In Guadeloupe, ‘massive’ death of black sea urchins worries scientists

Posted on Saturday 06 August 2022 at 09:23

In Guadeloupe, scholars’ concern is growing. “Two to three months ago, we witnessed a rapid and massive death of the sea urchin population of the corona,” explains Malika Rene Troelvaux, a biologist at the University of the West Indies.

An epidemic epidemic of black sea urchins, with very tall and fragile tops, was reported in the turquoise waters of all Caribbean islands.

With other partners such as the State or Ifremer (French Research Institute for the Exploitation of the Sea), the University’s Biobiology Laboratory and Aquatic Ecosystems (Borea) Unit have alerted as they prepare to launch a “sampling campaign” to try to identify the evil that plagues “sea urchins”.

It is an understatement to say that scientists were surprised by this wave of deaths: none of them were able to notice the early signs of the disease.

The rescue company called for any useful information to be shared via a website to help survey the condition of the various sites, and spearfishing enthusiasts confirm their surprise.

“It started at the Fery site, toward Deshaies (north of Basse-Terre, editor’s note) before descending toward Côte Sous-le-Vent,” says Elise Germain, submarine and employee of the Anse Caraïbe Plongée Club, to whom “the massacre was impressive. One week we saw sea urchins go from their normal state to their corpse state with their spines spread out on the ground.”

According to field comments obtained by scholars, not all sites are involved in Guadeloupe. However, the disease is a serious concern to the scientific community.

Not sought after by fishermen, “sea urchins have an important role in the balance of coral reefs,” notes Malika René Troilevaux.

“These are herbivorous animals involved in regulating marine algal blooms,” she adds, “along with other herbivorous fish such as catfish or parrotfish that live in the coral areas around the islands and are also threatened, particularly by fishing.”

According to a report by Ifrecor (French Initiative for Coral Reefs) published in 2021 on the health of coral reefs in French overseas territories, algae that develop “enter competition with corals and reduce their coral-recruiting capacity”, that is, the potential for regeneration.

– Back in the 80s –

According to several studies, the reefs of the Antilles are generally in poor condition. “It is estimated that there are still 20-30% of live corals in our area,” confirms Malika Rene Troilvo.

They are subject to many pressures: global warming that raises water temperature, ocean acidification, which is responsible for the bleaching phenomenon, and human-caused ones.

In Guadeloupe, another problem was added to the tourist pressure, the problem of sewage treatment.

According to the latest report by the Water Bureau, only five of the 17 sewage treatment and collective sewage plants complied with the standards imposed by the state.

And “some scientists explain that the discharge standards for nitrate and phosphate, decided by the European Union in particular, are not adapted to our waters because the thresholds are too high,” notes Mallika René Troelvaux.

This discovery fuels part of the scientific community’s concerns about the evil that plagues sea urchins.

In the 1980s, a similar wave of deaths hit sea urchin colonies (93% deaths) before gradually disappearing. “Except that pressures have increased since then,” warned Ms. Rene Trofilo, and “at the moment, we don’t know how the entire ecosystem will react.”

A sampling campaign should be launched soon to try to determine the causes of this wave of deaths.

Already in 2020, Guadeloupe National Park has warned of another disease, possibly of bacterial origin, discovered in Florida since 2014, that has infected coral reefs in the wake of the bleaching episode.

Since then, state services have recommended all diving clubs not touch the reefs and disinfect equipment because the disease can spread through contact.

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