Climate Change

Tusk records

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Science  28 May 2021:
Vol. 372, Issue 6545, pp. 930-931
DOI: 10.1126/science.372.6545.930-c

Understanding how climate change may affect Arctic species is challenging given that change has been gradual. The impact of environmental transition is reflected in dietary shifts of species at upper trophic levels. Narwhals provide a unique opportunity to track wider ecological change in the Arctic because modifications in their diets can be detected using isotope analysis of the dentine deposited over their lifetimes in their elongated tusks. Dietz et al. measured isotope ratios in the tusks of 10 male narwhals collected between 1962 and 2010. The data revealed patterns consistent with dietary shifts from ice-associated (sympagic) to open-water (pelagic) food species over that time. Further, mercury levels were found to increase with the trophic level of prey, as might be expected. However, in recent decades, mercury levels in narwhals' tissues rose sharply, possibly reflecting an environmental source–related change.

Curr. Biol. 31, 2012 (2021).

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