Svalbard reindeer dietary preferences: inter-annual variation and long-term changes based on δ13C and δ15N values in serum

Theme 1. Environmental protection
Session Name 1.11 Reindeer & caribou in the Arctic system: Interactions between environmental, social and biophysical processes
Datetime Sep 06, 2018 10:15 AM - 10:30 AM (UTC +3)
Presentation Type Oral
Presenter Tamara Hiltunen
Author(s) Tamara Hiltunen (University of Oulu, Finland), Jouni Aspi (University of Oulu, Finland), Audun Stien (Norwegian Institute of Natural Resource, Norway), Jeffrey Welker (UArctic, Univ of Oulu, Univ of Alaska, Finland)
Abstract text

Svalbard reindeer are found on an archipelago in the High Arctic between 74° and 81° north, a region that is undergoing significant changes in winter and summer climates. These climate change impacts range from negative effects on winter foraging such as rain on snow (ROS) events to the positive effects of warmer summers and more forage productivity.  This combination of negative and positive effects on forage resources may be especially important in controlling fecundity and long-term herd abundance and sustainability.  However, there is uncertainty in winter diets of these herbivores.

In this study, we collected serum samples from adult, female and male reindeer at the end of winter over a 15 year period. Serum samples were then analyzed for δ13C and δ15N values as the combination of these isotopes may reflect variation in the species or life forms that reindeer have used during the prior 1-3 months.  These serum isotope values and those of forage collected during winter will be used in Bayesian mixing models to ascertain diets between years and over the decade and a half of our study. Over the entirety of the study one main trend is a enrichment in the δ15N values and a simultaneous depletion in δ13C values.  These concurrent changes in serum isotope values indicate that winter diets were likely due to a shift towards more nutrient rich grasses and woody shrubs, however an alternative hypothesis is that there has been poorer forage conditions in winter causing increases in muscle catabolim.

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