ecosystem importance: sea otter's role (Introduction)

by David Turell , Friday, December 29, 2023, 18:28 (120 days ago) @ David Turell

An amazing influence if present:

https://www.sciencealert.com/thriving-otters-in-north-america-linked-to-nuclear-weapons...

"Three atomic weapons went off at Amchitka in the late 1960s and early 1970s, including the largest underground detonation the US has ever set off.

"No humans lived on the island, but the biggest blast, in 1971, killed at least 900 sea otters. The Atomic Energy Commission, the government agency in charge of nuclear research, had predicted at most 240 otters would die.

"If ecologists and others hadn't pushed to relocate some otters before the detonation, it probably would have been much worse.

"'There was pressure from the state of Alaska as well as environmental groups," conservation biologist and author, Joe Roman told Business Insider. "They ended up moving hundreds of otters."

"By the time the AEC was looking at Amchitka in the 1960s, the island's sea otter population was one of only a handful that had survived the sea mammals' near extinction a century earlier.

"Their luscious pelts were prized as "soft gold." In the 1700s and 1800s, hunters killed about one million sea otters to sell their fur.

"The drop in population was alarming, from between 150,000 to 300,000 in the early 1700s to around 2,000 just 200 years later. Russia, Japan, Britain, and the US signed a fur treaty to help protect the animals in 1911. Over the next several decades, sea otter numbers rose to around 30,000.

***

"A US Fish and Wildlife Service biologist, Karl Kenyon, had already worked on relocating some otters to areas they'd lived before the 18th century hunting. The detonations at Amchitka were a good reason to move even more, ecologists and biologists thought.

"If the AEC would pay for it, Vania said, the scientists could relocate the otters.

***

"Over the next 50 years, the sea otter populations in many of these locations, like Sitka, Alaska, would go from several dozen to hundreds or thousands. "All the sea otters — of which there are thousands — in Sitka now are the descendants of these airlifted sea otters," Roman said.

***

"'In the absence of sea otters, you have a lot of sea urchins," Roman said. "When you have a lot of urchins, they create what's called urchin barrens."

"The sea urchins eat the kelp holdfasts, which anchor the algae. Roman compares it to sawing down a forest. The kelp eventually disappear.

"One of the otters' favorite foods is sea urchin. And they can eat a lot of them. "They have very high metabolisms," Roman said. "They're eating machines." When the sea urchin numbers drop, the kelp return.

"In Sitka Sound, the sea otters reduced the sea urchin population by 99%. Kelp forests exploded in return.

"The forests provide food and shelter for more than 800 species, including sea lions, harbor seals, lingcod, gobies, moray eels, octopuses, crabs, sea anemones, and brittle stars," Roman wrote.

"The kelp forests are also amazing at capturing carbon, a concern for the warming planet.

"The otters can also affect land animals, Roman wrote, either directly, as food for wolves on Alaska's Pleasant Island, or indirectly, with the kelp forests that attracted birds that prey on fish.

***

"...the US didn't consult indigenous and First Nations people before unleashing the otters. The mammals brought back the kelp forests, but they destroyed a reliable source of food for many people.

"'Sea otters don't just eat urchins," Roman said. "They also eat geoducks and other valuable benthic invertebrates in the area." That includes crabs and clams. "And of course that brings them into conflict with fishers in that area," he said.

"Suddenly, otters appeared where they hadn't been for generations. "So no one remembers having sea otters in that area," Roman said. "They're used to harvesting these invertebrates, and they're quite abundant in the absence of a predator."

"Their voracious appetite is one reason some people call otters the "rats of the sea." For some Alaskans and Canadians, they're seen as a nuisance."

Comment: another example of ecosystem complexity showing how the whole bush of life interrelates and come from a 99.9% evolutionary loss of forms.