Ed Gullekson / Science Development
Skin damage is the first sign that something is wrong. Then the limbs fall and the body breaks down, collapsing on itself, because it splits. After all, what was once a starfish is just a dragon on the ocean floor.
Since 2013, sea star waste has killed so many sea stars along the Pacific coast that scientists say it is the greatest epidemic of disease ever seen in wild marine animals. Where there were dozens of stars in the past, divers now report no one.
And while the epidemic itself is a naturally occurring (if particularly devastating) phenomenon, recently published studies show that climate change may have exacerbated the death of the disease.
"We think that warm water anomalies made this starfish more susceptible to a disease that was already there," says Joe Gaydoss, Davis SeaDoc Society, California University's science director, and one author today. in the magazine Science Development.
He and the co-authors analyzed the data collected by the divers and found that the divers were less likely to see the stars of the living sea when the water temperature was extremely high.
"To think that the warmer water temperature itself can cause the animals to get sick or make them more sensitive, it's like a two-punch," says Gaydos. "It's a little nervous."
Globally, sea surface temperatures have risen steadily as Earth heats up due to man-made climate change.
The study did not investigate why warmer water could make sea stars more sensitive to disease. The authors believe that relatively simple immune systems could be weaker when the sea stars become hot.
And the same scuba diving survey also confirms the previous finding that the massive descent of sea stars causes a cascade of other ecosystem changes. Marine weapons, which are usually caught by a starfish, are gradually increasing. Whole stones once covered with sea stars are now being looked at.
Peas eat kelp.
"We see these big urine barrels where the urine has gone through and eat all the kelp," says Gaydos. Kelp forests, such as tree forests, are a place where many different species live and feed.
"We have higher biodiversity if we have more kelp. So it's a cascade," he adds. "If you looked at the ground, it would be almost like deforestation."
It is not clear whether sea star populations will recover in the coming years. The results of the study published last year showed that some sea stars can survive the disease, hoping that the animals will return over time.