What is the most pervasive threat to marine biodiversity posed by shipping? If that question conjures up images of fatal collisions between supertankers and migrating whales, or dolphins disorientated by ocean noise pollution jamming their sonar systems, think again. 

The answer could well be nurdles. That may sound like a particularly geeky version of a web-based word game, but it’s far more serious than that. Nurdles is the household name for the plastic pellets that form the building blocks for countless everyday items, from disposable cutlery to polycarbonate roofing and everything in between. 

Whatever name we give them, these plastic pellets, or nurdles, may well be the most serious threat to marine life that you’ve never heard of. Ultimately, they affect everything from seabirds, salmon and sardines to sea turtles, seals and supersized cetaceans – even seagrass. 

Because of their superficial resemblance to fish eggs, nurdles are often mistaken for food and ingested by turtles, fish, seabirds and other marine animals. 

Nurdles are innately toxic thanks to the chemicals they contain, but they also act as a magnet for environmental pollutants. These miniature poison pills then travel up the food chain, as larger predators (humans included) consume prey species that have swallowed the pellets.  

Over time, pellets that are not consumed directly will break down into even smaller microplastics, which are now such a ubiquitous problem that they have been found in human blood and tissue. 

Here are just a few of the many marine species that are known to be directly or indirectly affected by plastic pellet pollution. 

Grey seal

Atlantic grey seals on a beach in Norfolk, UK, where pellets have been found in large numbers. Credit: Ed Marshall

The UK harbours more than 120,000 grey seals, representing 40% of the entire world population and 95% of the European population. However, an estimated 53 billion nurdles also end up in UK seas every year, threatening our seal colonies with plastic pellet pollution. Some of the grey seal’s most important breeding grounds – including a well-known hotspot in north Norfolk – have been found to be polluted by nurdles. 

Seals are known to ingest microplastics, most probably as a result of eating prey that has itself consumed these toxin-laden substances. Scientific studies also suggest that microplastics such as nurdles may transport chemical contaminants into the bodies of marine animals that eat them. 

Seabirds

puffins seabirds plastics

Puffins have been found with plastic pellets in their stomachs. Credit: Sophie Hart

We’ve all seen those disturbing images of dead albatross chicks that have succumbed after being fed a diet of plastic by their unsuspecting parents, and they are by no means the only iconic seabirds to fall victim to the proliferation of plastic in our ocean. Autopsies carried out on dead puffins collected from one of the UK’s largest breeding populations on the Isle of May in Scotland have revealed that, along with their usual diet of sand eels, these charismatic seabirds have been eating nurdles. More recently, a staggering 91% of northern fulmars – a seabird of the open ocean – have been found to contain fragments of plastic, including an average of two industrial pellets per bird. 

Pellets found in the stomach of a northern fulmar in 2016 from the Skagerrak area. Credit: Jan van Franeker, Wageningen Marine Research

Sea turtles

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Juvenile turtles are known to consume fish eggs, which look very similar to pellets in shape and size. Credit: Jorge Martinez/FFI

Three of the world’s seven species of sea turtle are critically endangered, and the last thing they need is an additional threat to their survival. The diet of adult sea turtles – and thus their relative vulnerability to pellet ingestion – varies from species to species; leatherbacks, for example, are jellyfish specialists (which makes them susceptible to swallowing floating plastic bags), while hawksbills primarily eat sponges and mature green turtles are herbivorous. 

Turtle hatchlings are a different matter, however. At this early stage of development, all species consume a wide variety of food including fish eggs, exposing them to greater risk of ingesting toxic pellets, or starving to death as a result of their tiny stomachs being filled with indigestible plastic.  

Seagrass

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Pellets can smother seagrass meadows which are often used by juvenile fish as nurseries. Credit: Matt Curnock/Ocean Image Library

In coastal areas where they accumulate in large quantities, plastic pellets can also smother vital habitats such as seagrass meadows. Seagrass needs access to sunlight to photosynthesise and therefore grows in shallow coastal waters – the very areas most adversely affected by large-scale pellet spills at sea. 

The burial of seagrass beds beneath the piles of pellets washed ashore in the wake of nurdle spills not only deprives numerous marine species of a crucial food source and safe haven, but also reduces their effectiveness as a barrier against storm surges and a carbon-guzzling climate ally.  

How is this happening?

All this begs the question: how do these pellets of poison end up in our ocean? The answer is that they are shipped around the world in industrial quantities, often with scant regard for the fact that they amount to hazardous material. They leak from shipping containers during transportation as a result of poor packaging and handling, and they spill from ships when containers fall aboard in the wake of collisions and other maritime accidents. Pellet loss on land is problematic enough; at sea, it’s potentially disastrous. 

Like some lethal, lentil-sized invasive species, nurdles have been polluting the planet non-stop for almost as long as plastic has been around, but their injurious effect, particularly on wildlife, has only recently hit the headlines.  

Nurdles achieved notoriety last year following a serious accident at sea. When the X-Press Pearl caught fire and sank off the coast of Sri Lanka, it discharged an estimated 1,600 tonnes of tiny plastic pellets into the water. That’s a scarcely conceivable 80 billion pellets, every one of them a toxic time bomb. 

The graphic images spoke volumes. In the immediate aftermath of the spill, nurdles washed up along the Sri Lankan coastline, piling up on pristine beaches in drifts that were two metres high in places. It was the biggest plastic pellet pollution event ever witnessed worldwide, and has had a devastating impact on livelihoods, marine habitats and biodiversity. 

Fixing the problem

We can’t prevent acute events such as a ship blowing up and sinking, but we can ensure that the protocols are in place to contain the fallout from the resulting pellet spillage. Perhaps more importantly, it is in our gift to address the chronic problem of more ‘run-of-the-mill’ pellet loss. 

Calamitous though the X-Press Pearl spillage was, the tonnage of pellets discharged as a result of that one event is a drop in the ocean compared to the cumulative – and completely avoidable –impact of the vast quantities of nurdles that are needlessly spilled on a daily, even hourly, basis. 

Those drip-drip losses go completely unmonitored, their impact on marine species and ecosystems unquantified but undeniably detrimental, if not disastrous. The fact that the frequency of those everyday spills is unrecorded and their combined effect uncalculated does not make them any less harmful. 

Sri Lankan officials with a turtle carcass in the aftermath of the X-Press Pearl shipwreck. Photo: UNEP

The cliché that prevention is better than cure has never been more apposite. Where plastic pellets are concerned, it is realistically the only option. As anyone who has ever tried stuffing beads back into a leaking bean bag will understand, it’s easier to put a genie back in the bottle than it is to clean up a nurdle spill at sea. 

For the sake of our ocean and the myriad marine species it supports – from puffins and pufferfish to leatherbacks and lemon sharks – we need to stop polluting pellets from entering the environment in the first place. More secure packaging, better labelling, better handling practices and safer transportation would go a long way to achieving that goal. Surely that’s not too much to ask?