Grateloupia doryphora (Halymeniaceae, Rhodophyta) in Rhode Island waters (USA): Geographical expansion, morphological variations and associated algae

Within a five-year period (1994-1999), the population of the invasive seaweed Grateloupia doryphora expanded from its initial location on a central, southern coastline in Rhode Island, USA. It spread north, east and west in Narragansett Bay, and south along the open coast of Rhode Island Sound. Large numbers of G. doryphora thalli were found in the lower intertidal (below +0.2 m mean low water [MLW]), the subtidal (down to -5.5 m MLW), and tide pools (as high as +1.5 m MLW). Because the species has survived six winters and summers, it seems firmly established in Rhode Island. Regression analyses at nine stations on a latitudinal gradient indicate strong relationships between location in the bay and average maximum blade length (r = 0.91), width (r = 0.92), and polymorphism (r = 0.85). We also found significant differences in blade size and shape among the stations and in relation to depth. Near its exposed southern reaches, at its upper vertical limits, and in tide pools, this species was frequently dissected (\u3e 71% of observed individuals) and polymorphic. In the sheltered northern regions of this estuary and towards the lower vertical limit, down to -5 m MLW, blades were predominantly simple (74% of observed individuals) and either broadly linear or lanceolate. These included specimens as long as 175 cm, with a surface area over 3000 cm2, making this alga one of the largest Florideophyceae reported in the western North Atlantic. Throughout the study, 95-100% of blades were reproductive. No relationship was observed between the percentage of reproductive blades and the latitudinal position in the bay or vertical gradients. At the nine stations studied, 40 associated algal species were recorded within I m of G. doryphora thalli, and, of these, 33% were epiphytic. One endoepiphyte, Laminariocolax tomentosoides (Phaeophyta) appeared on no other host in Rhode Island waters. Data from this study may be incorporated in a model to examine expansion patterns of new invasions of G. doryphora and other introduced species, such as escapees from shipping or aquaculture

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

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

Effects of temperature and irradiance on filament development of Grateloupia turuturu (Halymeniaceae, Rhodophyta)

Grateloupia turuturu Yamada is an economically valuable red alga with great potential in nutraceuticals and pharmaceuticals. Filaments of G. turuturu are of primary importance in germplasm preservation and sporeling culture, although filaments were not present in its life cycle. In this study, effects of temperature (10, 15, 20, 25, and 30 °C) and irradiance (10, 30, 60, and 90 μmol photons m−2 s−1) with photoperiod 10:14 h (light/dark) on filament development were investigated. Our results indicated that 25 °C was the optimal temperature for the formation of discoid crusts regardless of the irradiance. Conditions of 20 °C and 60 μmol photons m−2 s−1 promoted the development of discoid crusts and formation of upright thalli