Parasite Philaster Sends 5000 Sea Urchins Dead to France's Reunion Island Shores

Since July, 5,000 dead sea urchins have washed up on the shores of Reunion Island in France. Scientists believe this major die-off is being caused by the parasite philaster.

5,000 Dead Sea Urchins

The inexplicable death of thousands of sea urchins found stranded on the western shores of Reunion Island in the Seychelles has left scientists puzzled. Since July of this year, more than 5,000 urchins have washed up lifeless on the French island in the Indian Ocean. As they investigate the source of these mass deaths, scientists have put forward a theory attributing the phenomenon to a parasite that had previously caused extensive die-offs.

It could be caused by a parasite called a philaster, according to biologist Jean-Pascal Quod, as it was just discovered for the first time on the island.

According to Quod, the parasite philaster is the most likely explanation for this extra mortality. But they won't be able to confirm that this parasite is actually the main cause of these deaths until they have completed the molecular biology investigation.

Philaster Parasite

Although it was initially identified in or around Reunion Island, this parasite has surfaced in various locations worldwide, linking it to significant sea urchin die-offs in the Caribbean and along the Mediterranean coast of Israel. This parasite undermines the sea urchins' immune systems, resulting in the gradual loss of their spines and suction abilities, ultimately culminating in their demise.

According to Quod, this compromises the sea urchin's immunity by upsetting its physiological balance. They do not yet know how the parasite got to the island; it could have originated from microplastics, algae, or the emptying of boat water tanks but they know that there is no way to stop it. The sea urchins will need to adapt, according to Quod, who claimed that the only choice was to accept this pathology.

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Philaster in the US

A parasite has been responsible for the catastrophic impact on coral reefs and other marine ecosystems in the Caribbean Sea, leading to the demise of long-spined sea urchins. Long-spined sea urchins, scientifically known as Diadema antillarum, play a vital role as herbivores, curbing the proliferation of algae. Unchecked algae growth could otherwise outcompete corals for resources and space, smothering them in algae and depriving them of vital light, ultimately resulting in coral death.

The sea urchins are crucial to preserving coral health and ecosystem balance in the marine environment because they graze on algae.

The first diadema fatalities were noted in late January 2022 at St. Thomas, US Virgin Islands. By the end of March, the condition had spread to Jamaica, the Mexican Caribbean, and the Lesser Antilles. By June of last year, it had been found in Florida, Curacao, and the majority of the Greater Antilles.

Even though P. apodigitiformis infections are currently untreatable, Ian Hewson, a marine ecologist from Cornell University said that learning more about the parasite could help researchers develop methods for keeping Diadema sea urchins, which are being raised for rewilding efforts throughout the Caribbean, healthy.