Growing up by the sea, I am used to find Sargassum floating in the water or washed up on the beach. We have always seen Sargassum and other seaweeds and plants which presence is normal in the marine and coastal environment. However, the quantity of Sargassum that has arrived through the Great Caribbean region since 2014 is unprecedented, as well as the consequences. That’s why there are studies being conducted to understand what this phenomenon is and how to deal with it, not an easy task. I had the opportunity of listening to a senior researcher of UNAM (Mexico’s National Autonomous University) and expert in seagrasses and tropical marine vegetation, she works at the Tropical Seagrass Systems Laboratory in Puerto Morelos. Many of the questions I had were answered during her talk at a local Planetarium. I am hereby sharing them with you.
I have recently learned that the Sargassum arrival has completely changed the dynamic of some very important coastal environments in our region and we all need to take a better look at the issue if we want to continue enjoying our beaches and reef in the future. The problem is not only how tourists perceive the beach and where we are putting the sargassum after it’s collected.
I used to think that Sargassum affected the tourism industry because visitors have high expectations and find it hard to enjoy the beach full with this brown colored alga. I have recently learned that the problem is way more worrying than the holidaymakers and a 10 day vacation in the Caribbean. We are not talking about the way the beach looks anymore, we are talking about an environmental issue that is not about to be solved any time soon. Sargassum might be a problem that our grandchildren (which aren’t born yet) will have to fix. If you want to learn more, keep reading.
Sargassum might be a problem that our grandchildren (which aren’t born yet) will have to fix.
What is Sargassum?
Sargassum is an alga that lives most of its lifecycle floating on the surface of the ocean. Sargassum does not originate on the bottom like other kinds of algae, it reproduces and grows while drifting with the currents and floats in the water column until it reaches the coast where, usually, exits with the movement of the water (waves and currents) onto the sand. It then dries, decomposes or simply goes back to the water and continue on floating.
We have two types of Sargassum in the Caribbean: Sargassum natans and Sargassum fluitans. Both species look almost exactly the same to the untrained eye.
Sargassum and seagrasses are NOT the same thing, they are totally different kinds of living organisms. Seagrasses are plants with seeds, flowers and fruits (yes, underwater flowers AND fruits! While Sargassum is an alga.
Sargassum is good…
In the open ocean, islands of Sargassum are formed as the currents reassemble large quantities and keep them together as a floating island thanks to the gyres. A gyre is a system of currents that forms a “cycle” movement. In a gyre, the water on the surface is pushed by the wind in “circles”, it turns and turns, keeping whatever floats in it within that same area. You must have heard of the Sargassum Sea, this place holds large quantities of Sargassum, in normal conditions sargassum stays within the gyre and only occasionally “escapes” the gyre, hence sargassum has been found in the Gulf of Mexico prior to the Sargassum crisis. However, the Sargassum we have found in the Caribbean since 2014 has not been proved to come from that place. More on this further down.
Hundreds of species or living organisms can be found within these masses of Sargassum, juvenile fish find shelter, crabs and other crustaceans drift with the Sargassum in the open ocean while they find food and a healthy habitat among these floats. Turtle hatchlings spend a great deal of time swimming with the Sargassum as it represents the only protection they can find during their first years in the ocean and Sargassum provides an ecosystem that guarantees food, shade and a home for many.
Sargassum has been documented since a really long time. Columbus mentioned it in his discoveries as far back as 1492, when he arrived in the American continent, and many explorers, scientists and researchers have known of its existence for a long time. Sargassum is part of the marine environment and has ecological value, when the quantities that reach our beaches are normal.
Sargassum is bad…
In recent years, we experienced an unprecedented arrival of Sargassum, this phenomenon reached the entire Caribbean region, the coast of Central and South America and even Africa. The amount that washed up on the white sand beaches was a big shock for everybody: tourists, locals, government, tourism industry, travel industry, scientists, press, etc. Literally, nobody had ever seen anything alike (although we all knew Sargassum, we had never seen this much). The first reaction was to remove it, but rather quickly people realized this was a task for thousands of people. Due to the fragility of the coastal environment, this had to be done by hand. Men and women worked endless hours to remove Sargassum from beaches and seagrass meadows. Only to find that overnight the quantities had increased and there was more to arrive.
So, how an alga that is supposed to be good and provide much value for the environment, as described above, can be such a stinky business to deal with from one day to another, and why our feelings are mixed between concerned and overwhelmed?
“The excess of Sargassum is detrimental to the environment, just like any excess. Excess of sugar is bad. Excess of Sargassum, is also bad” Brigitta van Tussenbroek
What are the immediate effects of Sargassum?
The islands of Sargassum accumulate near the coast where other marine ecosystems thrive, for example: seagrass meadows and coral reefs. It causes a bad smell and releases Hydrogen Sulfide.
Big amounts of sargassum can prevent turtles from nesting and can make it very difficult, if not impossible for hatchlings to reach the ocean from the nest.
Sargassum can cause beach erosion by altering the structure of the reef lagoons, by suffocating the seagrasses and by creating unbalance in the health of the beach ecosystem.
Seagrasses serve in fixing sediment and keeping sand in place, when seagrasses are gone, the sand might erode and the water will rise its level, recently we have experienced unprecedented levels of beach erosion too and it might be linked to the arrival of massive sargassum amounts.
Sargassum can be dangerous for our health, respiratory issues have been reported due to the concentration of gases that the decomposing Sargassum provokes.
Sargassum blocks the light that normally penetrates the surface, preventing many organisms from completing their photosynthesis process, therefore diminishing the amount of oxygen they produce (yes, the oxygen we breath is produced by seagrass and coral reefs in considerable amounts).
Who else is affected by the Sargassum?
Many living organisms are affected by the massive arrival of Sargassum.
Seagrasses need light to conduct photosynthesis, if big islands of Sargassum cover an extended area of seagrass, these will lack the sunlight and will not be able to produce oxygen which they normally release into the environment during the day, helping other organisms live (including me and you).
Seagrasses are plants, during the day they produce oxygen, but during the night they consume oxygen (since there is no sunlight available to produce it), being covered over long periods of time (by a shade like the one Sargassum islands create near the coast) will create a “night” environment where seagrasses only consume the oxygen to live -day or night- therefore altering the natural process of oxygen production. This, together with the bacteria involved in the decomposition of Sargassum will cause the depletion of all oxygen available in the water and the seagrasses will die along other organisms. When an environment lacks of oxygen, it is called apoxic. This is also a very smelly phase and if you’ve been in the Caribbean recently you will remember a stinky smell if you walk near the beach.
But, what about the fish?
Fish and other marine organisms are able to flee (in most cases). As the environment becomes hypoxic (low oxygen levels) or anoxic (no oxygen at all) animals move to healthier parts of the reef lagoon or the reef. But many organisms, such as seagrasses cannot just pack up and leave. Therefore, they die. Entire seagrass meadows have been swept dead due to the extended presence of Sargassum. But, who can live in a hypoxic environment then? Some algae live in more flexible conditions than seagrass, which is more sensitive to changes in the environment, and therefore can tolerate conditions like the ones the arrival or Sargassum produced, therefore it starts gaining territory in spots where seagrass decays at really fast rates.
So, what we would typically see, is that the seagrass, as its health deteriorates, gets “invaded” by the algae which will cover entire areas in a matter of days, and will suffocate the little chance it has to recover.
But, wait, why do we care about seagrass?
(I thought a dirty beach was already a big problem to deal with…)
When an excess of nutrients is put in an environment, such as in the seagrass meadows, the growth of the plants is altered. We know that Mexico has a less than optimal residual water management and we know for a fact that part of the residual waters of coastal communities, like Puerto Morelos, ends up in the ocean through filtration and leakages into the phreatic layer (because water in the Yucatan Peninsula is underground due to the porous ground which is mainly limestone).
Seagrass meadows are an essential link in the health of the ocean and the coral reef. They provide food, shelter, and a complete habitat for species that spend their life (or at least part of it) next to coral reefs.
When the Sargassum reaches the coast and accumulates near the beach, it starts decomposing, producing extremely high amounts of nitrogen and phosphor, these two elements are needed for many living organisms to thrive, in controlled amounts. These two elements are considered nutrients. However, the excessive arrival and decomposition of Sargassum increases the levels of nutrients that the living organisms can tolerate. We already know the levels of nitrogen and phosphor are considered high due to the gaps in residual water management, but scientists discovered that the arrival of Sargassum increased that amount even more, creating a crisis in the balance of an already fragile ecosystem.
Seagrass meadows are feeding grounds for turtles and manatees, they are also essential for many species of fish that are important for the economy (fisheries, tourism, etc.), and they are used by conch, rays, and other organisms during different stages of their life. If seagrass meadows are gone, all those other organisms will lack food, protection and a healthy environment to continue their functions within the chain, therefore disturbing food chains and altering its normal balance. Moreover, the economy can collapse as the fisheries and tourism rely on the health of the marine ecosystems (if there are no seagrass meadows there will be no more reef to snorkel at all!)
How long does it take to rehabilitate the seagrass meadows and reestablish that balance?
According to dr. Brigitta van Tussenbroek, it will take at least 10 years to rehabilitate these environments that has been affected due to the effects of Sargassum. It might take even longer, depending on the damage (up to 50 years), however the most worrying effect would be not to be able to recover them at all, meaning that if the seagrass is gone completely this might turn into a situation that has no return point. Knowing this puts your worries in perspective, most people talk about a crisis because tourists are unable to enjoy a white beach, just like the ones in the brochures, an aesthetic disturbance. But if we think about it, your 10 day holiday might be ruined due to the arrival of Sargassum. however…
In the Mexican Caribbean we might end up with 50 years of damage, if not permanent damage and loss of these incredibly rich and important habitats.
As dr. van Tussenbroek says: 4 years after the first massive arrival of Sargassum, we’re still in the beginning of this journey to understand what we can do about it, the problem has just started.
What else do we know about sargassum?
Sargassum can duplicate its biomass in about 18 days. Experiments were conducted where Sargassum was collected in an enclosure and was left floating, two weeks after, its weight accounted for twice of the initial amount.
Sargassum in the Caribbean DOES NOT come from the Sargassum sea, the journey of Sargassum has been studied and researched, and tracked back with satellite imaging and other technologies to the coasts of Brasil, where we now have a newly baptized “Small Sargassum Sea”. Sargassum travels north with the currents and is pushed by waves and wind, it enters the Great Caribbean then making its way to our coasts, and eventually, even crossing the Yucatan Channel into the Gulf of Mexico, that’s one long journey!
Scientists and government do not have enough data to make an accurate prediction about the future yet, but we know that the increase in Sargassum and other actual environmental issues are produced by the global changes we live in our times, namely global warming.
When Sargassum is a healthy environment floating in the column of water it is called Golden Tide, however after the later phenomenon in the Caribbean, it has been granted the less romantic name “Brown tide”.
Sargassum DOES NOT become sand, if that was the case we would have solved the beach erosion problem. Sand in the Caribbean is almost exclusively organic, crushed coral, shells and skeletons of other organisms become sand thanks to different processes. Sargassum does not have a link to the production of sand in the Caribbean.
Sargassum does not sting! However, some tiny organisms that live in the Sargassum may provoke a reaction or a rash, this does not come from the alga itself but from its passengers!
I hope I have answered some of the questions that you might have had regarding Sargassum. We’ve all had those questions and often we find it hard to get trustworthy information. The national university (UNAM) has a research station for marine sciences in Puerto Morelos since 1981, where they study Sargassum and its effects in our marine environment, especially on seagrass meadows. It was a pleasure to listen to Brigitta van Tussenbroek, one of their senior researchers, who has studied sea grasses since 1990 and to learn about her research and encouragement for government and industry to work towards integrative solutions and more importantly, anticipate and prepare to be resilient about these changes we experience.
El sargazo y el “síndrome blanco” son dos factores que están causando alta mortalidad de las colonias de coral del Arrecife Mesoamericano, sin que hasta la fecha se tengan protocolos o procedimientos para frenar los daños, manifestó la Dra. Claudia Padilla Souza, investigadora del Centro Regional de Investigación Acuícola y Pesquera Puerto Morelos.
Explicó que en el mar, el problema es que los sitios donde se da la afectación por sargazo hay una mortalidad muy alta de corales. Son áreas que después se tienen que intervenir con siembra para restituir su condición original, el problema es mayor en los arrecifes costeros, como el de Puerto Morelos.
Ahora tenemos la complicación del “síndrome blanco” que, en mi opinión, es consecuencia de un estrés en el que están los corales por muchas causas y ahora se incrementa por la presencia del sargazo, que rompe un umbral y por eso muestran procesos de enfermedades que anteriormente no tenían.
“El ´síndrome blanco´ es relativamente nuevo, no se sabe mucho del origen, el patógeno o el origen de la enfermedad y tampoco hay una cura o procedimiento para evitarlo”,explicó.
La entrevistada, quien tiene a cargo el proyecto de producción de corales y programas de restauración de arrecifes coralinos, señaló que ese programa empezó en 2009 con las primeras pruebas y sistemas de cultivo, a fin de producir los corales necesarios para su siembra en los sitios donde están deteriorados.
Con el proyecto han alcanzado una producción de 8 mil colonias de coral
Fue así como alcanzamos una producción de 8 mil colonias de coral de 8 diferentes especies y se trabajó también en la producción de “reclutas sexuales” para tener mayor diversidad genética de los organismos.
Sin embargo en cuanto al tema del sargazo, afecta directamente a los sistemas de cultivo porque se toma agua del mar para alimentarlos y, cuando hay presencia del alga , se torna turbia, con materia orgánica en descomposición que entra a los cultivos. Eso obligó a hacer modificaciones importantes en la infraestructura.
En el 2018 sembramos 3 mil 334 colonias en 1 mil 840 metros cuadrados y este año esperamos que la siembra y el área de intervención sea mucho mayor, prosiguió.
Ahorita trabajamos en 12 sitios de cuatro arrecifes, entre éstos el Parque Nacional Arrecifes de Puerto Morelos y el Parque Nacional Arrecife de Isla Mujeres y Punta Cancún.
MIAMI.- Para este año, la llegada de sargazo al Caribe será masivo, según pronostica la Universidad del Sur de la Florida. La situación podría ser similar a la de 2018 o tal vez aun peor, según las imágenes satelitales. “El último diciembre mostró una cobertura total de sargazo de 173 km2, en comparación con una media histórica de 59 km2 entre 2011 y 2017”, indica el informe.
“Estamos al tanto de las imágenes que sugieren que el sargazo estará en la región muy pronto -cuenta Hazel Oxenford, profesora de ecología marina para el centro de investigación de la Universidad de las Indias Occidentales en Barbados-. Dado que es un fenómeno nuevo, no conocemos sus estaciones todavía. No obstante, parecería que la zona de abarque se está expandiendo en tiempo y forma”, detalla.
Aun no hay explicación cierta del aumento. Una de las teorías lo atribuye a una nueva región de origen en el Ecuador donde las algas se forman, se consolidan y son periódicamente desprendidas. El patrón de retención o liberación varía de un año a otro y la cantidad de sargazo florece cuanto mayor es la temperatura del agua y los nutrientes. Los científicos aun no definen la explosión, pero la mayoría confirma que es consecuencia de la acción humana.
“El sargazo ha sido siempre un ecosistema marino en el Atlántico. En efecto, una enorme región de la parte oeste del océano se llama Mar Sargazo por la prominencia de algas”, explicó James W. Fourqurean de la Universidad de la Florida. De cualquier manera, en los últimos cinco años ha habido un enorme incremento que llega al Caribe que está lavando las costas y ha degradado playas y aguas costeras.
Industria y viajeros, en alerta
La industria hotelera ya está en alerta. Desde la Asociación de Hoteles de Cancún y Puerto Morelos surgió la iniciativa de lograr un compromiso con los 19 países del Caribe afectados y realizar un congreso donde se unifiquen esfuerzos para encontrar una solución. Hay quienes plantean usar embarcaciones que succionen el sargazo del mar y lo compacten, mientras otros se preocupan por evitar que se reproduzcan en altamar.
El año pasado, el estado mexicano de Quintana Roo, que alberga a Cancún, además de limpiar las playas, colocó barreras flotantes de contención. En Miami Beach y Fort Lauderdale, la ciudad limpió el exceso de sargazo con tractores y también lo mezclaba con la arena para hacerlo menos invasivo. Pero no se puede hacer a lo largo de toda la costa: hay lugares con alta densidad de huevos de tortuga que están protegidos.
Hazel cuenta que la mayoría de los países están formando planes de respuesta contra estas algas, si bien es difícil su recolección en el mar. “Por otro lado, generalmente no es recomendable debido a los beneficios ecológicos del sargazo en mar abierto”, explica.
Como respuesta a viajeros desconcertados, Christine Jimenez, francesa residente en Riviera Maya, creó la web www.sargassummonitoring.com. Gracias a sus mapas, los turistas pueden ver y enviar fotos de las zonas impactadas. “Pedimos que especifiquen fecha precisa y locación para proveer información confiable. El trabajo lleva tiempo, pero creemos que la gente ahorra mucho dinero para costear un viaje y no queremos que se desilusionen al llegar”, dice.
Jimenez asegura que gran cantidad de sargazo impactará en el Caribe y México. “Dado que no todas las algas están bloqueadas por las islas del Caribe podemos confirmar que llegarán a la Riviera Maya en algunos días. No podemos dar fecha exacta dado que depende de los vientos y las corrientes”, explica.
El programa de investigación SEAS ( www.seas-forecast.com) también ofrece información útil a quien esté pensando en visitar las playas cálidas. Creado en Texas, desde 2017 abarca a toda la zona del Caribe. En la web hay imágenes satelitales y pronóstico de la llegada de algas a las costas.
Possibility very high that large masses of sargassum currently in the Atlantic will find their way to the state’s beaches
Monday, January 14, 2019
Large quantities of sargassum are again likely to wash up on the beaches of Mexico’s Caribbean coast in 2019, according to an ocean researcher from the National Autonomous University (UNAM).
Brigitta Ine van Tussenbroek, a scientist at the university’s Institute of Marine Sciences and Limnology, said that satellite images from the University of Florida show that there are currently large floating masses of the brown seaweed in the Atlantic Ocean between southern Africa and Brazil.
The coast of Quintana Roo at Chetumal, Tulum or Cancún could all be affected, van Tussenbroek said, although she explained that more detailed monitoring and modeling is needed to say with confidence which beaches would see large amounts of sargassum.
“If it’s in open ocean, the possibility of it arriving on the Mexican coast is very high although it depends on local atmospheric conditions, like trade winds, that carry sargassum to our beaches,” she said.
Van Tussenbroek warned that if the seaweed arrives in quantities similar to those seen last year, the impact on local ecosystems and tourism will be severe.
In 2018, tourism declined in some parts of coastal Quintana Roo due to the presence of unsightly and smelly sargassum on beaches that draw visitors because of their usually pristine white sand.
Van Tussenbroek said that authorities at all levels of government need to work together to establish efficient and environmentally-friendly methods with which to collect sargassum before it reaches the coastline.
“In Quintana Roo, the tourism sector is extremely worried and actively participates . . in the mitigation [of the problem] but [the response] should reach another level, go beyond local action,” she said.
The scientist added that her suggestion is to “establish a state or national coordinating body, [that is] specifically dedicated to effective [sargassum] mitigation.”
Floating sargassum barriers were installed off some sections of Quintana Roo’s coast last year to prevent the seaweed from arriving on shore but authorities and citizens were still required to dedicate thousands of hours to clean the state’s beaches.
An unexplained invasion of Sargassum seaweed has been taking place on the coasts of Caribbean countries in recent years. Areas affected by the seaweed invasion include Barbados, Guadeloupe, Martinique, Puerto Rico, Saint Lucia, and Saint Martin.1, 2 The presence of this brown algae represents not only an environmental and economic disaster but a real threat to human health. After 48 h on the seashore, large amounts of toxic gas are produced through matter decomposition, including hydrogen sulphide and ammonia.3 The effects on humans of exposure to high concentrations of hydrogen sulphide have been described 4, 5, 6 and are of mounting severity with increasing concentration, leading to potentially fatal hypoxic pulmonary, neurological, and cardiovascular lesions. Although less documented, subchronic and chronic exposures can cause conjunctival and upper airway irritation, headaches, vestibular syndrome, memory loss, and modification of learning abilities. In the absence of any available specific treatment, management of hydrogen sulphide intoxication relies on supportive care, and prevention relies on individual protection.
Between January and August, 2018, doctors in Guadeloupe reported more than 3341 cases, and doctors in Martinique reported more than 8061 cases of acute exposure,7 among which three patients were admitted to intensive care. The number of consultations related to the effects of chronic exposure is also increasing in the local population. To mitigate this emerging airborne poisoning outbreak, the French Government has already promised €10 million to supply equipment that can be used to remove the seaweed within 48 h, to monitor hydrogen sulphide concentrations on the affected shores, to train doctors, and to assign experts in toxicology in affected areas. Despite this commendable first effort by the French Government, a mitigation plan to address this enigmatic Sargassum invasion should urgently be discussed at an international level to boost marine research, pool resources, and consolidate local political priorities.
We declare no competing interests. Written on behalf of the Research Group on Sargassum in Martinique.
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.
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.
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.
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.
Algues rouges et sargasses, une vengeance de la nature!
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. »
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. »