Marine debris on the shores of an isolated tropical atoll in the Indian Ocean

"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. 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.

Professor 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.

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.

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.

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.