Analysis of narwhal tusks reveals lifelong feeding ecology and mercury exposure
Runé Dietz, Jean‐Pierre Desforges, Frank F. Rigét, Aurore Aubail, Eva Garde, Per Ambus, R.J. Drimmie, Mads Peter Heide‐Jørgensen, Christian Sonne
Abstract
N) and mercury concentrations in annually deposited dentine growth layer groups in 10 tusks from Northwest Greenland (1962-2010), we show surprising plasticity in narwhal feeding ecology likely resulting from climate-induced changes in sea-ice cover, biological communities, and narwhal migration. Dietary changes consequently impacted mercury exposure primarily through trophic magnification effects. Mercury increased log-linearly over the study period, albeit with an unexpected rise in recent years, likely caused by increased emissions and/or greater bioavailability in a warmer, ice-free Arctic. Our findings are consistent with an emerging pattern in the Arctic of reduced sea-ice leading to changes in the migration, habitat use, food web, and contaminant exposure in Arctic top predators.