Plague Decimating Sea Urchins
AAAS: “Mysterious sea urchin plague is spreading through the world’s oceans.” In late 2022 urchins began dying en masse at the Gulf of Aqaba’s northern terminus near Jordan. By April of 2023 the outbreak reached Egypt’s Sinai Peninsula. “It’s surreal and horrific,” says Bronstein, a marine biologist at Tel Aviv University. This deadly wave may soon threaten these spiny, slow-moving invertebrates globally. “In early 2022, the first reports of mass urchin mortality, in a species called Diadema antillarum, came from the Caribbean Sea.” Researchers have apparently identified the bacterial origin of the plague, ‘a scuticociliate, a single-celled animal with hairlike appendages called cilia and a track record of causing diseases in sharks, fishes, and crustaceans.’ But never previously sea urchins. ‘When the disease first broke out in the Caribbean, “we were scratching our heads,” says Ian Hewson, an oceanographer at Cornell University who has studied diseases in sea stars and other marine animals.’ In the Red Sea, Bronstein’s team was able to identify the same scuticociliate seen in the Caribbean. “They also documented mass die-offs not just in Diadema urchins, but also in the closely related genus Echinothrix.” Without these key herbivores, corals can be smothered by overgrowths of algae blocking out the sunlight they need for survival. ‘If the same ecosystem shift were to occur around the world, the impacts to both reefs and the coastal communities that depend on them for livelihood could be massive, especially given the stress many reef ecosystems already face from overfishing and bleaching because of rising sea temperatures.’ If ship traffic constitutes a vector, testing ballast water could be a containment strategy. “In case the outbreak continues to spread out of control, Bronstein calls for maintaining urchins in captivity — quarantined, without seawater circulating directly from the ocean — in hopes of reintroducing the animals to affected habitats after the disease is gone.” Sea urchins may not be as cuddly as penguins + polar bears, but they are critical in littoral areas of the world ocean.
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