What Can Stable Isotope Analysis of Top Predator Tissues Contribute to Monitoring of Tundra Ecosystems?
Understanding how climate change and increasing human impacts may exert pressure on ecosystems and threaten biodiversity requires efficient monitoring programs. Indicator species have been proposed as useful tools, and predators and their diet may be particularly suitable. The vast and remote arctic tundra represents a good case study as shifts in ecosystem states are presently occurring, and monitoring is a major challenge. Here we assess what stable isotopes reflecting the diet of the arctic fox, a widespread and highly flexible top predator, can contribute to effective monitoring of the vertebrate prey basis of Arctic tundra. We used data collected over 2–5 years from six sites in the Eurasian Arctic and Greenland. Stable isotope signatures of arctic fox winter fur reflected both spatial and temporal variability in the composition of the vertebrate prey basis. Clear contrasts were apparent in the importance of marine resources, as well as of small rodents and their multiannual density fluctuations. Some important resources could however not be separated because of confounding isotopic signatures. Moreover, except for preferred prey, the proportions of prey in the diet may not necessarily reflect the relative importance of species in the community of available prey. Knowing these limitations, we suggest that the arctic fox diet as inferred from stable isotopes could serve as one of several key targets in ecosystem-based monitoring programs.
Keywordsecological indicator monitoring stable isotopes predator diet arctic tundra food web Vulpes lagopus
We thank all the people who contributed to field work in the different sites, and Sissel Kaino and Jennifer Stien for help in the lab. This study was supported by the Research Council of Norway’s International Polar Year Program (project Arctic Predators), the Norwegian Directorate of Nature Management (project Arctic fox in Finnmark), the Danish Environmental Protection Agency (Zackenberg Basic), the Netherlands Organisation for Scientific Research, and the Russian Foundation for Basic Research (Grant No. 047.017.038 to BAN), the Norwegian Polar Institute (Projects arctic fox, reindeer, ptarmigan and sea bird monitoring in Svalbard), and the State Nature reserve “Wrangel Island”. We thank three anonymous referees and John Pastor for constructive comments on a previous version of the manuscript.
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