Five years after marine scientists first sounded the alarm about a sudden collapse of the bull kelp forest off the Northern California coast, the state of the ocean offers little prospect of recovery any time soon.
Where lush stands of leafy kelp once swayed amid the waves, providing cover to young finfish and forage for abalones and other creatures on the ocean floor, a stark new world has materialized — one dominated by millions of voracious purple sea urchins that have stripped the ocean floor down to rock in some places. Were a tender frond of new kelp to sprout, it wouldn’t stand a chance of surviving long.
The barrens left behind are a stark and alarming contrast to what is typically one of the most thriving marine environments — seasonal kelp forests that support a rich ecosystem with life stretching from the sea floor to the surface, and up the food chain, supporting recreational and commercial fisheries and home to some of the North Coast’s most iconic wildlife, including abalone and sea otters.
The kelp forests also are a key barometer for the wider health of the world’s oceans, and without some recovery, their future as biodiverse stores for marine life and people hangs in the balance.
Laura Rogers-Bennett, a veteran biologist who works out of the UC Davis-Bodega Marine Lab, likened the kelp forest to a great floating woodlands stretching hundreds of miles along the coast.
“To lose 95% of your forest in a year and a half, that’s a catastrophe, an ecological disaster, and it’s had so much socioeconomic impacts, as well,” she said.
Experts are honing in on strategies to preserve remnant bull kelp that long flourished up and down the North Coast, hoping it may allow them to restore some portion of what once existed, when the time is right. Those pioneering efforts could also serve as model strategies for emerging urchin barrens around the world.
In labs around the West Coast, experiments are underway testing the feasibility of kelp cultivation and seed banking that might allow humans to boost natural recovery of the kelp forest at some point. Scientists elsewhere are breeding giant sunflower sea stars that might offset billions lost to Sea Star Wasting Syndrome, restoring a key predator of native purple urchins that have since multiplied so astonishingly. Others are trying to better understand the full dynamics of the ecosystem and how the transformation might be reversed.
It’s a daunting challenge, drawing on the talents of government, academic and nonprofit scientists, as well as commercial and recreational divers desperate to ensure the offshore waters of the future offer some sliver of the opportunities they have in decades past.
“It’s worth remembering that California has some of the best kelp ecologists in the world, so if we can’t figure out how to do this, it can’t be done,” said James Ray, kelp restoration coordinator at the Department of Fish and Wildlife. “It’s hard to know what the future environment is going to look like, but we’re not going to go quietly into the night.”
Multiple, interrelated factors led to decimation of kelp and allowed the simultaneous explosion of native purple urchins. And many studies indicate that, though the shift from kelp forest to urchin barren came rapidly, existing urchin densities mean there could be an extended period before any reversal.
Scientists nonetheless see promise in research underway that offers hope of restoring selective islands of kelp forest in the short-term — refuges that would allow for banking spores and preserving the species for the long-haul, until conditions might allow more extensive recovery.
The state of California also has assumed a more direct role in the response, including funding and project management. The Department of Fish and Wildlife and the Ocean Protection Council, a state agency, are developing a blueprint for long-term action that they hope to have finalized next year. Their interim plan, “a starting point for discussion,” is an effort to assemble a variety of strategies to apply toward the problem.
They include everything from farming bull kelp to produce genetically diverse spores for planting in the ocean, to culling and trapping the purple urchins, to captive breeding of the huge sunflower sea stars that once kept the urchins in check. All already are at various stages of development.