Polar bear diet may indicate prey distribution changes due to climate
shifts

Date:
October 27, 2021
Source:
York University
Summary:
How are warming temperatures and a loss of sea ice affecting
polar bears and their marine mammal prey in the Arctic? A York
University-led research team used a novel approach to the question
by monitoring what polar bears eat across Nunavut and where they
are catching their prey.



FULL STORY ==========================================================================
How are warming temperatures and a loss of sea ice affecting polar
bears and their marine mammal prey in the Arctic? A York University-led research team used a novel approach to the question by monitoring what
polar bears eat across Nunavut and where they are catching their prey.


==========================================================================
They found that polar bears can be used as indicators of environmental
shifts and highlight how these changes are disturbing the normal
distribution of marine mammal prey populations in the Arctic.

The researchers, including Faculty of Science PhD Candidate Melissa
Galicia, who led the research, and Professor Gregory Thiemann of the
Faculty of Environmental and Urban Change, have found polar bears,
originally thought to eat mainly ringed and bearded seals, are actually flexible eaters. They will eat what's readily available and this makes
them ideal as a monitoring tool to track environmental changes in
the Arctic.

"Polar bears need the sea ice to hunt. When there is a reduction in the
sea ice, they're hunting less or they're potentially hunting different
prey species," says Galicia. "Prey species, like whales and seals, also
need certain habitat conditions and because of environmental changes
in the Arctic, some marine mammals, such as prey species of bears, are redistributing. You're getting an increase in more sub-Arctic species,
like killer whales for instance." The researchers analyzed harvest
samples of polar bears from across Nunavut, provided by subsistence
hunters over a period of about eight years, and identified spatial hot
spots of prey species. The study suggests polar bear diet may provide
early evidence of changes in the distribution of mammals due to climate
change.

"I'm getting a large geographic representation of bears, especially
in areas that tend to be less studied," says Galicia, who was able to
analyze the fatty acids, such as omega 3s and omega 6s, in the fat tissue
of bears.



========================================================================== "Each bear will have a specific fatty acid signature, a kind of
fingerprint for individual bears and because of that you can see what
that particular individual is eating and what percentage of their diet
that represents." They found bowhead whale carcasses were increasingly becoming more common in polar bear diet potentially linked to killer
whales venturing further north and staying for longer periods of time.

The researchers say changes brought on by a warming climate -- the Arctic ecosystem is experiencing climate warming up to three times faster than
any other region -- will likely force widespread species redistribution, particularly in polar environments. The polar bears in Nunavut aren't experiencing climate changes to the same degree as some subpopulations
in western Hudson's Bay or Beaufort Sea areas, but ultimately that will
likely change.

"As temperatures across the Arctic warm and sea ice loss increases,
there will be profound cascading ecological consequences. What's not
known is how that will affect species, such as seals and whales, but
by monitoring the seasonal prey consumption of polar bears, scientists
can better keep track of where marine mammal prey species are showing
up and their seasonal distribution," says Thiemann.

There is currently little information on the abundance and distribution
of marine mammals across the Arctic so this study offers a way to gain
further insight and highlight potential range shifts.

The researchers say future studies of polar bear diets should
include prey species not typically found in the region and
help predict the severity and influence of climate-induced
change Video: https://www.youtube.com/watch?v=V7N5eCHIYrU ========================================================================== Story Source: Materials provided by York_University. Note: Content may
be edited for style and length.


========================================================================== Journal Reference:
1. Melissa P. Galicia, Gregory W. Thiemann, Markus G. Dyck, Steven H.

Ferguson. Polar bear diet composition reveals spatiotemporal
distribution of Arctic marine mammals across Nunavut,
Canada. Ecological Indicators, 2021; 132: 108245 DOI:
10.1016/j.ecolind.2021.108245 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/10/211027122011.htm

--- up 7 weeks, 6 days, 8 hours, 25 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)