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- Predicted regime shift in the seagrass ecosystem of the Gulf of Arguin driven by climate changePublication . Chefaoui, Rosa M.; Duarte, Carlos M.; Tavares, Ana I; Frade, Duarte; Sidi Cheikh, M.A.; Abdoull Ba, M.; Serrao, EsterThe Banc d′Arguin is a marine ecosystem of global conservation significance, the largest bird sanctuary of western Africa, supported by one of the most extensive seagrass beds in the world composed by three seagrass species, two temperate near their southern limit (Zostera noltei and Cymodocea nodosa) and one tropical at its northern limit (Halodule wrightii). Here we predict the fate of this seagrass ecosystem under climate change scenarios during the 21st century, using species distribution models and sea level rise estimates. We forecast a probable decline in total seagrass area of 3340 Km2 (78%) by 2100, involving the loss of both temperate seagrasses (Z. noltei, C. nodosa), the foundational ecosystem components. By 2050, only the tropical species (H. wrightii) would remain, which forms thin and sparse shallow stands functionally distinct from the previous tall dense meadows that span wider vertical ranges. Intertidal flats, the essential bird foraging habitats, would become unvegetated and also suffer a major reduction in area (114 km2 by 2050, 587 km2 by 2100). The large projected loss of foundational seagrass species portends a collapse of major ecosystem functions with profound impacts on biodiversity, fishery resources and ecosystem services.
- A fine-tuned global distribution dataset of marine forestsPublication . Assis, J.; Fragkopoulou, Eliza; Frade, Duarte; Neiva, J.; Oliveira, André; Abecasis, David; Faugeron, Sylvain; Serrao, EsterSpecies distribution records are a prerequisite to follow climate-induced range shifts across space and time. However, synthesizing information from various sources such as peer-reviewed literature, herbaria, digital repositories and citizen science initiatives is not only costly and time consuming, but also challenging, as data may contain thematic and taxonomic errors and generally lack standardized formats. We address this gap for important marine ecosystem-structuring species of large brown algae and seagrasses. We gathered distribution records from various sources and provide a fine-tuned dataset with ~2.8 million dereplicated records, taxonomically standardized for 682 species, and considering important physiological and biogeographical traits. Specifically, a flagging system was implemented to signal potentially incorrect records reported on land, in regions with limiting light conditions for photosynthesis, and outside the known distribution of species, as inferred from the most recent published literature. We document the procedure and provide a dataset in tabular format based on Darwin Core Standard (DwC), alongside with a set of functions in R language for data management and visualization.
- Not regionally extinct: rediscovery of ruppia drepanensis in Portugal, the westernmost range edge in EuropePublication . Gonçalves Frade, Duarte; Miranda Neiva, João; Martínez-Garrido, Jose; Davison, Anne; Caminiti, Luca; Ramos, Gonçalo Miguel da Cruz e Cunha Guinote; Pearson, Gareth Anthony; Serrao, Ester A.Ruppia drepanensis Tineo ex Guss. is an important habitat-forming aquatic plant in saline and brackish Mediterranean wetlands. The species is declining in several parts of its range due to hydrological changes and habitat degradation. R. drepanensis was considered Critically Endangered, possibly Regionally Extinct in Portugal, due to not being observed since 1986 despite extensive surveys of suitable habitat. We report on a new population, the westernmost known record for the species in Europe, identified with morphological and molecular data. Despite being inside a protected area, this population occupies a single small pond adjacent to a road, making it vulnerable to habitat changes. Ex situ conservation is recommended, including seed banking and/or the establishment of new populations.
- Cryptic diversity in colonizing seagrasses and implications for conservationPublication . Gonçalves Frade, Duarte; Serrão, Ester A.; Pearson, Gareth A.Seagrasses are foundational marine angiosperms that provide essential ecosystem services, yet many aspects of their diversity and evolution remain poorly understood. This is especially true for colonising seagrasses—small, fast-growing species that dominate dynamic or marginal environments and are becoming increasingly dominant in many regions. This thesis investigates the diversity of colonising seagrasses and its implications for conservation using a combination of phylogenetic, and ecological approaches. By compiling the first comprehensive review of hybridisation and polyploidy in seagrasses, I show that these processes are more widespread than previously recognised, particularly in Ruppia, the most widely distributed genus of colonising seagrass. Phylogenetic evidence indicates that multiple hybrid or allopolyploid Ruppia lineages have colonised oceanic islands (Azores, Madeira, Canary Islands), providing clear evidence of long-distance dispersal—previously considered unlikely for the genus. Additional phylogenetic analyses and botanical surveys reveal overlooked species even in mainland Portugal, a region with a long history of seagrass research, underscoring persistent biases toward larger, persistent species. To assess how colonising and larger seagrasses may respond differently to climate change, species distribution modelling was applied to three West African seagrasses: one colonising species (Halodule wrightii) and two larger species (Cymodocea nodosa, Zostera noltei). The models predict severe losses for the larger species by 2050, while Halodule is expected to persist and expand under most scenarios. Finally, through IUCN Red List assessments, this work reviews the conservation implications of ongoing regime shifts toward colonising species and addresses unresolved taxonomic challenges. Overall, this thesis provides essential baseline data on evolutionary processes, species, and regions that remain underrepresented in the global seagrass literature.