Rising Mercury Levels Linked to Fatal Disease in UK Porpoises

Marine mammals act as the ocean’s 'sentinel species'—living indicators of the ecosystem’s overall health. However, a new assessment of 738 harbour porpoises stranded along UK coastlines between 1990 and 2021 paints a worrying picture for marine biodiversity.

Researchers analysing liver tissue samples discovered that while concentrations of lead and cadmium have thankfully declined, levels of mercury and selenium have risen. The data revealed a distinct spatial pattern, with mercury accumulation peaking at lower latitudes and cadmium levels increasing further north.

The consequences of this pollution are severe. Because porpoises sit high on the food chain, they are vulnerable to bioaccumulation, retaining toxins from the prey they consume. The study confirms that elevated levels of zinc, mercury, selenium, and cadmium are significantly associated with a higher risk of mortality from infectious disease. These findings suggest that despite international agreements like the Minamata Convention, current pollution mitigation strategies may be insufficient to protect these vital marine predators from toxic threats.