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MEPS prepress abstract   -  DOI:

Sympatry and resource partitioning between the largest krill consumers around the Antarctic Peninsula

Ari S. Friedlaender*, Trevor Joyce, David W. Johnston, Andrew J. Read, Douglas P. Nowacek, Jeremy A. Goldbogen, Nick Gales, John W. Durban

*Corresponding author:

ABSTRACT: Understanding how closely-related, sympatric species distribute themselves relative to their environment is critical to understanding ecosystem structure and function and predicting effects of environmental variation. The Antarctic Peninsula supports high densities of krill and krill consumers, however the region is warming rapidly, with unknown consequences. Humpback and minke whales are the largest krill consumers here, yet key data gaps remain about their distribution, behavior and interactions and how these will be impacted by changing conditions. Using satellite telemetry and novel spatial point-process modeling techniques, we quantify habitat use of each species relative to dynamic environmental variables and determine overlap in core habitat areas during summer months when sea ice is at a minimum. We find humpback whales range broadly over continental shelf waters, utilizing nearshore bays while minke whales restrict their movements to sheltered bays and areas where ice is present. This presents a scenario where minke whale core habitat overlaps substantially with the broader home ranges of humpback whales. While there is no indication that prey is limiting in this ecosystem, increased overlap between these species may arise as climate-driven changes that affect the extent, timing, and duration of seasonal sea ice, decrease the amount of preferred foraging habitat for minke whales while concurrently increasing it humpback whales. Our results provide the first quantitative assessment of behaviorally-based habitat use and sympatry between these two krill consumers and offers insight into the potential effects of a rapidly changing environment may have on the structure and function of a polar ecosystem.