Invasion
Invasion Description
1st record: Guetaria, Basque Province/Spain/Bay of Biscay (1985, Casares et al. 1987, cited by Fernandez et al. 1990) Sargassum muticum has had boom-bust cycles in northern Spain, and is now regarded as incorporated into the seaweed community (Fernadez et al. 2020).
Geographic Extent
Southern France/Bay of Biscay; Guetaria, Basque Province/Spain/Bay of Biscay (1985, Fernandez et al. 1990); Aramar Beach, near Luanco/Spain/Bay of Biscay (1988, Fernandez et al. 1990; Arenas et al. 1995, 43 36N, 5 46W); Banugues/Spain/Bay of Biscay (1988, Fernandez et al. 1990); Cuderillo/Spain/Bay of Biscay (1988, Fernandez et al. 1990); Galicia/Spain/Ria de Arosa, Atlantic Ocean (1988, Fernandez et al. 1990); Galicia/Spain/Bay of Biscay (range expansion, Carreira-Flores et al. 2023); Portugal/Atlantic Ocean (1989;,Araujo et al. 2009; Chainho et al. 2015); Viana do Castello/Portugal/Atlantic Ocean (2003, Engelen et al. 2008); Porto Corvo/Portugal/Atlantic Ocean 2003, Engelen et al. 2008); Almograve//Portugal/Atlantic Ocean (2004, Engelen et al. 2008); Spain/Atlantic Ocean (Peña et al. 2014, maerl beds); continuous on Biscay coast/France-Spain/Bay of Biscay (Stiger-Pouvreau and Thouzeau 2015)
Vectors
| Level | Vector |
|---|---|
| Alternate | Natural Dispersal |
| Alternate | Hull Fouling |
| Alternate | Oyster Accidental |
Regional Impacts
| Ecological Impact | Competition | |
| In a lower intertidal region on the Bay of Biscay, northern Spain had negative impacts of the native red alga Gelidium spinosum, probably due to competition for light (Sanchez et al. 2005). Addition of nutrients in tide pools favored rapid growth and dominance of S. muticum, but colonization was resisted in plots with a dense canopy of the native Bifurcaria bifurcata (Sanchez and Fernandez 2005). Experimental removal of S. muticum found only limited impacts on total numbers of algal species, somewhat reducing the abundance of filamentous and foliose algae (Olabarrio et al. 2009b), or having no detectable impact on other algae (Sanchez and Fernandez 2005). High abundance of S. muticum in tide pools, in northern Portugal, was correlated with decreased abundance of native algae (Viejo et al. 1997). Modeling, based on field observations suggested that the most important feature favoring S. muticum over the native Cytoseira humilis was the persistence of non-fertile fronds of S. muticum, after reproduction, denying the space to Cytoseira humilis (Engelen and Santos 2009). Experiments with the effects of nutrient inputs found that S muticum had a complex response, and was favored by high inputs, with low variability, but not by low, highly variable inputs (Incera et al. 2009). In another set of experiments S. muticum became very abundant in tide pools with high nutrient input and mechanical disturbance (scraping with a chisel) (Bertocci et al. 2014). Nutrient fertilization of tidepools promoted the establishment and functional impacts (increased productivity and respiration) by Grateloupia turuturu and Sargassum muticum (Vieira et al. 2017). | ||
| Ecological Impact | Food/Prey | |
| Experiments with a range of grazing animals, the snails Littorina littorea, L. obtusata, Gibbula, spp., and Peringia ulvae, the sea-slug Aplysia punctata, the amphipod Gammarus insensibilis, and the isopod Stenosoma nadejda, generally preferred native algae to S. muticum, while the sea urchin Paracentrotus lividus showed no preference. Preferences were variable, but experiments did suggest that S. muticum was not under high pressure from grazers (Monteiro et al. 2009; Cacabelos et al. 2010; Engelen et al. 2011). Sargassum muticum, washed up on beaches, was a major food source for the amphipod Talitrus saltator and, to a less extent, for the isopod Tylos europaeus (Rossi et al. 2009; Olabarria et al. 2010). The S. muticum wrack had higher nutrient content than that of a native alga (S. muticum), but there were not consistent differences in invertebrates using the two types of wracks (Rodil et al. 2008). Overall, the invasion of S. muticum has increased the biomass, light-use efficiency, primary production, and respiration of tide pool systems in Portugal. However, this effect disappears during the seasonal die-off of this seaweed (Vaz-Pinto et al. 2014). | ||
| Ecological Impact | Habitat Change | |
| In turbid waters, Sargassum muticum replaces kelps, but provides habitat for fishes, crustaceans, and cuttlefish (Stiger-Pouvreau and Thouzeau 2015). In a study of epifaunal invertebrates, in intertidal communities in Galicia, northern Spain, results showed that S. muticum supported levels of abundance and diversity comparable to those of two native seaweeds (Gestoso et al. 2012). At several locations on the coast of Portugal, the epifauna of S. muticum differs from that of Cystoseira humilis in composition or abundance, but not in any consistent way (Viejo et al. 1999; Engelen et al. 2013). It is used by fishes, crustaceans, and cuttlefish (Stiger-Pouvreau and Thouzeau 2015). | ||
| Economic Impact | Fisheries | |
| Sargassum muticum can interfere with shellfishing and shellfish aquaculture, by covering the bottom, fouling shells, and equipment (Stiger-Pouvreau and Thouzeau 2015). | ||