Everyone knows the Sargasso Sea described by Christopher Columbus during his Atlantic crossing. She was discovered as the entire crew of her expedition began to find the time long and worried about touching the mainland again. It is located in Bermuda. But what is less well known is that a new Sargasso Sea is currently emerging further south in the tropical North Atlantic. This is the purpose of the Sargasso Expeditions, organised by the University of Aix-Marseille and the IRD (Institut de Recherche et de Développement), with the support of the French Oceanographic Fleet, Monaco Exploration, the Universities of Western Brittany, the West Indies, Pernabouco (Brazil) and Abidjan (Cote d'Ivoire).
Initially, the Sargasso Expeditions respond to a major concern of the populations of the French West Indies who have been repeatedly confronted, since 2011, with brown tides followed by considerable strandings. This has catastrophic consequences on benthic fauna and flora as well as on human health and activities. But in reality, these massive strandings of pelagic Sargasso are widespread all around the tropical North Atlantic Ocean. They can be found in the Lesser and Greater Antilles, on the coasts of Guyana, Brazil and West Africa and around the Gulf of Mexico. The analysis of satellite images has made it possible to reconstruct their course from the Atlantic Ocean, opposite the mouth of the Amazon, but the precise identification of these Sargasso species is not known, and the causes of the appearance of this "New Sargasso Sea" remain hypothetical.