The “baby boom” of ochre sea stars that followed a population crash a decade ago is enabling the species to recover on the Oregon Coast, according to new research by scientists in the College of Science and Cal Poly San Luis Obispo.
The study, published in Ecosphere, does not determine whether the boom was triggered by the wasting disease epidemic that pushed ochre sea stars to the brink of extinction in Oregon, or simply a fortunate coincidence.
But either way, a study of multiple sites along the coast revealed many encouraging signs for ochre sea star populations.
“Wasting disease remains in circulation and populations continue to fluctuate, but there’s also much evidence that ochre sea stars are bouncing back,” said the study’s lead author, Sarah Gravem, an OSU postdoctoral researcher when the project began.
Gravem, now an assistant professor at Cal Poly, and Bruce Menge, a distinguished professor of integrative biology, analyzed ochre sea star populations at eight locations over a 23-year period.
They found that many sea star baby boomers have reached adulthood and that population numbers are now at or exceeding pre-wasting disease abundances.
“After declines in sea star numbers of up to 84% in 2014, we quickly saw an 8,000% increase in young sea stars landing on shore,” Gravem said. “Populations are now large enough that sea stars are on the way to resuming their role as a keystone predator in the intertidal zone; at three-quarters of the study sites, predation on their favorite prey, California mussels, has recovered.”
