Beach-clogging sargassum doesn't have to go to landfills. It can enrich soils
Sargassum accumulates on the beach near Root Trail in Palm Beach. Megan Maccrthy/Palm Beach Daily News
July 7, 2025
The Great Atlantic Sargassum Belt, a thick mass of leafy, floating seaweed stretching across 5,000 miles of ocean, is forecast to be a nuisance of record-breaking proportions this year.
In May, scientists at the University of South Florida observed more than 37 million metric tons of sargassum in the Caribbean Sea, Atlantic Ocean, and Gulf of Mexico, and it’s coming our way, already washing ashore on Caribbean and U.S. beaches, including Palm Beach.
Sargassum contains high levels of arsenic and heavy metals, organic contaminants and marine debris, all environmental health hazards. When it dries, it releases hydrogen sulfide, a gas that smells like rotten eggs and which can cause respiratory problems. Now, finally, a West Palm Beach company has discovered how to remove these pollutants and turn sargassum into high quality organic fertilizer and other environmentally regenerative products.
Saegassum accumulates on the shore at Midtown Beach in Palm Beach on April 25. Meghan Maccarthy/Palm Beach Daily News
Sargassum is a golden-to-reddish brown seaweed, a large macroalgae that forms enormous mats atop the ocean’s currents. Unlike other seaweeds, such as the kelp that’s anchored to the shallow ocean floor, sargassum is a rich, free-floating ecosystem providing habitat, food resources, protection, and breeding grounds to hundreds of marine species. The leaflike blades of algae contain small berry-like air bladders called pneumatocysts that are filled with oxygen and act as mini-buoys to keep the mats afloat.
Much of it can be found in the western Atlantic’s Sargasso Sea, where it’s such an important ocean habitat to so many marine creatures that it’s been labeled the “golden floating rain forest." Important commercial fisheries species that rely on sargassum include gray triggerfish, amberjack, and mahi mahi, all of whom feed on the smaller marine life present in sargassum mats.
Juvenile sea turtles and sea birds use sargassum for feeding and shelter and in the South Atlantic and portions of the Gulf of Mexico, sargassum is designated as critical habitat for threatened loggerhead sea turtles under the Endangered Species Act. Indeed, nine species of endangered fish can survive only in sargassum.
But when sargassum is carried ashore by wind and ocean currents, the picture changes dramatically. Massive brown tides nearshore smother flora and fauna, including mangroves and ocean reefs, disastrously impacting coastal ecosystems. As its high levels of arsenic and other heavy metal contaminants dry and decompose on beaches, hydrogen sulfide is emitted, which can cause respiratory irritation. Tiny sea creatures and jellyfish also live in sargassum and can irritate skin. Additionally, sargassum mats may clog water intake pipes used in critical infrastructure such as desalination plants that produce drinking water.
Sargassum carried ashore by wind and sea currents at Midtown Beach in April can contain heavy metals and other contaminants. Meghan MacCarthy/Palm Beach Daily News.
Sargassum has existed for 30 million years, but dangerous inundation events of massive-sized algal blooms were first seen in 2011, fueled by land-based pollution and excess fertilizer loaded with nitrogen-rich chemicals. When these chemicals leach into rivers and aquifers they end up in the ocean where they boost growth of aquatic plants. The dramatic deforestation of the Amazon River basin and subsequent commercial farming there is considered a major factor in the increase in sargassum off the coast off west Africa.
The inundation on our beaches is disastrous for beachgoers, who cannot navigate the often ankle-to-knee-deep amounts of seaweed on the sand. Seaside businesses have had to close throughout the Caribbean, and fishermen also are affected, as fish leave the region and nets return full of dense algae.
These increasingly frequent bloom events are now referred to collectively as the Great Atlantic Sargassum Belt. The 2018 belt was the largest to date, with a biomass of more than 20 million tons. In just hours, some bays were overwhelmed with tens to hundreds of thousands of tons of sargassum. That year, beaches from French Guiana and Trinidad to Mexico and Florida were inundated.
By 2022, the sargassum belt had expanded even further, reaching 22 million tons. There is no clear forecast for how large or frequent these events may become in the future.
Inundation of sargassum, like this one in the beach near Root Trail in April, are becoming increasingly frequent, and there is no clear forecast fro how often they may occur. Meghan MacCarthy/Palm Beach Daily News.
Perhaps most alarmingly, sargassum absorbs such large quantities of arsenic and heavy metals from the ocean that, once beached, it is designated a hazardous waste and must be either buried, which is dangerous to marine animals, or carried off to landfills, where it releases vast amounts of methane and leaches arsenic into the soil. This removal has cost upwards of tens of millions of dollars.
Now enter Seaweed Greens, a small company in West Palm Beach that has discovered how to remove the arsenic and heavy metals from sargassum to create organic fertilizer, peat and excellent soil amendments. Simply put, this is the world’s first regenerative sargassum industry. They have developed a proprietary washing and bioreactor system that cleans sargassum of sand, salt and plastic, then detoxifies it by removing arsenic and heavy metals.
Specialized microbes are used to break down the seaweed, which is then processed into high-performance safe and organic agricultural products. This is a huge win/win in every possible scenario. The sargassum clogging our beaches, now listed as a toxic coastal biohazard, is no longer hauled to landfills where it releases methane and more arsenic; it is taken to the plant in West Palm where it is cleaned and processed, helping to restore coastal and marine ecosystems.
Seaweed Greens of West Palm Beach has developed a soil amendment made from refined seaweed that restores soil health with micro-nutrients that stimulates plant root growth. Provided By Seaweed Greens.
Seaweed Greens has developed a line of initial products:
∎ Pure: a soil amendment made from refined seaweed that restores soil health by introducing essential micro-nutrients that stimulate plant root growth. This is perfect for gardens, farms, golf courses and landscapes.
∎ Atlantic Peat: We cannot continue depleting our Everglades of its essential peat reserves. This sustainable peat alternative improves soil texture, boosts microbes, increases water retention, and supports root growth. Great for potting soil, compost, and as a top dressing.
∎ Plus 4: Balanced Fertilizer. This liquid fertilizer 4-0-2 made with sea minerals supports lush foliage, bright flowers and strong roots. Excellent on lawns, vegetable and flower gardens.
∎ Plus 8: Professional Fertilizer. This stronger-formula 8-0-3 is for commercial use, bosting root strength, drought resistance, and nutrient absorption. For farm and larger landscape use.
∎ Organic Pesticide. This natural pest control is made from seaweed extract and lactose bacteria, a byproduct of the cleaning process. It is totally safe for people and pets and ideal for gardens, farms and eco-friendly spaces.
Seaweed Greens aim to turn Sargassum, a growing marine hazard, into an environmentally friendly product. It uses for sargassum could help reduce landfill waste and pollution and protecting coastal ecosystems. Provided By Seaweed Greens.
Seaweed Greens is endeavoring to turn one of the world’s fastest-growing marine hazards into regenerative, earth-friendly products. Their model reduces landfill waste and pollution while supporting soil restoration, sustainable agriculture, and the protection of coastal ecosystems. They have launched a pilot program in West Palm Beach that processes 20 tons of sargassum daily. Additionally, they are offering a Sargassum Solutions Consultancy for communities across the United States and around the world to establish similar processing plants.
-Kim Frisbie
Original article on the Palm Beach Daily News is HERE.