BioInvasions Records (2014) Volume 3, Issue 2: 57–63 Open Access doi: http://dx.doi.org/10.3391/bir.2014.3.2.01 © 2014 The Author(s). Journal compilation © 2014 REABIC Rapid Communication The invasive brown alga Undaria pinnatifida (Harvey) Suringar, 1873 (Laminariales: Alariaceae), spreads northwards in Europe Dan Minchin1,2* and Julia Nunn3 1Marine Organism Investigations, Ballina, Marina Village, Killaloe, Co. Clare, Ireland 2Marine Science and Technology Center, Klaipeda University, 84 Manto, Klaipeda, Lithuania 3Centre for Environmental Data and Recording, National Museums Northern Ireland, 153 Bangor Road, Cultra, Co. Down, BT18 0EU, Northern Ireland E-mail: [email protected] (DM), [email protected] (JN) *Corresponding author Received: 14 January 2014 / Accepted: 6 March 2014 / Published online: 12 May 2014 Handling editor: John Mark Hanson Abstract The Asian kelp Undaria pinnatifida (Harvey) Suringar 1873 was found for the first time in Belfast Lough, Northern Ireland during 2012 and was probably established in 2013. This currently is the most northern locality in Europe. The recent expansion around Britain is likely to continue with further colonisation in Ireland and extension to Scotland. Conditions are suitable for colonisation of Celtic, North and perhaps Norwegian Sea coasts, where it is likely to become an important fouling organism on marinas, aquaculture equipment, and other structures. Its preponderance on marina and other pontoons suggests artificial structures are its preferred initial sites of colonisation. Key words: Ireland, invasion, alien, wakame, marina, fouling, non-indigenous Introduction on the Pacific coast of the United States in 2000 (Silva et al. 2002; Thornbur et al. 2004) and more The Japanese kelp Sargassum muticum (Yendo) recently with flotsam (Tracy et al. 2012). It occurred Fensholt is one of two brown algae that have in Mexico in 2003 (Aguilar-Rosas et al. 2004). spread to many continental coasts in the northern This kelp was recorded in Patagonia, Argentina, hemisphere. The Asian kelp Undaria pinnatifida in 1992 (Casas et al. 2004; Orensanz et al. 2002) (Harvey) Suringar, 1873, also known as wakame and later found in northern Argentina in 2011 and ito-wakame, has followed a similar pattern of (Meretta et al. 2012). expansion and spread; but occurs in both hemi- Undaria pinnatifida was first discovered in spheres. These two kelps are native to coasts of Europe in 1971 in the Etang du Thau, France the northwest Pacific Ocean from southeast Russia, (Boudouresque et al. 1985). It is thought to have China, Japan and Korea (Saito 1975; Kitayama et been introduced with Pacific oysters Crassostrea al. 1995). U. pinnatifida has an annual hetero- gigas (Thunberg, 1793) (Floc’h et al. 1991) (Figure morphic life cycle, alternating between the diploid 1), probably as the small and stress-tolerant sporophyte, which is easily recognised and may gametophyte stage. In April 1992, this kelp appeared occur for up to nine months, and a microscopic in the Venice Lagoon in the northern Adriatic haploid gametophyte stage. U. pinnatifida has Sea (Curiel et al. 1998), where it remains established expanded its range worldwide since the 1970s; it (Curiel et al. 2002; D. Minchin pers. obs.), and at was recorded in New Zealand in 1987 (Hay and Taranto, southern Italy in 1998 (Cecere et al. Luckens 1987; Stapleton 1988), Tasmania in 1988 2000). U. pinnatifida was brought from the Etang (Sanderson 1990), and elsewhere in Australia in du Thau and cultivated at different sites along 1996 (Campbell and Burridge 1998; Sanderson the west coast of France in the 1980s and 1990s - 1990; Primo et al. 2010; Younger 2011). It appeared in Brittany and on the Isle de Oleron (Perez et al. 57 D. Minchin and J. Nunn Figure 1. Distribution, showing dates of first records for each invaded country. Blue: cultivation of U. pinnatifida, Red: other populations. Red star: first Mediterranean record, Blue star first Atlantic record. The first Irish record arrowed. Lines indicate the probable future range of U. pinnatifida. For details see supplementary material Table 1S. 1984; Castric-Fey et al. 1996). It was in cultivation 1996 (Fletcher and Farrell 1999) (Figure 1). in Spain at Santander in 2000 (Peteiro 2008) and Since then, this kelp has spread up the east coast, in Galicia (Peteiro and Freire 2011). The first record as isolated populations, as far north as the of the species occurring in the natural environment Humber Estuary and on the west coasts it spread was close to the area of culture at Ousseant, to the Wyre Estuary and to the Isle of Man (NBN Brittany, in 1986, just three years following its Gateway 2013). This account reports its finding introduction for cultivation (Fletcher and Manfredi from Belfast Lough, Northern Ireland, which is 1995). Since then, the kelp has been found in presently the most northern site for this species northern Spain (Santiago Caamaño et al. 1990; in Europe, and we discuss how U. pinnatifida Cremades et al. 2006) and, in 2008, had spread may spread to sites even further north. into Portugal (MACOI 2008). Since its introduction for cultivation in the Atlantic, the alga gradually spread to Calais, northern France, in 1997; to Methods Zeebruge, Belgium, in 1999 (Leliaert et al. 2000); and in the same year to Yerseke, The Netherlands Undaria pinnatifida was one of several targeted (Stegenga 1999). non-indigenous species (NIS) in a survey of twelve In Britain, U. pinnatifida was first discovered marinas on the northern coastline of Ireland from in the Hamble, Southampton Water, in June 1994 the Foyle Estuary to Carlingford Lough (Figure (Fletcher and Manfredi 1995). By 1998, it had 1). The target list was based on the expansion of spread to Cowes, some 12 km away, and to NIS found elsewhere in Europe that might be Torquay, which is >150 km from the Hamble, by expected to appear in Ireland. 58 Undaria pinnatifida spreads northwards in Europe Figure 2. Left, Carrickfergus marina, only used for berthing of leisure craft. Middle, Mature sporophyte plant found on 2 September 2012 from Carrickfergus Marina. Right, Fringing cover of Undaria pinnatifida at the Queen Anne Battery marina, Plymouth in October 2006. Photographs: DM and JN. Thirty separate floating pontoon units were and Secchi disc readings ranged between 0.5 m examined, representative of the entire expanse of in an estuary to 4.0 m on the coast. At Carrickfergus each of the twelve marinas examined. Sampling Marina the salinity was 35 and the water transpa- consisted of using a scraper with a 15cm blade, rency exceeded 2.0 m, enabling good observation mounted on a pole, to remove attached biota on of the fouling organisms on the pontoons. the vertical face of each pontoon. In Britain, sporophytes were found mainly Water temperature was measured using an during the spring and summer and occurred most oceanographic reversing thermometer accurate to frequently at marina sites (Figure 3). The number 0.1ºC at depths of 0.3 m to 0.5 m. Salinities were of new records on the coast of Britain has been evaluated using a refractometer with an accuracy of increasing since the species was first recorded in ± 1. Water transparency was measured using a 30 1994 by Fletcher and Manfredi (1995). cm diameter Secchi disc to the nearest 25 cm. Sampling equipment was disinfected between Discussion sites using an iodine preparation (Iosan ® CCT: Ciba Geigy Agro Ltd, Waterford, Ireland). The three U. pinnatifida sporophytes found in The NBN Gateway (2013) database was 2012 (having probably arrived in 2011), and the examined to determine the cumulative frequencies presence of hundreds of smaller plants in the of observed sporophytes by season, the year of following year, indicate the species is established first record, and the structures or natural in Belfast Lough at Carrickfergus Marina. It is surfaces, where U. pinnatifida was found. likely that the pontoons will develop an extensive fringing cover within a few years. One year after Results its discovery at the Queen Anne Battery marina in Plymouth, south-west Britain, in 2005 it had The field survey took place from 29 August to 8 become the major fouling plant on pontoons September 2012. Only one marina, sampled on 2 (Figure 2). It is likely this kelp will spread to September 2012 at Carrickfergus (Figure 2) in other sites in Ireland and northwards to Scotland Belfast Lough (54º42'36.72"N, 05º48'47.45"W), and may even reach Orkney, the Shetlands, and provided three mature specimens of U. pinnatifida. Norway. It might expand its range as far north as All three specimens had sporophylls (Figure 2) the entrance to the Barents Sea where summer and thus were capable of reproducing. Indeed, on temperatures may attain ~10ºC (Ingvaldsen and 29 August 2013, one of us (JDN) revisited this Loeng 2009), which is sufficient for reproduction marina to find hundreds of small plants attached (Table 1). Colonisation is likely to take place near the surface of all pontoons examined within where there are hard natural surfaces, aquaculture the marina. activities, marinas, and offshore structures. U. Water temperatures ranged from 12.5 to 16.0ºC pinnatifida would appear to be spreading in British at all marina sites; at Carrickfergus Marina it waters, with many new records appearing since was 14.5ºC. Salinities ranged between 1 and 35 2010 (Figure 3). In time, it could become one of 59 D. Minchin and J. Nunn 25 the dominant fouling species at many marinas A and perhaps on mussel longlines, which has 20 happened in Brittany (Castric-Fey et al. 1993). Attachment to the floatation units of fish cages 15 might also take place, adding to drag where there are moderate to strong currents. 10 Undaria pinnatifida tolerates a range of exposure Frequency levels from sheltered marinas to moderately 5 exposed coastal areas where aquaculture activities might be expected to take place (Sanderson 0 1997).