Scientists zone in on cause of sea star wasting syndrome

·2 min read
Scientists zone in on cause of sea star wasting syndrome
Scientists zone in on cause of sea star wasting syndrome

In 2013, there was a massive sea star die-off along the North American Pacific coast. The mysterious disease, called "sea star wasting syndrome" (SSWS), caused the loss of limbs, which melted into goo.

The syndrome moved swiftly decimating some species, like the sunflower star, by 90 per cent in weeks.

Similar die-offs have happened in the past and continue to occur, but the 2013/2014 season was one of the worst. Scientists don't understand a lot about SSWS, but new research is putting experts one step closer to pinpointing the cause.

In a paper led by scientists at Cornell, it's suggested sea stars suffering from SSWS may be "drowning" due to elevated microbial activity and warming ocean temperatures which are robbing them of oxygen.

“As humans, we breathe, we ventilate, we bring air into our lungs and we exhale,” Ian Hewson, professor of microbiology in the College of Agriculture and Life Sciences, says in a statement.

“Sea stars diffuse oxygen over their outer surface through little structures called papulae, or skin gills. If there is not enough oxygen surrounding the papulae, the starfish can’t breathe.”

Hewson says ocean conditions can lead to large amounts of organic material. Bacteria thrive in this environment and as it consumes the organic matter, they deplete oxygen levels around healthy sea stars.

“It’s organic matter concentrations in the water,” he says. “If you have a dead and rotting starfish next to starfish that are healthy, all of that dead one’s organic matter drifts and fuels the bacteria, creating a hypoxic environment. It looks like disease is being transmitted.”

More research is needed, but the finding is important as it shifts attention away from pathogens, a previous focus.

“We should now include microorganisms that don’t directly cause the pathology, since they may hold a key to affecting sea star health,” Hewson says.

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