Emerging from a recent dive 40 feet below the surface of Puget Sound, biologist Ben Miner wasn’t surprised by what he found: The troubling disease that wiped out millions of sea stars up and down the West Coast had not spared this site along the rocky cliffs of Lopez Island.
He and another diver tallied the grim count on a clipboard he had taken underwater. Only two dozen adult sea stars were found in an area where they were once abundant. But Miner’s chart also revealed good news — a few baby sea stars offered a glimmer of hope for the creature’s recovery.
In scattered sites along the Pacific Coast, researchers and others have reported seeing hundreds of juvenile sea stars, buoying hopes for a potential comeback from sea star wasting disease that has caused millions of purple, red and orange sea stars to curl up, grow lesions, lose limbs and disintegrate into a pile of goo.
“Babies. That’s what we hope for,” said Miner, associate professor of biology at Western Washington University. “If you’re hoping for sea star populations to recover, it’s the best news you can get to be able to go to sites and see that there are babies.”
At one site in Santa Cruz, California, more babies were counted in the past year or so than in the previous 15 years combined, said Pete Raimondi, professor of ecology and evolutionary biology at the University of California, Santa Cruz. More sites had their highest year ever for number of babies, he said.
Not all the sites have seen juveniles and it hasn’t been broad. “It means something is going on up and down the coast and it’s a good sign,” Raimondi said.
Miner said juveniles, while not entirely immune, may be less susceptible to a virus fingered as the likely culprit of the sea star wasting disease, a sickness that has devastated about 20 species of sea stars from Alaska to Baja California since it was first reported off the Washington coast in June 2013.
Last fall, Miner, Raimondi and a team of scientists published new research linking a variety of densovirus to sea star wasting disease.
Now biologists like Miner and others are shifting to a new phase of study. They are tracking whether baby sea stars survive and what happens when a key predator of urchins, mussels and other species is lost. Juveniles were observed at some sites before adults died and many appeared to have survived after the die-offs, Miner said.
One theory for why there are so many juveniles is that when adult sea stars were stressed from the wasting disease, they released millions of eggs and sperm into the water column, increasing the chances for fertilization. Ideal conditions in recent months have helped push those larvae to the shore, where they’re able to cling to hard surfaces such as rocks and pilings to grow. Now, Miner said, “the question is when these babies get big, will you expect them to die like the adults?”
Raimondi added it will take a few years of monitoring to know for sure whether the sea stars will grow and repopulate.
“We want them back,” said Peg Tillery. “They’re part of the ecosystem. If they go away, what goes away next?”