Sargassum is a genus of large brown seaweed (a type of algae) that floats in island-like masses. Its berry-like structures are gas-filled bladders known as pneumatocysts, which provide buoyancy to the plant and allows it to float on the ocean’s surface.
The floating islands of Sargassum can stretch for miles across the ocean, sometimes as far as the eye can see. The Florida Keys and mainland South Florida are well known for their high levels of Sargassum covering their shores. Often called Gulfweed, it was even observed by Christopher Columbus on his voyages to the Caribbean, Central, and South America.
The Atlantic Ocean’s Sargasso Sea was named after the algae, as it hosts a large amount of Sargassum. It has often been said the Sargasso Sea is so thick with the seaweed that ships cannot sail through it, but that is not exactly true. Actually, the seaweed only occurs in drifts within the area.
A floating habitat and marine nursery
The vast, floating mats of sargassum provides food, refuge, and breeding grounds for an array of critters such as fishes, sea turtles, marine birds, crabs, shrimp, and more. Some animals, like the Sargassum fish (in the frogfish family), live their whole lives only in this habitat.
The camouflaged sargassum fish has adapted to live among drifting Sargassum seaweed. It is usually a small fish.
Some other small fish, such as this juvenile puffer, is also found in sargassum, as well as nudibranchs, Snails, and squid.
Sargassum serves as a primary nursery area for a variety of commercially important fishes such as mahi-mahi, jacks, and amberjacks. Because of its ecological importance, sargassum is designated as an Essential Fish Habitat, which affords these areas special protection, according to NOAA.
An ecological crisis in the Caribbean Sea
In summer 2015, large quantities of different species of Sargassum began accumulating along the shores of many of the countries on the Caribbean Sea. Some of the affected islands and regions include the Caribbean and Yucatan coast of Mexico, the Dominican Republic, Barbados, and Tobago. Another large outbreak occurred in 2018.
The seaweed washed up along the shores of the pristine beaches in the Caribbean, decaying and causing a foul odor, releasing fumes of sulfur compounds that rusted metals, and turned taps black in houses on the beaches, damaged modern conveniences, and caused respiratory problems, particularly for asthmatics.
The situation has also caused insurance problems for tourist operations and homeowners because the household and business losses do not fall into previous known insurance categories. Officials and scientists have been wondering what was causing the increase in sargassum, and we now know with a fair amount of certainty what is going on.
While it’s normal for the brown macroalgae to appear on Caribbean shorelines in smaller amounts, over the past 10 years, the size and volume of the amounts washing up on the beaches in the Caribbean have been increasing yearly, with last year being the worst year ever experienced.
Researchers know that the small amounts of Sargassum that arrive on the beaches in the Caribbean region come from the seaweed’s namesake sea in the eastern Atlantic. But in 2018, the massive influx of sargassum came from a new source – the equatorial waters between Brazil and West Africa.
Brigitta van Tussenbroek, an ecologist at the National Autonomous University of Mexico in Puerto Morelos, says pesticide and fertilizer runoff from the Amazon and Congo Rivers feeds algae blooms and the blooms are amplified by climate change. Adding rising ocean temperatures helps the seaweed to proliferate faster, as does deforestation in the Amazon.
“We, us humans, are to blame for the Sargassum problem,” says Dagoberto Ruiz Lavín, general director of Grupo Dakatso, which local hotels and the government had contracted to clear away the seaweed. “The future generations are going to have it much worse if we don’t do anything,” he says. “The Sargassum is not going to stop coming.”
Mexico’s Navy will try to save the day
Mexico News Daily is reporting that the Cancún-Puerto Morelos hotels association has estimated that cleaning the beaches of sargassum will cost at least 700 million pesos (US $36.7 million) this year. But Mexico doesn’t have the funds available for such a massive cleanup.
President López Obrador, speaking at his morning news conference Tuesday, announced that there was no need to hire private contractors because the ” Mexican Navy will lead efforts to combat the expected arrival of as much as one million tonnes of sargassum this year.
AMLO said there was no reason to hire experts on the removal of the “unsightly and smelly seaweed” because the Secretariat of the Navy (Semar) has its own “very good” experts and equipment. AMLO said the strategy would avoid extra costs and be more efficient.
“We’re asking the Secretariat of the Navy to help us, they have the equipment, they have experience and this problem is going to be solved,” López Obrador declared.
