#OctopusStory and Microplastics in the marine environment

_{By Natalie Harris, Marine Champion for the Hampshire and Isle of Wight Wildlife Trust.}

Alarmingly scientists have now found microplastics in every ecosystem that has been investigated, including the deep sea and Antarctic ice (Kim, 2021. Nature). 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 are fragments of plastic less than 5mm long, some can even be hard to see with the naked eye. They can occur as primary microplastics which are manufactured that 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 biobeads (ridged plastic pellets used in the wastewater industry). Additionally, they can exist as secondary microplastics which occur from the breakup of larger items (macroplastics) for example single-use plastics or from shedding from fabrics (Kurniawan et al. 2021). They can enter our oceans through the miss-handling of products, like container spills of nurdles or like the famous biobead spill from a water treatment plant near Truro, Cornwall in 2010 where over 5 billion bio-beads spilt into the Fal Estuary (Turner et al. 2019). Additionally, microplastics can enter through our waterways such as fabric fibres from laundry or simply from plastic pollution breaking up in our oceans. Once the plastic has entered the ocean, the action of UV degradation, the salinity of the water and wave abrasion causes the plastic to become brittle and eventually break up. 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. Microplastics can be found on the beach, often amongst the sand. If you want to have a look for microplastics yourself a great way to find them is to take a sieve to the beach and try sieving the sand, here the sand will fall out and you will be left with any microplastics. 

Microplastics cause great harm to wildlife often having cumulative effects. It 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. There is obviously a risk to humans here as we can consume microplastics through the consumption of seafood. Whilst studies researching the effects of microplastics on humans are still ongoing, there is evidence to support the idea that microplastic ingestion will cause organ inflammation and disruption. As well as physical impacts to the wildlife, microplastics can transfer toxic chemicals. Biobeads 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.

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 the plastic before it has the chance to break up, solutions can also 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.

By Natalie Harris, Marine Champion for the Hampshire and Isle of Wight Wildlife Trust.