Crabs and River Plastic in the Thames

Plastic is an amazing material, but so often its use is irresponsible, especially when it comes to its disposal.

When plastic breaks apart in the water it becomes smaller and smaller, it’s this stuff that we refer to as ‘microplastics’ (less than 5mm).

In previous posts we’ve highlighted some of the worst polluting rivers in the world. These are often in the developing world, and their current state is entwined with a long history of global capitalism, colonialism and racism.

But our rivers in the UK are not perfect, and the blame for ocean plastic falls at our doors too. For example, per km2, the River Mersey is more polluted than the Great Pacific Garbage Patch.

The problem is much closer to home, and the plastic in our rivers is having a damaging effect on British wildlife.

A study of crabs in the River Thames found a frankly shocking amount of plastic in the bodies of crabs.

Between the two studied species of crab, the common shore-crab, and the Chinese mitten crab, plastic was found in 71% and 100% respectively of animals dissected.

The majority of plastics in these animals was plastic fibres, broken down from synthetic fabrics. Scientists even found the tell-tale checkered pattern of a sanitary pad in the gut of a crab.

Microplastics are especially bad news for crabs because of their specific digestive system. Part of a crab’s gut is the gastric mill, which grinds food and squeezes out the good bits.

The problem is that plastic cannot be processed by crabs, which is in turn a problem for animals all the way up the food chain.

Hopefully, with greater awareness and a change in attitudes towards plastic disposal, we can make a change.

If you want to learn more about what you can do, check out @everydayplastic

Images and figures used with kind permission from 'Environmental Pollution', McGoran, Clark, Smith, Morritt, 2020 & Elsevier