Marine debris allows invasive species to 'hitchhike' into UK waters

New research led by the Centre for Environment, Fisheries and Aquaculture Science (Cefas) and funded by Defra highlights that invasive species are ‘hitchhiking’ across the sea on floating marine debris, such as plastics.

Marine debrisCefas says its scientists have been able to uncover the origin of floating marine debris and track how invasive species enter UK waters, through the adaptation of a computer model initially designed to predict the distribution of oil following an oil spill.

The researchers are under the impression that, in some cases, certain species may have travelled from as far as the east coast of America.

According to Cefas this advanced modelling technique will enable the UK, and countries worldwide, to track debris movements with higher accuracy and lay the foundations for an early warning system, to prevent and respond to emerging threats from non-native species.

Currently, 39 recorded marine non-native species, including the Slipper Limpet and Signal Crayfish, are recorded as harmful to UK native marine biodiversity, have found their way into UK waters.

This research aims to reiterate the importance of tackling global plastic pollution, with 80 per cent of marine debris made up of marine plastics, and over 800 million tonnes of plastic ending up in our oceans each year.

International Marine Minister, Lord Benyon, said: “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, most recently in championing calls to end plastic pollution by 2040.”

Where are the species hitchhiking from?

To obtain their findings, Cefas scientists used a large piece of marine debris collected off the southwest coast of the UK to identify animals, including Goose Barnacles, that hitchiked 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 the 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 southwest 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.

Cefas says that the species can be taken far beyond their natural ranges due plastic – which lasts far longer than natural material, so can continue floating for years.  

The importance of tracking marine debris

Cefas says that, although not all non-native species entering the UK will become established, those that do can be incredibly harmful to the environment. An increase in marine litter in UK seas means a potential increase in species being transported. It is therefore important to identify areas most at risk to help prevent their spread.

Dr Peter Barry, Marine Ecology Scientist at Cefas and lead author of the report, added: “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”.

Looking forward, Cefas will research how invasive species can be transported on other marine debris such as seafloor litter. In line with this, the agency is investigating what it is about plastic that attracts certain types of species to attach themselves to the surface.