Automated Nanocosm test system to assess the effects of stressors on two interacting populations.

There is a great need in environmental research for test systems that include ecologically important factors and that are also easy to use. We present here the automated test system Nanocosm, which is composed of populations of Daphnia magna and Culex pipiens molestus. The Nanocosm system allows the investigation of stressed populations in the presence of interspecific competition, which is a very important factor involved in the dynamics of ecosystems. With the Nanocosm system, the abundance and size structure of populations of both species are quantified by image analysis. The technique enables a time-efficient, non-invasive and reliable long-term monitoring of interactions between two aquatic populations. We recommend the Nanocosm system as a novel tool for the simplified integration of competition into environmental and ecotoxicological research as well as for the assessment of risk due to stressors.