SAN JUAN, Puerto Rico (AP) — A record amount of seaweed is choking the Caribbean coast from Puerto Rico to Barbados as tons of brown algae kill wildlife, choke the tourism industry and release toxic gases.
More than 24 million tons of sargassum covered the Atlantic in June, up from 18.8 million tons in May, according to a monthly report published by the University of South Florida Optical Oceanography Laboratory, which marked “a new all-time record.”
July saw no decline in algae in the Caribbean Sea, said Chuanmin Hu, a professor of optical oceanography who is helping produce the reports.
“I was scared,” he remembers feeling when he saw the historic number for June. It noted that it was 20% higher than the previous record set in May 2018.
Hu compiled additional data for The Associated Press that showed sargassum levels for the eastern Caribbean at a near-record high this year, second only to those reported in July 2018. Levels in the northern Caribbean are at the third highest, after July of 2018 and July 2021, he said.
Scientists say more research is needed to determine why sargassum levels in the region are reaching new highs, but the United Nations Caribbean Environment Program says possible factors include rising water temperatures as a result of climate change and nitrogen fertilizers and sewage waste fueling algae blooms.
“This year has been the worst year on record,” said Lisa Krimsky, a Florida Sea Grant researcher and faculty member and regional water resources specialist at the University of Florida. “It’s absolutely devastating for the region.”
He said large masses of algae have a serious environmental impact, with decomposing algae altering water temperatures and pH balance, as well as leading to declines in seagrass, coral reef and sponge populations.
“They’re basically drowning,” Krimsky said.
The “gold tide” has also hit people hard.
The concentration of algae is so great in some areas of the eastern Caribbean that the French island of Guadeloupe issued a health warning in late July. He warned some communities of high levels of hydrogen sulphide coming from huge rotting kelp beds, which could affect people with respiratory problems, including asthma.
The Biden administration declared a federal emergency after the US Virgin Islands warned last month of “unusually high levels” of sargassum affecting water production at a desalination plant near St. Croix struggling to meet demand amid drought.
“We’re consuming as much as we can produce right now,” said Daryl Jaschen, director of the islands’ emergency management agency. “We are very concerned about this.”
In addition, the US Virgin Island power station relies on ultra-pure water from the desalination plant to reduce emissions monitored by the US Environmental Protection Agency. The loss of such water would force the government to use a type of diesel fuel that is more expensive and in limited supply, officials said.
Experts first noticed large amounts of sargassum in the Caribbean Sea in 2011 that Hu and other scientists believe were created by stronger than normal winds and currents. The problem has worsened as the masses multiply, fueled by nutrients and strong sunlight.
“In the tropical Atlantic, everything was right,” Hu said. “Everything grows fast.”
Sargassum in moderation helps purify water, absorb carbon dioxide and is an essential habitat for fish, turtles, shrimp, crabs and other creatures. But it’s bad for tourism, the economy and the environment when too much accumulates just offshore or on beaches.
A carpet of brown algae recently surrounded an uninhabited island near the French Caribbean territory of St. Martin that is popular with tourists, forcing officials to suspend ferry service and cancel kayaking and snorkeling tours. The normally translucent waters around Pinel Island turned into a brown mud.
“This is the worst we’ve ever seen for sure,” said Melody Rouveure, general manager of a tourism company in the Dutch territory of St. Maarten in the Caribbean, which shares an island with St. Martin. “Ruined my personal beach plans.”
On Union Island, which is part of St. Vincent and the Grenadines, the algae invasion has forced some resorts to close for up to five months in the past.
Masses of sargassum have also strangled the Caribbean fishing industry. It destroys boat engines and fishing gear, prevents fishermen from reaching their boats and fishing grounds, and leads to a reduction in the number of fish caught. Barbados has been hit particularly hard as flying fish make up 60% of the island’s annual catch, according to the University of the West Indies.
An overabundance of sargassum has been blamed for the recent deaths of thousands of fish on the French Caribbean island of Martinique. It also worries activists about the plight of endangered turtles, with some dying at sea entangled in kelp or unable to lay their eggs as the kelp mat covers the sand.
In the Cayman Islands, a thick mat of sargassum had prompted officials to begin a test program in which crews pumped more than 2,880 square feet (268 square meters) of the algae from the water. But on Tuesday, the government announced it was suspending evacuation efforts because the level of decay made it impossible.
“The sargassum stranding in North Sound is unlike any we have experienced before in terms of its location, weather conditions and scale,” officials said.
Other island nations have opted to use heavy machinery to remove the seaweed from the beach, but scientists warn it causes erosion and could destroy the nests of the endangered turtles.
Efforts are ongoing to use sargassum as a fertilizer, food, biofuel, construction material or pharmaceuticals, but many Caribbean islands cannot remove the huge amounts of algae because they struggle financially and have limited resources.
Governor Albert Bryan of the US Virgin Islands said he asked President Joe Biden to declare a state of emergency for the entire tri-island territory, not just St. Croix, but that did not happen. Brian said he’s now trying to find local resources to clean up the beaches, “but a lot of things need money right now.”
Since 2011, large quantities of sargassum have invaded the Caribbean every year except 2013 – an anomaly that scientists believe may have been caused by a lack of nutrients and a change in wind strength and direction. And the record amounts reported in recent years are even more worrying for scientists and island governments.
“We don’t know if this is a new normal,” Krimsky said. “This has been devastating for over a decade.”