The best tools for tracking how well pollution-reduction laws are working may be seabirds.
Seabirds, including pelicans, gulls and terns, are at the top of the food chain, and they absorb the toxins and pollutants contained in the fish they eat, researchers write in the May 3 issue of the journal Science. And because seabirds forage over wide areas of oceans but come back to one spot each year to breed, they provide scientists with a one-stop-shop to sample from a broad geographic region.
Bioaccumulative pollutants build up in biological tissue over time and can be passed down in eggs or milk, in the case of mammals. Perhaps the most famous example is DDT, an insecticide now banned for agricultural use because it thins the eggshells of birds.