By Jan TenBruggencate
Advertiser Columnist

A major concern about the amount of plastic debris that floats in the oceans has been that marine creatures become entangled in it or swallow it.

Researchers have found Hawaiian monk seals trapped in netting that gets caught on the reefs, and albatrosses and other seabirds are regularly found dead, their bellies full of plastic cigarette lighters and other pieces of plastic debris.

A British scientist has now raised a third concern about drifting plastics in an article in the April 25 issue of the journal Nature.

Alien species may hitchhike aboard chunks of floating plastic, providing a new way to colonize new regions, says David Barnes of the British Antarctic Survey, part of the British National Environmental Research Council.

For Hawai'i, this presents a significant issue, because so much marine debris from all around the North Pacific ends up on our shores. The Northwestern Hawaiian Islands seem to get even more than the main islands.

"I've seen a lot of drift up at Midway, and a lot of plastic," said University of Hawai'i botany professor Isabella Abbott.

Barnes said the vast amount of floating debris now on the surface of the oceans presents marine organisms with "unparalleled availability, distribution and duration of transport."

While such things as pieces of wood or pumice (floating volcanic rock) have been on the seas for millennia and have carried forms of life from one part of the sea to another, the appearance of plastics has changed the picture enormously.

Barnes says the amount of plastic debris around the British Isles and in the Southern Ocean increased 100 times during the 1990s.

Barnacles, worms and mollusks travel readily on plastics, but the most common plastic-riders are bryozoans, a group of colonial marine animals that can look like plants or corals. Many of these creatures don't have any other good way of transporting themselves across oceans, so the availability of plastics can be a major factor in their spread, Barnes said.

Abbott said most plastics with flat surfaces are probably not very good vehicles for the movement of marine plants, or algae.

"Except for crustose corallines, I would not say it's a good substrate for algal growth," she said.

But things like floating pieces of rope and netting readily support plant communities.

The increasing flow of shipping across the oceans is also a source. In Hawai'i, new species have become established after arriving via the hulls of ships or in the bilge water of visiting vessels.

Barnes said the amount of floating rubbish caused by humans has probably doubled or tripled the likelihood of establishment of new species in different parts of the ocean.

Jan TenBruggencate is The Advertiser's Kaua'i bureau chief and its science and environment writer. Contact him at (808) 245-3074 or e-mail jant@honoluluadvertiser.com.