From tiny nurdles to tangles of deadly rubbish, every day we see the impact of human activity on our seas. Marine pollution is threatening our amazing wildlife, both in the water and along the coastline.

To mark Beat Plastic Pollution Day, Natalie Harris, a Secrets of the Solent Marine Champion and founder of the beach cleaning campaign, Clean Our Seas, tells us more about an insidious and often-overlooked form of pollution: microplastic. 

Microplastics are fragments of plastic less than 5mm long - some are even hard to see with the naked eye. They can occur as primary microplastics, which are manufactured at a standard size, such as: nurdles (plastic pellets used as the raw material in the production of plastic goods), cosmetic particles (such as those in facial cleansers) and bio-beads (ridged plastic pellets used in the wastewater industry). There are also secondary microplastics, which occur when larger plastic items (macroplastics) break up into smaller pieces, for example: single use plastics or shedding from synthetic fabrics.

Microplastics can enter our oceans through the mishandling of products, like container spills of nurdles or the famous bio-bead spill from a water treatment plant near Truro, Cornwall in 2010 where over 5 billion bio-beads were released into the Fal Estuary. Additionally, microplastics can enter through our water systems, such as fabric fibres from laundry, or simply from plastic pollution breaking up in our oceans. Once plastic has entered the ocean, the action of UV degradation, salinity of the water, and wave abrasion causes the plastic to become brittle and eventually disintegrate. It is said that plastic never breaks down, it only breaks up into smaller pieces. This is how microplastics can end up smothering our beaches.

It's relatively easy to find microplastics on our coastline. If you want to have a look for yourself, a great way to find them is to take a sieve to the beach and try sieving the sand. During the process, the sand will fall out and you will be left with any microplastics. 

Alarmingly scientists have now found microplastics in every ecosystem that has been investigated, including the deep sea and Antarctic ice. Whilst fish might be the obvious victim of microplastic pollution, it affects a wide range of wildlife including sea birds, marine mammals and even zooplankton who have been found to eat microplastics. Marine life close to the coastline can be particularly susceptible to microplastic ingestion due to the input from land sources. Due to the size, shape, and buoyancy of microplastics, marine life can mistake the fragments for food, or they can unintentionally ingest it (common for filter feeders), this is known as direct ingestion. Indirect ingestion, however, occurs when predatory fish consume already contaminated prey. Studies at the University of Exeter show how microplastics can enter the food chain via contaminated zooplankton which is a very important food source for the marine ecosystem. This is how microplastics can work their way up the food chain, through biomagnification. 

Microplastics cause great harm to wildlife often having cumulative effects. They can cause internal harm such as clogging and tearing. Digestive blocking will reduce the animals' feeding activity, in turn, leading to weight loss, nutrition deficiency, and reproductive and growth disruption.

As well as physical impacts, microplastics are able to transfer toxic chemicals. Bio-beads can contain high concentrations of toxic contaminants and the break-up of larger plastics into microplastics means contaminants from the original macroplastic are leached into the sea. Impacts of toxicity can lead to disruption in reproduction and growth impairments.

Microscopic plastics also pose a risk to humans as we can consume them indirectly through seafood. Whilst studies researching the effects of this are still ongoing, there is evidence to support the idea that microplastic ingestion could potentially cause organ inflammation and disruption.

Whilst microplastic pollution might seem extremely daunting, there are ways we can help the situation. By reducing plastic usage and implementing mitigation techniques such as washing machine filters, we can help reduce the source of microplastics. By participating in beach cleans we can remove plastic before it has the chance to break up. Other solutions include the active removal of microplastics from beaches using suction machines and large-scale sand sifters. Progress in scientific studies also suggests there will be ways of using bacteria to remove microplastics in the future.

What can you do?

Many thanks to Natalie for sharing her knowledge with us! If you'd like to join her in making a difference for our marine wildlife, why not consider becoming a Marine Champion too? There are several different roles and you'll receive all the training and support you need.