Browsing by Author "Boesiger, Lea Marianne"
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- Ecological impact of the invasive algal species Rugulopteryx Okamurae in the Atlantic, Southwest PortugalPublication . Boesiger, Lea Marianne; Paulo, Diogo; Lima, PedroInvasive alien species (IAS) are major drivers of ecosystem change, negatively impacting native communities and contributing to global biodiversity loss. The brown macroalga Rugulopteryx okamurae, native to the northwest Pacific, was introduced to the Mediterranean in 2002 and has become highly invasive since 2015, spreading from the Strait of Gibraltar to the northeastern Atlantic. Its rapid proliferation and competitive exclusion of other macroalgae has transformed shallow-water benthic habitats, posing significant challenges for benthic organisms. This study investigates the ecological impacts of R. okamurae on the benthic community in Sagres, Portugal, where the species was first documented in 2021. Using pre invasion data from the MARSW project, collected in 2018, we conducted a comparative analysis to assess changes in benthic community composition and biodiversity following the alga's establishment. Species abundances for demersal fish, cryptic fish, macroinvertebrates and algae were recorded through scientific diving, conducting an underwater visual census (UVC) combined with the quadrat technique. Biodiversity indices were calculated to complement PERMANOVA results, providing a comprehensive analysis of ecosystem changes. Results revealed significant alterations in species composition and declining levels of biodiversity, prompted by the loss of functional macroalgae diversity. The change in biodiversity among demersal fish was driven by the dominance of C. julis and C. exoletus, whereas cryptic fish and macroinvertebrates were more strongly affected by declines in species richness. R. okamurae demonstrated invasive behaviour that exceeded that of other introduced species, underscoring the necessity for long-term monitoring and targeted management strategies to mitigate the alga’s detrimental impacts on marine ecosystems.