Extensive surveys highlight the importance of marinas and leisure-boat traffic in the management of marine non-native species.

Although non-native species (NNS) have been recognised for decades as a threat to economic interests and native biodiversity, systematic monitoring of marine NNS around the UK has been very slow to develop, resulting in relatively fragmentary knowledge of the number, distribution and history of introductions. In North America, Rapid Assessment Survey (RAS) protocols emerged in the late 1990s as a cost-effective means of detecting NNS and plotting their distributions along extensive coastlines. These surveys focussed on the artificial habitats of harbours and marinas, both as convenient sites to visit and as priority localities for surveillance, given the potential role of small craft as vectors of bioinvasion; in addition, these sites are frequently close to shipping ports and aquaculture facilities.

In September 2004, John Bishop and members of his group co-hosted and participated in the first RAS in Europe, in which an international team of marine biologists, including experienced North American practitioners, recorded marine NNS in harbours and marinas along the South Coast of England1. In the following years the MBA Bishop group extended the coverage of these surveys beyond the South Coast, and conducted repeated RASs of the entire English coast, with the Welsh marinas added in 2014. This work was funded by, and reported to, The Department for Environment, Food & Rural Affairs (Defra), Natural England and the Welsh Assembly Government/Natural Resources Wales (NRW), with additional funds from the Bromley Trust and EU Interreg IVA France (Manche) England.

The surveys documented a surprisingly high, and increasing, prevalence of NNS in marinas and harbours around our coast, with an average of seven and a maximum of 13 sessile invertebrate NNS recorded per English site by 20122, and a similar number of algal NNS when these were surveyed—findings of particular concern since the sites are often within or adjacent to Marine Protected Areas. Through this work the group was instrumental in the discovery of eight animal NNS new to the UK, several being recent arrivals. Work in collaboration with the Station Biologique de Roscoff suggested that the recent flux of NNS was predominantly northwards from France to England3. The repeated English surveys, augmented by data from Scottish colleagues, also documented the very rapid spread between marina sites of some species with apparently low potential for natural dispersal, emphasising the role of small boat movements as an important vector for the spread of marine NNS along UK coasts3. These findings were in agreement with population-genetic studies by the group suggesting anthropogenic dispersal of NNS between marinas in saltatory movements largely unconstrained by geographical distance4.

In 2014, Defra/NRW-sponsored reports by The Centre for Environment, Fisheries and Aquaculture Science (Cefas) identified harbours / marinas as high-risk  ‘hotspots’ for the introduction and spread of marine NNS, but also singled them out as the habitat for which existing statutory monitoring is inadequate for the purposes of Descriptor 2 of the Marine Strategy Framework Directive (MSFD). The MBA’s non-statutory marina surveys were mentioned in this context.

Some of the non-native sessile animals present on the south coast of England

A comparable French report relating to monitoring of NNS within the MSFD highlighted marinas and leisure boats alongside other vectors, citing two papers by the MBA Bishop group on its RAS findings. The UK list of NNS to be monitored for Descriptor 2 of the MSFD was recently finalized, and approximately 60% of the chosen species occur regularly in marinas. Accordingly, the MBA’s detailed RAS data, which include systematically recorded absences, now form a major part of the information defining baseline species distributions for future MSFD monitoring. The compilation of the baseline data was undertaken by DASHH (the MBA Data Team), in collaboration with Bishop’s group, under a Defra contract.

A page from UK Biodiversity Indicators 2015. Measuring progress towards halting biodiversity loss. (Defra, 2016) Crown copyright

John Bishop and MBA colleagues were also involved in a Defra-funded project led by the Centre for Ecology and Hydrography (CEH) to develop a UK indicator of environmental health based on the prevalence of NNS. The annual set of biodiversity indices published by Defra now includes an indicator (B6) of pressure from invasive species. Data are compiled separately for terrestrial, fresh-water, and marine invasive species. The marine data are assembled by Jack Sewell and John Bishop as part of the MBA’s role as the marine data custodian for the GB Non-native Species Information Portal. Again, approximately 60% of the marine species contributing to this index regularly occur in marinas. The documentation of arrivals and their subsequent spread during the repeated RASs has contributed very substantially to the increasing trend of widely established marine invaders, which has been rising more steeply than those of the other habitats, highlighting very clearly the rapid rate of anthropogenic change in our coastal habitats.

  1. Arenas, F., Bishop, J.D.D., Carlton, J.T., Dyrynda, P.J., Farnham, W.F., Gonzalez, D.J., Jacobs, M.W., Lambert, C., Lambert, G., Nielsen, S.E., Pederson, J.A., Porter, J.S., Ward, S., Wood, C.A., 2006. Alien species and other notable records from a rapid assessment survey of marinas on the south coast of England. J. Mar. Biol. Assoc. U.K. 86, 1329-1337.
  1. Bishop, J.D.D., Wood, C.A., Yunnie, A.L.E., Griffiths, C.A., 2015. Unheralded arrivals: non-native sessile invertebrates in marinas on the English coast. Aquatic Invasions 10, 249-264. www.aquaticinvasions.net/2015/AI_2015_Bishop_etal.pdf
  2. Bishop, J.D.D., Wood, C.A., Lévêque, L., Yunnie, A.L.E., Viard, F., 2015. Repeated rapid assessment surveys reveal contrasting trends in occupancy of marinas by non-indigenous species on opposite sides of the western English Channel. Marine Pollution Bulletin 95, 699-706. http://plymsea.ac.uk/id/eprint/7143
  3. Dupont, L., Viard, F., Dowell, M.J., Wood, C., Bishop, J.D.D., 2009. Fine- and regional-scale genetic structure of the exotic ascidian Styela clava (Tunicata) in southwest England, 50 years after its introduction. Molecular Ecology 18, 442-453.

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