Tuesday May 6, 2025
Earth.com —
When ochre sea stars began dissolving along the Pacific coast in 2013, marine biologists feared a domino effect in the rocky intertidal zone. The orange-and-purple Pisaster ochraceus is a classic “keystone” predator – remove it, and the tightly knit ecological web can unravel.
What no one predicted was that the die-off would reverberate far beyond the tide pools, ultimately reshaping the menu – and the numbers – of sea otters hunting in adjacent kelp forests.
Sea-star wasting syndrome swept from Alaska to Baja California with unprecedented speed, leaving many local Pisaster populations functionally extinct in a matter of months.
On the Monterey Peninsula, field teams led by the Multi-Agency Rocky Intertidal Network (MARINe) watched decades-old monitoring plots lose nearly every visible star by late 2013.
Without those relentless predators to keep them in check, California mussels began carpeting the rocks. Within three years, mussel cover tripled, climbing from roughly five percent of available surface to more than eighteen percent.