Litter found in the remotest parts of the deep sea

20 January 2015

Deep sea litter

A selection of the rubbish found in the deep sea   

Rubbish found in the deep sea more than 1,000km (600 miles) from the coast reveals the truly global impact of human activities.

Food packaging and fishing gear were among the discarded items found by Museum scientists visiting some of the remotest parts of both the Indian and Atlantic Oceans.

The fishing gear could be found impacting the environment by entangling corals, scraping the sea floor or even ‘ghost fishing’ – still catching creatures despite not being tended by humans.

‘At most of the locations we visited by ship, we were the first team of scientists to study the area,’ said Museum marine biologist Dr Lucy Woodall. Most of the areas were more than 1,000km from any coasts and away from normal shipping routes. The most remote location was 1,600km from land and 1,500m deep.

‘With this in mind we could expect to not have seen much litter. However we did see litter on every feature we looked at,’ she said. Sometimes the litter was a single item, but in some cases the team found evidence of mass dumping, such as lots of glass bottles of the same type.

Patterns of waste

The team compared litter densities on seamounts and ridges (raised features on the sea bed) between the Atlantic and Indian Oceans to look for patterns. The density varied considerably between features within each ocean, but there were some patterns in the type of litter observed between the oceans.

The Atlantic Ocean features tended to accumulate more general waste, specifically food packaging. Around many seamounts in the Indian Ocean, which are often productive fishing areas, the team found accumulations of discarded fishing gear.

Inundated with plastics

The results of the research, led by the Museum with collaborators from the University of Bristol, the University of Oxford and the Scottish Marine Institute, were published this week in the journal Frontiers in Marine Science.

Recently, the team reported on the ubiquity of microplastics – tiny fragments of plastic and fibres – in the deep sea. While this debris likely represents a significant fraction of known plastic waste, the new discovery marks an additional source of plastic to deep-sea ecosystems.

Cleaning up our act

Deep-sea research is logistically challenging, and still relatively little is known about the sources and fates of litter in these ecosystems. As research is challenging, so would be cleaning it up, said Dr Woodall.

Instead, she thinks we should focus on reducing waste through recycling, minimising plastic packaging, and through schemes such as official disposal of damaged fishing gear.

  • by Hayley Dunning

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