Variations in behaviour and condition of a Southern Ocean top predator in relation to in situ oceanographic conditions

Responses by marine top predators to environmental variability have previously been almost impossible to observe directly. Using novel, animal-mounted instruments simultaneously recording movements, diving behaviour and in-situ oceanographic properties, we studied the behavioural and physiological responses of southern elephant seals to spatial environmental variability throughout their circumpolar range. Improved body condition of seals in the Atlantic sector was associated with Circumpolar Deep Water upwelling regions within the Antarctic Circumpolar Current, while High Salinity Shelf Waters or temperature/salinity gradients under winter pack-ice were important in the Indian and Pacific sectors. Energetic consequences of these variations could help explain recently observed population trends, showing the utility of this approach to examining the sensitivity of top predators to global and regional-scale climate variability.