Forests, Not Just Rain, Drive Mercury in Mountain-Lake Fish

Mercury occurs naturally, but air pollution and industrial discharges can add excess amounts to the environment. It can build to toxic levels in animals like insects and fish, affecting human and ecosystem health.

The study

A team of Department of the Interior scientists measured mercury in fish from lakes in high-elevation national parks of the western U.S., publishing their results in Science of the Total Environment in December 2024.

What they found

• Forests matter: fish in lakes ringed by more evergreen forest carried more mercury.
• More than precipitation: the surrounding forest appears to influence how much mercury reaches the lake — possibly more than mercury falling in rain or snow. Exactly how isn't yet clear.
• Why it matters: anything that changes the forest — wildfire, beetle kill — could change how mercury affects aquatic life.

Sources

Based on "Forests Affect the Amount of Mercury Pollution in Fish," by the editors of Park Science, Research Roundup, Volume 39, Number 1 (Winter 2024–25), National Park Service, summarizing Flanagan Pritz and others (2024), "Forest cover influences fish mercury concentrations in national parks of the western U.S."; a work of the United States government in the public domain.