02 August 2016

The huge volumes of litter we leave in the oceans is one of the greatest environmental problems of our time. Professor Henrik Kylin from Linköping University has studied how the beaches on a remote atoll in the Indian Ocean have been covered with litter, even though the atoll has no permanent residents.[No text in field]

The plastic in the oceans is one of the hottest topics in environmental research right now – and rightly so. For the animals, this litter is disastrous,” says Henrik Kylin, professor of environmental chemistry, whose research focusses on how environmental toxins are spread, and what damage they do to the environment.

To learn how litter is spread around the world, he has made numerous trips, including to Canada, Tanzania, the Arctic and the Antarctic. But today he is in his book-filled office at the Department of Thematic Studies - Environmental Change.

Rubbish – in piles or as a hidden threat

We don’t actually know how much rubbish there is in our oceans. But we know that most of it is plastic, and that much of this is not visible to the naked eye. It’s microplastic, which comes from emissions from our treatment plants or from larger pieces of plastic that have been decomposed by the sunlight or ground into smaller pieces by wave action. These miniscule particles, less than five millimetres in size, can be eaten by plankton, which are eaten by fish.

“The plastic fills the fish’s stomach, so it starves. But microplastic isn’t the only plastic that’s harmful to animals. For instance a sea turtle can easily mistake a plastic bag for a jellyfish,” says Professor Kylin.

This time, Kylin has joined researchers from Mauritius, South Africa and the Channel Islands to visit Saint Brandon, an atoll in the Indian Ocean, to study the larger debris that washes up from the ocean onto the beaches there. The results have been published in the journal Marine Environmental Research.

Sandals that have come 3,350 kilometres

On Saint Brandon, which belongs to Mauritius, the only economic activities are small-scale fishing and a little tourism. The atoll has no permanent population, but plenty of sea turtles – and for these it’s an important breeding ground. In terms of humans, in 2014 there weren’t more than 41 people temporarily stationed there, mainly for fishing purposes. But despite this minimal human activity, the beaches of the surrounding archipelago are cluttered with debris.

“We found nearly 30,000 objects on the islands, mostly made of plastic. That is equivalent to 76 objects along a 100-metre stretch of beach, which is quite a lot,” says Professor Kylin.

The researchers documented, classified and counted all debris larger than five millimetres. The most common objects found were flip-flops, energy drinks and compact fluorescent lamps. According to Professor Kylin it is unlikely that the small number of people that spend time on the islands could have made much of a contribution to the amount of debris, because the brand names on the flip-flops and energy drinks indicate that they come from countries including Indonesia and Malaysia, on the other side of the Indian Ocean. Thus this debris has travelled 3,350 kilometres, roughly the distance from Stockholm to Bagdad.

“The ocean currents are incredibly strong. The route has probably been affected by the North Equatorial Current and the Equatorial Countercurrent, which flow past the regions where the debris began its journey.” Prof Kylin gets a large inflatable globe – made of plastic – from a corner in his office. He points to Malaysia and traces the route the debris would have taken.

Affecting the food chain

So, how has this well-travelled rubbish affected the environment? The 11,000-odd flip-flops found by the research team are produced from plastic foam that contains DDT, PCBs and flame retardants. Also, after long periods in the water, they absorb environmental toxins which they transfer to the island shores.

“The lamps we found contain heavy metals that we have seen enter the islands’ food chains, for instance we have found them in corals and coral sand.”

One of the measures to reduce the influence of humans on the isolated atoll, according to Professor Kylin, is the regular cleaning of the beaches. But of course, it would be better if the debris didn’t end up in the oceans in the first place.

“We humans need to think about how we manage our rubbish. It’s not only about people on the other side of the earth, it’s about ourselves. We need to stop throwing rubbish from boats, and remember that if not disposed of properly, plastic bags can end up in the ocean.”

After studying debris in the Indian Ocean, Kylin will now move on to his next research project. This time his hunt for environmental toxins will take him to Bangladesh and India, where he will study microplastics in the Ganges.

Fact box:

  • Saint Brandon has several names; it’s sometimes called St. Brandon’s Islands and St. Brandon’s Atoll. However most maps refer to it as Cargados-Carajos Shoals, which in Spanish-Portuguese English means literally “Damn bloody shoals”.

The atoll is 56 kilometres long, 22 kilometres wide, and consists of 24 islands.


The flip-or-flop boutique: Marine debris on the shores of St Brandon's rock, an isolated tropical atoll in the Indian Ocean, Hindrik Bouwmana, Steven W. Evansa, Nik Colec, Nee Sun Choong Kwet Yivee, Henrik Kylin (2016), Marine Environmental Research, vol. 114, pages 58–64