‘Underwater Zombie Apocalypse’ is Eradicating Key Ocean Species
“We could be watching the extinction of what was a common species just 5 years ago.”
An “underwater zombie apocalypse,” is how University of California, Davis, veterinarian Joe Gaydos described a “sea star wasting disease” in a report from Science Magazine.
The disease has decimated 20 species of sea-stars since 2013 in waters from Mexico to Alaska, and scientists found a possibly worrying connection between the disease and warmer ocean temperatures. The marine epidemic has also now hit the sunflower star (Pycnopodia helianthoides)—a key predator within kelp forests.
Gaydos referred to a zombie apocalypse because of the process of decay that the stars go through due to the disease. When the disease hits sea stars or starfish they develop white lesions and then grow fissures that soon begin to melt away. The limbs of the starfish fall down and move off and within months, a colony of starfish disintegrates into pale mounds of rotten flesh.
Deaths of Starfish and Sunflower Star Empower Sea-Urchins to Destroy Kelp Forests
While marine scientists have reasons to believe the starfish disease is caused by a virus, they do not yet know the type of virus exactly responsible for the damage. Unfortunately, the sunflower star appears to be more vulnerable to the disease than sea-star. The sunflower star is a top predator in the kelp forest ecosystem, feeding on sea-urchins which feed on the kelp forests. If sunflower stars do not feed on sea-urchins, the urchins could destroy undersea landscapes making them virtually barren.
With the mysterious virus killing off starfish and sunflower-stars, sea-urchins have increased uncontrollably and resulted in the loss of more than 90 percent of California’s kelp forests. With the loss of kelp forests comes the death and displacement of other dependent species. Red abalone has starved to death in huge numbers following the destruction of kelp which they feed on, and several other fish species have been equally affected, especially those that hide in the kelp forests to evade predators.
Researchers from the National Oceanic and Atmospheric Administration (NOAA) dragged the seafloor of over 3,000 kilometers of coastline to sample marine biodiversity. They found that since the wasting disease began in 2013, 60 percent of sunflower stars were lost in some areas and up to 100 percent in other areas. Some scientists hope many of the sunflower stars are hiding in deep water far beyond the reach of researchers, but there is no evidence to substantiate this assumption.
Imperiled Sunflower Star Should Be Added To List of Endangered Species to Help Them Recover
Incidentally, researchers found that the wasting disease started decimating marine species when California’s coastal waters recorded the warmest three-year period on record—from 2014 to 2016—as Science Magazine reported. What this could mean is that warmer temperatures or climate change are contributing to the marine disease destroying both starfish and sunflower stars.
“Many of these outbreaks are heat sensitive. In the lab, sea stars got sick sooner and died faster in warmer water,” Drew Harvell, a Cornell University marine ecologist, told Science Magazine. “A warming ocean could increase the impact of infectious diseases like this one.”
Harvell added that the government must consider protecting sunflower stars by adding them to the U.S. Endangered Species List to help it recover. The recovery of the sunflower star should drive down the population of sea-urchins and enable the recovery of kelp forests and the species that depend on them.
“We could be watching the extinction of what was a common species just 5 years ago,” said Steve Lonhart, a kelp forest ecologist with the National Oceanic and Atmospheric Administration.
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