The unusual massive beaching of Sargassum around Dakar Peninsula (Senegal, Africa) in autumn 2022: opportunity or threat - Sorbonne Université Access content directly
Conference Papers Year : 2023

The unusual massive beaching of Sargassum around Dakar Peninsula (Senegal, Africa) in autumn 2022: opportunity or threat

M Faye
  • Function : Author
Amidou Sonko
  • Function : Author
  • PersonId : 1242274
  • IdRef : 268649456
Weinberger Florian
  • Function : Author
  • PersonId : 1095223

Abstract

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.
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hal-04502777 , version 1 (13-03-2024)

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Ndeye Coumba Bousso, Patrice Brehmer, Valérie Stiger-Pouvreau, Maxime Gautier, Cheikhou Kane, et al.. The unusual massive beaching of Sargassum around Dakar Peninsula (Senegal, Africa) in autumn 2022: opportunity or threat. EPC8 Scientific Opportunities for a Global Algal Revolution, Aug 2023, Brest, France. pp. 278-278. ⟨hal-04502777⟩
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