Quality of Sea-ice Habitat Traversed by Antarctic Krill Larvae Influences Recruitment Success

Antarctic krill are a key Southern Ocean species whose success is attributed to their adaption to the extreme polar seasonality. Overwinter sea-ice presence and characteristics exert a strong control on larval survival and subsequent recruitment. Our understanding of the mechanisms through which sea ice influences survival are mainly underpinned by small-scale observations, whereas planktonic larvae may be advected over large scales. Using a state-of-the-art sea-ice model we computed Lagrangian back-trajectories to simulate larval krill advection into three distinct recruitment regions and examined modelled sea-ice habitat characteristics along trajectories. From these results we identify potential overwintering habitats and present a conceptual model for explaining regional variability in sea-ice habitat drivers of recruitment. Crucially, many of these sea-ice habitats are currently under-sampled. This work can inform future sampling efforts that will improve our understanding of climate change impacts, and potential interactions with the krill fishery.