June 10, 2008

Deep-Sea Creatures Contaminated

Chemicals produced by humans have been found in deep-sea squid and
other creatures, further evidence that contaminants make their way deep
into the marine food web, scientists said Monday.

Researchers found a variety of chemical contaminants in nine species of cephalopods, which include octopods, squids, cuttlefishes and nautiluses. These species are food for dolphins, narwhals, killer whales
and other toothed whales. The researchers collected nine species of
cephalopods up to a mile down and deeper in the western North Atlantic
Ocean by trawling.

"It was surprising to find measurable and sometimes high amounts of
toxic pollutants in such a deep and remote environment," said Michael
Vecchione, a researcher with the National Oceanic and Atmospheric
Administration (NOAA).

Among the chemicals detected, all of which don't degrade and therefore persist for a very long time:

  • Tributyltin (TBT), an additive used to control growth of organisms and is found in antifouling paints for boats, wood preservatives.
  • Dichlorodiphenyl-trichloroethane (DDT),
    a pesticide banned in the U.S. in the 1970s but still used on a limited
    basis in some parts of the world to control diseases like malaria.
  • Polychlorinated biphenyls (PCBs),
    used to insulate electrical transformers and capacitors and in
    coatings, sealants, adhesives, paints, wood floor finishes, and in
    carbonless copy paper. PCB production was banned in the U.S. in the
  • Brominated diphenyl ethers (BDEs), used as flame retardants in a variety of household products, from plastics to foam in furniture and fabrics.

The findings will be published in the journal Marine Pollution Bulletin.

Recent studies have reported the accumulation of such chemicals in
the blubber and tissues of whales and other predatory marine mammals as
well as in some deep-sea fish.
Other investigators had speculated that the pollutants in marine
mammals had resulted from feeding on contaminated squids. However,
almost no information existed prior to this study about POPs in
deep-sea cephalopods.

Vecchione and colleagues wanted to see if whales had a unique
capacity to accumulate pollutants or if they were simply one of the top
predators in a contaminated deep-sea food web.

"The cephalopod species we analyzed span a wide range of sizes and
represent an important component of the oceanic food web," Vecchione
said. "The fact that we detected a variety of pollutants in specimens
collected from more than 3,000 feet deep is evidence that
human-produced chemicals are reaching remote areas of the open ocean,
accumulating in prey species, and therefore available to higher levels
of marine life. Contamination of the deep-sea food web is happening,
and it is a real concern."