Record amount of seaweed is choking shores in the Caribbean

SAN JUAN, Puerto Rico (AP) — A record amount of seaweed is smothering Caribbean coasts 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 blanketed the Atlantic in June, up from 18.8 million tons in May, according to a monthly report published by the University of South Florida’s Optical Oceanography Lab that noted “a new historical record.”

July saw no decrease of algae in the Caribbean Sea, said Chuanmin Hu, an optical oceanography professor who helps produce the reports.

“I was scared,” he recalled feeling when he saw the historic number for June. He noted 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 their third highest, following July 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 a rise in water temperatures as a result of climate change and nitrogen-laden fertilizers and sewage waste fueling algae blooms.

“This year has been the worst year on record,” said Lisa Krimsky, a researcher and faculty member with Florida Sea Grant and a water resources regional specialized agent at University of Florida. “It is absolutely devastating for the region.”

She said large masses of seaweed have a severe environmental impact, with decaying algae altering water temperatures and the pH balance as well as leading to declines in seagrass, coral reef and sponge...