The Invasive Macroalga Rugulopteryx okamurae: Substrata Plasticity and Spatial Colonization Pressure on Resident Macroalgae

Abstract

The present study constitutes the first evaluation of the space colonization strategies performed by Rugulopteryx okamurae when co-occurring with the resident macroalgal community in the introduced areas. Since the first apparition of the nonindigenous macroalga in the Strait of Gibraltar, its high propagation capacity together with its colonization ability has enhanced the establishment success of the species in detriment of the resident biota. In this study, we carried out observational surveys during 2017–2020 in order to assess the coverage levels of R. okamurae on different lighting conditions, surface orientations, and substrata types (artificial and natural). Results revealed that, beyond the high percent coverages already reported at illuminated and semi-illuminated natural rocky habitats, R. okamurae is able to settle on a wide variety of artificial substrata. The settlement performance of the species was also investigated and different mechanisms underlying the space colonization were proposed. Thus, R. okamurae was observed interacting with 43 resident macroalgal species at generally illuminated rocky habitats of the northern Strait coasts. Six colonization mechanisms were proposed for spatial growth scenarios. Overall, results pointed out that, in most of the cases where the invasive species co-occur with the resident community, R. okamurae would be favored as regards spatial growth success. Competitive interactions and environmental factors which influence results obtained must be addressed in order to fully predict impacts on resident communities. Moreover, together with previous scientific works, overall data provided in this study highlight the need to urgent implement management measures focused on habitats susceptible to be invaded, as well as studies on the ecology and dispersal vectors of R. okamurae in the Strait of Gibraltar and adjacent areas.

Rapid Spread of the Invasive Brown Alga Rugulopteryx okamurae in a National Park in Provence (France, Mediterranean Sea)

“…In only one year, R. okamurae became the most abundant species and carpeted the native community, leading to an increase in the number of dead colonies of the red gorgonian Paramuricea clavata (Risso, 1826) and a significant decline in the cover of the red alga key species Mesophyllum expansum (Philippi) Cabioch and M.L. Mendoza (Corallinaceae) [16,39,40].…”

Turning an invasive alien species into a valuable biomass: Anaerobic digestion of Rugulopteryx okamurae after thermal and new developed low-cost mechanical pretreatments

“…R.o. has spread through the Mediterranean Sea and beyond extremely quick and it has become a strong dominant species displacing local biota and causing an unprecedented ecological impact as well as being a source of negative impact on sea-dependant anthropogenic activities (El Aamri et al, 2018;García-Gómez et al, 2021;Sempere-Valverde et al, 2021). For the above-mentioned reasons, in 2020, R.o.…”

Composting the Invasive Toxic Seaweed Rugulopteryx okamurae Using Five Invertebrate Species, and a Mini-review on Composting Macroalgae

“…To date, more than 400 species of invasive marine algae have been counted worldwide, of which 50 affect the Iberian Peninsula [2,3]. In the short term, these invasions can become explosive and occupy a large part of the coastal seabed surface, generating tons of debris and causing severe environmental impact [4][5][6]. In the long term, some local seaweed species can be recovered and the native biota may eventually integrate the invasive species into the marine ecosystem [7].…”

“…In any case, the objectives of composting are always the same: that the sample is aerated, with an appropriate moisture level (~ 70%) and a good C/N ratio (~ 20-25) [32]. However, in the case of R. okamurae composting poses as additional technical difficulty the high concentration in sesquiterpenes [4][5][6]. In this sense, research on composting with other materials rich in terpenes, such as waste from aromatic plant factories, can serve us as a technical guide [33,34].…”