By: Staff Writer
May 9, 2025
The University of South Florida in a new report said that the levels of sargassum doubled in the Caribbean in just a month, signifying that the problem is becoming endemic to the region.
The report, which is the Outlook of 2025 Sargassum Blooms, said: “As predicted one month ago, total Sargassum amount in the tropical Atlantic (both western Atlantic and eastern Atlantic) continued to increase from December to January, and remained negligible or very low in the Gulf of Mexico and western Caribbean Sea. Increased amount was also found in the eastern Caribbean Sea but total amount still remained low (~ 0.1 million metric tons). The spatial distributions in the tropical Atlantic remained stable but total amount nearly doubled in a month, suggesting local growth. Compared to most previous years since 2011, Sargassum amount in the western Atlantic and eastern Atlantic all exceeded each region’s 75 percentile. More Sargassum entered the Caribbean Sea through the Lesser Antilles.”
Sargassum is now a major problem for the Caribbean which has impacted the tourist experience for visitors of islands affected and also has created a significant environmental problem due to the difficulty in cleaning up the local beaches from sargassum.
While, historically, the majority of Sargassum was located in the Sargasso Sea in the western North Atlantic, it is now originating from within the Caribbean sea.
Brian Barnes, Ph.D., an assistant research professor at the USF, provided the Source with more information about the large amount of sargassum and its potential effects on the U.S. Virgin Islands. Barnes emphasizes that more research is needed to understand the cause of the increase.
“Unfortunately, we do not have a good explanation for the significant increase of sargassum as the (report) states; this is an active area of investigation,” Barnes acknowledged. “In a broad sense, whenever a seed population meets appropriate conditions for growth, (such as the) temperature, nutrients, light regime, etc., there can be rapid biomass expansion,” Barnes explained. “This appears to be happening now in the eastern Caribbean, but the exact confluence of environmental factors is unknown,” he said.
Barnes noted that another area of ongoing research is the potential connection between cyclone development and the abundance of sargassum, including how factors such as ocean conditions and atmospheric changes might influence the amount of sargassum in the ocean.
“This is an active topic of research,” Barnes said. “Following previous hurricanes, we’ve seen both increases and decreases in sargassum abundance,” he added.
Although there has been a significant surge in sargassum, Barnes stated that much of the seaweed is currently not having a substantial impact on the U.S. Virgin Islands. However, that may change soon.