Doubly-labeled Water, Deuterium Dilution, Body Mass, and Blood Biochemistry Data from Female Polar Bears (Ursus maritimus) in the Southern Beaufort Sea by the USGS in April 2014-2016

To measure the specific activity of deuterium oxide and oxygen-18 in serum samples, we immobilized 9 female polar bears without dependent young. Following immobilization, we inserted an external jugular catheter to facilitate blood sampling and administration of isotopes. An initial blood sample was collected to serve as a baseline measure of 18O (oxygen-18) and 2H (deuterium). The bear was then injected intravenously with a precisely weighed dose containing 0.12 – 0.25 g/kg of 97% enriched 18O (Isoflex USA, San Francisco, CA) and 0.06 – 0.10 g/kg of 99.9% enriched 2H (Isotec, Inc., Miamisburg, OH or Cambridge Isotope Laboratories, Inc., Tewksbury, MA) with NaCl added to make it 0.9% isotonic and sterilized using a 0.2 µ Millipore filter. On injection, the syringe was back washed with blood three times to ensure all the DLW had been injected into the bear. The bear was kept immobilized for 2 hours after the injection of DLW to allow isotope equilibration. We collected serial blood samples 60, 90, and 120 minutes after dosing. We recaptured bears 8 – 11 days later to obtain a blood sample to measure final enrichment. At recapture, we weighed bears to measure changes in body mass. In 2015 and 2016, we dosed recaptured bears with 0.09 – 0.14 g/kg of 99.9% enriched deuterated water (D2O, Cambridge Isotope Laboratories, Inc.) and collected serial blood samples 60 and 90 minutes after dosing to measure changes in body composition between captures. Blood was collected in 10 ml glass evacuated tubes without anticoagulants (Serum Vacutainer, Becton Dickinson, Franklin Lakes, NJ) and centrifuged to separate serum from red blood cells. Serum was stored frozen in 2 ml cryogenic vials (Corning, Inc., Corning, NY) at -20°C until analysis.

Serum samples were analyzed for the concentrations of 18O and 2H by Metabolic Solutions, Inc. (Nashua, NH).

To obtain blood urea nitrogen and creatinine concentrations, serum samples from capture and recapture were analyzed using an Abaxis Vetscan VS2 chemistry analyzer (Abaxis, Inc., Union City, CA). Each sample was analyzed twice with the exception of bears 8 and 9 whose samples were only analyzed once.

Age was determined by counts of cementum annuli from an extracted vestigial premolar by C-D and Associates Biological Consulting (Spruce Grove, AB, Canada).

We measured total body mass at each capture using an electronic load cell suspended from an aluminum tripod.