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MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps14609

Sea-ice and macrozooplankton distribution as determinants of top predator community structure in Antarctic winter

Max F. Czapanskiy*, Jarrod A. Santora, Kimberly S. Dietrich, Megan A. Cimino, Elliott L. Hazen, Christian S. Reiss, Richard R. Veit

*Corresponding author:

ABSTRACT: The Antarctic Peninsula marine ecosystem is highly productive, with large populations of commercially and ecologically important species including Antarctic krill (Euphausia superba), Adelié penguins (Pygoscelis adeliae), and crabeater seals (Lobodon carcinophagus). The ecology of peninsula is rapidly changing due to accelerating climate change and fishing pressure. Systematic ecosystem surveys have focused on austral spring and summer, leaving an information gap on winter ecosystem dynamics. Using data from five consecutive ecosystem surveys, we quantified the composition and distribution of winter predator communities and investigated the physical and biological influences on community structure. Seabirds and marine mammals clustered into three communities: an ice-associated community represented by Adelié penguins and crabeater seals; a diverse marginal ice zone community dominated by fur seals and several species of seabirds including three petrels, kelp gulls (Larus dominicanus), and Antarctic terns (Sterna vittata); and an open water community consisting of Southern fulmars (Fulmarus glacialoides) and four species of petrels. These communities were distributed along an environmental gradient ranging from ice-covered, cold, saline waters to ice-free, warmer and fresher water with greater chlorophyll concentrations. Predator communities were also associated with different communities of macrozooplankton: ice-associated predators with an extremely diverse assemblage of typically mesopelagic zooplankton; marginal ice zone predators with a community of large-bodied euphausiids community (E. superba, E. crystallorophias); and open water predators with a community of small-bodied euphausiids (Thysanoessa macrura). Our synthesis of integrated winter predator and macrozooplankton communities relative to sea-ice concentration provide reference points for future ecosystem assessments within this rapidly changing region.