Sea stars bounce back after US west coast die-off

Sea stars, commonly known as starfish, have begun to bounce back after a massive die-off caused by a virus along the US west coast in 2013 and 2014, researchers said Wednesday.

The outbreak of sea star wasting, which made the animals melt and die, affected 20 different species from Baja California to Alaska, making it "one of the largest epidemics in a marine ecosystem in recorded history," said the study in the journal PLOS ONE.

The disease struck Oregon hard, arriving in April 2014 and spreading along most of the coast by June, infecting about 90 percent of sea stars, said the study led by Bruce Menge from Oregon State University.

Researchers tracked the dieoff, performing nearly 150 surveys of rocky intertidal habitats at nine sites along the Oregon coast between spring 2014 and fall 2015.

They found that about 80 percent of the populations died at the study sites.

The epidemic took root in cool water temperatures, driven by summer upwelling, and disproportionately affected adult sea stars and those that lived in tide pools, according to the report.

But by spring 2015, the sea star population began to recover by leaps and bounds.

"Study sites had up to 300 times as many new sea stars as in 2014," said the report.

"This recovery may be due to the increased availability of small prey, like mussels, resulting from the previous year's sea star loss."

Menge said the fact that sea stars off Oregon died during cooler, not warmer temperatures, suggests that a variety of factors were at play in driving the epidemic.

"Although up to 84 percent of local populations died, a massive recruitment of sea stars occurred the following spring, suggesting the possibility of rapid recovery," he said.

Source :AFP