Marine organisms can shred a carrier bag into 1.75 million pieces, study shows

A single plastic carrier bag could be shredded by marine organisms into around 1.75million microscopic fragments, according to new research.

Marine scientists at the University of Plymouth examined the rate at which bags were broken down by the amphipod Orchestia gammarellus, which inhabits coastal areas in northern and western Europe.

They discovered the organisms shred the material, with researchers believing this is an example of marine wildlife actually contributing to the spread of microplastics within the marine environment, rather than them simply being emitted from the water supply or forming through the physical and chemical break down of larger items.

The study was conducted by BSc (Hons) Marine Biology and Coastal Ecology students Daniella Hodgson and Amanda Bréchon, and Professor of Marine Biology Richard Thompson. It is published in Marine Pollution Bulletin.

Its main aim was to discover whether different types of plastic and the presence of a biofilm – a layer of organic material which accumulates over time – altered the rate at which such organisms broke down plastic debris.

Through monitoring in the laboratory and on the shoreline, researchers demonstrated the bags were torn and stretched by Orchestia gammarellus, with microplastics subsequently being found in and around their faecal matter.

The type of plastic (conventional, degradable and biodegradable) had no effect on the rate of ingestion, however the presence of a biofilm meant the shredding took place around four times as quickly.

This, the researchers say, is consistent with recent studies into the feeding behaviour of seabirds and suggests marine life might be increasingly attracted to marine debris as a source of food regardless of the potential harm caused.

Previous studies led by the University have shown that more than 700 species of marine life have been found to have encountered plastic debris, with clear evidence that ingestion and entanglement causes direct harm to many individuals.

Professor Thompson, Head of the University’s International Marine Litter Research Unit, said:

“An estimated 120 million tonnes of single-use plastic items – such as carrier bags – are produced each year and they are one of the main sources of plastic pollution. They already represent a potential hazard to marine life, but this research shows species might also be contributing to the spread of such debris. It further demonstrates that marine litter is not only an aesthetic problem but has the potential to cause more serious and persistent environmental damage.”

The full study – Ingestion and fragmentation of plastic carrier bags by the amphipod Orchestia gammarellus: Effects of plastic type and fouling load by D.J. Hodgson, A.L. Bréchon, and R.C. Thompson – is published in Marine Pollution Bulletin, https://doi.org/10.1016/j.marpolbul.2017.11.057.

By Auguste Le Roux (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons


A worldwide problem

Marine litter is a global environmental problem with items of debris now contaminating habitats from the poles to the equator, from the sea surface to the deep sea. This litter has negative consequences for wildlife, for economies and on human health. Over 700 species, including commercially important fish and shellfish, are known to encounter marine litter in the environment. The vast majority of the litter found on shorelines, at the sea surface and that affecting marine life is plastic, and it has been estimated that up to 12 million tons of plastic litter could be entering the ocean every year. There are solutions, but there is an urgent need for action.

At the forefront of marine research

The International Marine Litter Research Unit is proud to stand at the forefront of research in this area. In 2004 our team was the first to reveal the widespread occurrence of microscopic particles of plastic debris at the sea surface and on shorelines – pieces which we described as microplastics. We have published numerous scientific papers and reports on this topic, have advised governments and international organisations worldwide and we continue to research not only the extent of the problem, but also the solutions.

Our mission

The International Marine Litter Research Unit has a mission – to further our understanding of the impacts of litter on the environment and society, and to identify the solutions and the pathways necessary to achieve them.

Discovering microplastics

In 2004, Professor Richard Thompson OBE and his team showed that microplastic particles have accumulated in oceans since the 1960s and are now present worldwide. The International Marine Litter Research Unit described the accumulation of fragments of plastic debris in the oceans and much of its focus is on these microplastics. 

Our work has shown that microplastic debris now contaminates shorelines worldwide; that they are present in substantial quantities in remote locations such as the deep and the Arctic. A range of marine organisms including commercially important species can ingest these pieces and laboratory studies have shown there is potential for this to lead to harmful effects.

Former US President, Barack Obama, signed a bill outlawing the sale and distribution of toothpaste and exfoliating or cleansing products containing microbeads which are a type of microplastic. Our work on this topic has helped inform governments around the world. We submitted evidence to the UK Houses of Parliament in relation to the Environmental Audit Committee enquiry on microplastics.

Expertise

Our findings are underpinned by research conducted by the team at the University of Plymouth and in collaboration with other leading scientists worldwide. This expertise has guided industry, informed educational and artistic initiatives that raise awareness, and has provided evidence for government agencies and international organisations such as the United Nations.

Careers in marine biology and coastal ecology

Do you want to be an ecologist or marine biologist? Or are you dedicated to carving out a career in marine conservation? As a marine biology and coastal ecology student, your career options are as expansive as the oceans you study.

Whatever your career goals, we’ll work with you to give you the support you need, preparing you to make real impact in your chosen field.

Find out where marine biology and coastal ecology can take you.