Trawl suggests Red Sea has relatively low levels of plastic debris

Jan. 8 (UPI) -- A recent trawl of the Red Sea turned up surprisingly small amounts of plastic debris.

Globally, the growing prevalence of plastic pollution in the ocean is a serious problem. The latest findings by researchers at King Abdullah University of Science and Technology in Saudi Arabia suggest the problem is less pronounced in the Red Sea.

While not as bad there, researchers say it's still likely some of plastic making its way into the Red Sea is becoming captured by mangrove forests and coral reefs.

"Usually the main source of plastic in the sea tends to be litter and mismanaged waste," KAUST doctoral student Cecilia Martin said in a news release. "But on this coastline, the only large human settlement is Jeddah, with a population of 2.8 million people, and little tourism, so there are few people with the opportunity to litter."

KAUST researchers used plankton nets to trawl for plastic debris at 120 coastal sampling sites along the eastern margins of the Red Sea. The collected plastic fragments were sorted by size and type.

Nearly three-quarters of all collected debris consisted of fragments from broken plastic objects. Plastic bags and wrapping accounted for 17 percent of the pollution. Fishing lines or nets made up 6 percent of the collected plastic, while foam accounted for 4 percent.

Globally, rivers carry significant amounts of plastic to the ocean, but the Red Sea isn't fed by any permanent rivers. Scientists suggest winds account for most of the pollution.

"The winds and a few storms are most probably the main sources of plastic," Martin said. "This is reflected in our findings of proportionally higher amounts of plastic films compared to global trends."

The findings -- published in the journal Frontiers in Marine Science -- aren't all positive. It's likely some plastic has gone missing in the Red Sea, likely captured by mangroves and coral reefs.

The missing plastic could be damaging fragile ecosystems.

"Mangroves are perfect traps for macrolitter," said Martin. "At high tide, floating items reach the forest and then, as the tide drops, get stuck in seedlings and mangrove aerial roots, pneumatophores, which act as a mesh to trap them."

Previous studies have shown a variety of marine organisms ingest plastics, including corals, mollusks, crabs and plankton.