Cancún | 17 de diciembre de 2018

La Universidad del Sur de Florida lanzó una llamada de alerta para el Caribe debido a las cantidades de sargazo que pueden arribar en 2019, que podrían ser mayores a las que afectaron en el 2018 a Quintana Roo, lo que causó un gran impacto para los hoteleros de Riviera Maya y Cancún, como reveló REPORTUR.mx (Hoteleros de Riviera Maya admiten la bajada de precios y ocupaciones).

Rosa Rodríguez Martínez, maestra en ciencias de la Universidad Nacional Autónoma de México (UNAM), que forma parte del Comité Técnico, informó que con base a la distancia a la que actualmente están las manchas del sargazo, su arribo al mar Caribe mexicano puede ser en el primer trimestre del año, según recogió Sipse (Lanzan iniciativa para declarar desastre natural arribo de sargazo).

El informe de la universidad estadounidense fue analizado en Cancún durante la segunda reunión ordinaria del Comité Estatal Científico Técnico para el Sargazo, que encabeza la Secretaría de Ecología y Medio Ambiente (Sema), en el que estuvieron presentes los representantes de diversos sectores de la sociedad.

Las noticias no son buenas, porque la acumulación del alga marina que se ve actualmente en el centro y oeste del océano Atlántico representan “una señal alarmante” en el Caribe para 2019, lo que puede presentar una gran cantidad de sargazo a partir de enero, similar o mayor a la de 2018, detalla el reporte.

“Del sitio en donde está ahorita la mancha del sargazo tardaría aproximadamente 32 semanas en llegar la Península de Yucatán, y si se toma en cuenta que se reproduce en cuestión de días, la cantidad podría ser mayor a la del 2018, pues (las imágenes satelitales muestran que) en este noviembre hay más sargazo que el año pasado (y que fue el que recaló en el 2018 en Quintana Roo)”, explicó la maestra en ciencias.

Source : Reportur.mx

Wednesday, October 31st, 2018

The Government of Belize has granted $1.5 million to help contain and control of sargassum in the municipalities of San Pedro, Caye Caulker, Placencia and Hopkins, which will be disbursed through the Belize Tourism Board. Minister of Tourism and Civil Aviation Hon. Manuel Heredia announced GOB’s assistance and other tax reliefs at a press conference the BTB offices in Belize City on Wednesday afternoon, October 31.

To help the affected coastline properties at these destinations defray the cost of fighting the sargussum scourge, GOB has also agreed to waive two per cent of the of the 9 percent hotel tax due which all hotels pay in their monthly accommodation tax returns, a 22 per cent reduction in tax for these resorts. This tax relief will remain in effect for the months of October, November, December 2018, through January 2019.

Furthermore, GOB through the Ministry of Finance is providing additional tax relief by way of duty exemption on all materials, equipment and machinery which the affected properties at these four destination may choose to import to address the sargassum blight.

The government decided to offer this assistance on the recommendation of the Sargassum Task Force (STF) led by Minister Heredia, BTB chairman Einer Gomez and BTB Director of Tourism Karen Bevans. With the high tourism season about to start, The STF had assessed the gravity of the sargassum problem during several visits to coastal properties around the country, during which they had consulted with the owners of these seaside resorts to work out a joint strategy to deal with the problem.
During these visits, the BTB team came to recognize that the owners of these blighted resorts have had to incur significant expenses in cleaning up and disposing of the sargasssum scourge, and to erect barriers to deflect the sargassum off their beachfronts, all of which have increased their operating costs.

The BTB has promised all interested parties that the STF continues to research and consult in find a long term solution to the sargassum blight, and will continue to seek new ways to address this situation. They promised to update all interested parties as new developments arise. The STF includes the National Emergency Management organization (NEMO), Fisheries Department, the Tourism minstry, the BTB, the Coastal Zone Management Authority, Ministry of Health, the Belize Tourism Industry Association (BTIA), the Belize Hotel Association (BHA) and representatives of the tourism property owners in San Pedro, Caye Caulker, Hopkins and Placencia, and these village councils.

Source : The San Predro Sun

The brown seaweed is more than just an eyesore on some beaches.

By Melissa Gaskill

The spring and summer seasons brought a new style for the Caribbean’s iconic white-sand beaches — mounds and mounds of brown, stringy, stinky sargassum.

Divers encountered piles of the seaweed floating nearshore and ­covering beaches in Little Cayman, ­Barbados, ­Antigua, and other destinations throughout the Caribbean and western Atlantic. The unattractive, stinky seaweed kept many away from the sand and ­sometimes interfered with dive plans.

Sargassum is usually a diver’s friend. This vital marine ecosystem provides food, shelter, breeding grounds and nursery habitat for a wide variety of life, including fish, sea turtles and birds. As mats lose their buoyancy and sink, they feed creatures throughout the water column. The algae also add nutrients and structure to beaches.

But in recent years, sargassum has appeared in unusually great quantities, called blooms, and in places it typically did not. Research shows that blooms result from increased runoff of nutrients from land and warmer waters. Where they end up depends on wind, tides and ocean currents, which have shifted as a result of climate change.

But Hazel Oxenford, a fisheries biologist at the University of the West Indies in ­Barbados, points out that many areas ­remained unaffected.

“The news created impressions of whole islands covered by great, ­stinking plumes of sargassum,” ­Oxenford says. “But it comes ashore on ­windward coastlines, and most tourism infrastructure in the Caribbean is on the ­leeward side of islands.”

In Barbados, for example, sargassum inundated the east coast, which is generally considered too rough for diving.

And while the stuff covered beaches at Little Cayman’s ­resorts, most dive sites lie on the ­opposite side of this small ­island. In general, dive shops simply adopted the ­strategy of frequenting dive sites ­unaffected by sargassum, says marine biologist and dive ­instructor Andre Miller of ­Barbados Blue Watersports.

The seaweed did get swept into large bays on the southeast coast of Barbados and those on Antigua where — as the seaweed decomposed — it turned the water brown.

One Barbados dive instructor blamed it for a temporary drop in viz from 100-plus feet to about 15 feet in Carlisle Bay. The thick mats also can make it difficult to launch boats and foul the engines of those who encounter it.

Sargassum blooms also affect ­marine life that attract divers in the first place. Miller reports that recent blooms have killed sea turtles, dolphins and fish. Floating mats can block needed sunlight from sea-grass beds and coral reefs, and heavy beach accumulations appear to discourage sea turtles from ­nesting. Sea turtle hatchlings can die due to ­hyperthermia, exhaustion, drowning and ­predation as they navigate thick seaweed on the beach and in the water.

Divers making plans for next spring and summer can check the Sargassum Watch System, maintained by the ­University of South Florida’s Optical ­Oceanography Laboratory. It shows satellite images of Caribbean locations affected by past blooms, making them candidates to ­experience future blooms.

Travelers also can view and share ­sargassum images on Texas A&M ­University at Galveston’s Sargassum ­Early Advisory System Facebook page, and ask experts questions about conditions in the Caribbean and Gulf of Mexico. The system uses NASA satellite imagery of blooms and scientific tracking of ocean currents to make short-term predictions of where sargassum might land.

Ironically, sargassum mats make for ­interesting dive sites. Species commonly found beneath them include many types of jacks, flying fish, tripletail, cobia, dolphinfish, vermilion snapper, swordfish, pipefish, scrawled filefish, gray triggerfish, barracuda, tuna and billfishes, as well as juvenile sea turtles and a variety of crustaceans.

Avoid them or embrace them, though, sargassum blooms may be the new normal, Miller says. And we have only ­ourselves to blame.

Source : Scuba Diving

In the Caribbean, sargassum deposits have grown to unprecedented sizes, obscuring the sand and turning nearshore waters into seething sargassum soup.

Juliet Lamb – October 24, 2018

They’d seen seaweed before, but nothing like this.

From the shores of Nigeria, to remote villages in the West Indies, to the tourist beaches of Quintana Roo and the glossy high rises of Florida, the seaweed kept coming. Each incoming tide added to the precarious cliffs of algae until they were taller than grown men. The piles reeked of decay, disgorging dead fish and smothered turtles. Tourists stayed away. Out in the harbors, boats floated, useless, on dense tides of solid brown weeds. In the past, villagers might have harvested the beached seaweed to dry or bury as fertilizer, but the sheer volume of it on the shoreline—trapped and rotting—made any practical use impossible. They could only watch as the piles grew higher. The year was 2011, and something was wrong.

An attempt to find a solution to this ecological mystery has been underway for the better part of the past decade, a search that has stretched from the Sahara Desert to the Amazon rainforest, from the Bermuda triangle to outer space. More importantly, it would serve as a reminder of how little we know about what’s happening in the oceans that occupy the majority of our planet—and of how rapidly our own actions might be changing them beyond recognition.

If you’ve ever been out on a boat, you’ve probably seen pelagic sargassum. It floats on the ocean’s surface in narrow, shifting bands, driven by the competing forces of wind and water. From above, sun-baked sargassum rafts look like barren, discolored ribbons of oceanic detritus. From below, they are as complex and teeming with life as inverted coral reefs. Green-brown fronds trail spherical air sacs; coin-sized sea turtles and fish whose patterns imitate sun on water dart in and out of the algal forest. In tropical waters, where nutrients are scarce and marine life scattered, a sargassum raft is an oasis of life and productivity. Floating sargassum acts as a mobile buffet, supporting entire food chains, from primary producers to top predators.

Looking closer at a sargassum mat, you might notice two different plants: needle-leaved Sargassum natans, which forms the majority of pelagic sargassum biomass, and broad-leaved, bushy Sargassum fluitans, which makes up the rest. Although the sargassum family includes hundreds of other members, most are sedentary plants tethered to the seafloor. These two species, found only in the Atlantic, are the only fully pelagic (open sea) members of their genus.

For a long time, the origins of floating sargassum remained a mystery. Were the plants that formed them completely free-living? Or had they once been rooted before becoming detached by waves or storms? The confusion stemmed from the fact that nobody had ever found reproductive organs on either of the two floating sargassum species. Eventually, observers concluded that pelagic sargassum really do reproduce at sea. When enough nutrients are available, the plants undergo rapid growth and, in a process called vegetative fragmentation, break into smaller pieces. These independent offshoots eventually form mature plants, and the cycle begins again.

It’s no coincidence that the location of the Sargasso Sea matches that of the Bermuda Triangle.

Adding further to the mystery, until fairly recently, observers could only guess at where sargassum mats came from. In a 1914 speech to the American Philosophical Society, naturalist William Farlow summed up a few of the more colorful speculations: “Von Marten’s theory that the gulf-weed originated in the Indian Ocean and was carried by currents round the Cape of Good Hope to the Sargasso Sea has nothing to support it, nor can the theory of Ed. Forbes that the floating gulf-weed is the survival of Sargassum growing on the submerged Atlantis be seriously considered.”

Thanks to remote sensing, we now have a more accurate idea of where sargassum originates (unfortunately, not Atlantis). Although small blooms of sargassum occur throughout the tropics, most sargassum production is concentrated in a few hotspots, particularly the northwestern Gulf of Mexico, where sargassum plants grow and fragment each spring during periods of high nutrient availability. Their offshoots catch a ride on powerful loop currents to the Gulf Stream, which eventually brings them to the Sargasso Sea, east of the Bahamas. The Sargasso Sea, considered the world’s only sea with no terrestrial boundaries, is enormous, borderless, and bright blue. It is ringed by competing oceanic currents that convey passive oceanic drifters—hatchling sea turtles, larvae from fish and eels, trash—into a sort of watery holding cell. Those that can leave under their own steam eventually do, once they grow large enough; those that can’t either spin off on fortuitous ocean currents or float around in a permanent raft of flotsam until they decompose. While the Sargasso Sea likely doesn’t produce much new sargassum—nutrients there are too scarce to support large-scale growth and fragmentation—it’s very good at collecting it.

It’s no coincidence that the location of the Sargasso Sea matches that of the Bermuda Triangle, a mysterious stretch of ocean where things are known to vanish, never to be seen again. Sailors from Columbus onward reported sargassum mats thick enough to impede navigation—or even disable ships. Writing for the royal geographical Society in 1925, Captain C.C. Dixon asked:

Who could know whether this weed got thicker and thicker till there was no turning back? Its changing tints and shadows as daylight faded and at the approach of dawn needed but little help from the imagination to be wrought into fearsome monsters that inhabited its depth and whose very appearance would steal away one’s sanity.

Mariners imaginatively conjured a gyre of ghost ships from every era of navigation, tangled in sargassum and doomed to turn in endless circles until they disintegrated or sank. In modern times, the Sargasso Sea is described, perhaps more realistically, as containing a large amount of seagrass diluted over a vast region, only occasionally forming the epic mats described in early narratives (never thick enough to actually trap a ship).

Until recently, sargassum patterns were relatively easy to predict. From their Sargasso Sea stronghold, modest quantities might shoot off into the Gulf Stream, catch lateral currents, or ride storm surges that convey them to tropical beaches on either side of the Atlantic. However, in 2011, that pattern abruptly changed. In the Caribbean, sargassum deposits grew to several meters thick, obscuring the sand and turning nearshore waters into seething sargassum soup. Along the shores of West Africa, similarly unprecedented levels of sargassum choked the ocean beaches.

Although news coverage of the sargassum bloom tended to focus on lost revenue from tourism, excess sargassum is more than just an aesthetic concern. At sea, sargassum is buoyant and full of life; landlocked, it’s heavy and putrid. While small amounts of beached sargassum can create refuges for invertebrates and provide foraging areas for shorebirds, large quantities quickly become unusable and dangerous. Deep deposits can bury hatchling sea turtles, who emerge from nests laid months earlier to find themselves beneath meters-deep vegetation. Decaying sargassum also releases hydrogen sulfide, a noxious gas that can be mildly toxic to humans.

The source of the sudden sargassum influx proved difficult to pinpoint. Initial theories ranged from the effects of dispersants used to sink oil during the 2010 Deepwater Horizon oil spill in the Mississippi Delta to unusually severe African dust storms that airlifted nutrients to the Atlantic.

Oddly enough, the eventual solution came from outer space. Images of ocean reflectivity from satellites proved able to distinguish floating sargassum mats, which appear as dark spots, from the surrounding water. By examining satellite imagery from that year, scientists noticed a new hotspot for sargassum production: an area off the northern coast of Brazil, at the outflow of the Amazon River, where in the past hardly any sargassum growth had been detected. The amount of sargassum produced in this new area dwarfed any previous estimates from outside the Sargasso Sea. Although sargassum production fluctuates between years, the assumption was always that the lack of nutrients in the offshore waters of the Sargasso Sea imposed a ceiling on the amount of sargassum that could grow at any given time. This new hotspot, disturbingly close to shore, next to a highly productive river mouth, isn’t limited by a lack of nutrients or blocked in by an oceanic gyre. You’d be hard-pressed to find a more ideal producer and exporter of sargassum.

By all predictive measures, sargassum blooms are here to stay.

Since 2011, the increase in sargassum production and distribution has persisted, with abnormal sargassum blooms in at least five of the last eight years. 2015 was a new record year, and 2018 is already on track to surpass it; peak deposits are expected in late summer and through the fall. The blooms reflect a combination of environmental conditions, but are particularly severe in years with above-average sea-surface temperatures and high levels of nutrients in the Amazon river. Nutrient levels in the Amazon basin are increasing, driven mainly by nitrogen and phosphorous from fertilizers used in areas of rainforest recently converted to farmland. Downstream, their fertilizing effects are equally powerful for marine vegetation, sargassum included.

Although it’s difficult to know exactly how sargassum blooms first took hold in the region, they aren’t likely to go away any time soon. The continuing conversion of Brazilian rainforests to agriculture fuels a constant demand for fertilizer, of which Brazil is one of the highest consuming nations on earth. Between steadily rising sea-surface temperatures and ever-increasing nutrient loads, it seems almost certain that high sargassum productivity will persist or increase in the Amazon outflow, and could spread to similar regions of nearshore tropical ocean. By all predictive measures, sargassum blooms are here to stay.

So, what’s the solution? Mass harvesting of sargassum at sea is impractical, with negative consequences for the many marine species that use sargassum mats as refuges, nurseries, and foraging areas. Once the plants wash ashore, removing the massive piles becomes even more challenging—and potentially damaging to sensitive beach habitat. Until now, measures to address the sargassum influx have been short-term and piecemeal. Mexico has hired thousands of people to manually rake the seaweed, deployed floating barriers to keep it from reaching beaches, and used hydraulic pumps to collect it on the open ocean. However, there are signs of developing interest in the potential uses of sargassum: in fertilizers, biofuels, sunscreens, or food products. Learning to live with sargassum will depend on finding a balance, for tourists and fishermen as well as for pipefish and sea turtles.

Meanwhile, much about sargassum remains a mystery. It may not grow on the lost city of Altantis, or harbor ancient galleons doomed to spend eternity floating in circles. Although American and European eels are known to breed in the Sargasso Sea, nobody has ever seen them spawn in the wild. Perhaps it’s time for a new sargassum mythology: not one of monsters or shipwrecks, but of the profound mystery and vulnerability of the ocean itself.

Source : JSTORE Daily

Algues rouges et sargasses, une vengeance de la nature!

Radio Canada

Emission Medium Large animée par Catherine Perrin.
Interview de Denis Jimenez « The ocean Cleaner  » et Dolores Planas Biologiste.

C’est la pollution, le déversement d’engrais et la déforestation qui sont à l’origine des algues toxiques qui causent la mort de milliers de poissons, de tortues, de dauphins et de plantes aquatiques depuis la fin de l’été au large de la Floride. Plus au sud, le Mexique et les Caraïbes sont également aux prises avec la multiplication des sargasses. Dolores Planas, professeure émérite en sciences biologiques, et Denis Jimenez, constructeur de bateaux, expliquent à Catherine Perrin comment les ouragans stimulent la progression de ces algues, puis donnent un aperçu des solutions possibles.

Selon Dolores Planas, l’actuelle vague d’algues rouges a été déclenchée par les ouragans de la saison 2017. « Si vous regardez aujourd’hui l’évolution des nouveaux ouragans, vous verrez qu’il y a des vents très forts qui remuent l’eau, indique-t-elle. Alors, les nutriments qui se sont accumulés au fond des zones côtières remontent à la surface. Les petites algues n’attendent que de la nourriture pour se reproduire et [proliférer], comme c’est arrivé à d’autres reprises. Normalement, ces phénomènes d’algues rouges dans les zones des côtes de l’Amérique du Nord et du Mexique durent trois, quatre mois. […] Jamais elles n’ont explosé comme elles le font présentement. »

Étouffantes sargasses
Denis Jimenez, pour sa part, a mis au point une barrière flottante pour récupérer les sargasses au large du Mexique et de la Floride. Il croit qu’elles peuvent être utilisées pour fabriquer des engrais, du bioplastique ou du biogaz. « Ces derniers temps, surtout cette année, nous sommes très [touchés] par ces algues qui viennent s’échouer sur les plages et tuer tout ce qui est en dessous, dit-il. Elles consomment tout l’oxygène. Malheureusement, tout ce qui est faune et flore en dessous meurt, y compris les coraux. En se décomposant, elles provoquent la mort de tout un écosystème. Elles ont tendance à se décomposer sur place et à transformer l’eau qui était transparente et limpide en mer café. »

Source : Medium Large – Radio Canada

By Yucatan Times on October 16, 2018

Hurricane “Michael” generated rains, strong winds and high tides in Quintana Roo, causing the massive arrival of sargassum to the coasts of places like Cancún and Mahahual, Isla Mujeres and Cozumel.

Alfredo Arellano Guillermo, head of the Secretariat of Ecology and Environment (Sema), said that the massive arrival of sargassum is expected to decrease considerably during this month and during November, due to the change of currents of the season.

Isla Mujeres

The municipal president of Isla Mujeres, Juan Carrillo Soberanis, indicated that Michael did not impact the island. However, the currents generated by this hurricane brought a considerable amount of sargassum to the coastal areas, so he made a call to society asking for their collaboration to clean up the beaches.

“The gusts of wind that were felt in Isla Mujeres were intense, and the waves brought a lot of sargassum that was concentrated in these areas of the municipality, so it was necessary to carry out cleaning work to keep our beaches free of seaweed. in order to maintain a good image towards tourism, “he added.

Meanwhile, Kerem Pinto Aguilar, director of the Federal Maritime Terrestrial Zone (Zofemat), reported that in Playa Centro approximately three and a half tons of sargassum were removed, while in Playa Norte an approximate of four tons was accumulated. The seaweed was removed with the help of specialized machinery.

He argued that with these actions, the municipal government reaffirms its commitment to continue offering both islanders and visitors clean white sand beaches and turquoise blue waters for healthy recreation.

Source : The Yucatan Times

Playa del Carmen mayor-elect

3-meter-high piles of seaweed are paralyzing tourism and fishing, says the Morena party senator.

The mayor-elect of Solidaridad, Quintana Roo, estimates that tourism has dropped as much as 35% due to sargassum seaweed washing up on a 480-kilometer-long stretch of otherwise pristine Caribbean beaches.

Laura Beristain Navarrete told the newspaper Milenio that the sargassum situation is of national importance. Piles of seaweed as high as three meters are paralyzing tourism and fishing, she said.

“Environmentalists and the government are looking for alternatives,” said the incoming mayor, who is also a senator with the Morena party.

She and fellow Morena senators are planning a series of meetings with specialists and elected officials to discuss the damage caused by the seaweed, the results of which will be presented to president-elect Andrés Manuel López Obrador.

The intention of these meetings is to create a governmental agency dedicated to addressing the sargassum crisis.

Options include placing nets offshore to contain the seaweed before it reaches the beaches. The weed would then be collected by boats. Another option would be to use tractors to collect the seaweed after it washes up on the beaches.

Senator Beristain said beach clean-ups should occur daily in the state to remove the sargassum.

State authorities said last week that 80,000 cubic meters of the seaweed had been removed between June 22 and July 22 on beaches in Cancún, Solidaridad, Tulum, Puerto Morelos, Othón P. Blanco and Cozumel.

The president of the Cancún and Puerto Morelos hotels association described the impact as huge, and of international proportions, given that it’s not just Mexico’s problem, but one affecting all the islands of the Caribbean.

Some people are suggesting that it should be declared an international emergency, Roberto Citrón said.

Two researchers warned this week that the sargassum could cause a serious environmental disaster for beaches in the region.

Source: Mexico News Daily

Massive seaweed infestations are killing sea turtles and befouling beaches across the Caribbean—and scientists say it’s just the beginning.
By EMILY ATKIN
August 29, 2018

“Beach, eat, drink, dance, repeat.” These are Rihanna’s favorite things to do in Barbados. In a June 7 interview with Conde Nast Traveller, the pop star gushed over her home country, a small island nation in the middle of the Caribbean. “When I’m in Barbados, all is right with the world,” she said. But not all was right with Barbados.

The same day, the local The Daily Nation newspaper reported on an “invasion of the Sargassum seaweed”—a brown, leafy algae that had washed up in thick mats on the white-sand beaches of the island’s eastern shores. The next day, the country’s government declared it a national emergency. Seen from afar, the bloom looked like a coppery oil spill slicking the sea. But a closer look revealed dead wildlife entangled within it.

The June Sargassum invasion in Barbados claimed the lives of three sea turtles, six dolphins, and “countless” fish and eels, The Daily Nation reported. But surely more have perished in the months since, as sheets of the bulbous-tipped seaweed—sometimes several feet deep—have become regular visitors to the country’s eastern and southern shorelines.

A dead baby sea turtle in beached Sargassum seaweed in Palm Beach, Florida.Nancy Jones Peterson
“We’ve had mass mortality of sea turtles that have gotten trapped under ever-thickening piles,” said Hazel Oxenford, a Barbados-based fisheries biologist at the University of the West Indies. “When the turtles try to come up for air, they drown.” Because these Sargassum beachings are primarily happening during nesting season, which runs from March until the end of October, baby turtles attempting to crawl from their eggs toward the ocean are also getting caught in it.

Barbados isn’t alone. In the last six months, more than 700 beaches across the Atlantic Ocean, Caribbean Sea, and Gulf of Mexico have been hit with mass beachings. Mexico, Belize, Guadeloupe, Martinique, and the British Virgin Islands are covered in it, taking a toll on tourism and fishermen alike. “The fishermen could not go to sea for two or three days,” a worker in Dominica told Hakai Magazine. “They couldn’t get the boats out because it was so thick.” South Florida, too, has seen an “assault.” It’s the worst year for Sargassum beachings ever.

There’s not a lot of history to trace, though. Sargassum algae only started becoming a real problem seven years ago. The true origin of these mass invasions, and the cumulative impacts of them, are thus not fully known. Some experts speculate there could be positive impacts along with the negative ones. But much of the story of this new phenomenon remains a mystery.

Sargassum researchers do appear confident in two things, though. The first is that these algal blooms constitute a new type of natural disaster—one that, like hurricanes, can be expected every single year. The second is that this new risk is not entirely natural. Humans have made these blooms far more likely.

There are more than 100 different species of Sargassum in the world, but two types in particular keep popping up on Caribbean beaches: Sargassum natans and Sargassum fluitans. Unlike most other types of seaweed, which begin life attached to the ocean floor, these species reproduce vegetatively on the ocean’s surface. They’re also thought to originate in the Sargasso Sea in the North Atlantic, the only named sea that never touches land; it’s bound only by ocean currents, leaving the sea itself relatively still.

The Riviera Maya in Mexico is suffering a seadweed onslaught this year, which the government is trying to stop with a barrier in the sea.STR/AFP/Getty Images
The floating mats of Sargassum within the Sargasso Sea are so vast and thick, they often look like land masses. Out there, that’s always been a great thing. As the National Ocean Service explains, Sargassum mats provide “essential habitat for shrimp, crab, fish, and other marine species that have adapted specifically to this floating algae.” Threatened and endangered eels, sharks, and dolphinfish spawn there; birds use it for food. Commercial fish like tuna also feed on the algae, making the Sargasso Sea a fisherman’s dream.

Problems with Sargassum only started to arise in 2011. Seemingly out of nowhere, the seaweed began to amass in huge quantities on “beaches across the Caribbean, trapping sea turtles and filling the air with the stench of rotting egg,” according to a report in the journal Science. The foul odor stems from hydrogen sulfide, which the seaweed releases when it rots on land.

The 2011 event was originally considered a freak occurrence. “We thought it was all over,” Oxenford said. “But it came back in 2014, and then again in 2015 in a big way, and it spread much further.” This year, the Sargassum onslaught has stretched out over more than 1,000 square miles of the Caribbean Sea alone. And it’s not the only sea affected this year, according to a map of 2018 beachings.

Where did it all come from? Naturally, scientists originally assumed the Sargasso Sea. But in 2016, a team of researchers published a paper asserting it came from a huge patch of Sargassum floating in the tropical Atlantic, east of Brazil. “None of it ever tracked northward into the Sargasso Sea,” University of Southern Mississippi marine biologist James Franks, who worked on the paper, told Science. He believes ocean currents are sweeping this new source of Sargassum up the Brazilian coast toward the Caribbean.

Brian LaPointe, an algal bloom expert at Florida Atlantic University, said he also believes the tropical region near Brazil is the nursery from where it all came.* His research asserts the seaweed has a “dynamic existence,” continually moving from the equatorial currents toward the Caribbean and the Gulf Stream, with some eventually settling in the Sargasso Sea.

LaPointe considers all the Sargassum beaching events to be part of one big algal bloom: “The largest harmful algal bloom on our planet,” he said. And if he knows one thing about algal blooms, it’s that they thrive off of two things humans keep putting into the ocean: heat and nitrogen.

More studies will be required to fully understand Sargassum’s rapid spread, but a growing number of researchers feel comfortable pointing to humans as a culprit.

“This is another symptom of climate change and ocean pollution,” Oxenford said, pointing to how humans have warmed the ocean. As InsideClimate explains, “More than 90 percent of the excess heat trapped by greenhouse gas emissions has been absorbed into the oceans that cover two-thirds of the planet’s surface.” In particular, the heat content of the ocean surface—where Sargassum grows—has increased dramatically since the 1950s. A 2017 study published in Biogeosciences cites “high anomalously unprecedented positive sea surface temperature” as a potential factor in the blooms.

Annual deviations from the long-term heat average in the top 700 meters of the ocean.climate.gov
Lew Gramer, a marine scientist at the University of Miami, has also described a possible “correlation” between climate change and Sargassum’s spread due to changes in ocean circulation. “An unusual pattern of winds and ocean-surface circulation over the Sargasso Sea in late 2009 and early 2010 preceded the first mass beachings,” he said. “And this pattern actually coincided with an anomaly in a sea-level air pressure index that is also studied by climate scientists, the North Atlantic Oscillation (NAO).” Some researchers have linked changes in the NAO to global warming.

Another factor appears to be nitrogen, which humans have continuously poured into the ocean via fertilizer runoff and overflowing sewage systems. Nitrogen pollution is widely known to feed algal blooms, including Sargassum, and is a possible cause of the red tide plaguing the Gulf coast of Florida.

The main source of this pollution is still in dispute. The 2017 Biogeosciences study, for example, asserts the pollution responsible came from agricultural runoff into the Amazon River, as well as “deforestation, agroindustrial and urban activities in the Amazonian forest.”

Sargassum on the beach of the city of Le Gosier on the French Caribbean Island of Guadeloupe in April 2018.Helene Valenzuela/AFP/Getty Images
LaPointe, however, believes the Sargassum infestations are fed by all land-based nutrient pollution—from the Amazon, but also the Congo and the Mississippi, among other places. “We have greatly altered the nitrogen cycle on this planet,” he said, adding that local sources of nutrient pollution near Sargassum beachings are exacerbating the issue. In places like Florida and the Caribbean, those sources are most often inadequate wastewater infrastructure. “Human sewage is creating a much bigger role than anyone wants to admit,” he said.

If one thing is clear, though, it’s that the people who helped cause Sargassum’s spread are not all affected by Sargassum beachings. For Oxenford, that’s a frustrating reality. “It’s yet another man-made problem that’s been thrown at the Caribbean that isn’t our doing,” she said. But if the Caribbean and other affected areas are to thrive, they must figure out how to fix it—or at least prevent it from causing more damage.

Nancy Jones Peterson has seen the impact of Sargassum beachings up close. Earlier this summer, as she walked the beach at Phipps Ocean Park in Palm Beach, Florida, she came across a small but thick mat of brown algae. The registered nurse took a closer look, and found three dead baby sea turtles.

“There they are,” she said in a video posted to Facebook, her voice shaking. “The poor babies tried to get out to the ocean, and all these seaweed—caught up in the seaweed and they didn’t make it out.”

The Barbados Sea Turtle Project has been documenting similar discoveries on its Facebook page. In one video, a woman digs out an adult turtle from a pile of Sargassum even taller than she is.

This phenomenon has Oxenford particularly worried about the health of local marine environments. “As the seaweed stats to rot, the bacterial population grows enormously and you have huge oxygen demands,” she said. “It starts suffocating organisms.” The thickness of the seaweed mats also block sunlight from getting to sea grass and corals, threatening those organisms, too.

But Oxenford is adamant that not all is lost for local marine life or the tourism and fishing industries. Far from it. “We still have our sunshine and our clear water and beaches with no sargassum,” she said.

Due to ocean currents, Sargassum beachings are also only really happening on eastern and southern parts of Caribbean islands; the western and northern shores are clear. Sea turtle populations overall should be able to survive the beachings, as many nesting sites are not on affected beaches. Some tourist towns in Mexico have installed floating barriers to keep the seaweed from washing ashore. The U.S. has sent two Sargassum boats to help with cleanup in Quintana Roo region of Mexico, which includes Cancun and Playa del Carmen.

“I see this as a solvable problem,” Oxenford said. But not solvable in the sense that the Sargassum will ever go away. “It’s the same way hurricanes are not solvable,” she said. “But we’ll learn to live with it.” Living with it will require a new system where algal blooms are treated like hurricanes. Blooms will be predicted and forecasted, with different levels of alerts to denote the scale of the Sargassum event. Countries will need to implement management and response plans—and fund them appropriately. Ideally, Caribbean countries won’t have to pay for all of it, since they’re aren’t solely or even largely to blame for it.

It’s a daunting task, for sure, but Oxenford isn’t alone in looking at the silver lining. On a different walk on the beach a few days later, Peterson found another sheet of Sargassum—this one containing whole nest of dead hatchlings. “Around 50 to 100, they were all in the seaweed,” she said.

But this time, one was moving. There was no time to waste. Immediately, she said, she took it to the Loggerhead Marine Life Center in Juno Beach, where it she was told it would be rehabilitated and released. Her video from that day has a happy ending.

*Correction: A previous version of this story incorrectly described Brian LaPointe’s research on the origin of massive Sargassum blooms. He does not believe they originated in the Sargasso Sea.

Source : The New Republic magazine