Mercury in Ringed Seals (Pusa hispida) from the Canadian Arctic in Relation to Time and Climate Parameters

Area of Science:

• Environmental Toxicology
• Marine Mammal Research
• Arctic Ecology

Background:

• Arctic marine mammals, like ringed seals, accumulate mercury, posing dietary risks to Indigenous communities.
• Understanding mercury (THg) and selenium (Se) trends in these seals is crucial for assessing ecosystem health and human safety.

Purpose of the Study:

• To investigate temporal trends of total mercury (THg) and selenium (Se) in ringed seals across the Canadian Arctic over 45 years.
• To examine the influence of age, diet, and climate parameters on mercury levels in ringed seals.

Main Methods:

• Analysis of ringed seal (Pusa hispida) muscle and liver samples collected between 1972 and 2017 from five Canadian Arctic regions.
• Statistical analysis including temporal trend analysis, variation partitioning, and correlation with climate indices (Arctic Oscillation, North Atlantic Oscillation, Pacific/North American pattern).

Main Results:

• Total mercury (THg) levels in seal liver showed no temporal change, but muscle THg decreased in Hudson Bay and Ungava/Nunatsiavut.
• Carbon stable isotopes indicated dietary shifts over time in four regions.
• Age, climate parameters (especially Arctic Oscillation), and diet explained significant variations in THg levels.

Conclusions:

• While liver mercury levels remained stable, muscle mercury shows regional declines, suggesting complex environmental interactions.
• Climate indices and age are key drivers of mercury trends in Arctic ringed seals.
• The study highlights the dynamic nature of mercury contamination in Arctic food webs and its links to environmental change.