A Pinch of Plastic

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Every single piece of plastic ever made still exists, and now it’s being found in crabs in the River Thames

Crabs in the river Thames have been found to have massive amounts of plastic crammed into their stomachs. From sanitary pads to clothing fibres, our human waste (primarily that of plastic material) is finding its way into the food chain and affecting wildlife, from crabs in the Thames to whales in the oceans. 

A recent study investigated the stomach contents of 55 shore crabs and 57 mitten crabs in the Thames and found that almost all crabs had plastics in their digestive tracts. One crab had a full popped yellow balloon in its stomach while another contained remnants of a sanitary pad. 

Most crabs were found to have tightly wound fibers stuffed in their stomachs. These fibers, and other plastics that have made their way into the crabs, are known as microplastics: any plastic material smaller than a grain of rice, or 5mm. This includes better known plastics such as microbeads in cosmetics (which were banned several years ago), film from plastic carrier bags. It also covers less commonly discussed materials like fibers from clothes, wet wipes and sanitary products. 

These plastics enter the waterways from sewage systems, washing machines, litter, industry and fishing boats. This consequently leads to the entanglement of aquatic species and ingestion, most often leading to death by suffocation, infection or starvation from a false sense of being full. Plastics also contain a variety of endocrine-disrupting chemicals, which alter normal hormone functions, affecting animals’ reproduction and the viability of offspring. 

Another issue when it comes to wildlife exposure to plastics is that every piece of plastic ever made still exists today. Plastic cannot biodegrade; instead, it breaks up into microplastics and becomes easier for wildlife to ingest. When trawling the riverbed of the Thames, the crew pulled up motor tires and plastic carrier bags that had been submerged for decades. Crabs, as well as fish, seabirds, turtles and larger mammals like dolphins and whales, mistake these plastics for food and become victims of plastic pollution. 

The issue is then  exacerbated by the bioaccumulation of plastic up the food chain. Predators feed on large numbers of prey items and ingest the plastic within them, meaning the concentration of plastic increases as you move up the food chain, leading to large ocean wildlife like whales washing up on beach shores with stomachs packed full of macro- and micro-plastics. 

The research on crabs in the food chain of the Thames is minimal. Pollution Specialist Alexandra McGoran said: “Crabs are a very unusual sink for plastic, they seem to retain a lot of them for potentially a long time. We don’t know if they are predated on, and if that high dose is delivered to other animals.” 

However, there is the potential for these plastics to be passed from crabs up to higher up the food chain, to larger predators and out into the ocean from the river. 

As with many other consumption issues, there are actions we can take as individuals to reduce our impact and limit the amount of microplastics we release into the environment. For example: only wash when you need to, use washing products that catch fibres before they exit the washing machine, purchase second-hand when possible and switch from single-use plastics to reusable alternatives. 

image source: alamy.com