Scientists learning the metabolism of free-ranging polar bears within the Arctic have came upon why the lack of sea ice is hurting their survival: They burn energy at a quicker price than beforehand thought.
The findings, described within the journal Science, reveal alarming information concerning the polar bear’s unsustainable physiology within the face of ongoing local weather change.
As human-produced greenhouse fuel emissions proceed to gasoline international warming, the Arctic sea ice ranges proceed to shrink by about thirteen.2 % per decade. On the similar time, a variety of polar bear populations have been on the decline — for instance, dropping by about forty % within the Beaufort Sea in the middle of a decade.
“We have documented declines within the inhabitants, declines within the abundance, declines within the survival charges, declines within the physique situation within the inhabitants,” stated lead writer Anthony Pagano, a analysis wildlife biologist with the U.S. Geological Survey’s Anchorage workplace. “And it seems to be associated to modifications in sea ice which are occurring.”
However understanding the precise relationship between the lack of ice and the plight of the polar bear has been somewhat murky as a result of it is troublesome to trace the actions of those monumental apex predators in distant areas.
“What we do not actually know a lot about is, what are the precise mechanisms which might be driving these declines?” stated Pagano, who can also be a Ph.D. scholar on the College of California, Santa Cruz. “We do not have loads of details about actually the essential biology and pure historical past of those animals once they’re on the ocean ice and the way they make the most of the ocean ice setting.”
For this research, the scientists put trackers on 9 feminine polar bears within the Beaufort Sea area. These trackers included accelerometers and GPS-outfitted video cameras to doc the bears’ actions. From 2014 to 2016, they tracked the bears’ actions for eight to eleven days in April, the start of the season when the bears are often extremely lively hunters, placing on the majority of the physique fats that may see them by means of the remainder of the yr.
To measure the animals’ power expenditure, they dosed the bears with doubly labeled water — water molecules whose hydrogen and oxygen atoms had been changed with heavier isotopes with additional neutrons. The hydrogen atoms would go away the physique in water (corresponding to urine), as would a few of the oxygen atoms. However different oxygen atoms would go away within the type of exhaled carbon dioxide (as a result of water…