Scientists know that the primary way methylmercury affects people is through consumption of fish and shellfish. But how does the toxic substance get into species that live in the open ocean?
A new study uses chemical signatures of nitrogen, carbon, and mercury to answer those questions. The work opens the door for new ways of tracking sources of mercury poisoning in people.
Researchers wanted to know if tuna and other open-ocean fish pick up methylmercury by eating contaminated fish that live closer to shore. They studied 11 species of fish, including red snapper, speckled trout, Spanish mackerel, and two species of tuna.
The found that coastal fish and open-ocean fish are feeding from two separate food webs. The finding runs counter to the long-held view that the open ocean is too oxygen-rich to support methylation -- but it is consistent with recent studies suggesting more methylation may be occurring in that environment than was previously thought.