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Marine Pathways Project 2012-2015

Project Summary

The marine pathways project was undertaken by organisations within the UK and Ireland and contributing to the delivery of the Non-Indigenous species descriptor of the Marine Strategy Framework Directive (MSFD). The overall aim of the project was to protect marine biodiversity in the UK and Ireland by managing key pathways by which marine invasive non native species (NNS) are introduced and spread. The project ran from 2012 until April 2015.

Commercial shipping, recreational boating, aquaculture and natural dispersal have been highlighted as potential pathways by which invasive NNS may be introduced. The project therefore aimed to understand the risk associated with each of these pathways. In addition, the project investigated biosecurity measures which may be implemented to reduce the risk of introduction and spread of NNS, as well as conducting research into eradication, control and management strategies which will play a role in elimination or reducing spread of NNS in the event of an introduction.

View project reports, documents and links produced by the Marine Pathways Project.


Marine NNS are an increasing problem and can have huge environmental, economic and social impacts. Environmental impacts include loss of biodiversity through displacement of native species, loss of genetic diversity and introduction of pathogens into native populations. Social impacts are the consequence of disruption to industries such as recreational boating, commercial shipping and aquaculture. It is thought that the cost of marine NNS to marine industries in Great Britain alone is in the region of £40 million per year.

The Marine Strategy Framework Directive (MSFD) is an EU directive, formally adopted in July 2008, which aims to manage and protect the marine environment across Europe. The central goal of the directive is to achieve Good Environmental Status (GES) in marine waters of EU Member States by 2020. The framework promotes an ecosystem based approach to manage the sustainable use of marine waters for both economic and social benefit. The MSFD is compiled of a list of descriptors on which GES will be assessed. In accordance with the understanding that NNS may have negative impacts on the marine environment and the need for their management and control, one of the eleven MSFD descriptors refers to NNS, stating:

“Non- indigenous species introduced by human activities are at levels that do not adversely alter the ecosystems”.

For more information on specific NNS, their identification, impact and distribution please visit the Non-native Species Information Portal. 

Aims and Objectives

The aim of the marine pathways project was to:

‘protect marine biodiversity in the UK and Ireland by managing key pathways by which marine invasive non-native species are introduced and spread.’

The key pathways include commercial shipping, recreational boating, aquaculture and natural dispersal. For example, marine NNS can be introduced and spread via ships ballast water, hull fouling and aquaculture stock imports and movements.

The main objectives of the marine pathways project were:

  • Development of protocols and methodology for the detection of NNS both inshore and offshore
  • Identification of locations at high risk of the introduction of NNS to facilitate risk based monitoring and management
  • Raising awareness of marine NNS with stakeholders
  • Work with stakeholders developing codes of practice to reduce the risk of introduction and spread
  • Research strategies for the control and eradication of marine NNS

The project supported the implementation of International and European policy drivers including:

  • Marine Strategy Framework Directive descriptor 2 (Non Indigenous Species)
  • Water Framework Directive Good Ecological Status
  • Biodiversity 2020 Target 5 Invasive Alien Species

Organisations involved

Key organisations involved in the management and implementation of the project included: Centre for Environment, Fisheries and Aquaculture Science (CEFAS), Department for Environment, Food and Rural Affairs (DEFRA), Irish Sea Fisheries Board, Natural England, Natural Resources Wales, Scottish Natural Heritage, Scottish Government, Welsh Government.

Work was also carried out by leading universities and research centres including the Marine Biological Association, The University of Bangor, Firth of Clyde Forum, The Scottish Association for Marine Science, Wales Wildlife Trust and Cornwall Wildlife Trust.

Project Conference

The Marine Pathways Project Conference was held on 25th February 2015 at the Mercure House Hotel in Cardiff. The aim of the conference was to bring together those involved in the delivery and organisation of the project and stakeholders and industry representatives for which marine non-native species are of importance. The day focused on three key areas: biosecurity, monitoring and management and involved both presentations and group discussions. The day was a huge success and the project team would like to thank everyone for attending and sharing their expertise and experience.

Please find links below to conference presentations and discussion session outputs. 

Marine Pathways Project Conference programme (PDF)


Marine Pathways Project - Monitoring for NNS

In order to manage and control NNS an understanding of the current abundance and distribution of NNS is required. In addition, to be able to respond rapidly to NNS introductions and limit subsequent spread and minimise impact, early detection of NNS introductions is crucial. Monitoring and surveillance of NNS to determine abundance and distribution and detect introductions rapidly will therefore be key to NNS control and management. Four projects concerned with the practical approach to NNS monitoring were being conducted as part of the marine pathways project:

  • Welsh inshore monitoring network.
  • Offshore monitoring of mooring buoys around Great Britain.
  • Inshore and offshore monitoring work in Scotland.
  • Citizen science for monitoring NNS.

In addition, a desk based study was conducted to investigate marine monitoring and its potential to be adapted and used to monitor NNS:

  • Current marine monitoring and its potential to be adapted and used to monitor NNS.

Please see below for more details.

Welsh inshore monitoring network

An 18-month project to develop an early warning system for detecting NNS in Welsh coastal waters was undertaken. During the project, the research scientists worked closely with coastal-based industries in Wales including oyster farmers, marina operators and lobster and crab fishermen to identify the optimum ways to detect new marine invasions.

A 1-month trial at an oyster farm in the Menai Straits to test the proposed monitoring method for aquaculture sites was successfully completed. Additional experimental work also took place from Spring to Autumn 2014.

The results obtained from the project will aid Wales to develop a robust system for finding marine NNS in the early stages of establishment. This will increase the number of management options available and reduce the economic and environmental costs associated with invasive NNS. The project ended March 2015. This work was supported by Natural Resources Wales and carried out by Bangor University.

Wales Marine Non-native Species Inshore Monitoring Network (PDF) (Bangor University 2015)

Offshore monitoring of mooring buoys around Great Britain

Offshore mooring buoys provide a potential tool in the early detection of NNS introductions into marine waters given their offshore location and their frequent servicing. Work under the marine pathways project was undertaken using 5 offshore mooring buoys to:

  1. Determine whether there is potential for marine NNS to attach to offshore structures such as buoys.
  2. Investigate sampling and identification techniques which will allow the detection of marine NNS attached to offshore structures. Sampling techniques being investigated include both scrapes and settlement panels.
  3. Assess the overall merit of using buoys and potentially other offshore structures as an early warning system for the introduction of marine NNS into UK coastal waters.

This work was completed in March 2015 and was led by Cefas.

Marine non-indigenous species monitoring and risk management (external link) (Cefas 2014)

Inshore and Offshore monitoring in Scotland

The main aim of this work is to trial a means of detecting non-native marine species in inshore and offshore Scottish waters.

Settlement plates or scrape samples were used at a variety of sites to collect samples of both algae and fauna. The sample sites were:

  • Four offshore buoys
  • Two inshore buoys
  • Two marinas (Oban and Tarbert)
  • Two shell fish farms (Loch Fyne, Loch Creran)
  • Two fin fish farm (Lynne of Lorne, Loch Fyne)

A large amount of biological material was collected, requiring specialist identification. Analysis of the collected material aimed to:

  • determine the suitability of scrapes versus installation of settlement panels and photographs (rapid assessment will also be performed to collect baseline data) to detect non-native macro algae and fauna
  • determine the most cost-effective number of scrapes required at each inshore site to give 95% confidence of identifying all NNS present
  • trial the effectiveness of analysing for a hit list of species based on recent surveys and DEFRA horizon scanning exercise versus complete analysis.

This was a collaborative project between The Scottish Association for Marine Science, Scottish Government and Scottish Natural Heritage.

Assessing the effectiveness of early warning systems for the detection of marine invasive non-native species (PDF) (Cook, E. J., Beveridge, C., Twigg, G & Macleod, A., 2015)

Citizen science for monitoring NNS

This part of the marine pathways project investigated the efficacy of citizen science relative to other methods for monitoring marine NNS. Cornwall Wildlife Trust, in collaboration with the Marine Biological Association of the United Kingdom, has developed a citizen science programme as part of their Local Action Group work on marine NNS surveillance. One aim of the programme was to build a network of volunteers to gather data on marine NNS by recruiting boat owners to deploy settlement panels from the pontoon at their marina berth. Participants in the panel project were required to submit digital images of their colonised panels after a minimum period of eight weeks’ immersion. The images were then inspected by experts for the presence of NNS. The project design aimed to provide verifiable biological data on the presence of a range of taxa across a wide geographical area. Also, the project aimed to raise awareness of the impact of NNS within the recreational boating community.

This project evaluated the efficacy of using volunteers to provide photographic surveillance by comparison with data from traditional sampling methods.

The specific aims of this project were:

  • To evaluate the adequacy of photographic images taken using a range of camera equipment e.g. high specification and resolution vs. amateur equipment.
  • Comparison of photographic data vs. laboratory assessment of preserved panels.
  • Comparison and evaluation of Rapid Assessment Surveys (RAS) undertaken by experts vs. settlement panel sampling.
  • Examine how techniques could be utilised as part of the Marine Strategy Framework Directive (MSFD) monitoring programme.
  • Provide guidance for spatial distribution of panels to provide effective detection of marine NNS.
Investigating the efficacy of citizen science for monitoring marine invasive non-native species (external link) (Cefas 2014)

Current marine monitoring and its potential to be adapted and used to monitor NNS

The marine environment is heavily monitored, however NNS are not the focus of the monitoring undertaken. As part of the marine pathways project, a study was conducted by Cefas in 2013/2014 to investigate the adaptability and applicability of current monitoring in the management and control of NNS.

The key objectives of the study were to:

  1. Assess current UK marine monitoring programmes and gather information relevant to their potential use in a monitoring programme for NNS.
  2. Determine the suitability of the monitoring programmes to detect NNS.
  3. Assess geographical coverage of the monitoring programmes.
  4. Assess the geographical coverage in relation to different taxonomic groups.

Consideration was also given to whether current monitoring is being conducted at locations which may be at high risk of introduction of NNS (more information on the assessment of the introduction of NNS into marine waters of GB and Ireland can be found on the page: NNS introduction pathways assessment).

This project has commented on the feasibility of adaptation and amendment of current monitoring to include NNS. This project, in addition to the projects undertaken to investigate the practicalities of inshore and offshore monitoring, has contributed to the development and implementation of a monitoring strategy for NNS.

Marine Non-indigenous Species Monitoring and Risk Management (external link)  (Cefas 2014)

Marine Pathways Project - NNS introduction pathway assessment

Why investigate NNS pathways of introduction and their intensity?

There are a number of pathways by which marine NNS can be introduced into and spread within marine waters. Key pathways include shipping, recreational boating, aquaculture stock movements and natural dispersal. Prevention of introduction and early mitigation following introduction are recognised as the most effective approaches to reducing the potential impacts of NNS. This is especially true in a marine environment where control and eradication may be very difficult or impossible.

Assessment of introduction pathway activity intensity was the focus of recent work by Cefas. By assessing the intensity of introduction pathway activity it is possible to identify coastal areas where NNS may be more likely to be introduced.

Assessment of the intensity of introduction pathway activity

In order to determine where introduction pathways activity is likely to be high data corresponding to each pathway was sought. For the shipping pathways we acquired data corresponding to shipping traffic into and within marine waters around Great Britain (GB) and Ireland, for the recreational boating pathway we used data which provides an indication of the likely recreational cruising routes into and within marine waters around GB and Ireland, for the aquaculture pathway we sought information regarding the import of live shellfish into GB and Ireland. Finally, to gain insight into the likelihood of NNS introduction via natural dispersal we considered prevailing current around GB and Ireland and the proximity to other landmasses.

We split the coastline of GB and Ireland into 50k grid squares and using the data sought, scored each grid based on the relative intensity of each pathway activity. By grading each grid according to the score we created heatmaps which can be used to easily visualise where introduction pathway activity is high compared to others areas and where it is lower compared to other areas.

Marine Non-indigenous Species Monitoring and Risk Management (external link)  (Cefas 2014)

Why is it important to consider introduction pathway activity?

Introduction pathway activity will facilitate the management of NNS for example, by highlighting areas where the likelihood of introduction of NNS may be increased and therefore where monitoring should be focused. Introduction pathways assessment will ultimately aid the prevention of NNS introduction and early detection of NNS following introduction.

Marine Pathways Project - Biosecurity guidelines and awareness raising

Marine pathways project advisory groups

Advisory groups for different sectors; commercial shipping and industry, fisheries, aquaculture and recreational boating and water use, were established. The hope is that these groups will provide practical advice on NNS awareness raising, delivering guidance and training based on their individual experiences and expertise. Advisory groups are comprised of representation from industry as well as specialist advisers and helped ensure that any information, guidance, best practice and training produced as part of the project was fit for purpose and practical. The direct involvement of industry also helped to disseminate information and encourage buy-in from users. Pathway advisory groups are still used by the Marine Pathways Group

Raising awareness of NNS - North Wales Marine Aliens Project

Monitoring and management of marine NNS is crucial to reduce their impact. A greater awareness and understanding of NNS will aid their monitoring and management.

In association with the marine pathways project, the North Wales Marine Aliens project was established. The aim of this project was to develop a network of volunteers engaged in marine non-native or alien species issues. Work by these volunteers facilitated the work of the marine pathways project team by aiding early detection of NNS introductions and prevention of their spread.

This marine aliens project was carried out during the winter of 2013/2014 through a series of workshops targeted at three specific communities, these were:

  • Outdoor activity sector.
  • Environmental professional and volunteers.
  • General interest, clubs & activity groups.
  • These workshops were held in Feb/Mar 2014 to which a total of 68 people attended.

Project webpages have been established on the North Wales Wildlife Trust website (external link)

The contents of these pages include species information, biosecurity and links to project partners. It is a fully bilingual resource which is continually updated to include new information. A North Wales Wildlife Trust facebook page was also created. Interested parties can join this and find out the most up to date information regarding Marine Alien Species research, discoveries and opportunities.

This work was led by Natural Resources Wales and the North Wales Wildlife Trust.

Project report: Developing a Network of Volunteers to Champion the Issue of Marine Alien Species (PDF) (North Wales Wildlife Trust and Natural Resources Wales, 2015).

Appendices (ZIP) containing:

  1. INNS Projects (Excel)
  2. INNS Project Plan (JPG)
  3. Introduction to the Workshop (PowerPoint)
  4. Marine Alien Species: An Overview (PowerPoint)
  5. Marine Alien Species: Champions (PowerPoint)
  6. Marine Alien Species: Biosecurity (PowerPoint)
  7. Event Poster Template (Word)
  8. CCD Marine Plants Bilingual (PDF)
  9. Mitten Crab (JPG)
  10. Pacific Oyster (JPG)
  11. Wakame (JPG)
  12. Slipper Limpet (JPG)
  13. Wireweed (JPG)
  14. Useful Links (JPG)
  15. Roller Marine Aliens (PDF)
  16. MASC Logo (JPG)
  17. MASC Logo (PNG)
  18. MAS Information (Word)
  19. NWWLT Marine Pathways Champions Project Report 31 March 2014 (PDF)

Biosecurity Guidance

Analysis of the pathways by which species are arriving and spreading has identified key sectors whose activities can contribute to the spread of invasive species. These sectors are also part of the solution and can play an important role in invasive species management by implementing best practice biosecurity. The project worked with the Pathways Advisory Groups and other volunteer groups to incorporate advice on simple, easy and effective biosecurity measures and biosecurity planning into industry guidance and training. The specific aims of the marine pathways project work on biosecurity were:

  • Engagement with industry and dissemination of guidance leading to increased awareness of the potential impacts from invasive marine species which will hopefully lead to the sector voluntarily adopting best practice to limit the introduction and spread of high impact species now and in the future.
  • Increased awareness contributing to surveillance for potential invaders and better information on the distribution of species already established.

Marine pathways project members were involved in delivering guidance for producing site and operation-based plans for developing the introduction of non-native species.

Marine Pathways Project - Control and eradication of NNS

The central goal of the marine pathways project is to protect marine biodiversity in the UK and Ireland by managing key pathways by which NNS are introduced and spread. However, it is not possible to prevent all introductions of NNS. Therefore, work under the marine pathways project also included experimental studies concerned with control and eradication of NNS so that we are better equipped to deal with NNS in the event of their introduction. Three experimental projects were undertaken under the marine pathways project which aim to gather information which will aid the control of NNS following their introduction or spread. These are:

  • Project 1: ‘The control and eradication of Didemnum vexillum off the West coast of Ireland’.
  • Project 2: ‘The Dee Chinese Mitten Crab Project’.
  • Project 3: ‘The extent of Grateloupia turuturu in Wales‘.
  • Project 4: 'Survey of feral Pacific oyster in Scotland'.

Details of each project can be found below.

Project 1. The control of Didemnum vexillum off the West coast of Ireland.

The carpet sea squirt, Didemnum vexillum, is a colonial sea-squirt (tunicate) native to Japan. Over the past decade this species has spread rapidly outside of its native range and has now been recorded at over 100 locations across the U.K, U.S.A, Italy, Canada, New Zealand, The Netherlands, France and Ireland. Once established this species can grow rapidly, extensively coating living and non-living underwater surfaces.

This species was first documented in Ireland in June 2005 where it was discovered fouling immersed man-made structures within Malahide marina. The hulls of boats, pontoons, chains, ropes and buoys were extensively fouled and assemblages of native biota were overgrown by colonies of this invader. Subsequent to this initial discovery, it has been documented at a number of other sites throughout the country including; Clew Bay, Carlingford Lough, Galway Bay and most recently in Strangford Lough, Northern Ireland.

Impact of Didemnum Vexillum

This species has been of major concern globally because of its potential to alter marine ecosystems and the threat that it poses to aquaculture operations. Potential impacts include the following:

  • Overgrows native plants and animals
  • Forms dense mats on oyster bags reducing water flow and food supply
  • Significantly increases fouling on aquaculture equipment
  • Envelops economically important shellfish (oysters, mussels & scallops)
  • Dominates substrate in fouling communities
  • Reduces structural complexity, diversity and availability of marine habitats
  • Jeopardises the functioning of productive fishing grounds
  • Disrupts aquaculture processes and requires labour intensive management to remove & mitigate impacts
  • Increase labour costs & decrease profitability
  • Fouls boat hulls, pontoons, buoys, chains and ropes within marinas

Experimental work – assessment of two different control treatments.

Invasive species are a known threat to biodiversity and to the operation of aquaculture businesses. Any initiative to manage invasive species will have positive benefits for the achievement and maintenance of site integrity ultimately facilitating the continued operation and growth of the aquaculture sector. The project actions included research, awareness raising within the aquaculture sector, and testing control initiatives. The work carried out has identified an increased presence of Didemnum vexillum in Clew Bay compared with previous years. It establishes on hard substrates but once “anchored” can grow over various surfaces including seaweed.

Experimental work was carried out in Clew Bay using two simple control treatments; Acetic acid (vinegar), (a number of studies have identified this as an eco-friendly chemical found to reduce Didemnum vexillum cover by 80 – 100%) and bag turning (farmers found that fouling is reduced significantly when oyster bags were turned regularly, causing desiccation stress to Didemnum vexillum).

These treatments wereapplied either individually or in combination to oyster bags over a six month period. In addition, the timing, frequency and variance of the application of the treatments were investigated to determine if any of these factors influence their success.

Over the course of the experiment, levels of Didemnum vexillum for each treatment were monitored and oyster health and condition recorded. Overall, this experimental work aimed to develop environmentally sustainable, cost effective and time efficient methods for managing Didemnum vexillum in aquaculture that protects stock and reduces the potential future spread of Didemnum vexillum. The outcome of this work will contribute to codes of practice that may be adopted by farmers for the management of invasive species in aquaculture.

This work was led by the Irish Sea Fisheries Board or Bord Iascaigh Mhara.

For further information on this work please contact Martina O’Brien, UCD, Dublin Ireland at martina.o-brien@ucdconnect.ie

Project 2. The Dee Chinese Mitten Crab Project.

The Chinese mitten crab originates from eastern Asia, in temperate and tropical regions between Vladivostock (Russia) and southern China, including Japan and Taiwan. This species of crab can have serious impact on marine and freshwater ecosystems where it predates and outcompetes native invertebrate and fish populations. During its breeding season it may also burrow into river banks, increasing erosion, river turbidity and causing the collapse of river beds.

The aim of this two year project (2013 – 2015) was to gain more of an understanding of mitten crabs in North Wales, focusing on the River Dee.

The main objectives of the project were to:

  1. Gain an estimation of population size.
  2. Explore the geographical extent within the catchment.
  3. Examine the environmental cues driving migration.
  4. Examine the effectiveness of methodology.
  5. Look at Pathways management and raise awareness of the mitten crab issue with stakeholders in the Dee catchment.
  6. Obtain mitten crab DNA samples for a related study based at the Natural History Museum in London.

This work was supported by Natural Resources Wales (NRW) and carried out by the North Wales Wildlife Trust.

Project report: Monitoring of Chinese mitten crabs (Eriocheir sinensis) on the River Dee (PDF) (Natural Resources Wales 2016)

Project 3. The extent of Grateloupia turuturu in Wales.

Grateloupia turuturu, or Devil’s tongue weed, is a NNS in the UK. It impacts the marine ecosystem by out-competing native species. G. turuturu was first recorded in Neyland Marina, South Wales, in 2008.

A survey was undertaken by Natural Resources Wales in 2013 to:

  1. Establish and record where this species is located within Neyland Marina and the surrounding Milford Haven area.
  2. Determine the feasibility of eradication of this species from this area.

Pontoons and other floating structures were surveyed, involving people snorkelling around the structures and recording presence/absence of G. turuturu. 38% of the pontoons and other floating structures surveyed had G. turuturu growing on them. Neyland Marina was probably the site of introduction as this was the epicentre of all of the G. turuturu records within the area.

The extent to which this species spread indicates that eradication will be very difficult. Ultimately this study highlighted that control and eradication of G. turuturu and other NNS will be improved by predicting where introductions are likely to occur and acting rapidly following detection of introduction.

This work was led by Natural Resources Wales

Project 4. Survey of feral Pacific oyster in Scotland

The Pacific oyster (Crassostrea gigas) has become the main species of oyster farmed in Europe. Originally native to Japan and North East Asia, it was first introduced for cultivation in the UK from Canada during the 1960s. Feral populations have become established in the wild, ranging from France north to Scandinavia, however in the UK established feral Pacific oyster beds have only been identified in the south east of England. Warming coastal seawaters around the whole of the UK may contribute to further developments in this trend.

A survey funded by the Scottish Aquaculture Research Forum (SARF) started in spring 2014 aimed to examine the existence, if any, of feral populations (or ‘self settlers’ rather than geographically displaced individuals, such as displaced from aquaculture or discarded) in Scotland. Intertidal surveys were carried out at a variety of potentially suitable locations around Scotland to determine if Pacific oysters were present, and record the biological and physical characteristics of the area surrounding any settlement of oysters found. Surveys took place throughout 2014, and reported in 2015. This project informed the development of policy and management in Scotland to support the sustainable development of Pacific oyster farming and the maintenance of protected sites.

This work was led by Scottish Association of Marine Science, Scottish Aquaculture Research Forum & Scottish Natural Heritage.

Project report: Survey of Wild Pacific Oyster Crassostrea gigas in Scotland (PDF) (Cook, E.J., Beveridge, C.M., Lamont, P., O’Higgins, T., Wilding, T., 2014)