“Increasing Pollution and Climate Change Fuel Explosive Growth of Sargassum Seaweed”

A recent study reveals that the rapid growth of sargassum seaweed in the Caribbean Sea and West Africa is due to increased nutrient pollution and warming seas. These floating algae build-ups obstruct fishing boats, harm tourism, disturb turtle nesting sites, reefs, and mangroves, and emit harmful gases that can damage human health and electrical equipment.

The research, conducted by teams from the Universities of York and Southampton in the UK, along with the University of the West Indies in Jamaica and Barbados, examined the composition of sargassum biomass to explore its potential for creating sustainable products. Despite being a plentiful biomass, the seaweed's high arsenic content limits its potential uses.

Dr. Carla Machado, the study's lead author, noted that while small amounts of sargassum washing ashore in the Caribbean once provided a habitat for turtles, crabs, and fish, and contributed to beach formation, the massive sargassum blooms of the past decade are a growing global problem with significant impacts on affected countries.

The project brought together international experts in biomass composition and satellite imaging to track, sample, and study the sargassum, offering new insights about this macroalgae. For biomass to be usable, it needs to have a consistent composition, which ensures efficient and predictable processing. The study found that the biochemical composition of the sargassum remains constant throughout the year.

Researchers tested various processing methods, such as shade drying or freezing, and found that the protein content remained the same. However, the processing method did impact the levels of other components, like alginate, which has multiple applications, including in biomaterials.

Sargassum samples were collected in Jamaica throughout 2021, coinciding with the eruption of La Soufrière in St. Vincent in April 2021. Using drift patterns, the researchers estimated that the samples collected in August 2021 would have been exposed to volcanic ash for about 50 days. They found that the algae exposed to volcanic ash contained less arsenic but had accumulated other elements such as nickel and zinc.

Dr. Thierry Tonon, from the University of York, emphasized the importance of understanding how sargassum responds to environmental conditions to uncover its biology and potential value. He pointed out that the sargassum belt also receives additional nutrients from Sahara dust blowing across the Atlantic, suggesting that large amounts of seaweed washing up on shores could become a regular occurrence.

The researchers stressed the need for further investigation into sargassum and its behavior in the future. This could provide evidence to guide an international response to the challenges it presents to people and the environment and potentially transform it into a useful resource. Professor Robert Marsh from the University of Southampton noted that the sargassum stranded around Jamaica in late summer 2021 carried distinct traces of volcanic ash from four months earlier, confirming that the sargassum reaches Jamaican beaches each summer after a months-long journey adrift in the central tropical Atlantic.