Sunday , February 28 2021

Disease, hot ocean water causing mass starfish death according to new study

VANCOUVER – Hot springs and infectious diseases have been identified as the cause of a sunflower starfish death along the Pacific coast, a new study finds.

Sunflower starfish are among the largest starfish in the world and come in a variety of bright colors including purple and orange.

Some of them are more than a meter long and are so fast that they "literally cross the seascape," said Joseph Gaydos, the senior author of the study.

"But when that disease happens, it's like a zombie apocalypse," said Gaydo, of the SeaDoc Society, University of California, Davis.

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"He may have 24 arms and suddenly he is walking and his arms are falling. And then, suddenly, the whole body seems to melt.

So what used to be a "big, beautiful starfish," and weighed about five pounds, resembles a pile of calcified parts in a few days, he said.

"It's a really ugly and fast disease for these sunflower starfish."

By 2013, scientists began to realize that species populations were shrinking between 80 and 100 percent in shallow and shallow water from Alaska and British Columbia to California.

Population information was collected by divers and deep-sea nets.

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Sunflower starfish are found in waters from hundreds of meters to just three meters.

Diego Montecino-Latorre, a co-author of the study, and also of the University of California, Davis, said that scientists have discovered an association between rising water temperature and watching fewer stars.

Gaydos said the water temperature rises are not the same in all areas.

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The oceans "are not like a bathtub" with consistent temperatures, he said, adding that some locations in California had increased by about 4 ° C, while locations in Washington saw an increase of 2.5 ° C.

One of the theories presented by scientists is that an increase in temperature makes sea stars more susceptible to the disease that was already present, especially since the starfish do not have complex immune systems, he said.

Co-author of the study, Drew Harvell, a professor of ecology and evolutionary biology at Cornell University, said that the heat wave in the oceans caused by global warming is aggravating starfish disease and killing the starfish more quickly.

Gaydos said sunflower starfish are ravenous predators and when they subside, the number of sea urchins may increase.

These outbreaks of disease can have a major effect on the entire ecosystem, he said.

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"Kids can knock out algal forests, and when you lose algae, you lose biodiversity," he said. "Kelp is a place for fish to hide, kelp is a food for other animals."

Algae beds were already struggling, he added.

"Seaweed also does not do well when ocean temperature increases, so it's like a double blow to sea kelp."

One of the options to help sea kelp is the selective collection of sea urchins, which is being tested in California, said Gaydos.

And one option to help the starfish population of sunflower is captive breeding, where the most virus-resistant animals can be selected, he said.

Gaydos said death is an alert.

"It's hard to keep an eye on what's happening in the ocean, but we need to pay attention because it happened in a very short period of time," he said. "So that an entire species almost disappears, that's not good."

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