Jacksonville-area beachgoers may be noticing more conversation around sargassum this year, the floating brown seaweed that can pile up along shorelines across Florida during warmer months. But despite growing attention and improved tracking tools, scientists say predicting exactly how much sargassum will wash onto Northeast Florida beaches this summer remains difficult.
According to Matthieu Le Henaff, an oceanographer in the Physical Oceanography Division of NOAA’s Atlantic Oceanographic and Meteorological Laboratory, researchers can monitor large-scale sargassum movement across the Atlantic and Caribbean but forecasting exactly where and how much will come ashore is still a challenge.
Here’s what to know about sargassum and which tools to use to get a better sense of sargassum patterns across Northeast Florida beaches.
How to track sargassum conditions in Florida beaches near you
For residents and visitors trying to monitor conditions, experts recommend using online tracking resources such as the USF Sargassum Watch, Ocean Viewer, and the updated Sargassum Inundation Risk tool, which now provides daily estimates with improved detail and resolution.
While forecasts cannot pinpoint exactly which beaches will see the most sargassum, scientists say improved monitoring tools help communities better understand the broader movement of sargassum across the region.
Scientists cannot predict exact sargassum levels on Jacksonville Beaches. Here’s why
While tracking technology has improved, experts say there are still major limits to forecasting how much seaweed will actually wash ashore.
“It is currently not possible to predict the amount of Sargassum that is going to reach the coast during a given period of time,” Le Henaff explained. “The main reason is that this quantity results from a combination of complex processes that are difficult to predict individually. For example, weather forecasts beyond 7-10 days, let alone when combined.”
That uncertainty also makes it impossible to determine exactly which Northeast Florida beaches may see the largest buildup.
For the same reasons mentioned previously, it is not possible to identify which beach will be impacted, Le Henaff said.
That means conditions could vary from Jacksonville Beach to Neptune Beach, Ponte Vedra Beach, and St. Augustine, depending on winds, currents, and short-term weather patterns.
What factors are contributing to current sargassum levels across Florida?
The sargassum affecting Florida originates far beyond the state’s coastline. Scientists trace it back to what’s known as the Great Sargassum Belt, a massive stretch of floating seaweed extending from West Africa across the Atlantic into the Caribbean Sea and Gulf of Mexico.
“The Sargassum that impacts Florida coasts comes from the Gulf, and before that from the Caribbean Sea,” Le Henaff said. “It is part of the Great Sargassum Belt, which extends from West Africa to the Gulf, and which since 2011 has become the main location of Sargassum.”
Researchers are still studying why the belt dramatically expanded beginning in 2011, but Le Henaff said the region appears to provide especially favorable conditions for growth.
“Since this shift in 2011, the reason of which is still the topic of research, Sargassum appears to have found a favorable habitat — warm waters and the presence of nutrients — in which it thrives, leading to increasing quantities over the years,” he said.
Why does South Florida seem to get more sargassum than Jacksonville?
According to experts, ocean currents play a major role in determining which Florida beaches see heavier impacts.
The Loop Current carries sargassum through the Gulf of Mexico before becoming the Florida Current along the state’s southeast coast and eventually the Gulf Stream farther north. Winds then help push the seaweed toward shore.
That circulation pattern helps explain why South Florida often experiences heavier accumulations than parts of the Gulf Coast.
“Because of the wide West Florida Shelf, the Loop Current that transports most of the Sargassum flows at a significant distance from the Tampa Bay area, which limits the amount of Sargassum reaching Tampa and St. Pete,” Le Henaff said.
Meanwhile, Southeast Florida sits much closer to the seaweed currently carrying.
“On the other hand, the Florida Current flows really close to Fort Lauderdale and Miami, so Sargassum is often pushed to the shore in that area,” he explained.
How does Sargassum affect North Florida beaches differently compared to beaches farther south, such as Tampa, St. Pete, Palm Coast, Fort Lauderdale, and Miami?
Experts say Northeast Florida, including Jacksonville, Ponte Vedra and St. Augustine, is expected to see less sargassum than South Florida because the Gulf Stream sits farther offshore as the continental shelf widens.
“Going northward, the Florida Current/Gulf Stream is further away from the coastline as the continental shelf widens,” Le Henaff said. “So we can expect the amount of Sargassum reaching the coasts to be less than in the Miami area, but it can still be very significant.”
That means beaches across Northeast Florida could still experience periods of noticeable sargassum buildup this season, even if impacts are expected to be less severe and less consistent than those farther south.
Doris Alvarez is a Breaking and Trending Reporter for The Florida Times-Union. You can get all of Jacksonville’s best content directly in your inbox each weekday by signing up for the free Daily Briefing and News Alerts newsletters at jacksonville.com/newsletters.
This article originally appeared on Florida Times-Union: Sargassum tracker, patterns and impacts in Northeast Florida beaches
Reporting by Doris Alvarez Cea, Jacksonville Florida Times-Union / Florida Times-Union
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