, and (iv) by copepod stage structure, in particular stage-specific feeding and mortality rates; by implementing it into the corresponding mathematical model.
