Voracious Purple Sea Urchins Are Ravaging Kelp Forests on the West Coast
by Brigit Katz/Smithsonian.com
The coastal waters of northern California were once home to undulating forests of bull kelp, a type of seaweed that offers shelter to a host of sea creatures. But a series of adverse ecological events have jolted the region’s marine ecosystem out of whack. Populations of purple sea urchins, a voracious, kelp-eating species, have exploded. And now, according to a new study in Scientific Reports, more than 90 percent of bull kelp canopy along 217 miles of California’s coast is gone.
The first sign of trouble arose in 2013, when sea stars in the area were hit with a mysterious disease and began “wast[ing] to nothing,” as the University of California, Davis puts it in a statement. Sea stars play an important role in their ecosystem, preying on native purple urchins (Strongylocentrotus purpuratus) and keeping their numbers in check. With mass numbers of sea stars dead, the urchins proliferated, chomping their way through the kelp forests.
Researchers aren’t sure where the sea stars’ illness came from, reports Discover’s Leslie Nemo. But they believe climate change was responsible for what happened in 2014 when a record-breaking marine heatwave that fueled the bull kelp’s decline.