For studying the performance and adaptability of pelagic key species in all their ontogenetic complexity we use a comprehensive setup of sampling devices, experiment designs, and analytical tools on different scales. Using animals from the field we want to identify the seasonal physiological and genetic traits in relation to key environmental factors in Polar regions such as food quantity and quality, photoperiod and sea ice. Process-oriented studies will help us to a) get a mechanistic understanding how key organisms are synchronized with their high seasonal environment and b) to identify their performance window in respect to increasing sea water temperature.