Sargassum 2 Joint call 2021: Understanding and predicting Sargassum Blooms

Prior to 2010, Sargassum brown algae bloomed only in the tropical North Atlantic, in the Sargasso Sea. Currently, it has been observed on the Brazilian coast, as far as the Mexican coast and throughout the Caribbean Sea. At the same time, in the western Atlantic, it is flourishing on the African coasts, from Sierra Leone to Ghana, creating the Atlantic Sargassum Green Belt (ASGB) with possible continuity between the eastern and western parts. Questions of the influence of climate change on modifications in hydrodynamic conditions in the equatorial zone and possibly on changing wind and precipitation drift patterns and associated rivers inputs are not elucidated in relation to the increase and geographic shift in ASGB.

The large, continuous influxes of Sargassum seaweed currently affecting the Caribbean and U.S. coasts are the worst since 2011 with 20 million tons in 2018 with an ASGB of over 8800km in length. The economic impact of their stranding is in the millions of euros, especially in the tourism industry and the associated emissions of hydrogen sulfide (H2S) and ammonia (NH3) have a significant effect on the health of coastal residents. The marine ecological impacts have not yet been assessed.

It is imperative to increase our knowledge of hydrodynamic conditions to improve  management of Sargassum influxes. This is the basis to develop a reliable understanding of the causes of occurrence and their inter-annual variability in order to better predict the years of high Sargassum bank flotsam conditions. These research questions are the focus of this joint call, which focuses on 3 themes:

1. Construction of a common data set to feed the different hydrodynamic models;
2. Biological model of Sargassum ;
3. Development of an integrative model coupling hydrodynamics and biology of Sargassum explaining the variability of Sargassum events;

This call for projects aims to provide pragmatic solutions to the sargassum stranding and enrich the knowledge on this phenomenon that affects more particularly the islands of the Caribbean. Funds will be available thanks to the ANR, CONACYT (Mexico),FACEPE (Brasil) and NOW (Nederlands).