In Guadeloupe, “massive” mortality of black sea urchins worries scientists

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AFP, published on Saturday, August 6, 2022 at 09:23 In Guadeloupe, the concern of scientists is increasing. “For two to three months, we have witnessed a rapid and massive die-off of diademed sea urchin populations,” explains Malika René-Trouillefou, a biologist at the University of the West Indies. Fragile peaks have been reported in the turquoise waters of all the Caribbean Islands With other partners such as the State or the Ifremer (French research institute for the exploitation of the sea), the laboratory of the Biology of the organisms unit and aquatic ecosystems (Borea) of the university has sounded the alarm and is preparing to launch a “sampling campaign” to try to identify the evil that affects these “sea urchins”. It is an understatement to say that scientists were surprised by this wave of deaths: none of them could observe the first signs of Help was requested to share any useful information through a website to help with the report of the state of the different places, spearfishing enthusiasts confirm their sudden. “It started at the site of Fery, towards Deshaies (north of Basse-Terre, NDLR) before going down towards the Côte Sous-le-Vent,” says Elise Germain, diver and employee of the Anse Caraïbe Plongée club, for who “the slaughter was dazzling. Within a week we saw how the sea urchins went from their normal state to a corpse state with their spines around, spread out on the ground.” According to field comments obtained by the scientists, not all places are affected in Guadeloupe. However, the disease is of great concern to the scientific community: not sought after by fishermen, “sea urchins play an important part in the balance of coral reefs”, observes Malika René- Trouillefou. “They are herbivores that participate in the regulation from the proliferation of seaweed,” he adds, “along with other herbivorous fish such as catfish or parrotfish that inhabit the coral areas around the islands and that are also threatened, particularly by fishing.” According to a report of Ifrecor (French Initiative). for Coral Reefs) published in 2021 on the health of corals in the French Overseas Territories, the algae that develop “enter into competition with corals and reduce their ability to recruit corals”, meaning the possibility to be renewed.- Prior to the 80s -According to various studies, the reefs of the Antilles are generally in poor condition. “It is estimated that there are still between 20 and 30% of living corals in our regions”, confirms Malika René-Trouillefou, responsible for the bleaching phenomenon, and those caused by man. In Guadeloupe, another problem has been added to the tourist pressure, that of sewage treatment. According to the latest report from the Water Office, only five of the 17 collective treatment and sanitation stations complied with the standards imposed by the State. And “some scientists explain that the discharge standards in terms of nitrates and phosphates, decided especially by the European Union, do not adapt to our waters because the thresholds are too high”, points out Malika René-Trouillefou. This finding feeds some of the fears of the scientific community. about the damage suffered by sea urchins, to gradually disappear. “Except that the pressures have increased since then,” warns Ms. René-Trouillefou, and “at the moment, we don’t know how the whole ecosystem will react.” A sampling campaign should be launched shortly to try to determine the causes of this wave of mortality. Already in 2020, the Guadalupe National Park had warned of the presence of another disease, probably of bacterial origin, detected in Florida since 2014, which had affected the coral following a bleaching episode. Since then, the State services have recommended to all diving clubs not to touch corals and to decontaminate the equipment because this disease can be spread by contact.
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