BioInvasions Records (2015) Volume 4, Issue 3: 147–155 Open Access doi: http://dx.doi.org/10.3391/bir.2015.4.3.01 © 2015 The Author(s). Journal compilation © 2015 REABIC Research Article Rapid assessment of marine non-native species in the Shetland Islands, Scotland Samuel B. Collin1, Jacqueline F. Tweddle2,3 and Rachel J. Shucksmith1* 1NAFC Marine Centre, Port Arthur, Scalloway, Shetland Islands, ZE1 0UN, UK 2University of Aberdeen, King's College, Aberdeen, AB24 3FX, UK 3Marine Scotland Science, Marine Laboratory, PO Box 101, 375 Victoria Rd, Aberdeen, AB11 9DB, UK E-mail: [email protected] (SBC), [email protected] (JFT), [email protected] (RJS) *Corresponding author Received: 26 February 2015 / Accepted: 29 April 2015 / Published online: 2 June 2015 Handling editor: Vadim Panov Abstract The Shetland Islands, northern Scotland, have a highly active and diverse maritime environment, and local marine industries form an important part of the local economy. The potential for damage caused by non-native species is high. As part of an assessment of the current status of non-native species in Shetland, a series of rapid assessment surveys, coupled with a settlement panel monitoring programme, were carried out at 18 sites between May 2012 and October 2014. Eight non-native species were detected in our surveys, three of which (Corella eumyota Traustedt, 1882; Bugulina simplex Hincks, 1886; and Dasysiphonia japonica (Yendo) Kim, 2012) had not been previously recorded. Observations by SCUBA also reported the first UK record of Schizoporella japonica Ortmann, 1890 growing on natural substrate. A literature review revealed three additional non-native species that have been documented in Shetland but were not detected in our survey work. The results from this study highlight the speed at which non-native species can spread over regional scales, and that more active harbours contain greater numbers of non-native species, indicating the potential of hull fouling and ballast water exchange for transporting non-native species. Key words: invasive, United Kingdom, survey, tunicate, bryozoan, alga economy (e.g. oil and gas, commercial shipping, Introduction fishing and aquaculture). Advances in marine technology and the globalisation of maritime trade The potential for damage caused by non-native have increased the number of international vessels species (NNS: organisms that have been introduced visiting Shetland, particularly for shipping, oil and to new environments outside their natural range gas transportation, and tourism (Shelmerdine via artificial means; Carlton 1996; Colautti and 2015), which has raised the potential for NNS MacIsaac 2004) and the need for effective introductions, particularly through hull fouling surveillance and monitoring, are becoming an and ballast water exchange (Carlton and Geller increasing concern for governments, decision 1993). makers, industries, and conservationists (Mack et The high-level of international activity found al. 2000; Hooper et al. 2005; Pimental et al. 2000). in Shetland suggests it could be an initial point To ensure early detection of new introductions, of entry to Europe for marine NNS from all over and that managerial action is carried out the world. Once introduced, the diverse array of appropriately and efficiently, it is important to national and regional maritime activity in Shetland assess the current status of NNS and identify could then spread NNS to other locations in the potential pathways and threats (Hewitt et al. 2004). UK and Europe through secondary transportation In the Shetland Islands, northern Scotland, (Clarke Murray et al. 2011; Sylvester et al. 2011). marine industries are fundamental to the local Likewise, the same links to mainland UK and economy (Shetland Islands Council 2013) and Europe provide a pathway for NNS established have created a highly active and dynamic marine in these areas to be introduced to Shetland. 147 S.B. Collin et al. Figure 1. Map of the Shetland Islands and locations of the NNS rapid assessment surveys (triangle), survey sites used for monitoring (circle), and public SCUBA diver observations (cross). Contains Ordnance survey data © Crown copyright and database right 2011. The potential for damage caused by NNS in modiolus Linnaeus, 1758 and eelgrass Zostera Shetland is considerable. The economic threat marina Linnaeus, 1753), due to competition (Byers posed to local marine industries, in particular to 2000), predation (Grosholtz et al. 2000), and the local aquaculture industry (e.g. biofouling of altering the physical structure of native habitats mussel farms: Ramsay et al. 2008; Rius et al. (Gribben 2013), also creates cause for concern. 2011), is of concern. Additionally, the ecological To ensure potential threats are detected early threat to Shetland’s nationally and internationally on, and management action is implemented rapidly, important (i.e. designated as Marine Protected regular surveying and monitoring of high-risk Areas and Special Areas of Conservation) marine sites (i.e., most likely sites of introduction) is habitats and species (e.g. horse mussels, Modiolus required. As part of the Shetland Island’s Marine 148 Marine non-native species Shetland Scotland Spatial Plan (NAFC Marine Centre 2014), a rapid target species and background information were survey assessment of local marinas and docks made available online via the NAFC Marine was carried out by the NAFC Marine Centre to Centre website (NAFC Marine Centre 2015) and assess the current status of NNS in Shetland. In sent to various marine users, including: marinas, addition, a literature review was carried out to aquaculture companies, and recreational boaters. identify any potential threats from future Samples of suspected NNS collected by the public introductions, and a monitoring programme of were brought to the NAFC Marine Centre for selected high-risk sites was established. identification. Methods Settlement panel monitoring Rapid Assessment Survey In conjunction with the rapid assessment survey, Rapid assessment surveys (Arenas et al. 2006; settlement panels were deployed at eight of the Minchin 2007) were carried out at 18 marinas survey sites (Figure 1) to assist with detecting and ports around Shetland between May 2012 NNS that may not have been clearly visible in and October 2014 (Figure 1 and supplementary the initial survey (e.g. fouling species on the material Table S1). A target list of NNS already under-surfaces of pontoons). The eight sites were present in northern Scotland (in particular Orkney, chosen based on the high level of local, regional, due to its proximity to Shetland) and those and international maritime activity (higher potential considered ‘high risk’, based on the Marine Aliens for NNS introduction and secondary spread). II Consortium’s ‘Identification Guide for Selected The settlement panels consisted of two black, Marine Non-native Species’ (Marine Aliens II 3-mm thick, correx (polypropylene) plastic sheets Consortium 2014), was created prior to survey work. (15 × 33 cm and 15 × 17 cm), which were scored, The rapid assessment surveys consisted of folded, and cable-tied together to create a single visual inspections of pontoons, including floating sampling unit (Marine Aliens Consortium UK and submerged items (buoys, ropes, and creels), 2010). The settlement panels provided vertically- as well as scrape samples from the pontoon sides and horizontally-oriented surfaces for recruitment (sampling an area of 30 × 30 cm down to 50 cm (both shaded and non-shaded). By providing a depth). When possible, a visual inspection of variety of surface orientations, the probability of navigation buoys was carried out by boat (Sullom detecting a range of species is increased because Voe, Scalloway harbour). In October 2014, complete larval behaviour during settlement is highly variable visual surveys (including the undersides) of the between species and factors such as light and pontoons at Port Arthur (Scalloway) and Victoria gravity have been found to influence settlement Pier (Lerwick) were carried out when the pontoons (e.g. Bingham and Young 1993; Vermeij et al. were removed for maintenance and winter storage. 2006). All sites surveyed are used year round by Two to three settlement panels were deployed recreational and commercial vessels, and have at each site (depending on site size and resident yachts and small leisure craft. accessibility) and were positioned at a depth of 1 Additionally, all sites contain floating pontoons m below the surface. Integrated weights ensured (with constantly submerged surfaces) and provide the panel remained at a constant depth hard substrate in sheltered environments that is throughout the deployment period. Settlement suitable for the recruitment of fouling species. panels were left in situ for about three to six Large ports (e.g. Lerwick and Sullom Voe) that months (three-month periods during the summer are regularly visited by international vessels [April – July – September] and for six months in were included in the rapid assessment survey, as winter [October – March]), to allow sufficient well as smaller harbours that are important for recruitment of resident species before being the fishing and industries (e.g. Scalloway, replaced with new panels. Collected panels were Cullievoe). Surveying smaller harbours/marinas stored in seawater until examined (usually the with local maritime activity provided valuable same day). All organisms were identified to information on the current distribution