Scientists Advancing Knowledge of Sargassum

Seagriculture EU 2024

Large patches of Sargassum adrift near the island of Saint Martin. Photo: Vely Michel 2018

The stranded seaweed blocks fishing boats; threatens tourism; disrupts turtle nesting sites, reefs, and mangroves, and releases toxic gas, which impacts human health and damages electrical equipment.

First reported by Christopher Columbus in the 15th century, floating mats of sargassum have long been present in the North Atlantic. However, since 2011, a floating population has established between West Africa and South America and increased in size to form “the great Atlantic sargassum belt” — a 9,000km-long macroalgal bloom, visible from space and estimated to weigh 35 million tons. 

The massive blooms of sargassum are thought to be caused by nutrient pollution and warming seas, and vast quantities of the seaweed end up in landfills each year.

Unlocking its potential

The research team, from the Universities of York and Southampton, alongside colleagues from the University of the West Indies in Jamaica and Barbados, set out to learn more about sargassum’s biomass composition to unlock its potential to be used to produce sustainable products. While the seaweed is an abundant biomass, its possible uses are limited due to its high arsenic content.

“The small quantities of sargassum that used to wash ashore in the Caribbean provided a habitat for turtles, crabs and fish and contributed to beach formation as it decomposed,” said first author of the study Dr Carla Machado, a research associate in the Department of Biology.

“But the vast sargassum blooms of the past decade are a global problem that will continue to grow and have a major impact in the affected countries,” she said. “This research project has brought together international researchers specializing in biomass composition and satellite imaging to track, sample and study sargassum, providing crucial new knowledge of this little-understood macroalgae.” 

Consistent composition

For a biomass to be utilized, it needs to be consistent in its composition; this ensures it can be processed efficiently and behave predictably during production. 

The results of the study showed that, overall, the biochemical composition of sargassum is consistent throughout the year. The researchers tested different processing methods for the seaweed, including shade-drying or freezing, and found the protein content of the seaweed stayed the same. However, the method of processing did affect levels of other components such as alginate, which can be processed for many applications, including biomaterials. 

New normal

Lead author of the study, Dr Thierry Tonon from the Department of Biology at the University of York said, “Understanding sargassum’s response to environmental conditions is crucial for unlocking its biology and potential value. With the great sargassum belt also receiving additional nutrients from Sahara dust that blows across the Atlantic, huge quantities of the seaweed washing up on coastlines looks set to become the new normal.”

“It is very important for Caribbean Islands being affected by the sargassum inundation to be able to benefit from its valorization,” said Professor Mona Webber, from the University of the West Indies. “Understanding how the sargassum we collect in Jamaica has changed en route to our shores and factors that could affect especially the arsenic content, will propel us towards safe use of the algal biomass.”

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Seagriculture USA 2024
Contact Phil Ganz



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