No sea knows calm, but each sea moves and changes in its own way. In the case of the Sargasso Sea —which has no terrestrial barriers, but is flanked by sea currents, within the Atlantic Ocean—, its changes have become evident, albeit indirectly, for a decade, thanks to the presence of sargassum on the coasts of the Mexican Caribbean. This presence has not been received without reaction, the actions that have been taken to mitigate it, although diverse, remind us of the battles of Heracles against the Hydra. One more head always appears.
According to reports from NASA and the University of Florida, by the end of 2021, the sargassum within the great sargassum belt had been steadily decreasing. But by January 2022, estimates of the amount of sargassum increased from 1.7 million tons in 2021 to four million, leaving it as the fourth most abundant start to the year with the highest abundance of these algae since 2011 1. In other words, sargassum also changes and does so rapidly.
In March of the same year, both the tourist centers and the government of Quintana Roo —as well as the federal government since the Secretariat of the Navy's General Plan for the Care of Sargassum— are preparing for part of those four million tons of floating sargassum to land on the Mexican coast. And contain, as much as possible, their presence on the beaches.
Because Sargassum, as a good unwanted guest, stinks after a few days. When decomposed, sargassum releases ammonium and hydrogen sulfide, which is harmful and even lethal to many native species, including seagrass grasslands and coral reefs in the area. The huge brown spots that seem to float ethereally on the shores turn into rough branches that make swimming impossible. They keep tourists away from other beaches. The warning is clear: we must get rid of the saffron. If possible, prevent it from arriving. So the question arises: who is responsible for the fact that, year after year, sargassum is present on the beaches of Quintana Roo?
The answer is not simple. Or rather, it doesn't exist. There is no single person responsible for this. Its causes are multiple and, in many cases, far from the national territory. The Sargasso Sea, as we mentioned, is surrounded by tides, which bring various components from multiple corners of the world.
The sargassum that we see off the Caribbean coast does not come directly from the Sargasso Sea. Between 2009 and 2011, a very abrupt change in pressure within the North Atlantic Oscillation—an annual climate phenomenon—pushed part of the sargassum from the Sargasso Sea to the Caribbean. And the conditions he found in this other sea couldn't be tastier 2. In addition to a warmer climate, sargassum found an almost inexhaustible source of nutrients—which, like sargassum, should not be there either—: the fertilizers used in South America 3.
How do fertilizers get to the sea?
Large regions of the Amazon rainforest have been deforested to make way for farmland that will feed livestock to satisfy a meat company that generates excess products. Since rainforest soil is rapidly lost after deforestation, cropland fields are literally flooded with fertilizer to allow for the growth of pastures consumed by cattle.
This excess fertilizer is carried with irrigation and rain to the Amazon and Orinoco rivers, which flow into the Atlantic and the currents are responsible for carrying these nutrients to the Sargasso Sea. There, the two species of algae that make up sargassum (Sargassum fluitans and Sargassum natans) have multiplied. In the words of Leticia Durand and Juanita Sundberg, “we have fertilized the sea” 4.
Added to this is the fact that the change in temperature generated by climate change has modified the winds and currents and, as a result, the Sargasso Sea has begun to colonize the south, forming what we now know as the great belt of Sargassum —which also knows no calm, and extends from the Caribbean to the African coasts—, bringing it closer to the Mexican coasts, mainly those of Quintana Roo 5.
Coasts that also see this excess of fertilizers reflected in their ecosystems now. According to Brigitta I. van Tussenbroek, researcher in Puerto Morelos at the Institute of Marine Sciences and Limnology (ICMyL) of the National Autonomous University of Mexico (UNAM), in an interview with the New York Times, “invasive sargassum generates a hundred times more nutrients than these ecosystems require, so bacteria and other microorganisms grow uncontrollably and affect native species, in addition to muddying the landscape” 6.
Excess nutrients, excess sargassum, excess variables, excess causes. It sounds like there's not going to be a single solution either. A multitude of solutions are going to be needed. Or at least, a community.
Although the causes of sargassum are external to them - or at least, uncontrollable -, the community of Quintana Roo has not been left idly by. Omar Vázquez, a resident of Puerto Morelos and owner of a nursery in that same area, began using sargassum as fertilizer for his plants during 2015. As he experimented with this material, he realized that he might have other applications that would help him fulfill one of his wishes. By 2018, Omar had built his own house made of sargassum bricks.
Each brick or block is made of between 40 and 60% sargassum, the rest of the material is adobe, so the bricks must be allowed to dry in the sun for ten days before they can be used. This mixture and process, in addition to reducing brick costs by 50%, eliminates the fetid smell of sargassum. The resulting bricks are stronger than ordinary adobe and around 2,150 bricks are required to build a house, that is, about twenty tons of sargassum.
Vázquez, who already patented the process, started making the bricks manually, but since 2019 he has already had a factory with specialized machinery in the town of Mahahual, also in Quintana Roo. Vázquez, who is nicknamed 'Mr. Sargazo', has not only managed to sell his product to construction companies in the area, but he has also built and donated houses for low-income people.
Researchers Javier Arellano and Hugo Lazcano, from the Colegio de la Frontera Sur, in Chetumal, propose that the more up-to-date information we have about the presence of sargassum on the coasts, the better prepared the inhabitants and businesses of the area can be prepared to deal with it. What Arellano and Lazcano propose, in order to have up-to-date information up to the minute, is to have the collaboration of these same inhabitants in a citizen science project.
Arellano and Lazcano developed an application for cell phones that allows users to upload photographs of Sargassum to a server along with their location, date and time of the photograph. In a first phase of testing, the team of researchers managed to obtain more than a thousand photographs in ten different cities over two months. These photographs are then analyzed by a software that they created themselves and generates a real-time report of where Sargassum 7 is located.
Although the researchers expected greater citizen participation, they noticed that as time went by, more and more users joined and were also more consistent in their use of the app. They also plan, for a next phase, to share the application with other groups that are already working on the coasts, such as garbage collectors, turtle camps and the hotels and businesses themselves, since all of them would benefit from this information. Another theme that unites these actors is water.
Having clean water, as well as sustainable processes, helps that the negative effects that sargassum is having on the coasts - such as nutrient saturation and high levels of toxicity for native species - can literally be diluted even a little.
The civil association Centinelas del Agua has among its programs an Area of Education and Sustainable Culture, where they give courses and workshops for both children and teachers. What these Sentinels are looking for is to make all the water in the subsoil of the Yucatan Peninsula visible. Because this water is not only an essential part of the area's ecosystems, but also what connects the mainland with the sea, uniting the basins with the reef. And therefore, making it clear that the way in which inland water is cared for - or neglected - also has an impact on the coasts and the sea 8.
The problem of sargassum is complex. As we saw, it contains many variables that cover both hemispheres of the planet. We cannot predict how much will arrive or how it will change, they have many causes, and yet the sum of them all falls short in the face of the algae growths we observe. All of these characteristics are typical of a complex system.
Complex systems are precisely difficult to predict, they have many variables that interact with each other, and the whole is more than the sum of its parts.
Fortunately, studies on these systems remind us that the challenge we have with sargassum will be difficult to overcome, but that it is not impossible.
Although you can't predict how a complex system will react or where it will move in the face of changes, this is the part that gives us the most hope: they are sensitive to small modifications. In other words, a small action can change the current state of the system and perhaps reverse it, or at least change the system to another state where excess sargassum is not generated. There is a scale on the hydra that is more sensitive, an Achilles' heel within reach of Heracles. The problem is to know what that action will be. Therefore, we need a sea of proposals, made in community, to be able to find that turning point. The answer is there, we just have to implement it and it can come from communities, the government, the academy, or civil society organizations. Or the sum of all.
To learn more about ecosystems, ecosystem services and citizen participation, visit www.serviciosecosistemicos.mx
This article was produced as part of the Conservation and Sustainable Use of Marine Biodiversity in the Mexican Caribbean project of the National Commission for Protected Natural Areas and the German Agency for International Cooperation GIZ, in collaboration with the Mexican Network of Science Journalists.
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