By Stephen Beech via SWNS
Seaweed clogging up the Caribbean could be used to produce sustainable goods, say scientists.
British researchers have been working to track the spread of sargassum which is wreaking environmental havoc as well as causing economic damage across the region.
The huge mass stranded seaweed blocks fishing boats, threatens tourism and disrupts turtle nesting sites, reefs and mangroves.
It also releases toxic gas which impacts human health as well as damaging electrical equipment.
First reported by Christopher Columbus in the 15th Century, floating mats of sargassum have long been present in the North Atlantic.
But since 2011, a giant floating mass has established between West Africa and South America, and increased in size to form “the great Atlantic sargassum belt” – a macroalgal bloom more than 5,000 miles long that is even visible from space and estimated to weigh 35 million tons.
Scientists believe the massive blooms of sargassum are thought to be down to nutrient pollution and warming seas.
Vast quantities of the seaweed end up in landfill each year as it becomes a global environmental issue.
Researchers from the Universities of York and Southampton, alongside colleagues from the University of the West Indies, set out to learn more about sargassum to unlock its potential to be used in the production of sustainable products.
But the seaweed’s possible uses are limited due to its high arsenic content.
Study first author Dr. Carla Machado said: “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.
“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.”
Dr. Machado, of York University, added: “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.”
She explained that for a biomass to be utilized, it needs to be “consistent” in its composition to ensures that it can be processed efficiently and behave predictably during production.
The results of the new study, published in the journal Proceedings of the National Academy of Sciences (PNAS), showed that, overall, the biochemical composition of sargassum is consistent throughout the year.
The research team tested different processing methods for the seaweed – including shade-drying or freezing – and found the protein content of the seaweed stayed the same.
But the method of processing did affect levels of other components such as alginate, which can be processed for many applications, including biomaterials.
The researchers collected samples of sargassum in Jamaica throughout 2021, which coincided with the April 2021 eruption of La Soufrière volcano on the Caribbean island of Saint Vincent.
Using drift patterns, the team calculated that the sargassum samples they collected in August 2021 would have spent around 50 days exposed to ash from the eruption.
They discovered that seaweed that had likely been in contact with volcanic ash contained less arsenic, but had accumulated other elements including nickel and zinc.
Lead author Dr. Thierry Tonon, also of York University, 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.”
The team say more work needs to be done to increase understanding about sargassum and how it is going to behave in future.
Dr. Robert Marsh, of the University of Southampton said: “The sargassum beaching around Jamaica in late summer 2021 carried distinct traces of the volcanic ash that settled upon it around four months earlier, just to the east of St Vincent.
“This novel ‘volcanic tag’ confirmed that sargassum arrives each summer at Jamaican beaches after a months-long journey drifting with currents from the central tropical Atlantic.”
Dr. Hazel Oxenford, from the University of the West Indies, said: “Volcanic ash collected in my garden from the St Vincent eruption was used to determine its chemical signature.
“Being able to detect those components in sargassum after it travelled more than 1,700 kilometers across the Caribbean to Jamaica was exciting.
“It confirmed our predicted transport pathway for sargassum, showed that the seaweed lives for at least four months and demonstrates the marine connectivity across the region.”
Professor Mona Webber, also from the University of the West Indies, added: “It is very important for Caribbean Islands being affected by the sargassum inundation to be able to benefit from its valorization.
“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.”
