April 10, 2026 — Mercury released into the oceans affects marine environments worldwide. Traditionally, its distribution and quantity have been estimated using marine biogeochemical simulation models.
An international study led by Japanese researchers analyzed blood mercury concentrations in more than 11,215 seabirds from 108 species, of which 659 were newly collected samples and over 10,556 were from previous studies. This is the first biologically based estimate of oceanic mercury distribution.
The study found that mercury levels in seabirds vary according to prey trophic level, bird body weight, and foraging depth. The findings were published in Science of the Total Environment.
Mercury emissions into the ocean have risen since the Industrial Revolution, primarily due to increased atmospheric mercury from coal combustion. Mercury travels long distances by wind and enters the ocean through rainfall.
In the ocean, some mercury becomes highly toxic and bioaccumulates in the food chain, ultimately concentrating in the tissues of seabirds that consume fish and zooplankton.
Professor Akiko Shoji and Researcher Jumpei Okado of Nagoya University Graduate School of Environmental Studies, along with Senior Researcher Bungo Nishizawa of the Japan Fisheries Research and Education Agency, led an international study with 12 institutions from four countries.