Bousso N.C. auteur aut IRD Brehmer Patrice auteur aut IRD Stiger-Pouvreau V. auteur aut IRD Gautier M. auteur aut IRD Kane C. auteur aut IRD Diop M.S. auteur aut IRD Faye M. auteur aut IRD Faye S. auteur aut IRD Baldé B.S. auteur aut IRD Sonko A. auteur aut IRD Diedhiou F. auteur aut IRD Quack B. auteur aut IRD Diadhiou H.D. auteur aut IRD Fricke A. auteur aut IRD Aroui Boukbida Hanane auteur aut IRD Weinberger F. auteur aut IRD Ndiaye W. auteur aut IRD text bookSection eng text/pdf reformatted digital access Huge strandings of holopelagic Sargassum along the Senegalese coast were observed throughout the summer of 2022. The unusual nature of such stranding has mobilized the community, sparking questions from civic society and industrialists. We report on this Sargassum arrival to participate in a global scientific endeavour and to inform local stakeholders. Volunteers reported stranding from north to south of Senegal, harming the coastal life, including turtle fatalities. We analyzed the stranded biomass for taxonomic identity and heavy metal concentrations (As, Cd, Pb and Hg). We differentiated the Sargassum collected into six morphotypes based on morphological details. We noticed the presence of the species S. natans I, S. fluitans III and S. natans VIII. Chemical nuclear magnetic resonance (HRMAS NMR) fingerprintings were obtained to compare morphotypes and sampling sites. In comparison to previous studies throughout the tropical Atlantic Ocean, preliminary analyses revealed low quantities of arsenic and high concentrations of cadmium and mercury in the thalli. For all these heavy metals except lead, the concentrations are higher in S. natans I. Arsenic concentrations were variable between sampling sites but lead and mercury concentrations were spatially homogeneous. For agricultural purposes, the maximum values for As and Cd were above some recommended limits. For animal feed, all As concentrations were below the permissible level (40 ppm EU, European Union). Additional analyses are underway to validate these first results and study the biochemical composition of the samples. specialized SENEGAL 034BIOVEG01 040PECHE 020PHYCHI Connan S. ed. edt IRD Creis E. ed. edt IRD Jacquemin B. ed. edt IRD Markov G. ed. edt IRD Potin P. ed. edt IRD 278 Paris Société Phycologique de France 2023 European Phycological Congress, 8., Brest (FRA), 2023/08/20-26 https://www.documentation.ird.fr/hor/fdi:010092436 [F B010092436] https://www.documentation.ird.fr/hor/fdi:010092436 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/2024-12/010092436.pdf IRD - Base Horizon / Pleins textes 2024-12-10 2025-01-06 fdi:010092436 fre