What to do with sargassum, the algae that releases toxic gases? 14 years after the first invasion, Martinique and Guadeloupe are slowly moving forward to recover it.
Fourteen years after the first invasion of sargassum seaweed in Guadeloupe and Martinique, and while new massive influxes have been invading their coasts in recent weeks, the French islands are gradually making progress on the issue of their recovery.
"We can't say today or tomorrow that we're going to do this or that with the sargassum. What's important is to do research." At the Sargcoop II conference, held in late March in Gosier, the president of the Guadeloupe region, Ary Chalus, paid attention to "ideas on the ground, some of which were developed in coalition with the entire Caribbean" and intends to "continue this work."
He is particularly interested in "predicting" these arrivals of brown algae from the Atlantic, because "let's imagine that a company invests 5 or 10 million in a recovery plant and tomorrow there is no more sargassum, what do we do?" he asks.
And he recalled the "enormous" sums spent by local authorities and the state to divert, collect, or store this algae, which releases toxic gases when it rots once washed ashore. "Close to 30 million euros for Guadeloupe, between 2018 and 2024," said its vice-president in charge of the environment, Sylvie Gustave Dit Duflot.
The stakes are economic, health-related, and environmental, emphasizes Ferry Louisy, vice-president of the Guadeloupe Departmental Council. Along with other elected officials, he highlights "the disruption to marine biodiversity" and calls for "collective commitment." "For the moment, it's just being stored, so we need to make the most of it."
"The EU says it's time to move towards recovery. But how can we recover when we don't have the same health standards?" asks Ms. Gustave Dit Duflot. "We must first decontaminate?" she explains, "because in France, we cannot recover something full of heavy metals, arsenic and - a specific feature of the French Antilles - chlordecone," the pesticide used until 1993 despite warnings about its dangerousness, which has permanently contaminated soil and water.
There are avenues for recovery: "biofuels, bricks, cosmetics or even biochar, coal with which to amend the soil, which improves its fertilization properties and could, according to some research, sequester chlordecone" , explains Charlotte Gully, coordinator of the circular economy center at Ademe Martinique.
In terms of "valuation, we have to give it time," she believes, because if "it works in the laboratory, now the big question is how to move it to industrial scale."
"Little by little, we are closing the doors, we are experimenting in an increasingly applied manner so that we can say for France 'this will be the strategy,'" she continues.
Ademe has launched a call for projects with the National Research Agency "to support pilot projects and demonstrators in the region," explains Ms. Gully.
Among the projects under study, Ulises Jauregui, professor of environmental sciences at the Technological Institute of Santo Domingo (Dominican Republic), hopes to develop in Martinique "a process that significantly reduces the arsenic content" of sargassum, to transform it into "liquid biofertilizer".
However, for Olivier Marie-Reine, president of the Blue Economy Commission at the Territorial Collectivity of Martinique, "we must sort through all these ideas, because they represent economic opportunities for some, but they are expensive."
He calls for "mutualization in the long term, otherwise the bill will be enormous." He mentions the daily challenges: "collection at sea" and "deviating" barriers (preventing the stranding of sargassum on the coasts), on which "there has been good and bad."
For Ms. Gully, the two territories have "the same concern: developing waterproofed storage sites that collect and process sargassum juices, and the same problem," which is "identifying the land to do this because it's complicated on our islands."
In the meantime, and while the Sargassum 3 plan is being prepared, we must "talk about Sargassum" internationally, insists Sylvie Gustave Dit Duflot, who would like to see, at the Oceans Congress in Nice in June, "the Sargassum issue [...] raised during the final declaration with all the heads of state, because from the moment a topic is raised at the international level, it becomes a reality and we must deal with it."
Nice Matin
