The Distribution of Undaria pinnatifida (Phaeophyceae, Laminariales) on the Coast of St. Malo (Brittany, France)

Introduced brown algae in the North East Atlantic, with particular respect toUndaria pinnatifida (Harvey) suringar

“…These include mainly the floating pontoons of marinas, and to a lesser extent floating wharves and the hulls of small boats, although plants have also been observed growing on a wide variety of structures attached to, or suspended from the floating pontoons, including ropes, buoys and tyres. A similar tendency for plants to colonise floating structures, at or just below the water line, has been reported by Hay (1990) for Undaria in Wellington Harbour, New Zealand, by Floc'b et al (1991Floc'b et al ( , 1996 and Castric-Fey et al (1993) for Undaria in Brittany, and by Brown and Lamare (1994) for Undaria in Timara Harbour, New Zealand.…”

“…Subsequent to its accidental introduction into the Mediterranean French coastal waters at Sete, most likely with imported oysters, the large kelp Undaria pinnatifida was deliberately introduced into the North Atlantic, to Brittany, in 1983 by IFREMER for commercial exploitation (Perez et al, 1984;Perez-Cicera et al 1991;Castric-Fey et al, 1993). It was initially cultivated at three sites: the island of Groix in the south, the island of Ushant in the Bay of Lampaul to the west near Brest, and in the La Rance estuary near St. Malo.…”

“…Interestingly, Saccorhiza polyschides is a common fouling alga on the outer harbour wails and occurs quite abun-dantly in the sublittoral fringe area of the adjacent rocky shore. In view of speculation about possible competition between Undaria pinnatifida and Saccorhiza polyschides in the North Atlantic (Hay, 1990;Castric-Fey et al, 1993;Fletcher & Manfredi, 1995) the eventual cohabitation of these two species at Torquay is likely to provide an excellent opportunity for some experimental studies. With this in mind, some experiments were initiated in 1997 and the results will be presented in a later commu-!…”

“…This relatively unfilled niche was very quickly taken up by the Undaria plants and they became the most dominant algal component, attaining substantial biomass values. Whether such an available "space" is present in the subtidal region on natural substrata along the south coast of England remains to be seen, although observations on populations of Undaria on the north coast of Brittany indicate that major settlements are present (Castric-Fey et al, 1993).…”

“…Undaria can play a strong pioneering role) -The ability to colonise a wide range of artificial structures, including floating structures, which not only assisted the introduction of Undaria into the south coast of England via boats but also strongly contributed to its marginal dispersal -The ability to colonise a wide range of substrata, including a range of host plants and animals -A fast growth rate, producing large canopy-forming sporophytes -A large reproductive spore output, with fertile plants found throughout the year -A wide seasonal distribution period, with plants present throughout the year -A wide physiological tolerance with respect to temperature, light and salinity (Floc'h et al, 1991) -A wide vertical distribution in the subtidal region (down to 18 m in Brittany according to Floc'h et al, 1991;Castric-Fey et al, 1993) In combination, all these factors have contributed to the successful establishment of Undaria on the south coast of England and will undoubtedly further contribute to its continued success and expansion throughout a much wider area of the North Atlantic. Certainly it is likely to considerably extend its geographical distribution, quite probably from Norway to Mauritania as suggested by Floc'h et al (1991).…”