Fishes from the depths of the ocean show significant signs of microplastic ingestion

It is estimated that 5.25 trillion pieces of plastic are floating on the surface of the ocean and some of this plastic will eventually descend to the ocean floor. Scientists from the Natural History Museum and Royal Holloway, University of London have sampled 30 mesopelagic specimens to find that 66.7% of the fishes contain microfibres, including anthropogenic fibres such as viscose and polyester.

The fishes from the new study were sampled around Tristan da Cuhna and St Helena in the South Atlantic from the RRS Discovery in early 2019 at depths down to 1000m. The sampling was part of the Blue Belt Programme, a marine survey of British Overseas Territories funded by the UK Government.

Thirteen species of mesopelagic fishes identified from 30 specimens were compared with two species collected from a rock pool or surface water near the shore.

The study found that, although with a small sample size, mesopelagic fishes, which are understudied, can ingest microplastics. The results from the new study provide a valuable insight into the potential impacts in an ecosystem known to be a significant sink for microplastics.

Alex McGoran, NERC DTP PhD student (Royal Holloway, University of London and NHM) who led the study said: ‘I’m not surprised that plastic has made it into the depths of the ocean. Two thirds of the individuals we looked at had plastic in, viscose was present in 51% of the specimens. As neither of the two surface water species contained plastic, we were unable to fully compare between the surface and deep ocean specimens. A fangtooth fish we looked at, had consumed, a bearded sea devil, a bolitaenid octopus and a cock-eyed squid. The squid and the sea devil both had plastic in them so there could have been a trophic transfer, meaning that when they themselves were eaten, the microplastics could have been unintentionally ingested by the predator.’

Viscose is a semi synthetic material which has been chemically treated and modified for use in clothing such as artificial silks, and sanitary items such as pads and wet wipes. The researchers discussed the potential impact of the material in comparison to microplastics.

PhD student Alex McGoran continues: ‘We don’t have much information on how long this kind of material lasts in the environment, but recent studies find that whilst microplastics are incredibly abundant, these viscose and other cellulose-based materials may be even more abundant. It could be that there is a physical impact, but the chemical impact might be less than in microplastics.’

Senior Curator, Fish at the Natural History Museum James Maclaine said: ‘As part of the Blue Belt Programme, we carried out as much sampling, surveying and measuring as we could around Tristan and St Helena. This will hopefully increase our understanding of these seamounts and their biodiversity so we are better able to protect them in future.’

Tissue samples were collected from the specimens by technician Kirsty Lloyd for incorporation into the Museum’s BioBank. Researchers will now be able to access them as part of CryoArks. This project aims to gather all of the tissue and DNA samples in freezers in zoos, universities and museums around the UK and make them available for people to use.

The paper was published in Frontiers Marine Science on 12 February 2021.

Notes for editors

Media contact: Tel: +44 (0)779 969 0151 Email: press@nhm.ac.uk

About the Natural History Museum:

The Natural History Museum is both a world-leading science research centre and the most-visited natural history museum in Europe. With a vision of a future in which both people and the planet thrive, it is uniquely positioned to be a powerful champion for balancing humanity’s needs with those of the natural world.

It is custodian of one of the world’s most important scientific collections comprising over 80 million specimens. The scale of this collection enables researchers from all over the world to document how species have and continue to respond to environmental changes - which is vital in helping predict what might happen in the future and informing future policies and plans to help the planet.

The Museum’s 300 scientists continue to represent one of the largest groups in the world studying and enabling research into every aspect of the natural world. Their science is contributing critical data to help the global fight to save the future of the planet from the major threats of climate change and biodiversity loss through to finding solutions such as the sustainable extraction of natural resources.

The Museum uses its enormous global reach and influence to meet its mission to create advocates for the planet - to inform, inspire and empower everyone to make a difference for nature. We welcome over five million visitors each year; our digital output reaches hundreds of thousands of people in over 200 countries each month and our touring exhibitions have been seen by around 30 million people in the last 10 years.

About Royal Holloway, University of London – royalholloway.ac.uk

Royal Holloway, University of London, is ranked in the top 20 universities in the UK.   Through world class research that expands minds and changes lives, the dedication of our teachers and the feel of the Royal Holloway experience, ours is a community that inspires individuals to succeed academically, socially and personally.

The university was founded by two social reformers who pioneered the ideal of education and knowledge for all who could benefit. Their vision lives on today.  As one of the UK’s leading research-intensive universities we are home to some of the world’s foremost authorities in the sciences, arts, business, economics and law.  We are strengthened by diversity, and welcome students and academics who travel from all over the world to study and work here, ensuring an international and multi-cultural perspective within a close knit and historic campus.