The rising spectre of a ‘plastic ocean’

Plastic refuse could be problematic for the oceans.
Image courtesy of Shutterstock.

The recent high winds, waves and tides across the UK have transformed many of the nation’s beaches, with sand removed, cliffs eroded and properties damaged. Amongst the changes, many people will have noticed dramatic increases in the amount of plastic debris. Ranging from the banal to the curious, these fragments of 21st Century life are the signature of a problem that is threatening our oceans.

Plastic litter is now almost everywhere in the world’s oceans, extending from the coast far out to sea, and down onto the sea floor. Large pieces of plastic such as bottles, plastic bags, cigarette lighters and old toys can be found on most beaches and readily spotted from the decks of ocean-going vessels. And there’s more, microplastic fragments – those smaller than 5mm – and even less obvious nanoscale plastics (less than 1mm in size), are readily detectable in sand, sediment and even in the tissues of marine organisms.

One of the main causes of this global problem is increasing plastic manufacture, with annual production increasing from just 1.5 million tonnes in the 1950s to a staggering 280 million tonnes in 2011.

Despite the ubiquity of plastic in the ocean, our knowledge about the effects of this debris is limited. As if to underline the issue, a recent horizon scan of global conservation issues identified microplastics as a serious emerging global environmental threat.

Numerous organisations have drawn attention to the plastic litter issue, yet the scale of the problem is not widely appreciated by either the public or politicians. And right on cue, research is beginning to show that plastic litter is affecting a number of marine animals, including birds, turtles and invertebrates, with studies also finding plastic fragments in the guts, respiratory structures and tissues of marine species.

Yet few, if any, practical measures have been put in place to manage the situation.

In June of 2013, I was one of over a hundred scientists who met at the University of Siena in Italy to clarify what is known – and what remains to be investigated – concerning plastic litter in the sea.

We discussed several important areas that need further investigation, including the need for answers to questions like: How much plastic is getting into the marine environment each year?; What are the key sources?; Where do the different types of plastic litter accumulate?;

Is plastic taken up by marine organisms?; Is it damaging to them?; What is the extent of economic, environmental and human health costs resulting from the presence of plastic litter in the marine environment?

Identifying questions like these allows us to focus our research efforts as a community, and ensure we’re targeting the right areas with the limited funding that exists.

But science alone cannot solve the rising possibility of an ocean where beaches of plastic, rather than sand, are commonplace. Public education programmes are needed to increase awareness of the scale and severity of the issue, whilst guidelines and regulations to ensure the safe disposal of plastics need to be developed and enforced. Ultimately, the global community needs to work towards a reduction in the use of plastics and develop environmentally friendly alternatives.

There is clearly much to be done to bring the issue of plastic litter in the seas to the attention of the public, policymakers and politicians. Fortunately, the European Commission and other funding organisations around the world have at last begun to support research work in this area. Nonetheless, as with many environmental problems of our time, the need for positive action to limit the plastic debris in our oceans has become undeniably immediate.

Professor Michael Depledge
Chair of Environment and Human Health
University of Exeter Medical School

Read more about the issue in this review recently published by Professor Depledge.

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