It’s well documented how human activities are causing toxic algae blooms, dead zones and islands of floating plastic in the ocean. The Ocean Conservancy recently released a report that found that by 2025 there could be one ton of plastic in the ocean for every three tons of fish, while factories and farms create runoff filled with DDT, PCBs and mercury that finds its way into the ocean.
What is less documented is how these plastics and chemicals are coming back to land. The contaminants get absorbed by plankton and other ocean microbes, which are then eaten by fish or larger creatures. At every step up the food chain, the chemicals tend to “bio-magnify,” Mallory says, accumulating and concentrating in their bodies.
His studies found that fulmars are like the great cleaners of the ocean, ingesting a lot of plastic as well as chemicals that sometimes adhere to plastic. When the birds get back to Cape Vera, they vomit or defecate onto the cliffs, and the contaminants are then washed down into the freshwater pools beneath.
Mallory says that the levels of DDT in the sediments of these ponds are relatively high, and the insects that live in them absorb some of the chemicals.
“We may think of the Arctic as this remote, pristine region, but it’s not,” adds Jennifer Provencher, a graduate student in eco-toxicology at Carleton University in Canada who frequently collaborates with Mallory. Provencher has found plastic and chemicals in the stomachs and livers of the thick-billed murres that live on the cliffs of Coats Island in the north of Hudson Bay. She has also found that great skuas can ingest plastic from preying on northern fulmars.
birds like kittiwakes, horned puffins and red-faced cormorants—the latter of particular concern because the population is dropping quickly—are absorbing large amounts of phthalates.
This group of chemicals is sometimes used to make plastic flexible or harder to break, and they can persist even after the plastics themselves break down in the ocean. While the effects of the chemicals aren’t very well understood, the Centers for Disease Control and Prevention say that some types have affected the reproductive systems of laboratory animals.
— source smithsonianmag.com By Joshua Rapp Learn