According to a new study, a mysterious spill of disease on starfish around the world could be the result of respiratory distress. These environmental changes are likely to deplete oxygen in the oceans, according to scientists, and cause starfish to ‘drown’.
In research published online Wednesday in the journal Frontiers in Microbiology, scientists have uncovered cases of so-called sea-star-spill syndrome. The disease, which causes the tissue of the creature to decay and eventually splinter, can cause mass death. Outbreaks recorded over the past seven years have even threatened some species with extinction.
Now scientists can finally know what is to blame: warming ocean temperatures is leading to an increase in organic matter and bacteria that absorb oxygen in these watery habitats. The resulting low-oxygen environments prevent starfish from breathing properly, the researchers found.
“When people breathe, we exhale, we breathe air and we exhale,” 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 papulae do not have enough oxygen, the starfish cannot breathe. ”
Hewson and his colleagues discovered that warming conditions can lead to higher than usual concentrations of organic matter in the ocean, which in turn causes a type of bacteria called copiotrophs to thrive. These microorganisms feed on carbon, and when they consume organic matter, they deplete oxygen in the water.
When starfish in these environments cannot get enough oxygen, they experience shortness of breath and begin to develop the lesions that are characteristic of starfish syndrome, according to the study.
“It’s a waterfall of problems starting with changes in the environment,” Hewson said.
Scientists are eager to find the cause of syndrome for wasting starfish, because the disease can lead to major deaths.
“If you have a dead and rotting starfish next to the starfish that is healthy, it drives all the organic matter out of the dead and drives the bacteria, creating a hypoxic environment,” Hewson said. “Diseases seem to be transmitted.”
Hewson added that more research is needed to better understand the ecological conditions that contribute to the weakening of starfish, which may include extensive studies to look at the broader domino effects.
“We must now include microorganisms that do not directly cause the pathology, as this may be the key to affecting the health of the starfish,” he said.
