The genus Grateloupia C. Agardh (Halymeniaceae, Rhodophyta) in the Thau Lagoon (France, Mediterranean): a case study of marine plurispecific introductions

Abstract

M. Verlaque, P.M. Brannock, T. Komatsu, M. Villalard-Bohnsack and M. Marston. 2005. The genus Grateloupia C. Agardh (Halymeniaceae, Rhodophyta) in the Thau Lagoon (France, Mediterranean): a case study of marine plurispecific introductions. Phycologia 44: 477–496.

Based on morphological data and molecular analyses [Nuclear ribosomal internal transcribed spacer (ITS), rbcL and mitochondrial cox2-cox3 spacer sequences] of Grateloupia spp. populations in the Thau Lagoon (France, Mediterranean) we demonstrated that at least five exotic species of Grateloupia were introduced. These include: (1) Grateloupia asiatica, a recently described species that was previously misidentified as G. filicina in Japan and Grateloupia sp. in the Thau Lagoon; (2) G. lanceolata from Japan; (3) G. luxurians, a Pacific species described as G. filicina var. luxurians; (4) G. patens from Japan; and (5) G. turuturu, a Japanese species previously misidentified as G. doryphora in the NE and NW Atlantic and Mediterranean Sea. These nonnative species probably were introduced in the Thau Lagoon in the 1970s along with the massive importations of Japanese oysters, Crassostrea gigas, into Europe for mariculture purposes. Since their introduction, they all have established large, reproductive populations with the exception of G. patens. The Mediterranean Grateloupia specimens are genetically and morphologically similar to Pacific specimens of the same species, although in the Thau Lagoon, G. asiatica specimens are morphologically more variable than those found in Japanese populations. This is the first report of G. asiatica in the Mediterranean Sea and Europe. Based on morphological data and molecular analyses (rbcL sequences) G. subpectinata is placed in synonymy with G. luxurians.

ACKNOWLEDGMENTS

This work was supported by ALIENS (‘Algal Introductions to European Shores’), a fifth Framework Program of the European Union to M.V. and by grants to M.M. and M.V.-B. from Rhode Island Sea Grant College Program (Project No 5-32207) and the Roger Williams University Research Foundation. The authors are indebted to Dr Fredericq who kindly provided us with specimens. We thank Prof. Gérard Pergent, Laboratoire Ecosystèmes Littoraux, Universitéde Corse, for the loan of Japanese specimens of ‘The Marine Algae of the Seto Inland Sea’, and the anonymous reviewers for the valuable comments, suggestions and providing the in press manuscript of De Clerck et al. and rbcL sequences of G. luxurians. We also are indebted to Michèle Perret-Boudouresque for bibliographic assistance.