A nasty-tasting shellfish could be just the job for cleaning rivers

SHELLFISH thrive in waters rich in nutrients. These include the nitrogen used in fertiliser, which passes from the land into rivers and then into the sea. The shellfish grow, as do the profits of those who harvest them. The problem comes when discharges into the sea are tainted with more noxious material, such as bacteria that pose a threat to human health. Once the bugs are in the shellfish, they can be passed on to anyone who eats them. This problem--and another, of excess nitrogen that can ca...