Millions of mussels, clams and other marine creatures die from heat wave 'catastrophe'

A record-breaking heat wave affecting the Pacific Northwest and parts of Canada has cooked millions of mussels, clams and other sea creatures alive.

About two weeks ago, Alyssa Gehman, who studies marine ecology community, was looking to go for a swim along Kitsilano Beach in Vancouver, British Columbia, to escape the heat.

"The first thing I noticed as I was walking down to the beach was that it smelled quite terrible," Gehman told USA TODAY. "There was a rotting, baking shellfish smell."

As she came across the edge of the water, she noticed beds of dead mussels on the beach.

"I also saw dead crabs floating by," Gehman said. "And that was really sad to me, and it was also indicative that there's likely many animals that were also killed during this heat wave event."

Christopher Harley,  a marine ecologist who also observed the dead creatures on Kitsilano Beach, said it looked like "an ecological catastrophe" he had never seen before. 

Back at the Hurley Lab in the University of British Columbia, where he and Gehman work, the researchers are looking into the broader ramifications of the mass mortality of animals on the shores of many places, including Lighthouse Park in West Vancouver, Stanley Park in Vancouver, and other islands nearby.

Mussels are one of the animals they have been examining.

According to Gehman, mussels during low tide tightly close their shells and keep water inside of them so they don't dry out. 

"They can survive temperatures that are pretty similar to the same temperatures that humans can survive, up to a little over 100 degrees," Harley said. "But we were measuring temperatures on the shore above 120, so it was much hotter than anything they could handle."

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The death of the sea creatures can affect entire ecosystems, too. For instance, one mussel can filter up to 6 gallons of water a day, Gehman says, which means the mussel cleans the water out and make it so the water is clear.

"This can matter for plants that live in the water because the water needs to be clear so that the sun can get to the plant that's growing," Gehman said.

Shellfish like mussels and clams provide food for other species, including starfish and migratory seabirds, and provide habitat.

"Mussel beds in particular host dozens and in some cases hundreds of species, so when we lose the mussels we lose the habitat and then all those other species as well," Harley said.

The deadly and record-breaking heat wave in parts of the Western U.S. and Canada two weeks ago would have been "virtually impossible" without the influence of climate change, according to a study released Wednesday by leading scientists, who said global warming made the extreme temperatures at least 150 times more likely to occur.

Hundreds of people were reported to have died because of the heat, and the majority of deaths were in British Columbia. More than 100 people died in Oregon, a death toll described as "horrific" by the state's governor, Kate Brown. 

Contributing: Doyle Rice