One of the last remaining kelp forests near Elk, Calif., on the Northern California coast.

This Sept. 26, 2019 photo shows an aerial view of one of the last remaining kelp forests near Elk, Calif., on the Mendocino County coast, which has lost more than 90 percent of its bull kelp in less than a decade. Tens of millions of voracious purple sea urchins that have already chomped their way through towering underwater kelp forests in California are now spreading north to Oregon, sending the delicate marine ecosystem off the shore into such disarray that other critical species are starving to death. (AP Photo/Terry Chea)