Wetenschap - 27 augustus 2015

Plastic lost in the ocean

tekst:
Roelof Kleis

Plastic is disappearing from the plastic islands in the oceans, and at a fast rate. Jan Andries van Franeker has demonstrated this by comparing plastic samples from these islands to the stomach contents of northern fulmar on the North Sea. Where all that plastic goes to remains a mystery.

When a northern fulmar is washed up somewhere along the Dutch North Sea coast, there is a fair chance it will end up on Jan Andries van Franeker’s dissecting table. The biologist (at Imares, on the island of Texel) has been monitoring these birds since the late nineteen seventies. Van Franeker is chiefly interested in their insides: to be precise, in the bits of plastic in their stomachs. The northern fulmar acts as a gauge of the pollution of the sea.

In over three decades of research, Van Franeker has handled nearly 1000 northern fulmars. Birds which met their end for one reason or another and were washed up on the beach. A network of volunteers helps him with this, bringing him an average of 40 birds per year. ‘But it varies tremendously. In top years I can get 140 birds in. But this year I got extremely few, only 11. I need to expand my network. About 40 birds is a good sample.’

Until the beginning of this century this was a labour of love and did not bring in a cent. That changed in 2002 when the Ministry of Infrastructure and Environment commissioned a study of the northern fulmar as a window into pollution levels in the North Sea. Nowadays the bird is the official yardstick for pollution in the North Atlantic. An acceptable limit has been set at fewer than 10 percent of the washed-up birds with more than 0.1 grams of plastic in their stomachs. Van Franeker monitors this annually for the government. It is actually decades since that European norm has been achieved. Almost 60 percent of the birds have too much plastic in their stomachs, reveals Van Franeker’s work. But there is good news as well. In spite of the explosive increase in the use of plastic in recent decades, the net weight of the plastic in the fulmars’ stomachs has increased very little. ‘That is a relative gain,’ explains Van Franeker, looking on the bright side. But there is one big reservation. The weight of the plastic may not have risen, but the number of plastic particles per bird has. The average northern fulmar in the nineteen eighties had five pieces of plastic in its system: half what fulmars are carrying around today.

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The reason for this is a change in the makeup of the plastic waste in the sea. The amount of ‘industrial’ plastic has gone down by 75 percent within two decades. Van Franeker: ‘We are talking about the plastic pellets four or fi ve millimetres in diameter that are used for plastic products. There has been a big drop in the number of those industrial pellets. Apparently much less is getting lost in factories and during transportation.’ But these heavier pellets have been replaced by a big increase in the lighter particles of consumer plastic. Plastic that comes from you and me and ends up in the sea. The question is, where does the industrial plastic go to? Since the discovery of the ‘plastic soup’, the answer has seemed obvious: in one of the five plastic islands on the oceans. But is that really the case? Van Franeker compared his plastic data on the northern fulmars with data from the Sea Education Association (SEA), which has been monitoring the amounts of plastic in the North Atlantic gyre since 1986. With a large net the SEA fi shes out plastic from the top layer of the plastic ‘island’ there and does some simple calculations to work out the density of plastic per square kilometre.

There is a striking similarity between the two data sets. At the heart of the plastic island too, the industrial plastic has gone down by three quarters, from about 1000 to 250 particles per km2. The amount of consumer plastic has remained roughly the same. The big drop in industrial plastic proves incontrovertibly, says Van Franeker, that plastic is disappearing from the islands on a large scale. ‘With a continuous influx you would expect more and more industrial plastic. But that is not what is happening. On the contrary, even with a continuous infl ux of waste, the island is losing plastic. And at a fast rate: 75 percent in less than 20 years. That is incredibly fast. And where it goes to, nobody knows.’

Van Franeker’s analysis supports alarming fi ndings published last year, which show that only fi ve percent of the plastic dumped in the oceans every year is in the plastic islands. Van Franeker: ‘There must be stuff sinking to the bottom. And bits of the plastic definitely break off and get washed up along coasts. And I am convinced that animals contribute too by ingesting the plastic. Birds grind it down and spread it in their excreta. But where the rest goes remains a mystery.’ The research on the lost plastic is still in its infancy. The problem with it is, says Van Franeker, that the smaller the plastic, the harder it is to track it down. ‘Ultimately you are talking about the nano scale. Then the question is what that plastic does to the environment. That question about the possible environmental damage is even harder to answer. You can show effects in the lab, but is that how it works in the natural world?’

But prevention is better than a cure, reckons the Texel-based biologist. ‘As long we don’t have those answers, I favour caution. And the government should be playing a far bigger role there, if you ask me. There is a big question mark hanging over the excessive use of plastic that is going on now. The use of packaging material is unregulated and people just do what they like. There is a complete lack of regulations. Why isn’t there a deposit on plastic bottles, for instance? In Scandinavian countries, plastic bottles are reused. Why can’t we do that here?

Information about the fulmar research at Imares can be found at www.wur.nl/plastic-stormvogels 

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THE OCEAN CLEANUP Dutchman Boyan Slat is getting publicity around the world with his idea for cleaning up the plastic islands in the oceans. ‘A lot of money and eff ort that would be better spent in other ways,’ says biologist Jan Andries van Franeker. Far and away the most plastic at sea is not found in those islands. And the islands are not containers where the plastic collects permanently, but are more like dynamic waystations. ‘So it’s also doubtful what results you will get. We don’t know exactly what the side eff ects of that kind of cleanup would be. You sweep it all up and will catch all kinds of other things with it, such as seaweed and plankton. It is much more eff ective to tackle the problem in polluted estuaries.’ Van Franeker deplores the image people have of the plastic islands, too. ‘They are not the sort island you could stand on. That image was powerful for drawing attention to the problem but now it is time the public got a more realistic picture of the plastic islands.’


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