Invasion of the Reds? Long-term shifts on intertidal seaweed at distribuition limits

• Autor(a) principal: Liulea, Sabin
• Data de Publicação: 2021
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.1/17472
• topic: Distribution limits; Biodiversity; Climate change; Portugal; Seaweed; Domínio/Área Científica::Ciências Naturais::Outras Ciências Naturais

The effects of climate change on biodiversity are well documented on the Portuguese intertidal marine flora. However, heatwaves and extreme events have been increasing in frequency and intensity since the last assessment. The present study aims to update the Portuguese intertidal macroalgae database and see how it changed since 2003 and its baseline in the 1960s. To achieve this objective, we assessed the relative abundance and sampled, for subsequent taxonomical identification, in October 2020, and in late May and late June 2021 in the north (Ancora, Montedor, and Viana do Castelo) and in the south (Carrapateira, Sagres, and Lagos) of Portugal, which coincides with the rear-edge distributions of many cold and warm-water species. In the sampling campaigns, we identified 184 different taxa and determined their relative abundance. From 2003, we observed a 62% and 72% decrease in Northern and Southern species, respectively, while the Cosmopolitan species dominated. Also, from the 13 cold-water species not detected in the sampling campaigns, Himanthalia elongata, Laminaria hyperborea, and Saccharina latissima can be highlighted since, for instance, these provide an abundant quantity of biomass, diversity, and coastal protection. Last, the novel presence of the invasive Rugulopteryx okamurae in the intertidal, in Lagos 2021, meant a 57% decrease in the macroalgae species richness. These flora changes may be related to climate change as it negatively impacts the survival of seaweeds. Further research is needed to see how the rest of the Portuguese intertidal flora is facing climate change and which effects can cause. In addition, monitoring of R. okamurae is imperative as it negatively transforms the seascape.