In the Aleutians, climate change and ocean acidification impacts add to legacies of past exploitation

Centuries of human impacts could make it harder for Southern Bering Sea ecosystems to adapt to climate change

A northern sea otter is seen in waters near Kodiak, Alaska. (Lisa Hupp / U.S. Fish and Wildlife Service)

The Bering Sea region, the Pacific gateway to the Arctic Ocean, is home to ecosystems on land and in the ocean that are both abundant and fragile. It’s also changing very quickly — and those changes offer a preview of the changes in store for other parts of the Arctic. This story is part of an ArcticToday series on the changing Bering Sea — and what those transformations mean for fish, wildlife and people.

In the waters around the Aleutian Islands, the 1,200-mile chain that arcs across the southern edge of the Bering Sea from Alaska to Kamchatka, modern climate change has layered atop a centuries-old legacy of human assaults to send combined impacts cascading through the marine ecosystem.

Evidence is in the once-colorful corals that have nurtured schools of fish supporting some of the world’s largest commercial seafood harvests. Under the clear waters is a pale world that signals a habitat in a tailspin.

Adding to the assault is ocean acidification, to which the Bering Sea is especially vulnerable. The shallow Bering, with its relatively cold waters, abundant sea life and wide seasonal fluctuations, is naturally primed to hold carbon. And carbon emitted by fossil-fuel burning is absorbed from the atmosphere into the water, lowering pH levels and threatening calcium-building life forms — not just the coral reefs, but shellfish such as crabs, as well the tiny creatures such as pteropods that make up the diet of fish like salmon.

The corals’ demise is happening just as information about them and their place in the ecosystem is emerging. The first exploration of Bering Sea corals and associated sponges was conducted in 2002, and new species are still being discovered.

“Just as we’ve realized how widespread the reefs are and how important they are, they’re disappearing before our eyes,” Rasher said. “They’re changing before we even get to know them.”

Barren corals in the western Aleutians are attacked by sea urchins. (Joe Tomoleoni / USGS).

The stakes go beyond otters, kelp and corals.

Warming and acidification threaten the Bering Sea’s multibillion-dollar fishing industry. From pricey king crab to cheap fish patties used in fast-food sandwiches, the Bering Sea provides about half the nation’s commercially harvested seafood. It depends on the sustainable management of the ecosystem.

Yereth Rosen, Arctic Today, 12 February 2021. Full article.

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