Concerned Scientists Investigate Sea Urchin Deaths in the Caribbean

SAN JUAN, Puerto Rico (AP) — Sea urchins are dying across the Caribbean at a rate scientists say could rival a mass die-off that last occurred in 1983, alarming many who warn the trend it could further decimate the region’s already fragile coral reefs.

Dive shops began reporting the deaths in February, stumping scientists and worrying government officials who are receiving a growing number of reports of sea urchin deaths from islands such as Antigua, St. Lucia, Dominica. , Jamaica, St. Vincent, Saba, and the US Virgin Islands, as well as Cozumel in Mexico.

“It’s very concerning, particularly because it’s happening so fast,” said Patricia Kramer, a marine biologist and program director for the Atlantic and Gulf Rapid Reef Assessment, a scientific collaboration to improve reef conditions in the region.

At first, the mortality event was related only to black sea urchins, diadema antillarum, which are recognizable by their extremely long and thin spines. But two other species have since been affected, including the rock-boring sea urchin and the West Indian sea egg.

The deaths worry Kramer and other scientists, including Dana Wusinich-Mendez, Atlantic-Caribbean team leader for the US National Oceanic and Atmospheric Administration’s coral reef conservation program: “Losing our sea urchins would be really devastating.”

The deaths are concerning because sea urchins are grazers known to be efficient herbivores that remove macroalgae from coral reefs and clear space for baby sea corals to attach, the two scientists said.

“They’re sort of the unsung heroes of the reefs because they do a lot of good things,” Kramer said.

While macroalgae are an important source of food and shelter for some fish, too much of them can degrade coral reefs that are under stress from warmer-than-average ocean temperatures and a disease known as stony coral tissue loss.

Overfishing in the Caribbean had already led to an increased abundance of macroalgae, which was kept in check by sea urchins that are now dying off, said Shamal Connell, an officer with the St. Vincent and the Grenadines Fisheries Service overseeing the research.

“It is very urgent that we find a solution,” he said.

The Florida-based Gulf and Caribbean Fisheries Institute and the Atlantic and Gulf Rapid Reef Assessment recently created a network to investigate deaths, analyze tissue samples and find solutions.

Kramer noted that very few black sea urchin populations recovered from the 1983 event that began in the Atlantic Ocean near the Panama Canal and spread north and then east over the next 13 months.

During that time, only black sea urchins were affected, with 90% or more of the population dying, albeit at a much slower rate than the current event, he said.

“Just when we’re getting to the point where they’re recovering, they’re dying,” Kramer said.

The island of St. Thomas, US Virgin, was the first to report the latest round of deaths in February, though it’s unclear if that’s where the event began.

In mid-March, the Dutch Caribbean island of Saba reported similar deaths, noting that 50% of the sea urchin population in its port died a week later. Saba authorities said they have about 200 sea urchins in a hatchery and are collecting information on the new mortality event, adding that they are treating some with antibiotics that could cure them or prevent them from getting sick.

Meanwhile, Monique Calderón, a fisheries biologist for the St. Lucian government, said scientists on the eastern Caribbean island are considering launching their own survey to get more details on where sea urchins are dying and why.

“When the last die-off occurred in the 1980s, the sampling that was done was not robust enough to determine what exactly was the problem, what could have caused it,” Calderón said, adding that he hopes to find an explanation with improved technology.

She said dive shops in St. Lucia and other Caribbean islands have reported seabeds littered with spines from sea urchins or sea urchins floating in the water when they are normally anchored to a reef through known hydraulic structures. like tube feet. Divers have also found dying sea urchins with fallen spines or with their white skeletons poking through their bodies.

The loss of sea urchins comes amid coral bleaching events as a result of high ocean temperatures and the presence of a disease known as stony coral tissue loss that has affected more than 30 coral species in almost two dozen Caribbean countries and territories, according to Atlantic. and the Gulf Rapid Reef Assessment program.

Coral reefs also provide protection from rising sea levels and storm surges generated by hurricanes that have become more powerful with global warming, and are a key attraction for a region that relies heavily on tourism.

“We are concerned that a true crisis is unfolding in the Caribbean,” the Diadema Response Network stated in a recent report on the loss of sea urchins.

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