In 2013, the lives of millions of sea stars were mysteriously extinguished. Organs that were once strong, searching for weapons, searching for sustenance, broke away from the rest of their bodies and melted into a sick goo.
“There were weapons everywhere,” explained ecologist Drew Harwell the AtlanticEd Yong last year. “It looked like an explosion zone.”
Desperate remains of these animals, usually able to regenerate their own limbs, were scattered throughout the West Coast of North America, in one of the largest mass wildlife death events ever reported. More than 20 species of sea stars were dangerous.
In some areas, the sunflower star (Pycnopodia helianthoides) The population dwindled to an average of about 90 percent in weeks, a disadvantage seen when the once common and abundant species disappeared from most of its range in just a few years.
This sea star wrecking (SSW) also found the starfish in captivity, which kills different animals within days.
This led scientists to suspect some kind of pathogen, such as viruses or bacteria, infecting these amazing marine organisms. However, later studies exacerbated the major viral suspicion.
Meanwhile, more sea stars have died worldwide, including half a world away in Port Phillip Bay, Australia.
Now, marine biologist Citali Aquino and his colleagues at San Francisco State University have finally solved this mystery, causing something more complicated.
By comparing the type of bacteria within healthy sea stars and those suffering from wasted disease, researchers found bacteria that thrive in low-oxygen environments, abundant in sick animals, such as copiotrophs – bacteria that are highly nutritious Liked the atmosphere of the elements.
Experiments conducted back in the laboratory confirmed that the receding water of oxygen gave rise to melting lesions of tissue in 75 percent of sea stars. Adding additional nutrients or phytoplankton to the water also led to a deterioration in the health of the sea star.
Re-analyzing tissue samples from the 2013 incident, the researchers detected excess nitrogen – a sign that these animals succumbed to death.
Marine microbiologist Ian Husson of Cornell University said, “Sea stars put oxygen on their outer surface in very small structures, called papules or skin gills.” “If there is not enough oxygen around the papula, the starfish cannot breathe.”
These microorganisms are not directly causing disease, but when the increased levels of organic matter are stealing the oxygen supply of the sea stars to feed the germs. As a result, the sea stars literally sank into their own atmosphere. Their decaying bodies then increase nutrients for microorganisms, creating a terrible feedback loop of sea star death.
Aquino and team noted that most SSW events are reported to occur in late fall or summer, when phytoplankton that increase nutrient levels in water through photosynthesis are more abundant.
Warmer temperatures are known by the drivers of phytoplankton blooms, and an ocean wasting incident in Australia followed the longest and most intense heat wave on record. Elsewhere incidents of sea destruction have also increased sea temperatures.
“Hot water may not have that much oxygen [compared with colder water] By physics alone, “Huson told Erin Garcia de Jesus Science news.
None of this is good for our future on a warming planet.
Vermont biologist Melissa Pespeni, who was not involved in the study, reported Science news This complex conflation of biological and environmental factors is a new kind of idea for ” [disease] Transmission. “
The devastating destruction caused by the loss of these precious stars of the sea has already resonated throughout the ecosystem. The sunflower star is a ragged predator with 24 arms that spans 1 m (3.3 ft), making its way across the ocean to feed for sea urchins, snails, and other invertebrates.
Without the sea urchins possessing sunflowers and other sea stars, these vegetarian birds are eating their way through vast kelp forests. By 2016, sea urchins had already reduced kelp populations by 80 percent in some areas, destroying once underwater forests.
“This is a very clear example of the trophic cascade, an ecological domino effect that occurs at the end of a food chain,” said Marine Ecologist Isabel Cote of Simon Fraser University.
“It’s a stark reminder that everything is connected to everything else.”
This research was published in Frontiers in microbiologywhy