Warming oceans may be choking off oxygen to starfish, causing them to 'drown'

A mysterious waste disease observed in starfish around the world may be the result of shortness of breath associated with ocean warming, according to a new study. According to scientists, these environmental changes are likely to lead to a lack of oxygen in the oceans, causing starfish to “drown”.

In research published online Wednesday in the Frontiers in Microbiology JournalScientists explained cases of the so-called Sea Star Wasting Syndrome. The disease, which causes the creature’s tissues to break down and eventually fragment, can trigger mass death. Outbreaks recorded over the past seven years have even put some species at risk of extinction.

Now scientists may finally know what they are to blame for: The warming of sea temperatures is leading to an increase in the organic material and bacteria that take up oxygen in these watery habitats. The resulting low-oxygen environments prevent starfish from breathing properly, the researchers found.

“As humans, we breathe, we ventilate, we bring air into our lungs, and we exhale,” said Ian Hewson, a biological oceanographer at Cornell University and one of the authors of the new study. said in a statement. “Starfish distribute oxygen over their outer surface through small structures called papules, or skin gills. If the papules do not contain enough oxygen, the starfish cannot breathe. “

Hewson and colleagues discovered that warming conditions can lead to above-average concentrations of organic matter in the ocean, which allows a type of bacteria called copiotropes to thrive. These microorganisms feed on carbon and consume oxygen in the water when they consume organic substances.

When starfish cannot get enough oxygen in these environments, they experience shortness of breath and begin to develop the lesions characteristic of starfish wasting syndrome, according to the study.

“It’s a cascade of problems that begins with changes in the environment,” said Hewson.

Scientists have been eager to find the root cause of Sea Star Wasting Syndrome as the disease can lead to large deaths.

“When you have a dead and rotting starfish next to healthy starfish, all of that dead body’s organic matter drifts and powers the bacteria, creating a hypoxic environment,” Hewson said. “It looks like a disease is being transmitted.”

Hewson added that more research is needed to better understand the environmental conditions that contribute to Sea Star Wasting Syndrome. This could include expanded studies to examine the broader domino effects.

“We should now include microorganisms that are not directly causing the pathology as they may be key to affecting starfish health,” he said.

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