Data for: Unprecedented shift in Canadian High Arctic polar bear food web unsettles four millennia of stability

Stable carbon (δ13C) and nitrogen (δ15N) isotope analysis was conducted on
modern and archaeological polar bear bone collagen from the Canadian
Arctic Archipelago to investigate potential changes in polar bear foraging
ecology over four millennia. Polar bear δ13C values showed a significant
decline in the modern samples relative to all archaeological time-bins,
indicating a disruption in the sources of production that support the food
web, occurring after the Industrial Revolution. The trophic structure,
indicated through δ15N, remained unaltered throughout all time periods.
The lower δ13C observed in the modern samples indicates a change in the
relative importance of pelagic (supported by open-water phytoplankton)
over sympagic (supported by sea ice-associated algae) primary production.
The consistency in polar bear δ13C through the late Holocene includes
climatic shifts such as the Medieval Warm Period (MWP, A.D. 950–1250) and
the early stages of the Little Ice Age (LIA, A.D. 1300–1850). These
findings suggest that polar bears inhabit a food web that is more pelagic
and less sympagic today than it was through the Late Holocene. We suggest
that modern, anthropogenic warming has already affected food web structure
in the Canadian Arctic Archipelago when modern data are contextualized
with a deep time perspective.