The main focus if this study was modelling of coastal ecosystems. Coastal marine ecosystems are subject to complex factors including tides, freshwater flows and nutrient loads.

Danish shallow estuaries often have a dense benthic community of filtrating organisms such as mussels. Filtration activity is dependent on turbulent water mixing which is mostly created by wind stress on the water surface. In two studies the relative importance of wind stress and nutrient loading as determining factors for phytoplankton production was investigated in a dynamic ecosystem model. The model was developed for Roskilde Bredning and tested in Kertinge Nor. The model showed that grazing by benthic filter feeders can control pelagic production even under high nutrient additions. However, the probability of periodic phytoplankton and ephemeral algae blooms is increased with increased loads, leading to a less stable ecosystem.

Filtration rate of the blue mussel
The filtration response to particle concentrations in the blue mussel was investigated in a dynamical model. The model was used to explore the consequences of different existing hypotheses in order to improve the possibility of hypothesis testing against data in the future. The tested hypotheses were 1) optimal foraging and 2) ingestion limitation. Both hypotheses in most cases gave a similar response, in which filtration rate decreases with increasing particle concentration and increasing particle quality. The main difference between the hypotheses was found at low particle concentrations. The optimal foraging hypothesis (1) leads to reduced filtration rates at low food qualities and quantities while there was no such response under hypothesis 2. However, such a response has been reported in the literature.

Disko Bay, West Greenland
In order to investigate the consequences of a changing ice cover in Disko Bay on the western coast of Greenland, a dynamical model was applied to the planktonic food web in Disko Bay. According to the model, a situation without ice will lead to an ecosystem dominated by protozoans, since ciliates and heterotrophic dinoflagellates would be the major grazers on the diatom spring bloom. The large copepods ascend to the surface waters after winter hibernation in April after the diatom bloom has sunken out. In a situation with less ice coverage, the primary productivity is increased but copepod production is reduced, resulting in lower trophic transfer to higher trophic levels.