Foul-smelling, unsightly mats of brown sargassum seaweed have swamped local beaches again this summer, prompting town officials to search for solutions to what is expected to be a recurring problem for years to come.
The sargassum assault has triggered complaints about the odor and concerns about the well-being of sea turtle hatchlings who can get tangled up in the thick and stringy seaweed while trying to make their way to the ocean.
The seaweed itself is not toxic but presents potential hazards to humans, pets and marine life once it reaches land, dries and begins to decompose. Tiny sea creatures that live in it can cause skin rashes and blisters. Rotting sargassum produces hydrogen sulfide gas, which smells like rotten eggs and can irritate the eyes, nose and throat.
For the first time, the Town of Palm Beach has won permission from state environmental authorities to bury a large concentration, several feet deep, of the seaweed on the far North End shore near the Palm Beach Inlet, Town Council President Margaret Zeidman said this week.
“There is a huge amount of [dried] sargassum on the far north beach,” she said. “It has been accumulating there for the last six weeks because of the [Palm Beach] inlet jetty. It gets trapped there.”
The town cleans its public beaches by raking the seaweed and burying when necessary. It cannot be hauled away without an environmental permit, according to Public Works Director Paul Brazil.
But Town Councilwoman Bobbie Lindsay said a more ambitious solution was needed to remove the large concentration of sargassum fouling the far north beach. Rob Weber, the town’s coastal manager, worked with the Florida Department of Environmental Protection and Florida Fish and Wildlife Conservation Commission to gain approval for a “pilot project” to bury the seaweed. The plan is up for consideration at Tuesday’s Town Council meeting.
A contractor would use heavy equipment to bury the sargassum in a deep trench or pit, and the town would monitor the area to make certain that sea turtle activity is not affected by the buried sargassum now or in the future, Zeidman said. If the project is approved, the next step could be to solicit construction bids and determine the cost.
The naturally occurring sargassum seaweed floats freely on the ocean surface, providing habitat for migratory marine animals, including sea turtles. But over the last decade, excessive amounts of it have washed up on beaches in the Caribbean and Florida. Ocean currents and wind direction dictate when it arrives here.
The problem is getting worse and will require a long-term solution, Lindsay said at the Aug. 9 council meeting. A record-setting 24 million tons of sargassum blanketed a large swath of the Atlantic Ocean this summer. It has smothered beaches in the Caribbean, threatening wildlife and tourism.
“Since 2018, it’s been a very serious problem,” Lindsay said. “This year, it’s all over our beaches. We need to decide what we are going to do about this because this may be the new normal every summer.”
Zeidman said the town has asked Brian Lapointe, a research professor and algae expert at Harbor Branch Oceanographic Institute, to help it better understand the problem and what can be done about it. Lapointe is expected to join Tuesday’s council meeting via a Zoom connection. The discussion is scheduled for 2 p.m.
Sargassum has occurred naturally for eons. But excessive blooms began showing up in 2011. Seven years later, NASA satellites revealed what was then the largest marine algae bloom on the planet: a sargassum belt that contained over 22 million tons of seaweed reaching 5,500 miles across the Atlantic Ocean to West Africa. Satellite images revealed abnormally high amounts in 2021 and again this year.
Florida’s coastal communities naturally want the ugly, smelly seaweed moved off their beautiful beaches. In an interview Wednesday, Lapointe said disposal of sargassum can present environmental concerns because it may contain relatively large levels of arsenic and cadmium, and it can also be contaminated with fecal coliform bacteria from human sewage that’s been dumped into the ocean.
Warmer climate, agriculture fuel the sargassum blooms
Lapointe said research shows the excessive blooms are caused by the growing nitrogen footprint caused by human activity, and by warming temperatures and Saharan dust clouds.
Like red tide and blue-green algae blooms, sargassum blooms are fed by nutrients – primarily nitrogen that comes from fertilizers that are primarily used to grow crops, Lapointe said.
The algae blooms thrive in warmer waters. Climate change also contributes to the sargassum blooms by turbo-charging the upwelling of nutrients from deep ocean waters to the surface of the Atlantic.
“We humans have more than doubled the amount of nitrogen on the planet since the 1980s,” Lapointe said. Nitrogen finds its way into the Atlantic Ocean through multiple sources, including the Amazon, Mississippi and Congo river basins, he said.
Researchers including Lapointe are attempting to obtain funds from the National Science Foundation to better understand the origin of the sargassum blooms. He said the problem may be traceable to deforestation of the watershed of the Congo River, resulting in an escalating flow of nitrogen through the massive African waterway and into the east Atlantic. Among the world’s great rivers, the Congo is second only to the Amazon in discharge volume.
“That has not been well studied at all,” Lapointe said. “We need research money. If we found [the origin of the problem] was largely due to the Congo River, we could perhaps start to clean up the river.”
A recent study projects that extreme rainfalls and changing weather patterns will boost the amount of nitrogen in U.S. rivers and other waterways by an average of 19 percent over the remainder of this century.
“Climate change is going to increase nitrogen runoff by 20 percent, even if every human on the planet disappeared tomorrow,” Lapointe said.
Zeidman suggested the town partner with Lapointe to develop a long-term plan that could involve a consortium of municipalities and agencies and that might find a use for the sargassum, provided tests showed it to be free of toxins such as arsenic. Other communities have tried options including plowing it under the sand; collecting and washing it for conversion into a natural fertilizer or mulch; and large-scale removal, which is labor-intensive and expensive.
“We will figure this out,” Zeidman said.