Haul aboard
Chris Baker, The Guardian 27 Feb 08;
The discovery of large amounts of microplastic in remote seas suggests marine pollution is at worse levels than previously thought
When the crew of the Greenpeace ship Esperanza last year pulled in its 1-metre-net from the surface of the Atlantic about 200 miles south-east of the Azores, it was surprised only by the quantity of what it found.
Washing around in the net were nearly 700 minuscule and unidentifiable fragments of plastic; 57 pieces of synthetic fishing line and leftover strands from dumped nets and rope; a handful of flakes from old plastic bags, including one with a zip-type seal still attached; and a dozen so-called nurdles - white pellets, looking like grains of rice, which are the raw material of the packaging industry. All this microplastic had been collected in just four nautical miles.
"When we conducted the first trawl and brought the sample back on board, I was shocked, and so were the crew," says Adam Walters, a researcher at Greenpeace's laboratory in Exeter. "We had been sailing then for over a month, looking at the ocean every day, and had no idea that all this plastic was floating by the ship."
It was not just the Atlantic Ocean. Wherever the Esperanza went last year as part of Greenpeace's Defend Our Oceans campaign, it trailed its sample net from a boom beside the ship. It was more or less the same story everywhere. After the contents of the trawl had been tipped into a washing tank, and once the sea creatures - jellyfish, by-the-wind-sailors, brightly coloured sea snails, or small crabs hitching a ride on something - and the larger pieces of floating debris had been removed, there was always the same mosaic of pieces of microplastic floating on the surface.
Walters says: "We knew there were big pieces everywhere so we would expect to find small pieces, but it was a shock. It is shocking when something you thought was pristine turns out to be polluted in that way. When you are in the middle of nowhere, thousands of miles from land, and you are scooping up pieces of plastic it is quite shocking."
In the north Pacific, where a gigantic sea of rubbish - dubbed the great garbage patch, and which may contain 100m tonnes of flotsam - swirls around in a system of currents known as the North Pacific Gyre, a large amount of microplastic was expected; indeed, the highest concentrations were found there. But Esperanza also discovered an unexpectedly high number of particles in the Atlantic, around the Canary Islands and the Azores. The haul of microplastic continued in the Mediterranean, the Red Sea, the Indian Ocean, in the Bay of Bengal, and off Malaysia and the Philippines. Only in the furthest reaches of the south Pacific did the count go down.
David Santillo, senior scientist at the Exeter laboratory, says: "I think it is the first time anyone has really looked in the Indian Ocean, over other parts of the Pacific, and in the Atlantic. I don't think anyone else has been able to look where we have looked. It is giving us a first look at the nature of the problem in other areas. It is showing that the problem is not restricted to the North Pacific Gyre. We found microplastic at some level almost wherever you go in the world, even well offshore.
"I think the Atlantic is showing a similar problem as the North Pacific Gyre - perhaps, on the evidence we have got, not as abundant, but it warrants further investigation. It was interesting that we were finding that spike there. It may be that we were lucky, but it may be symptomatic of the situation in the Atlantic itself."
Plastic makes up 60%-80% of marine litter, and at least 267 species, including 44% of seabirds, and 43% of marine mammals, are known to have suffered because of entanglement or ingestion. The Marine Conservation Society's annual beach clean reports increasingly smaller pieces of plastic being found on Britain's beaches. According to the United Nations Environment Programme, there are about 13,000 pieces of plastic litter in every square kilometre of the ocean's surface.
Microplastic, invisible until you look very closely, would add to the equation. The ever-present nurdles, for example, are shipped around the ocean in vast quantities, to be remelted and remoulded to make finished plastic packaging. A scavenging animal may easily mistake them for fish eggs.
Richard Thompson, reader in marine ecology at Plymouth University, has been able to track the historic build-up of microscopic particles of plastic, using plankton samples collected regularly on silk screens for more than 40 years, on shipping routes between Aberdeen and Shetland, and Orkney and Iceland. In the 1960s and 70s, the number of plastic particles recorded remained fairly static, but rose dramatically in the samples from the 1980s and 90s - a trend that reflects plastic production, from about 5m tonnes a year in the 1950s to 230m tonnes today.
Thompson says: "The amount of small fragments and microplastic is likely to increase, and that material is going to survive in the environment for hundreds, if not thousands, of years. Everyday items, such as plastic bags and plastic bottles, are fragmenting and it is difficult now to find a shoreline that does not contain plastic. There seems nothing to stop them fragmenting into the microscopic particles I am reporting.
"It is something we need to get a much better understanding of. I really think we need more research to find out what the long-term implications are."
Analysis of the samples taken during the Esperanza's voyage should be completed by May, in time to be presented to a meeting of the scientific group of the London Convention - which protects the marine environment from human activities - on preventing pollution caused by dumping waste in the sea. In the meantime, the microplastic from the samples sits in the Exeter laboratory - looking harmless in small glass jars, but perhaps a unique snapshot of a serious problem.
