NORTHWEST

Marine ecologist Alyssa Gehman encountered this mussel bed during the late June heat wave in Vancouver, British Columbia.

Amid the crushing summer heat wave that has slammed the Pacific Northwest and parts of Canada, Alyssa Gehman, a marine ecologist who lives by the sea in Vancouver, B.C., walked down to the shore to go for a swim. As expected, the beach was packed with others looking to beat the heat.

She made her way to the edge of the water. It smelled like putrid shellfish — cooking.

All around her, beds of mussels had popped open, dead. The heat beating down on the rocks had killed them, and she could see dead tissue between their shells.

A dead crab floated in the water, she said.

Gehman studies marine community ecology, but this was the first time she had seen anything of this “magnitude of mortality.” An estimated 1 billion small sea creatures — including mussels, clams and snails — died during the heat wave in the Salish Sea, off more than 4,000 miles of linear shore, according to marine biologist Chris Harley.

Record-breaking temperatures hit the Pacific Northwest at the end of June, with an all-time high in British Columbia of 121 degrees. British Columbia reported at least 719 people suffered “sudden and unexpected deaths,” three times more than what would normally occur in the province during a seven-day period.

Lisa Lapointe, the province’s chief coroner, said in a statement last week that the extreme heat probably was “a significant contributing factor” in the increased number of deaths.

Harley’s research team used infrared cameras to measure temperatures on the shoreline rocks — recording some readings as high as 122 degrees.

With mechanisms to keep from drying out, mussels are able to withstand high temperatures. They hold water inside their shell and close up on land, when exposed by tides. They grow in beds, which provide a thermal buffer. But the record heat was just too much.

The Harley Lab at the University of British Columbia is looking into the mass mortality event on the shore and trying to determine just how many animals died, how animals that survived were affected, how it happened and how likely it is to happen again.

Ken Fong, head of the marine invertebrates stock assessment research program for Canada’s department of fisheries and oceans, said that the agency is monitoring the effects of the heat wave and that it is too soon to provide an assessment of how many sea animals might have died.

He said that although this heat wave was “quite extraordinary,” the department has noted that marine heat waves of different magnitudes have been occurring with more frequency on Canada’s Pacific coast since at least 2014.

Still, Fong said, “We haven’t seen this type of mortality or die-off like this in the past.”

He attributed the incident to a “perfect storm”: a very low tide in the afternoon in the Strait of Georgia that happened to coincide with the hottest part of the day, exposing the sea animals to the worst of the extreme heat.

The heat also affects businesses. Many shellfish farms on coastal regions were hit by historically hot temperatures.

Typical beach oyster production cycles are two to three years long, so mass oyster deaths are devastating for farmers, said Jim Russell, executive director of the British Columbia Shellfish Growers Association. “If you lose 80 percent of your oysters across all sizes, then you are really out of business for two or three years,” he told The Washington Post.

Hama Hama Oysters, a fifth-generation, family-run oyster farm in Washington state, in a post on Instagram said that its dead shells were “impressive in number.” Exhibiting some brave-face humor, a post described the impact on the business’s clam beds in Hood Canal as “clamitous.”

Experts warn that climate change is driving changes in weather, including heat waves. “Extreme weather events are getting more frequent, and climate change has a significant role to play in that,” Canadian Prime Minister Justin Trudeau said this month.

Lissa James Monberg of Hama Hama Oysters told The Post in an email that “these ‘once in a hundred year’ weather events are really coming at us pretty quickly, one after another, which is getting pretty exhausting.”

In its post on social media, the oyster farm urged people to “vote for politicians who are brave enough to address climate change.”

Losing mussels and other bivalve mollusks such as oysters and clams can throw off the entire ecosystem, Washington-based marine biologist Emily Carrington told The Post. Shellfish perform critical ecosystem services, modifying their local environment just by their presence and aggregation. They filter a high volume of water and play a central role in the food chain, she said.

Harley said she thinks the mass loss of shellfish could serve as a “wake-up call.”

“The pandemic was a big, scary, intimidating problem, and most of us were willing to make a few small changes that really helped,” he said. “We can do the same thing with climate change.”