There has much coverage of the plight of sunflower sea stars, the large starfishes with 16 to 24 arms that inhabit the Pacific Coast of North America. A wasting disease that hit the population starting in 2013 killed off more than 90% of the population from Mexico to Alaska. Only recently has the underlying cause of the disease been identified: a specific bacterium of the Vibrio genus. But sunflower sea stars aren’t the only species that have fallen victim to the wasting disease. In fact, it has killed billions of sea stars in up to 20 species.
Sea stars – or starfish as they are often called – are not just exotic-looking creatures on the seafloor. They are keystone predators that fulfill important roles in undersea ecosystems. The sunflower sea star feeds on sea urchins and eliminating most of them from much of the Pacific coast led to a sea urchin population explosion that in turn decimated the kelp gardens upon which urchins feed.
A similar drastic die-off of ochre sea stars, also called purple sea stars, over the past decade led to a population explosion of California mussels, their favorite food.
A recent study by Oregon State University and Cal Poly San Luis Obispo has revealed a baby boom of ochre sea stars leading to surging populations of the colorful starfish. The wasting disease is still present in many places and populations continue to fluctuate, but it is clear that ochre sea stars are bouncing back. Enough of the sea star baby boomers have reached adulthood and, in many places, populations are at or exceeding pre-wasting disease abundances.
