by Omar Vidal

The massive invasion of Sargasso seaweed in the Mexican Caribbean is a potential catastrophe in the making. If we don’t start to take this problem seriously, there could be serious economic, social and environmental impacts and the whole country could suffer as a result. It’s time to call on science and technology to help us find a solution.

A few days ago, I flew over a 45 kilometre stretch of the Quitana Roo coast. What I saw, looking down from 3,000 metres, took my breath away - a myriad of huge, ochre-striped waves floating in endless, parallel stripes on top of the blue ocean, moving relentlessly towards the coast. It looked like a scene out of a science fiction film.

This was the long-awaited arrival of Sargasso seaweed, a marine macro-algae that has been amassing on the shores of the tropical Atlantic Ocean in increasing volumes over the past few years, and then remains trapped in the Caribbean Sea and the Gulf of Mexico. It is the self-same seaweed that we associate with the legendary Sargasso Sea – the notorious seaweed that once entangled pirates ships that dared to venture through the northern Atlantic Ocean in the XVII and XVIII centuries. The Sargasso Sea in the only sea without a land boundary - it is entirely surrounded by other seas. Christopher Columbus "discovered" it during his first voyage to America and it has been a source of inspiration for many authors, such as Julio Verne and Horacio Quiroga, ever since.

However, we can't blame this mysterious sea for the immense quantities of Sargasso seaweed that now plague the beaches of more than 20 Caribbean countries. These macro-algaes have always inhabited the Caribbean’s coastal estuaries and lagoons. The first massive arrival known to date in Mexico was in 2011, followed by a repeat in 2014 and 2015, as documented by Brigitta van Tussenbroek, scientist from the institute of Ocean Sciences and Limnology of the UNAM. Ever since, massive quantities of Sargasso have appeared annually, reaching their highest volumes in 2018. According to Alfredo Arellano, Minister of Environment and Ecology of Quintanta Roo, between June and December 2018, authorities gathered half a million tons of Sargasso off the beaches of seven different townships. It all appeared to indicate there would be an even larger invasion of Sargasso in 2019 - which would be disastorous for the tourism industry of Quintana Roo and the Riviera Maya.

There are several hypotheses as to why Sargasso seaweed is developing in such great quantities and how it reaches the Caribbean. Brian Lapointe from Florida Atlantic University believes Sargasso's excessive growth is due to an overabundance of nutrients in urban wastewater and agricultural fertilizers. In other words, our careless dumping of wastes into the rivers and sea is feeding the Sargasso monster which is now growing faster than ever.

The increase in levels of atmospheric carbon dioxide (the main greenhouse gas causing climate change) and its greater absorption into the sea may also be a cause of the freakish proliferation of Sargasso. It’s also possible that Sargasso feeds off the excess nutrients and fertilizers being dumped into the Amazon River which then flows out to sea in Brazil. Changes in sea currents in the Atlantic, due to global warming, would enable the Sargasso to drift across to the areas where it accumulates in great quantities, such as in the Mexican Caribbean. Once here, the Sargasso can feed again, absorbing more nutrients from Mexico's many sewage and other waste systems that drain out to sea, transforming the seaweed into the “Super Sargasso” that today invades the beaches of Quintana Roo.

These are only hypotheses and we still have a lot to study and learn about Sargasso. Whatever the causes may be, and regardless of its geographical origins, one thing is clear - judging by what we’ve seen in the last few years, the massive influxes of Sargasso seaweed look set to continue. So we had better get ourselves properly prepared to face the economic, social and environmental challenges that this unwanted visitor will bring.

It’s a complex problem. Sargasso doesn’t only impact on Mexico's Caribbean tourism industry and the thousands of people and families who depend on it - it also threatens the region’s fisheries. Sargasso’s harmful effects on the environment are becoming more serious, from its impact on coral reefs and mangroves, to its effect on marine fauna (for example on turtle nesting on beaches). It’s also worth remembering that the mechanic shovels that rake the beaches to clean them of Sargasso inevitably also remove some of the sand which irreversibly affects coastal ecosystems and dunes.

It is therefore very surprising that the federal and regional authorities and hoteliers haven't yet taken serious measures to get a grip on the Sargasso menace; especially since we have been aware of the size and growing threat of the Sargasso invasion since 2015. They seem to be paralyzed. It may be true that they have set up committees of scientists, government officials and the private sector to study the phenomena and that multidisciplinary corrective strategies have been designed. But reality shows that none of these measures have truly risen to the challenge.

We always start to worry about the impact of Sargasso at the beginning of April, when its presence on our beaches begins to annoy our visitors. But once the tourists go home we bury our heads in the sand for the rest of the year. Problems don't go away or resolve themselves by pretending that they don't exist - even ostriches know this!

We are facing a massive challenge that requires serious political will and long-term investment. We urgently need to find innovative solutions that can hold back the Sargasso invasion of our beaches but without creating further problems for the marine environment. This is a task for our scientists and technicians who should be backed up by the National Commission on Science and Technology. But this will only be possible if the federal, state and municipal authorities, as well as the tourism sector, stop passing the buck, start facing up to their responsibilities, and jointly contribute the necessary finances.

As it stands, it seems that the “Super Sargasso” has come to the Caribbean and is here to stay. We would be well advised to prepare wisely if we want to win the war against this invasion.

Scientist and Environmentalist Twitter: @ovidalp
Translated by Eliza Illueca-Colley
This article first appeared in Spanish in El Universal newpaper of Mexico.
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