海角大神

Young starfish are staging a comeback in Oregon and Northern California, after a virus that melts the animal devastated adult populations along the northern West Coast starting聽in 2013.

"The number of juveniles was聽off the charts聽鈥� higher than we'd ever seen 鈥� as much as 300 times normal," said Bruce聽Menge, an Oregon State University聽marine biologist and the study's lead author, in a statement the university released Wednesday.聽"It wasn't a case of high settlement, or more sea stars being born. They just had an extraordinary survival rate into the juvenile stage."聽聽

Menge聽and the rest of the team聽attribute the聽population spike to an unusual "sm枚rg氓sbord"聽of food available because of the absence of聽adult sea stars聽who compete聽with juveniles for the larval and juvenile mussels and barnacles they feed on. The adult聽population聽decreased by as much as 84 percent there, according to the statement. 聽

Scientists are now scrambling to determine why the聽virus聽鈥斅爁ound in sea stars聽as far back as 70 years ago聽鈥� 聽has turned into聽an聽epidemic聽before the "wasting disease"聽attacks this聽new generation of purple聽sea stars, as it聽continues聽to kill the adults聽along the West Coast.聽聽

Sea star聽recovery isn't a question of "will or won't [it] happen,"聽but rather when and how long, Peter Raimondi, a聽University of California,聽Santa Cruz ecologist and evolutionary聽biologist, told PBS聽NewsHour. But some researchers worry that the juvenile invertebrates could still develop the illness as adults.

"We're kind of just waiting to see as we move into late spring and early summer of this year whether we have fresh outbreaks."聽聽

Raimondi co-authored聽a聽2014聽study that identified a聽densovirus聽as the cause of the聽disease聽that melts聽sea stars until they are just slime and calcium carbonate.

Starting in 2013, the聽disease聽killed millions of sea stars聽from Mexico to southern Alaska, in some regions,聽destroying as much as 95 percent of some populations. Although聽minor outbreaks of the disease聽had previously聽been recorded, the current聽epidemic is considered one of the聽most devastating marine ecosystem epidemics ever, according to an Oregon State University聽study published Wednesday that revealed the聽population聽of larval sea stars聽along the Oregon coast have聽increased. 聽

Juvenile sea star populations in聽both Trinidad, California,聽and聽Santa Cruz,聽California,聽were also found聽to have increased, although not as much as in聽Oregon.聽Yet, scientists up and down聽the Pacific Coast聽aren't resting on these laurels. They are in a dash to determine why the virus is killing this keystone species. 聽

It appears environmental stresses triggered聽the outbreak, Dr. Menge聽told PBS聽NewsHour.聽Some argue聽the main culprit聽is warming sea聽temperatures. But, the聽Oregon outbreak聽occurred during a period of upwelling, where聽colder聽water rose聽to the surface.聽聽

鈥淚t doesn鈥檛 mean necessarily that temperature is not involved, but it鈥檚 likely a much more complicated story,鈥澛燤enge聽told NewsHour. His team is exploring the impact of聽ocean acidification.聽Along with colder water,聽upwellings聽can carry acidic waters from the ocean floor to the surface.