Divers armed with hammers — and otters — may stop sea urchin devastation off California

California scientists are declaring war on sea urchins.

The spiny invertebrates that resemble 1980s koosh balls are gobbling up California’s coastal kelp faster than it can reproduce.

“Kelp forests as lush and impressive as the towering redwoods that grow farther inland once dominated these nearshore waters,” according to The Nature Conservancy.

Satellite, drone and piloted aircraft imagery surveys have revealed that kelp forests in the region have declined by 96%, according to the environmental organization.

It’s an “underwater wasteland,” the organization reported.

The trouble lies in the sea urchin’s sudden lack of predator. Sea stars used to eat them. Now, according to scientists, global climate change caused the Pacific Ocean to overheat and it’s killing off the sea stars.

With the warming ocean temperatures, “more than 90% of the global sunflower sea star population has been wiped out by a gruesome affliction known as sea star wasting syndrome, a disease that breaks down the star’s body and eventually reduces its many limbs to mush,” according to TNC. And that’s just in the last decade.

Without a predator, the ravenous urchins now run amok, their populations exploding. Their gluttony for California’s kelp forests also wreaks havoc on the coastal fish, experts told KSWB.

So, experts decided to take things into their own hands.

On beaches in Mendocino and Monterey, fish and game wardens are now encouraging recreational divers to bring hammers on their dives to smash any urchins they see.

“They jump in the water, like any diver would with scuba gear, and they swim around the reefs with hammers, crushing as many urchins as they can,” fisheries scientist Lydall Bellquist told the outlet.

While turning divers into urchin killers is one way to solve the problem, there may be a gentler – and more natural – solution on the horizon.

According to a study published Jan. 18 in the PLOS Climate journal, otters may be the key to protecting and regenerating kelp forests. According to the study, otters are another important predator to sea urchins.

Otters can often be seen snacking on urchins while floating on their backs.

Researchers in the study found that a larger population of otters correlated with healthier kelp forests. In this way, putting efforts toward otter conservation may be California’s way toward regrowing its lush underwater ecosystems.

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