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

Ndeye Coumba Bousso, Patrice Brehmer, Valérie Stiger-Pouvreau, Maxime Gautier, Cheikhou Kane, Mamie Souadou Diop, M Faye, Saliou Faye, Bocar Sabaly Baldé, Amidou Sonko, et al.

<figure><img src="image_1.png" /></figure>

## ► To cite this version:

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

HAL Id: hal-04502777

https://hal.sorbonne-universite.fr/hal-04502777

Submitted on 13 Mar 2024

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_2.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
# The unusual massive beaching of Sargassum around Dakar Peninsula (Senegal, Africa) in autumn 2022: opportunity or threat

Ndeye Coumba Bousso, Patrice Brehmer, Valérie Stiger-Pouvreau, Maxime Gautier, Cheikhou Kane, Mamie Souadou Diop, M Faye, Saliou Faye, Bocar Sabaly Baldé, Amidou Sonko, et al.

<figure><img src="image_1.png" /></figure>

## ► To cite this version:

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

HAL Id: hal-04502777

https://hal.sorbonne-universite.fr/hal-04502777v1

Submitted on 13 Mar 2024

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_2.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
<figure><img src="image_3.png" /></figure>

# "Scientific Opportunities for a Global Algal Revolution"

## Program and Book of Abstracts

Edited by Solène Connan, Emeline Creis, Bertrand Jacquemin, Gabriel Markov and Philippe Potin

<figure><img src="image_4.png" /></figure>
<figure><img src="image_3.png" /></figure>

# "Scientific Opportunities for a Global Algal Revolution"

## Program and Book of Abstracts

Edited by Solène Connan, Emeline Creis, Bertrand Jacquemin, Gabriel Markov and Philippe Potin

<figure><img src="image_4.png" /></figure>
**Brief Statement Organizers**

When we commenced organising EPC8 we still faced the real possibility that the pandemic
could throw the organisation off the rails. Nonetheless, we decided against ‘hybrid’ because
four years after EPC7-Zagreb it would be great to finally meet face-to-face again. E-meetings
save costs and time and produce less CO2, but who is not tired of meeting on a computer screen?

We organised the program with 20 symposia in six overarching themes, covering all that keeps us busy. All symposia accommodate micro- and macroalgal presentations to inspire you with research adventures including those in ‘the other phycological denomination.’ Since all of you teach, reach out, and publish, we included symposia about those topics as well. Each conference day has four parallel symposia, from different themes, so as to minimise your choice-stress. Since, posters are integral to the information exchange, we put the poster sessions centre-stage and have devoted plenty of time to them.

We went out of our way to ensure gender balance and diversity. We invited symposium conveners from all over Europe and beyond, and we asked them to consider especially ‘young, rising stars’ as keynote speakers. Young scientists are our investment in the future of phycology.

Enjoy EPC8 and Brittany!

Inka Bartsch, Solène Connan, Philippe Potin & Wiebe Kooistra
**Brief Statement Organizers**

When we commenced organising EPC8 we still faced the real possibility that the pandemic
could throw the organisation off the rails. Nonetheless, we decided against ‘hybrid’ because
four years after EPC7-Zagreb it would be great to finally meet face-to-face again. E-meetings
save costs and time and produce less CO2, but who is not tired of meeting on a computer screen?

We organised the program with 20 symposia in six overarching themes, covering all that keeps us busy. All symposia accommodate micro- and macroalgal presentations to inspire you with research adventures including those in ‘the other phycological denomination.’ Since all of you teach, reach out, and publish, we included symposia about those topics as well. Each conference day has four parallel symposia, from different themes, so as to minimise your choice-stress. Since, posters are integral to the information exchange, we put the poster sessions centre-stage and have devoted plenty of time to them.

We went out of our way to ensure gender balance and diversity. We invited symposium conveners from all over Europe and beyond, and we asked them to consider especially ‘young, rising stars’ as keynote speakers. Young scientists are our investment in the future of phycology.

Enjoy EPC8 and Brittany!

Inka Bartsch, Solène Connan, Philippe Potin & Wiebe Kooistra
# The unusual massive beaching of *Sargassum* around Dakar Peninsula (Senegal, Africa) in autumn 2022: opportunity or threat

Bousso, N.C.<fnref n="1" />,<fnref n="2" />,<fnref n="3" />*, Brehmer, P.<fnref n="3" />, Stiger-Pouvreau, V.<fnref n="4" />, Gautier, M.<fnref n="4" />, Kane, C.<fnref n="1" />, Diop, M.S.<fnref n="2" />,<fnref n="3" />,<fnref n="5" />,<fnref n="6" />, Faye, M.<fnref n="1" />, Faye, S.<fnref n="2" />, Balde, B.S.<fnref n="2" />, Sonko, A.<fnref n="3" />, Diedhiou, F.<fnref n="2" />, Quack, B.<fnref n="6" />, Diadhiou, H.D.<fnref n="7" />, Fricke, A.<fnref n="8" />, Aroui Boukbida, H.<fnref n="9" />, Weinberger, F.<fnref n="6" /> & Ndiaye, W.<fnref n="2" />

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 (HR-MAS 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.

# Holopelagic *Sargassum* along a degradation gradient: variation in biochemical composition and impact on potential valorization

Châtelain, B.<fnref n="1" />*, Stiger-Pouvreau, V.<fnref n="1" />, Bonesteve, A.<fnref n="1" />, Gloaguen, N.<fnref n="1" />, Thouard, E.<fnref n="2" />, Dromard, C.<fnref n="3" /> & Connan, S.<fnref n="1" />

<footnote n="1">¹Ecole Supérieure Polytechnique (ESP), UCAD, BP: 5085, Dakar, Sénégal</footnote>

<footnote n="2">²ISRA, Centre de Recherches Océanographiques de Dakar Thiaroye, CRODT, Dakar, Sénégal</footnote>

<footnote n="3">³IRD, Univ Brest, CNRS, Ifremer, Lemar, SRFC, Dakar, Sénégal</footnote>

<footnote n="4">⁴Univ Brest, CNRS, IRD, Ifremer, LEMAR, F-29280 Plouzané, France</footnote>

<footnote n="5">⁵Laboratoire de Botanique et Biodiversité (LBB), Département de Biologie Végétale, UCAD, BP: 5005, Dakar-Fann, Sénégal</footnote>

<footnote n="6">⁶GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel (GEOMAR), 24105 Kiel, Germany</footnote>

<footnote n="7">⁷Consultant en Pêche et Aquaculture, Freelance, Sipres 5, villa n 21, Cap des Biches, Dakar</footnote>

<footnote n="8">⁸Leibniz-Institut für Gemüse- und Zierpflanzenbau (IGZ), Theodor-Echtermeyer-Weg 1 14979 Großbeeren, Germany</footnote>

<footnote n="9">⁹Instrumentation, Moyens Analytiques, Observatoires en Géophysique et Océanographie, UAR IMAGO, IRD BP: 1386 Route des Hydrocarbures, Dakar, Sénégal</footnote>

<footnote>*boussocoumba@yahoo.fr</footnote>

<footnote n="1">¹Univ Brest, CNRS, IRD, Ifremer, LEMAR, F-29280 Plouzane, France</footnote>

<footnote n="2">²IFREMER, Unité Biodiversité et Environnement de la Martinique, 97231 Le Robert, France</footnote>
# The unusual massive beaching of *Sargassum* around Dakar Peninsula (Senegal, Africa) in autumn 2022: opportunity or threat

Bousso, N.C.<fnref n="1" />,<fnref n="2" />,<fnref n="3" />*, Brehmer, P.<fnref n="3" />, Stiger-Pouvreau, V.<fnref n="4" />, Gautier, M.<fnref n="4" />, Kane, C.<fnref n="1" />, Diop, M.S.<fnref n="2" />,<fnref n="3" />,<fnref n="5" />,<fnref n="6" />, Faye, M.<fnref n="1" />, Faye, S.<fnref n="2" />, Balde, B.S.<fnref n="2" />, Sonko, A.<fnref n="3" />, Diedhiou, F.<fnref n="2" />, Quack, B.<fnref n="6" />, Diadhiou, H.D.<fnref n="7" />, Fricke, A.<fnref n="8" />, Aroui Boukbida, H.<fnref n="9" />, Weinberger, F.<fnref n="6" /> & Ndiaye, W.<fnref n="2" />

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 (HR-MAS 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.

# Holopelagic *Sargassum* along a degradation gradient: variation in biochemical composition and impact on potential valorization

Châtelain, B.<fnref n="1" />*, Stiger-Pouvreau, V.<fnref n="1" />, Bonesteve, A.<fnref n="1" />, Gloaguen, N.<fnref n="1" />, Thouard, E.<fnref n="2" />, Dromard, C.<fnref n="3" /> & Connan, S.<fnref n="1" />

<footnote n="1">¹Ecole Supérieure Polytechnique (ESP), UCAD, BP: 5085, Dakar, Sénégal</footnote>

<footnote n="2">²ISRA, Centre de Recherches Océanographiques de Dakar Thiaroye, CRODT, Dakar, Sénégal</footnote>

<footnote n="3">³IRD, Univ Brest, CNRS, Ifremer, Lemar, SRFC, Dakar, Sénégal</footnote>

<footnote n="4">⁴Univ Brest, CNRS, IRD, Ifremer, LEMAR, F-29280 Plouzané, France</footnote>

<footnote n="5">⁵Laboratoire de Botanique et Biodiversité (LBB), Département de Biologie Végétale, UCAD, BP: 5005, Dakar-Fann, Sénégal</footnote>

<footnote n="6">⁶GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel (GEOMAR), 24105 Kiel, Germany</footnote>

<footnote n="7">⁷Consultant en Pêche et Aquaculture, Freelance, Sipres 5, villa n 21, Cap des Biches, Dakar</footnote>

<footnote n="8">⁸Leibniz-Institut für Gemüse- und Zierpflanzenbau (IGZ), Theodor-Echtermeyer-Weg 1 14979 Großbeeren, Germany</footnote>

<footnote n="9">⁹Instrumentation, Moyens Analytiques, Observatoires en Géophysique et Océanographie, UAR IMAGO, IRD BP: 1386 Route des Hydrocarbures, Dakar, Sénégal</footnote>

<footnote>*boussocoumba@yahoo.fr</footnote>

<footnote n="1">¹Univ Brest, CNRS, IRD, Ifremer, LEMAR, F-29280 Plouzane, France</footnote>

<footnote n="2">²IFREMER, Unité Biodiversité et Environnement de la Martinique, 97231 Le Robert, France</footnote>