MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps13551

ABSTRACT: Cephalopods play a major role in marine ecosystems, yet very little is known about the dynamics in the habitat and trophic ecology during the different stages of their life cycle, particularly in the Southern Ocean. Here, we applied stable isotopic analyses of δ¹³C (a proxy of foraging habitat) and δ¹⁵N (a proxy of diet/trophic position) in two sections of 10 squids species’ lower beaks [i.e. the tip of the rostrum (juvenile) and wing (adult stage)], collected from the diet of Antipodean and Gibson’s albatrosses breeding at Antipodes and Adams Island (South Pacific), respectively. Higher δ¹³C values in early stages (-20.8 ± 1.7 ‰) than in adults (-21.6 ± 1.9 ‰) suggest that Southern Ocean squids tend to move southwards during their life cycle, with oceanic fronts being an important habitat for these species. Our results also suggest that adults may move southwards with climate change, possible impacting top predators living in northern islands. Overall, δ¹⁵N values revealed an increase in the trophic position from early stages (+6.7 ± 2.7 ‰) to adults (+9.0 ± 2.5 ‰) in all species, suggesting different feeding strategies between species and life-stages (zooplanktivorous, piscivorous and omnivorous).