Researchers claim to have finally figured out what caused the ten-year epidemic that killed over 5 billion sea stars off the North American Pacific coast.
Often referred to as starfish, sea stars often have five limbs, while certain species can have up to 24. Their color spectrum includes tapestries of orange, purple, brown, and green as well as plain orange.
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Beginning in 2013, a major die-off from Mexico to Alaska was caused by an enigmatic sea star wasting sickness.Over 20 species have been wiped out by the disease, which is still going strong today. The sunflower sea star was the most severely affected species, losing around 90% of its population in the first five years of the outbreak.
Marine disease ecologist Alyssa Gehman of the Hakai Institute in British Columbia, Canada, who assisted in identifying the cause, described it as “really quite gruesome.”
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According to her, healthy sea stars have puffed limbs that protrude straight out. However, they develop sores due to the wasting sickness, and eventually, their arms fall off.
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A study that was published on Monday in the journal Nature Ecology and Evolution identifies the cause as bacteria that have also affected shellfish.
According to Rebecca Vega Thurber, a marine microbiologist at the University of California, Santa Barbara, who was not involved in the work, “the results answer a long-standing question about a very serious disease in the ocean.”
Following numerous false leads and detours, it took experts almost ten years to determine the disease’s source.
According to Melanie Prentice of the Hakai Institute, co-author of the current study, “early research suggested the cause might be a virus, but it turned out the densovirus that scientists initially focused on was actually a normal resident inside healthy sea stars and not associated with disease.”
Because researchers examined tissue samples of dead sea stars that no longer contained the body fluid around the organs, other attempts missed the real murderer.
However, the most recent study includes a thorough examination of this fluid, known as coelomic fluid, which is where the bacteria Vibrio pectenicida was discovered.
According to microbiologist Blake Ushijima of the University of North Carolina, Wilmington, who was not involved in the study, it is extremely difficult to determine the cause of so many environmental diseases, particularly underwater. He added that this team’s detective work was very important and intelligent.
Scientists have a higher chance of helping sea stars now that they understand the cause.
According to Prentice, scientists may now be able to determine which of the surviving sea stars are still healthy and decide whether to move them or breed them in captivity before relocating them to regions where practically all of the sunflower sea stars have disappeared.
Researchers might also investigate whether certain groups are naturally immune to the disease and whether probiotics or other treatments can increase immunity.
Researchers suggest that because healthy starfish eat surplus sea urchins, such recovery efforts are crucial for entire Pacific ecosystems, not just sea stars.
Despite their seemingly harmless appearance, sunflower sea stars consume nearly everything that inhabits the ocean floor, according to Gehman. They eat a lot of food.
Because there were fewer sea stars, the sea urchins, which they typically eat, multiplied rapidly. Within ten years, they devoured around 95% of Northern California’s kelp forests. Numerous creatures, including as fish, sea otters, and seals, rely on these kelp forests for both food and habitat.
Thurber likens the kelp forests to the ocean’s rainforests, and researchers believe the new discoveries will enable them to replenish sea star populations.
