Sea birds gobble up plastic because it has a smell that reminds them of food, scientists have discovered. Plastic debris poses a serious environmental threat to many kinds of marine life, including fish, turtles and birds. Until now the reason why some sea birds have such a voracious appetite for the stuff has been a mystery. New research shows that plastic waste in the ocean emits the aroma of a sulphurous compound certain birds have associated with food for thousands of years. It effectively tricks them into believing plastic will provide a nutritious and healthy meal. Among the birds most severely affected by plastic consumption are “tube nosed” species such as petrels and albatrosses which have a keen sense of smell. As part of the study, the scientist’s anchored mesh begs containing plastic beads into the ocean at Monterey Bay and Bodega Bay off the coast of California. The beads were made of the three most common types of plastic debris, high density polyethylene, low-density polyethylene , low density polyethylene, and poly-propylene. After three weeks the bags were collected and the beads analyzed by flavor and smell experts at University of California Davis’ Institute for Wine and Food Science. The tests confirmed that after a period of time in sea water the plastic reeked of the sulphur compound dimethyle sulphide, or DMS. The chemical was emitted by marine algae growing on the surface of the beads. Previous research had shown that DMS is released when algae is eaten by animals such as krill, small crustaceans which are a favourite food of seabirds. For the birds, the smell of DMS is like a dinner gong telling them where to find a meal. Seabirds that track the scent of DMS to find prey are six times more likely to eat plastic than those which do not.
