The collapse arrived in a wave of heat and sickness. Between 2014 and 2020, a marine heatwave combined with a devastating wasting syndrome that decimated the sunflower sea star, the primary predator of the purple sea urchin. Without the stars to hunt them, the urchins multiplied into an army, devouring the holdfasts of the giant kelp until the great amber forests simply drifted away. In parts of Northern California, the loss exceeded 95%, leaving behind "urchin barrens"—vast underwater territories where nothing remains but the sharp, clicking shells of the scavengers.
Nature’s balance, once broken, does not always right itself. In these barrens, the urchins have entered a state of starvation. They are hollow and nutritionally worthless, yet they persist in a dormant state for years. The southern sea otter, usually the guardian of the kelp, refuses to eat them; there is no reward in cracking open a shell that offers no meat. To bring the otters back, the humans must first do the heavy work of the vanished sea stars.
Teams of divers now descend to cull the urchins by hand, clearing the rocky reefs to allow the kelp spores to settle. It is a meticulous, taxing labor. Yet, as the green shoots of the Macrocystis pyrifera rise again, the cycle restarts. The remaining urchins, now fed by the new kelp, grow plump once more. This is the signal the otters have been waiting for. At the Monterey Bay Aquarium, rescued pups are raised by surrogate otter mothers, learning the essential art of the hunt before being released into these recovering glades.
The success of the work is visible in the rhythm of the waves. In British Columbia, where the otters have firmly re-established themselves, the kelp has returned in a thick, protective fringe that buffers the coast and breathes life back into the sea. There is a quiet precision to it: the diver’s hand clearing the stone, the otter’s tool—a small, smooth rock tucked into a fold of skin—cracking the shell, and the forest rising, inch by inch, toward the light.