It weighs 20m tons, stretches from West Africa to the Gulf of Mexico and washes up beaches that create an unhappy stench. Now, researchers say that a large turn of brown seaweed can become an annual event.
Scientists say that the explosion in sargassum seaweed has only materialized in 2011. However, new research shows that it has appeared almost every year since then, forming the largest flower of macroalgae ever recorded. In addition, the tune band ̵
Scientists say seaweed can be a boon to marine wildlife, providing habitat for creatures, including fish and birds.
But it also causes problems. Thick mats can block sunlight while if large mats die and sink, it can prove fatal to marine life, including corals.
Tanget has also proved to be devastating to humans. Increasing amounts of dishwashers in tourist destinations, creating stinking masses that threaten the tourism industry and pose a threat to health. Last month, the Mexican state declared Quintana Roo an emergency over sargasum .
"There are good consequences and there are bad consequences," said Dr. Chuanmin Hu, co-author of the University of South Florida study. "Many people in the Caribbean are literally crying because their economy has suffered so much."
Writing in the journal Science, Hu and colleagues says that sargassum is far from unusual in the Atlantic: the sea mats that they say were first reported by Christopher Columbus gave the Sargasso Sea region in the North Atlantic its name. 19659002] However, the phenomenon of such a large amount of macro algae appears to be a recent development that was first shown in satellite data in 2011. While the discovery was exciting, there was a hitch. "The satellite used to study the flower ceased to function in 2012," Hu said.
Now, Hu and colleagues report the analysis of a 19-year record of another set of data from a satellite instrument that measures wavelengths of light reflected from the sea surface. They say, allow them to investigate how the flower has evolved and examine what the future holds.
The results show that between 2000 and 2010 there was little seaweed in the central Atlantic: most were found in the Gulf of Mexico and the Sargasso Sea.
But in 2011 a large flower arose and evolved in subsequent years in a large band – in 2018 it stretched 5,500 miles (8,850 km).
The researchers found the flower tops in the middle of the year and say data models suggest that it appears to evolve greatly from small populations of seaweed in the central Atlantic, with some contribution from West Africa.
"They are always there, but when the ocean conditions are right, they just develop into blooms, and then large amounts of sargassum are transported to the Caribbean," Hu said.
The trigger for the 2011 event seems to have been an adaptation of the circumstances with conducive sea surface temperatures and salinity that combine with an increase in nutrients – partly from upward movement of cool nutrient-rich water in the Eastern A tlantic and an increase in Amazon emissions. in previous years.
So far, 2019 also looks like a huge flower. "It's another record year," Hu said, adding that the frequent repeat of the Great Atlantic Sargassum Belt allows the phenomenon to be the new status quo. "We can't predict a few years, but we can predict the next decade in general," he said.
The view that the team says could be reinforced by the finding that rising levels of nutrients are flushed into the ocean via the Amazon in the spring and summer each year due to human activities, including deforestation and fertilization. The team reports that total fertilizer consumption in Brazil increased by 67% between 2011 and 2018.
But the team says they are still trying to identify the factors behind the flower. "I don't think we've completely solved the mystery," Hu said.