Polyester oysters and plastic soup
Anthony Gallagher, professor of marine sustainability, explores how our oceans are increasingly contaminated by plastic microfibres – and what that means for the marine food chain.
Over the last few years, we’ve seen a backlash against the use of plastic microbeads in face scrubs and other products. Vast quantities of these tiny grains of plastic were being washed down our plugholes and finding their way into the ocean, and eventually into the guts of marine organisms.
Several countries, including the UK, are now in the process of regulating or banning microbeads entirely. A clear victory for the environment, then?
Yes… and no. Microbeads are just a single part of a wider problem, with microplastic pollution from a range of sources continuing to contaminate our coastlines and our oceans. One of the most pernicious – and surprising – of these, we are beginning to discover, is clothing.
The insidious microfibre
Polyester fleece first became popular in the 1980s, and these days you’ll find it in everything from outdoor wear to haute couture. But every time you wash your clothes, microscopic plastic fibres too small to get caught in the washing machine’s filter are working loose.
Through the sewers, through the water treatment plants, and out into the wild ocean… where tiny water-filtering animals like plankton, oysters and other molluscs draw them in.
Research I carried out last year into the water composition in the Solent estuarine complex showed alarming levels of these microfibers, which – in addition to turning our oceans into a kind of plastic soup – can block the digestive systems of smaller creatures, and even pass into the blood.
Worse, the plastics attract and bind other contaminants, such as pathogens and heavy metals. And once consumed by the critters at the bottom of the food chain, contaminants can steadily work their way up and up –until they end up on your plate.
My research into microplastics contamination in the Solent has been supported by coastal studies carried out by Plymouth Marine Laboratory and the University of Exeter, among others. But we’re only now starting to look at the wider implications.
From coastline to the deep ocean
In the Solent we found a high propensity for plastics, which we classified by shape: fibres, regular shapes such as the ubiquitous microbeads, and irregular shapes, thought to be broken down from larger forms.
Levels of irregular shapes were rather low – which makes sense, as the Solent estuary’s tidal processes would be flushing them out every ten days or so. The plastics simply don’t have time to break down too far.
But flushing out to where?
Earth’s oceans are not a series of closed systems – they are all connected. So the plastic being washed out of the Solent and countless other coastal environments has to be finding its way into the deep oceans – but there’s been little research so far to confirm that.
However, I’ve recently co-authored a research paper that looks at the Costa Rican thermal dome – an area in the Pacific where deep cold water wells up to the surface, creating a region which is rich in nutrients and marine life.
Part of the leatherback turtle migration path, and a year-round habitat for endangered blue whales, this ecologically important area is primarily threatened by commercial fishing activity. But chronic microplastic pollution is also a likely – but as yet uninvestigated – problem.
By sampling plankton in the dome for the presence of microplastics, we have learned more about levels of contamination in the pelagic ocean. Following the recent UN resolution on plastics, hopefully our data on oceanic microplastic contamination may be able to inform ecology policy regarding this unique ecosystem – and help shape our global approach to the problem.
Impact on the food chain
Closer to home, action is already under way. The European Commission presented a strategy on plastics at the end of 2017, dealing with wastage and leakages of plastic to the environment as part of the wider Circular Economy Action Plan.
In support of that strategy, I’m developing a project to examine the potential impact of microplastics on seafood supply chains, particularly oysters, along the French and British sides of the English Channel.
Every report done on seafood shows them to be contaminated by plastics – filling up the guts of the animal, and allowing heavy metals and persistent organic pollutants to accumulate in the food chain.
Finned fish are normally cleaned and dressed before consumption, and the guts discarded – removing most (but not all) of the potential contaminants.
Not so with oysters and other shellfish, which are usually eaten whole. So the potential for foodchain contamination ought to be of serious interest to gourmands, pescatarians and seafood lovers! Yet awareness of plastics contamination, and understanding of the risks, is still relatively poor among consumers and the public.
So part of this project would be to better understand perceptions, and to create a cross-Channel forum of scientists, businesses and decision makers who can identify the environmental and commercial challenges and start implementing the kind of practical, effective solutions that can start to make a difference.
Thinking smarter – thinking circular
Ultimately, we need to start thinking more critically about the products we use, and how we manage them. Plastic is the epitome of man-made innovation, and an essential part of modern life. But management of its supply chains, and its lifecycle, remains atrocious.
40% of the 350 million tonnes of plastic produced each year goes on single-use items such as plastic bottles – and as my research shows, even longer-life items like clothes have unexpected environmental impacts.
So as the concept of the circular economy – making recycling and reuse a fundamental part of the product lifecycle – gathers traction with the public and policymakers alike, we’ll hopefully see a more conscientious, long-term view of how we manage plastics.
And perhaps, with time, our oceans can begin to recover.
Interested in studying or researching sustainability and the environment? Check out our sustainability science honours degree, or our postgraduate research programme.