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

• Main Authors: Verlaque, Marc, Brannock, Pamela M., Komatsu, Teruhisa, Villalard-Bohnsack, Martine, Marston, Marcia
• Format: Text
• Language: unknown
• Published: DOCS@RWU 2005
• Subjects: Pacific; Crassostrea gigas
• Online Access: https://docs.rwu.edu/fcas_fp/917; https://doi.org/10.2216/0031-8884(2005)44[477:TGGCAH]2.0.CO;2

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.