Effect of diet, location and sampling year on bioaccumulation of mercury, selenium and cadmium in pelagic feeding seabirds in Svalbard

• Biomagnification potential of Hg and Cd both in Arctic and Atlantic food webs.
• Trophic position explains Hg variation in kittiwakes but not in little auks.
• Selenium was associated with Hg in little auks, but not in kittiwakes.
• High Se:Hg molar ratios indicate low risk of Hg toxicity.

Hepatic concentrations of mercury (Hg), selenium (Se) and cadmium (Cd) were determined in black-legged kittiwakes (Rissa tridactyla) and little auks (Alle alle) from two fjords in Svalbard (Kongsfjorden; 78°57′N, 12°12′E and Liefdefjorden; 79°37′N, 13°20′E). The inflow of Arctic and Atlantic water differs between the two fjords, potentially affecting element accumulation. Trophic positions (TP) were derived from stable nitrogen isotope ratios (δ15N), and stable carbon isotope ratios (δ13C) were assessed to evaluate the terrestrial influence on element accumulation. Mercury, Cd, TP and δ13C varied significantly between locations and years in both species. Trophic position and feeding habits explained Hg and Cd accumulation in kittiwakes, but not in little auks. Biomagnification of Hg and Cd were found in the food webs of both the Atlantic and the Arctic fjord, and no inter-fjord differences were detected. The δ13C were higher in the seabirds from Kongsfjorden than in Liefdefjorden, but this did not explain variations in element accumulation. Selenium concentrations were not influenced by Hg accumulation in kittiwakes, indicating baseline levels of Se in this species. In contrast, correlations between Hg and Se and lower Se:Hg ratios in little auks from Kongsfjorden than in Liefdefjorden indicate a more pronounced influence of Se–Hg complex formation in little auks feeding in Atlantic waters.