November 14, 2023

SEA MENACE: A North Atlantic Environmental and Economic Crisis By Jenny Latchman-Atkins,
14 November 2023


When we think of paradise, we often transport ourselves to a tropical island. A book in one hand and a cocktail in the other while kicking back on a white sandy beach, inhaling the warm salty air, and listening to the rhythmic musings of the beautiful blue ocean. Islands in the Caribbean Sea, the Quintana Roo coastline in Mexico, and popular beaches along the Florida coast historically have earned the title of paradise”.


Along with breathtaking beaches, this region boasts some of the most biologically rich marine environments in the North Atlantic Ocean, which includes extensive coral reefs, mangroves, seagrasses, and thousands of species of fish and marine mammals. Each year, millions of visitors descend with the dream of enjoying a pristine environment ripe for rest, relaxation, and recreational sports such as sailing, fishing, snorkeling, and diving. However, since 2011, these precious coastal regions have come under threat from a 20-ton sea menace!




First noted by Christopher Columbus in 1492, the Sargasso Sea is the largest region of the North Atlantic Ocean, with an area of about 3.5 million km2. Sargassum, a brown pelagic macroalgae, or seaweed, has historically thrived in healthy quantities in the Sargasso Sea. It has provided critical support for a myriad of commercially viable, endangered and endemic marine species such as whales, sea turtles, frogfish, shrimp, tuna, swordfish and marlin. With a vibrant ecosystem, and an array of flora and fauna, the Sargasso Sea has been referred to as the “Golden Rainforest”.  Because of its important biodiversity, the Sargasso Sea is protected by the Hamilton Declaration and overseen by the Sargasso Sea Commission.


To the bewilderment of everyone, in 2011 satellite imagery from NASA showed an explosion of sargassum growth in a new southern geographical location, creating what is widely referred to as, the Great Atlantic Sargassum Belt, or the GASB. Floating more than 5,000 miles from the west coast of Africa through the Caribbean Sea and into the Gulf of Mexico, the GASB is the largest and reportedly the most harmful algal bloom on the planet! Experts predict that during its most fertile months, the GASB contains an average of 20 million tons of toxic matter and it has caused a range of environmental, economic, and social problems, with implications for coastal communities, tourism, and marine ecology.



While the exact culminating factors that spurred the initial development of the GASB remain a subject for discussion, contributing factors that aid in the continued

proliferation of sargassum have been identified as:

  • Nutrient Influx:

○ Agricultural runoff from the Congo, Amazon, Orinoco and Mississippi rivers.

○ Dust from the Saharan Desert.

○ Upwelling of nutrient dense water from the deep sea.

  • Changes in natural ocean currents and wind patterns have pushed sargassum into areas where it was previously uncommon.
  • Climate change provides an abundance of sunshine and warmer ocean temperatures are thought to facilitate the rapid growth of sargassum.






The GASBs magnitude causes migratory interference for native and non-native fish populations. Fisherfolk may find their regular catch is no longer plentiful or available, while new varieties of fish and marine species may migrate into the area. Dr. Shelly-Ann Cox, Fisheries Officer, Barbados, notes that while there has been a decrease in flying fish and mature dolphin fish in Barbados, they’ve seen an increase in juvenile dolphin fish and small lobsters, which are normally uncommon. Floating sargassum mats block essential sunlight, which is necessary for the healthy growth and development of coral reefs, seagrass and sea moss beds, and mangrove forests. These reefs, beds, and forests not only help to shore up coastlines; they also provide habitats for a myriad of marine species and aid in capturing carbon from the atmosphere.


Arriving seemingly overnight and smothering beaches at an accelerated rate, sargassum’s arrival requires a rapid response as decomposition begins within approximately 48 hours of making landfall. As it decays, sargassum changes the pH level of the water at the shoreline. Dr. Brian LaPointe, Research Professor at Florida Atlantic University’s Harbor Branch Oceanographic Institute, has been studying the changes and states that the resulting nitrogen/phosphorus imbalance causes additional stress to coral reefs and can lead to coral bleaching. “Dead zones” where decomposing sargassum sucks oxygen from the water are also common, leaving native plants and marine life struggling to survive.


Sadly, it doesn’t stop there. Six of the seven sea turtle species are on the endangered species list and all are found in this region of the North Atlantic Ocean. Nesting sea turtles may have to travel miles to find a clean beach to lay their eggs, and incubating eggs are at risk of being crushed during beach clean-up. The sex of incubating sea turtles also may be altered, as sargassum strandings can change the temperature surrounding the eggs, a determining factor in the sex of the embryo. Once hatched, the journey out to sea and safety is thwarted. Hatchlings are at increased risk from sun exposure, disorientation, and predators, as they inchmeal across mounds of washed-up sargassum trying to make it to the ocean and safety.


Environment and Public Health

As the GASB makes its 5,000+ mile journey, it absorbs carbon dioxide from the atmosphere, and toxins and heavy metals such as lead, arsenic and cadmium from the ocean. This is a favorable side effect, but sadly, collected sargassum is then often dumped on land in deep landfills. Further research has to be done, but this common practice raises the question of whether the potential now exists for these toxins and heavy metals to seep into the local groundwater.

Dr. Brian LaPointe, Research Professor at Florida Atlantic University’s Harbor Branch Oceanographic Institute, works with several islands across the Caribbean. He shockingly states, “they have literally taken the beach to the dump”. This is not an exaggeration, heavy machinery, such as bulldozers, used over several years to remove sargassum, have caused extensive beach erosion. The loss of shorelines have lasting impacts to tourism, recreational activities and, of course, causes the natural loss of coastal habitats and can lead to flooding.


Arriving seemingly overnight and smothering beaches at an accelerated rate, grown men can almost get lost in it. Removal needs to take place rapidly as decomposition begins within approximately 48 hours of sargassum making landfall. As it rots, it releases hydrogen sulfide, which has the unmistakable stench of rotting eggs, ammonia and methane, which cause impacts to human health and adds to greenhouse gas emissions. Tourists and local residents have reported an increase in headaches, nausea, rash, upper respiratory irritation, sneezing and an inability to concentrate. Dr. Dabor Resiere, Intensive Care Unit, University Hospital of Martinique, has been the lead author of several papers citing the potential for even more serious medical conditions such as cardiovascular, ocular and neurocognitive symptoms with prolonged exposure to hydrogen sulfide and ammonia.


Local residents have also complained of mental health stresses, as they are plagued with insomnia and are no longer able to enjoy their natural resources. A family day at the beach is hampered by the fly-infested mass on the beach, the brown sludge at the shoreline, and the unmistakable stomach-turning stench. The corrosion of electrical appliances such as fridges, microwaves, AC units, and jewelry has also been reported and are attributed to the off-gassing of the decaying sargassum.

In 2015, the government of the Quintana Roo state of Mexico hired 5,000 day laborers, working in four-hour shifts, to remove seaweed from more than 100 miles of beach. In tourist-haven Cancun, workers raked approximately a half-million cubic feet of seaweed which amounted to more than 1,000 truckloads.



“The greatest single threat to the Caribbean economy I can imagine”, Hilary Beckles, Vice Chancellor, University of the West Indies said on the issue of the sargassum influx. According to the World Travel and Tourism Council’s 2019 report, the Caribbean is ranked as the most tourism-dependent region in the world, with eight out of the ten most tourism-dependent countries located there. In 2022, $37.5 billion was reportedly generated from tourism alone. Tourism is the lifeblood of the Caribbean, and with these statistics, it is not difficult to conclude that if tens of millions of visitors can no longer enjoy their vacations, over time, the potential exists for a massive loss in tourism revenue with far-reaching and potentially catastrophic results. On a local and much more personal level, fisherfolk will continue to experience a strain on their financial stability with:

  • Fewer overall days at sea.
  • Changes in available catch.
  • Difficulty getting their boats through the sargassum mats.
  • Increasing cost of repair to their boats and fishing gear because of sargassum damage.


Research is being conducted by the educational and scientific community, and a few private-sector companies are racing to develop solutions for valorization and mitigation.

Solutions being discussed include:

  • Collect sargassum while it’s at sea. A costly endeavor, but one that mitigates beach erosion and several other issues associated with decomposing sargassum after it makes landfall. There are several companies that have developed specific boats or re-engineered fishing boats for open-sea sargassum collection.
  • Remove sargassum from beaches by hand with rakes and carts, which reduces beach erosion and protects coastal ecosystems. This also provides employment opportunities for local residents.
  • Remove harmful nutrients, then sink sargassum deep into the ocean. This sequesters carbon in the deep sea for hundreds, if not thousands of years. However, this also leaves questions about how this practice might impact the deep sea over the long run.
  • Develop safe and sustainable onshore methods for storage and disposal.
  • Valorize sargassum by repurposing it for industrial or cottage industry use, i.e. biofuel, plastics, fertilizer, paper, and construction materials, such as bricks.
  • Fund further research into the true root cause of the phenomenon to better understand the threat.
  • Engage and hold accountable specific countries and entities whose practices aid in the development of the GASB.
  • Anchor mesh barriers offshore to prevent sargassum from reaching the beaches, thus allowing safe collection out at sea.
  • Implement wide use of SaWS – Sargassum Warning System, a system using data from NASA and developed by one of sargassum’s leading researchers, Dr. Chuanmin Hu, Professor, University of South Florida, to better prepare for major influxes.




Without doubt, this is a geo-political issue involving nations on the African and South American continents, the United States, Mexico, and independent Caribbean nations, as well as the Caribbean territories of countries of the European Union. Experts agree that the The Great Atlantic Sargassum Belt isn’t going anywhere for the foreseeable future. Therefore, innovation and financial aid to support sustainable clean up, disposal and repurposing efforts are vital to help preserve the region’s future and to avert further crisis. Of the seventeen SDGs established by the United Nations, the impact of the Great Atlantic Sargassum Belt relates to at least seven, and thankfully the UN is working through the UNEP and UNDP across the region on the issue, but more needs to be done.  It is critical that all stakeholders are engaged, these include:

  • International governments, including those involved with the G7, G20 and COP
  • Regional governments
  • Tourism industry
  • Scientific and educational communities
  • Environmental agencies
  • Private sector
  • Local residents

Ultimately, we are one interconnected and interdependent global community, and therefore a menace to one is a menace to all.



The author, Jenny Latchman-Atkins, is of Caribbean descent. She is passionate about exploring the effects of the Great Atlantic Sargassum Belt and has written a feature-length documentary, “Sea Menace”, to explore the four pillars of impact: Ecology, Environment, Public Health, and the Economy. Watch the Sea Menace Sizzle Reel to meet Jenny and hear more about the topic. To support the making of this film, don’t hesitate to get in touch with her directly at [email protected].