A hitchhiker’s guide to floating marine debris

Invasive species are recognised as one of the greatest threats to marine biodiversity worldwide, second only to habitat loss, and cost the UK economy £120 million a year.

Image credit: coniferconifer on Flickr
(CC BY 2.0)

But the threat to UK waters could be reduced as pioneering research led by the Centre for Environment, Fisheries and Aquaculture Science (Cefas) and funded by Defra sheds new light on invasive species 'hitchhiking' across the sea on floating marine debris, such as plastics. In some cases, certain species are thought to have travelled from as far as the east coast of America, thousands of miles away.

By adapting a computer model originally designed to predict the distribution of oil following an oil spill, Cefas scientists were able to uncover the origin of floating marine debris and track how invasive species enter UK waters.

There are 39 recorded marine non-native species, including the Slipper Limpet and Signal Crayfish, considered as harmful to UK native marine biodiversity. It is hoped this advanced modelling technique will enable the UK and countries worldwide to more accurately track the movements of debris and pave the way for an early warning system to prevent and respond to emerging threats from non-native species.

With 80 percent of marine debris made up of marine plastics, and over 800 million tonnes of plastic ending up in our oceans each year, this research reiterates the importance of tackling global plastic pollution, supporting calls from Environment Secretary Thérèse Coffey at the UN Conference of Biological Diversity (CBD) COP15 last year for greater ambition and support to protect 30 percent of the world's ocean by 2030.

International Marine Minister Lord Benyon says, 'This research sheds light on a lesser-known consequence of plastics and litter entering our ocean, with floating debris threatening valuable marine biodiversity by transporting invasive, non-native species into the UK.

'It underlines the importance of global action that impacts our marine life and the UK is at the forefront of these efforts, mostly recently in championing calls to end plastic pollution by 2040.'

In this first of a series of leading research papers, Cefas scientists used a large piece of marine debris collected off the southwest coast of the UK to identify animals, including goose barnacles, hitchhiking their way into UK waters from sub-tropical and tropical waters generally below 40 degrees latitude.

Using the date the piece of debris was found and growth rates of the animals attached to the debris, scientists were able to calculate the time the debris had travelled through the ocean and 'back-track' its journey and likely origin. This has enabled the identification of 'hot spot zones' along the south west coast (where many of these species from the tropics make first landfall) containing a high concentration of marine debris that can pose a greater risk of transportation of invasive, non-native species.

Dr Peter Barry, Marine Ecology Scientist at Cefas and lead author of the report says, 'While this type of hitchhiking movement has been identified among various species and regions before, there is still a lot we don't know about how invasive species enter our waters. A real challenge for scientists has been to identify where the hitchhikers have come from. This model allows us to retrace their journey to understand where and how an invasion pathway is operating.'

'Although not all non-native species entering the UK will become established, those that do can be incredibly harmful for the environment. With the increase in marine litter in our seas, it's important for us to understand how these species are being transported, and to identify areas most at risk to help prevent their spread.'

Cefas will now research how invasive species can be transported on other marine debris such as seafloor litter, complementing work taking place internationally to better understand the sources of marine debris and how these enable invasive species to spread.

The UK continues to be a leading voice in tackling marine plastic pollution, co-sponsoring the proposal to prepare a new international, legally binding plastics treaty and is a founding member of the High Ambition Coalition to End Plastic Pollution, a group of 50 countries calling for a target under the treaty to stop plastic from flowing into our lands and ocean by 2040.

The UK took an ambitious stance at the Intergovernmental Negotiating Committee (INC1) in November last year, pushing for a treaty that will restrain the production and consumption of plastic to sustainable levels, address plastic design, and encourage more recycling and re-use of plastic.

In December last year, the Environment Secretary Thérèse Coffey attended the UN Conference of Biological Diversity (CBD) COP15 in Montreal where she called for greater ambition and urged more countries to join the more than 120 nations who already support the pledge to protect 30 percent of the world's ocean by 2030.

The Aquaculturists

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