Identity and origin of pelagic sargasso



Project type

National, International


Project duration

Start Date

October 20, 2020

End Date

October 19, 2023


Sargasso strandings have been causing major ecological, economic and societal damage in the Caribbean since 2011. These strandings are associated with the recent presence of these pelagic species in the tropical North Atlantic in an area known as the ‘new Sargasso Sea’. The ORIGINS project is a contribution to theme 1 (Characterisation of the genus Sargassum) of the AAP Sargassum. The research and methodological developments we propose are based on the synergy between phycologists, molecular ecologist, microbiologists, marine ecologists and physicists. The project is divided into five themes (WP):

WP1 – Species delimitation and phylogeny. The main objective is to determine the exact delimitation of Sargassum species. To achieve this goal, we propose an integrative approach combining morphological analysis, DNA analysis and chemical fingerprinting.

WP2 – Connectivity across the ocean. We aim to assess genetic connectivity among pelagic Sargassum populations, coupled with Lagrangian modelling.

WP3 – Microbes, a tool to detect the origin of Sargassum. The microbiome associated with Sargassum has been shown to be geographically dependent and will be used to study short-term relationships between different aggregations and between different parts of the Atlantic.

WP4 – Carbon and nitrogen pathways in Sargassum. The contribution of continental nutrient inputs from major rivers in the Atlantic Ocean versus offshore nutrient inputs from upwelling systems will be studied using stable isotope analyses.

WP5 – Sample collection. Consortium members are experts in sargassum and marine ecology who have access to relevant areas in the Atlantic, Gulf of Mexico and Caribbean regions. WP5 will provide samples to carry out the tasks of the previous WPs.

The project brings together 10 partners, 7 from France and 3 from the USA. Among the French partners, 1 laboratory and 1 company are located in the French Caribbean (Guadeloupe and Martinique respectively) and among the American partners, 2 of them belong to the Caribbean region (Florida and Texas).

Project labelled by the Mediterranean Sea Cluster.



The team


PI des différents partenaires:

  • MIO : THIBAUT Thierry (PI)
  • ISEM : VIARD Frédérique
  • ISYEB : ROUSSEAU Florence
  • LEGOS : LLIDO Jérôme
  • BOREA : BEZAULT Etienne
  • LEMAR: CONNAN Solène
  • SUEZ Consulting/Safege SAS : JAVEL Fabrice
  • ECKERD COLLEGE (US, Florida) : SIUDA Amy
  • SEA (Sea Education Association, US, Massachusetts) : WHITTAKER Kerry
  • TAMUG (US, Texas) : KAISER Karl