Some good news among plenty of terrible news when it comes to the environment, the ocean, and marine life: Sea stars, or starfish, have come back in huge numbers along the Northern California coast, marking the first such boom since a virus killed off a huge number of starfish along the West coast several years ago. As the Eureka Times Standard reports, tons of baby starfish survived the summer and winter of 2015, according to new data from Oregon State University researchers, and numbers are unprecedented. Reportedly the number of juvenile sea stars recorded on rocks along the Oregon coast was 300 times normal, and a similar though not quite as huge an abundance have been found on the California coast by Humboldt State University Marine Lab researchers.
The virus that caused many sea stars to die off starting in 2013 is called "sea star associated densovirus," and scientists concluded four years ago that the virus had been present though relatively dormant in West Coast sea stars for decades. A population boom appears to have helped spread the virus and cause wasting and death in vast numbers, as PBS News Hour reported in 2014, though some hypothesized that warming waters exacerbated that.
As the AP reports, picking up the story from Eureka, some scientists disagree with that theory because the virus appeared to flourish in colder months. Researchers two years ago concluded that while many densoviruses do not killed their hosts, this one appeared to weaken the immune system of sea stars, causing the wasting disease and die-off.
Between 2013 and 2014, in some areas of the coast between Alaska and Mexico, 95 percent of sea stars were killed. So the new data is encouraging.
The marine ecosystem has seen huge impacts from the disappearance of the starfish, too. Starfish prey on sea urchins, and the urchins have been devastating sea kelp forests all along the coast as a result of not being preyed upon.
Below, video about the densovirus after it was discovered in late 2014. It remains present in starfish, but it appears environmental factors over the last year have altered its impact on the starfish population.