In the HVI PolarTime we will investigate in all developmental stages in krill how important life cycle parameters will be mediated by environmental cues via endogenous timing systems (circardian/circannual; WP1). In parallel, the functional characteristic of the circadian clock machinery in krill will be studied (WP2). The krill, needed for this kind of investigations, will be provided from long and short term experimental studies under different light and temperature regimes at the Australian Antarctic Division Krill Aquarium. This is the only location worldwide to be able to close the life cycle of krill and to maintain adult krill from the field for years in adequate condition. In addition, we will study whether krill populations from different areas and light regimes differ in their clock machinery to understand the evolutionary history and therefore the adaptive phenotypic and genetic plasticity of the endogenous clock machinery in krill (WP3). The knowledge that we derived from our investigations on krill will act as a solid basis to study and understand the mechanisms of temporal synchronization of other key polar pelagic organisms (WP4). Finally, mathematical modeling will be used to transfer the results from the physiological, genetic and field studies to an ecosystem level and to understand and predict the effect of climate induced changes in polar pelagic ecosystem at the species and community level (WP5).