Sargassum, the brown tide that is invading the Caribbean

The phenomenon has broken records this year and has become one of the great environmental concerns of the coastal areas of the region

Tourists swim at Xcalacoco beach next to sargassum in Playa del Carmen, Quintana Roo.
GLADYS SERRANO

More than six centuries ago, the first European expeditions that crossed the Atlantic to reach the American continent sighted a phenomenon known as sargassum. While documenting it, some of those explorers feared that their ships would get stuck in that brown tide. Now, in the last decade, sargassum has been invading the Caribbean coasts, destroying its ecosystem and becoming a threat to the tourism sector.

It all began in the summer of 2011, when sargassum started to accumulate on the beaches of many destinations with crystal clear waters and white sands. Mexico was one of the first countries to report it, but this environmental problem, which is lethal to many species and also harmful to human health, concerns almost the entire Caribbean region. This year, the amount of sargassum has already reached historic figures in the Atlantic Ocean: in June, more than 24 million tons of the “brown tide” were recorded in the Caribbean coast, from Puerto Rico to Barbados, according to a report from the oceanography laboratory of the University of South Florida.

What is sargassum?

The term refers to an uncontrolled growth of the species Sargassum fluitans and S. natans, brownish seaweed that live in suspension in the seas and move along the Atlantic, dragged by ocean currents. Although most seaweed live in the depths, with their roots attached to the bottom of the sea, these two species can live at the surface because they have gas vesicles, an adaptative mechanism that improves photosynthesis and allows them to spend their lives floating, explains Rosa Rodríguez, a marine biologist at the Institute of Marine Sciences and Limnology of the National Autonomous University of Mexico (UNAM).

While the uncontrolled accumulation of these algae is toxic in coastal regions, causing the massive death of many marine species, in the open sea they play a very important role in maintaining ecological balance. The Sargasso Sea, in the North Atlantic Ocean, is an exceptional ecosystem that provides food and shelter for hundreds of species, some of them unique to this floating habitat. In addition to serving as a platform for the protection and sustenance of marine fauna, it is part of the migration path of species such as eels, turtles and whales.

Why did it become a problem?

When the unrestrained blankets of sargassum reach the coast, they prevent light from filtering to the seabed, which is essential for the biology of corals and types of algae that produce food through photosynthesis. This, in turn, affects the biodiversity of the system they support.

A woman walks on a bridge surrounded by sargassum in Puerto Morelos, near Cancun.
EDGARD GARRIDO (REUTERS)

One characteristic of sargassum is how quickly it can grow: in favorable conditions, it is able to double its biomass in less than 20 days. When the seaweed decompose on the shore, they consume large amounts of oxygen, causing anoxia and emitting toxic gases like hydrogen sulfide and methane, which are very dangerous for humans and can cause the mass death of many species.

The excess of nitrogen and phosphorus derived from the putrefaction process serves as fertilizer for them to grow more, generating leachates, sulfidic acid and arsenic, which are responsible for the fetid and rotten smell that has now become common in some Caribbean tourist destinations. Yet another problem, says the UNAM specialist, is the poor disposal of sargassum, which ends up becoming a pollutant.

Why is it produced, and where does it come from?

According to the strongest hypotheses, climate change is behind the spread and uncontrolled growth of sargassum. For years, various scientific studies have warned of how changes in the ocean currents due to the melting of the poles and glaciers, as well as the excessive ocean fertilization, are making this an increasingly common phenomenon.

The discharges and waste from industries and agriculture at the mouths of the great rivers of South America, such as the Amazon and the Orinoco, whose sediments and organic matter are pushed north by the currents, have caused seaweed to reproduce at a record speed, creating the Great Atlantic Sargassum Belt, a buildup of seaweed that is devastating the Caribbean coasts. “It is a clear example of how climate change affects us directly and indirectly,” points out the biologist.

Which regions are being affected?

Far from being an isolated phenomenon, the problem is impacting a large part of the Caribbean. The beaches of Belize, Honduras, Jamaica, Cuba, Mexico, the Dominican Republic and Barbados, or islands such as San Andres, Guadeloupe or Martinique, among others, are affected by the blankets of seaweed every year. “But large arrivals of sargassum have also reached the north coast of Brazil and even Florida,” says Rodríguez. This brown tide is not only impacting the Caribbean. The biologist explains, “it arrived in the Gulf of Mexico long before, but not in such high volumes.”

Sargassum at Yabucoa beach, in Puerto Rico, last august.
JONATHAN ALPEYRIE (BLOOMBERG)

The first report of the appearance of sargassum came from local fishermen and a newspaper in 2011, according to Chuanmin Hu, an oceanographer with the University of South Florida team, which began tracking its growth in the Gulf of Mexico in 2006.

Is sargassum here to stay?

Hu is the author of a study that in 2019 warned that a change in the ocean currents was increasing the possibility that recurrent sargassum blooms in the tropical Atlantic and the Caribbean Sea would become the new norm. According to Hu, the data suggests that the amount of sargassum that reaches the coasts is growing steadily. According to Rodríguez, even though there is not enough information on the biomass that is reaching the different regions of the Caribbean, which fluctuates every year, “everything suggests that not only the problem will remain, but it will take a turn for the worse.”

Can it be controlled?

Since the problem was pointed out by environmentalists and hotel owners, governments have sought ways to clean their affected beaches in order to recover tourism. Nonetheless, Rodríguez explains that the resources invested so far have not been efficient. “Only a small area of the coast is being looked after, and ecosystems that are also affected by sargassum, like the mangroves and the jungle, are not being cared for,” she points out.

What’s more, the strategy of directly removing the buildup of seaweed from the coasts has a very negative impact. “A little sargassum helps prevent beach erosion, but when it’s a lot it has the opposite effect. And with the heavy machinery that is used to extract the seaweed, they remove a lot of sand,” says the UNAM expert. Another problem that stems from the removal of sargassum is how poorly they dispose of it. “Sargassum has a lot of arsenic, but also cadmium, lead and other heavy metals, as well as dangerous bacteria that pollute the environment,” she warns.

What to do with sargassum?

The arrival of sargassum in the Caribbean can be an opportunity for various industries, and in recent years different initiatives have promoted its use as a raw material.

The different properties of sargassum can be used by sectors ranging from construction to pharmaceuticals or the energy industry. Research centers and universities, for example, are using it as a source of biofuel, thanks to its composition of lignin, cellulose and hemicellulose; sodium alginate, a polysaccharide that can also be found in sargassum and that acts as a thickener, is used in the textile industry and for haute cuisine.

With the aim of promoting the principles of the circular economy, which uses everything while creating added value, some companies are taking advantage of the impurities left over from the alginate extraction process, such as fucoidans. These biopolymers, whose antitumor and immunomodulatory properties are currently being researched, could even be used as cancer therapies, according to some studies.

Source/Fuente: El Pais 18 august 2022

 

Puerto Rico: Buscan soluciones en el Caribe al sargazo, que marcó un récord histórico

La gran afluencia de algas tiene efectos adversos para la economía de los países y su ecosistema

Sargazo en Cancun. (FUENTE EXTERNA)

El problema del sargazo, la llegada de algas a las costas que en junio pasado alcanzó un nuevo récord histórico, preocupa en el Caribe, cuyo Mecanismo Regional de Pesca (CRFM, por sus siglas en inglés) trata de hallar soluciones y sacar rendimiento económico a esta marea parda.

Según informó este miércoles el CRFM, realizó un recorrido por los países afectados junto al instituto de investigación Plant and Food Research, de Nueva Zelanda, para conocer de primera mano cómo el Caribe ha enfrentado esta afluencia masiva de algas Sargassum.

El CFRM, con sede en Belice, subrayó en un comunicado la urgencia de aumentar la colaboración y las asociaciones público-privadas para convertir esta marea parda en las costas en « económicamente viable ».

Las algas de las especies « Sargassum natans y fluitans » se encuentran normalmente en suspensión en el océano Atlántico y son de forma regular arrastradas por las corrientes hasta las costas, aunque alarma su llegada excesiva.

La gran afluencia de algas tiene efectos adversos para la economía de los países y su ecosistema, ya que produce la muerte de peces y otros animales, libera gases nocivos y daña el turismo al ensuciar las playas.

« Esta gira marca un hito importante en el proyecto ‘Productos de sargazo para la resiliencia climática en el Caribe’, financiado por Nueva Zelanda, que busca mitigar los impactos ambientales y económicos de la afluencia de algas Sargassum a través de la creación de cadenas de valor inclusivas », indicó la nota del CFRM.

La gira incluyó visitas a Barbados, Santa Lucía, República Dominicana, Belice y México, donde los delegados sostuvieron conversaciones con varios actores involucrados en la recolección y manejo del sargazo.

« Pudimos observar de primera mano los efectos de la afluencia de sargazo en los países que visitamos. Esto nos permitió comprender mejor las iniciativas en curso para utilizar el sargazo », dijo Beverley Sutherland, coordinadora del proyecto en el CRFM.

Tras recopilar en una primera fase información, el objetivo del CRFM ahora es el desarrollo de productos y de procesos para productos derivados del sargazo.

El CRFM adelantó que, con base al análisis realizado a las muestras recolectadas, se enfocarán los esfuerzos en la formulación de fertilizantes líquidos y materiales de construcción con las algas.

Según un estudio del Laboratorio de Oceanografía Óptica de la Universidad del Sur de Florida, la cantidad de sargazo en el mar Caribe, el golfo de México y el área del Atlántico central aumentó de 18,8 millones de toneladas en mayo de 2022 a 24,2 millones en junio, estableciendo así un nuevo récord histórico.

En Puerto Rico, donde ha estado muy presente el problema, el Departamento de Recursos Naturales y Ambientales (DRNA) llamó a principios de mes a la calma asegurando que es « un proceso natural ».

El DRNA explicó que ese fenómeno se registra en la isla todos los años, aunque algunos con mayor cantidad de algas, como es el caso, y recomendó no acudir a las playas con más concentración de sargazo por los olores que emana.

Fuente : Diario Libre 17/08/2022

Puerto Rico : Record amount of seaweed chokes Caribbean beaches and shoreline

Lakes Beach along the east coast of Barbados is covered in sargassum.(Kofi Jones / Associated Press)

SAN JUAN, Puerto Rico — A record amount of seaweed is smothering Caribbean coasts from Puerto Rico to Barbados as tons of brown algae kill wildlife, choke the tourism industry and release toxic gases.
More than 24 million tons of sargassum blanketed the Atlantic in June, up from 18.8 million tons in May, according to a monthly report published by the University of South Florida’s Optical Oceanography Lab, which noted it as “a new historical record.”

July saw no decrease of algae in the Caribbean Sea, said Chuanmin Hu, an optical oceanography professor who helps produce the reports.

“I was scared,” he recalled feeling when he saw the historic number for June. He noted that it was 20% higher than the previous record set in May 2018.

Hu compiled additional data for the Associated Press that showed sargassum levels for the eastern Caribbean at a near record high this year, second only to those reported in July 2018. Levels in the northern Caribbean are at their third-highest, following July 2018 and July 2021, he said.

Scientists say more research is needed to determine why sargassum levels in the region are reaching new highs, but the United Nations’ Caribbean Environment Program says possible factors include a rise in water temperatures as a result of climate change and nitrogen-laden fertilizers and sewage waste fueling algae blooms.

“This year has been the worst year on record,” said Lisa Krimsky, a researcher and faculty member with Florida Sea Grant and a water resources regional specialized agent at the University of Florida. “It is absolutely devastating for the region.”

She said large masses of seaweed have a severe environmental impact, with decaying algae altering water temperatures and the pH balance as well as leading to declines in seagrass, coral reef and sponge populations.

“They’re essentially being smothered out,” Krimsky said.

The “golden tide” also has hit humans hard.

The concentration of algae is so heavy in some parts of the eastern Caribbean that the French island of Guadeloupe issued a health alert in late July. It warned some communities about high levels of hydrogen sulfide emanating from huge rotting clumps of seaweed, which can affect people with respiratory problems such as asthma.

The Biden administration declared a federal emergency after the U.S. Virgin Islands warned last month of “unusually high amounts” of sargassum affecting water production at a desalination plant near St. Croix that is struggling to meet demand amid a drought.

“We’re consuming as much as we can produce right now,” said Daryl Jaschen, director of the islands’ emergency management agency. “We’re very concerned about that.”

In addition, the U.S. Virgin Islands’ electricity-generating station relies on ultra-pure water from the desalination plant to reduce emissions monitored by the U.S. Environmental Protection Agency. The loss of such water would force the government to use a type of diesel fuel that is more expensive and in limited supply, officials said.

Experts first noted large amounts of sargassum in the Caribbean Sea in 2011, which Hu and other scientists think were created by stronger-than-normal winds and currents. The problem has worsened as clumps multiplied, fueled by nutrients and strong sunlight.

“In the tropical Atlantic, everything was right,” Hu said. “Everything grows fast.”

Sargassum in moderation helps purify water, absorb carbon dioxide and is a key habitat for fish, turtles, shrimp, crabs and other creatures. But it is bad for tourism, the economy and the environment when too much accumulates just offshore or on beaches.

A carpet of brown algae recently surrounded an uninhabited island near the French Caribbean territory of St. Martin that is popular with tourists, forcing officials to suspend ferry service and cancel kayaking and snorkeling tours. The normally translucent waters around Pinel Island turned into a prickly brown slush.

On Union Island, which is part of St. Vincent and the Grenadines, the seaweed invasion has forced some resorts to close for up to five months in the past.

Masses of sargassum also have strangled the Caribbean’s fishing industry. It damages boat engines and fishing gear, prevents fishermen from reaching their boats and fishing areas, and leads to a drop in the number of fish caught. Barbados has been especially hit hard since flying fish make up 60% of the island’s annual landed catch, according to the University of the West Indies.

An overabundance of sargassum was blamed for the recent deaths of thousands of fish at the French Caribbean island of Martinique. It also has activists concerned about the plight of endangered turtles, with some dying at sea entangled in seaweed or unable to lay their eggs given the mat of algae covering the sand.

In the Cayman Islands, a thick carpet of sargassum had prompted officials to launch a trial program in which crews pumped more than 2,880 square feet of seaweed out of the water. But on Tuesday, the government announced that it had suspended removal efforts because the level of decomposition made it impractical.

Other island nations have opted to use heavy machinery to remove seaweed from the beach, but scientists warn that that causes erosion and could destroy the nests of endangered turtles.

Attempts to use sargassum as fertilizer, food, biofuel, construction material or medicinal products continue, but many Caribbean islands are unable to remove the vast amounts of the seaweed because they are struggling financially and have limited resources.

Gov. Albert Bryan of the U.S. Virgin Islands said he asked President Biden to declare a federal emergency for the entire three-island territory, not just St. Croix, but that didn’t happen. Bryan said he is now trying to find local funds to clean beaches, “but a lot of things need money right now.”

Since 2011, large amounts of sargassum have invaded the Caribbean every year except 2013 — an anomaly that scientists believe may have resulted from a lack of nutrients and a change in wind strength and direction. And the record amounts reported in recent years are even more concerning for scientists and island governments.

“We don’t know if this is a new normal,” Krimsky said. “This has been devastating for over a decade.”

Source : Los Angeles Times 03/08/2022 BY DÁNICA COTO