December 30, 2017
Starfish Population Recovers Nicely After Sea Star Wasting Syndrome Causes Mass Die-Off

Earlier this decade, starfish populations were gutted by a mystery disease called sea star wasting syndrome, with millions of North American starfish dying in a span of just two years. But scientists have noticed that these populations are now recovering nicely in various parts of Southern California, just years after the massive die-off took place.

Alternately known as sea stars due to the fact that they are not actual fish, starfish have long been ubiquitous marine creatures, commonly found in many parts of the world. But in 2013 and 2014, these animals were found to have lesions on their bodies, which then resulted in tissue decay and death; according to the Orange County Register, starfish affected by this disease turned into "globs of goo" within a day's time. The disease would soon spread, killing any other sea stars near those that had previously melted to death.

In those two years, starfish populations from British Columbia to Mexico were decimated, as millions were affected by the disease known as sea star wasting syndrome. The mystery condition, which remains unexplained to this day, had also gutted populations in Southern California. But that's also where scientists have found scores of "palm-sized" sea stars appearing in tidepools, a good sign that the species is making a strong comeback in the area.

"They are coming back, big time," said Darryl Deleske, an aquarist at San Pedro, California's Cabrillo Marine Aquarium.

"It's a huge difference… A couple of years ago, you wouldn't find any. I dove all the way as far as Canada, specifically looking for sea stars, and found not a single one."
The Orange County Register added that starfish populations also appear to be recovering in other parts of Southern California, such as Crystal Cove State Beach, Long Beach, and Palos Verdes.

As explained by the University of California-Santa Cruz's page on sea star wasting syndrome, the 2013-14 die-off was not the first time such a major event took place. The disease had caused die-offs in the 1970s, 1980s, and 1990s, but this decade's event is considered unmatched in terms of magnitude and geographical reach. Although the disease's classic symptoms include white lesions followed by tissue decay, it can be preceded by a deflated or unhealthy appearance.

Initially spotted in ochre stars during a survey along the coast of Washington state in June 2013, the disease affected a number of other starfish populations and species, including mottled stars, sunflower stars, leather stars, rainbow stars, and six-armed stars. Die-offs were reported north of Vancouver, British Columbia, in August 2013, and were followed by similar events in various parts of California before the year was over. As of 2014, starfish in Mexico and Oregon were also affected by sea star wasting syndrome.

In the years that have passed since the mass starfish deaths, the Cabrillo Marine Aquarium's Deleske has mostly observed ochre stars making a return along the break walls of Long Beach and Los Angeles. He did note, however, that some species, such as pink stars and sunflower stars, have yet to make their presence felt in those areas. Deleske added that he and his colleagues had gotten "good results" a few months ago when they treated some sickened starfish with antibiotics.

Scientists are still trying to determine what exactly causes starfish populations to die off from sea star wasting syndrome. Previously, researchers had pinned the blame on the warming of water temperatures, but a report from Newsweek cited a 2014 UCSC study where scientists suggested that parvovirus, which can be carried by other invertebrates, might be linked to the disease, with the viral agent possibly "going rogue" and causing this decade's mass outbreak.