Sargassum is a plant that belongs to the family Sargassaceae which includes 150 species of brown algae. It is the species Sargassum natans and S. fluitans which are found in the Atlantic Ocean and which wash up on the coasts of the Caribbean islands.
Sargassum settles on rocks on the beaches of temperate regions or appears as free floating algae in the open sea. In the case of the Caribbean, it forms vast banks of brown algae woven in tight rows, their thickness can reach one meter and can spread up to several tens of kilometers on the surface of the Atlantic. When these algae pile up and dry, they release ammonia and hydrogen sulfide. Together, these toxic gases smell like rotten eggs and degrade the shoreline.
The deposits of algae on the coasts of Martinique are presented in 3 forms:
- Dry algae on the beach bottom: they do not seem to present any danger.
- Yellow algae in the water: live algae do not present any particular danger in themselves.
- Algae located on the wet sand area: these algae accumulate and form piles that enter into a process of putrefaction that causes the release of gases that are a source of nuisance.
Breathing in hydrogen sulfide and ammonia can cause a tingling throat, burning eyes, dry cough, nausea and digestive problems. These toxic gases do not spare marine fauna (fish, turtles...), nor the landscape (deterioration of houses and furniture).
Les dépôts d’algues sur les côtes martiniquaises se présentent sous 3 formes :
- Des algues sèches en fond de plage : elles ne semblent pas présenter de danger.
- Des algues jaunes dans l’eau : les algues vivantes ne présentent pas de danger particulier en elles-mêmes.
- Des algues situées sur la zone de sable mouillé : ces algues s’amassent, forment des tas qui entrent dans un processus de putréfaction à l’origine de dégagement de gaz source de nuisances.
Respirer de l’hydrogène sulfuré et de l’ammoniac peut entraîner des picotements à la gorge, des brûlures aux yeux, de la toux sèche, des nausées et des troubles digestifs. Ces gaz toxiques n’épargnent ni la faune marine (poissons, tortues…), ni le paysage (détérioration des maisons et mobiliers).
