The base of the marine foodweb is formed by a microbial ecosystem. Organic matter, first built up by autotrophic primary producers is subsequently integrated into microzooplanktonic, microbial and viral predators, or excreted directly, forming the nutritional basis for a large diversity of bacterial and archaeal heterotrophs. We strive to gain a more detailed qualitative and quantitative understanding of the associated mechanisms by mathematical analysis and modeling of empirical data, adopting methods from network theory, non-linear dynamics, and statistical modeling.