Extreme heat cooked mussels, clams and other shellfish alive on Canada’s beaches

(CNN) – The devastating heat wave that hit British Columbia days ago is responsible for the massive deaths of mussels, clams and other marine animals that live on the beaches of western Canada, according to scientists.

Christopher Harley, teacher from the Department of Zoology at the University of British Columbia found countless dead mussels split open and decomposing Sunday on Kitsilano Beach, a few blocks from his home in Vancouver.

Harley studies the effects of climate change on the ecology of rocky shores where clams, mussels and starfish live, so he wanted to see how invertebrates were doing with the record heat wave that hit the area from 26-28. of June.

The next day, Harley and one of her students went to Lighthouse Park in West Vancouver, a site she has visited for more than 12 years.

“(The situation) was a catastrophe there,” he said. “There is a very extensive mussel bed covering the shore and most of the animals had died,” he explained.

Unprecedented heat

The mussels cling to rocks and other surfaces and are used to exposure to air and sunlight at low tide, Harley said, but generally cannot survive temperatures above 37.8 degrees Celsius for long.

Temperatures in downtown Vancouver reached that threshold on June 26, 27 and 28. On the beach, meanwhile, it was even hotter.

Harley and his student used a FLIR thermal camera with which they were able to determine that there were surface temperatures above 51.5 degrees Celsius.

At this time of year, low tide happens in the hottest part of the day, so the animals can’t hold out until it grows back, he said.

Climate change scientists called the heat wave in British Columbia and the US Pacific Northwest “unprecedented” and warned that climate change would make these events more frequent and intense.

In fact, an analysis by more than two dozen World Weather Attribution scientists found that the heat wave “would have been virtually impossible without the influence of man-made climate change.”

The city of Lytton, which broke a historical temperature record, was practically destroyed in a fire.

In the province of British Columbia, 719 deaths were reported between June 25 and July 1, three times more than would normally occur during that period, according to authorities. Hundreds of people died in the United States and many had to be hospitalized from the heat.

1 billion animals may have died from the heat

Harley said the heat may have killed up to 1 billion mussels and other marine creatures in the Salish Sea, which includes the Strait of Georgia, the Strait of Puget and the Strait of Juan de Fuca, although he said it was an estimate. very preliminary.

The scientist explained that between 50 and 100 mussels can live in a place the size of the palm of your hand and that several thousand could fit in an area the size of a kitchen stove.

“There is about 6,400 km of shoreline in the Salish Sea, so when you scale from what we are seeing locally to what we expect, based on what we know where mussels live, you get very large numbers. very quickly, “he said. “Then you start adding all the other species, some of which are even more abundant,” he explained.

Can mussel beds recover in Canada?

Brian Helmuth, teacher in Marine Biology at Northeastern University, said mussel beds, as well as coral reefs, serve as an alert system for the health of the oceans.

Mussel beds “are the main structuring species, so they’re almost like forest trees that provide a habitat for other species, so it’s really obvious when a mussel bed disappears,” he said. “When we start to see the death of other smaller animals, because they move, because they are not that dense, it is not so obvious,” he explained.

He said the death of a bed of mussels can cause “a cascade effect” in other species.

Both scientists said they were concerned that these heat waves were becoming more common and that they weren’t sure if the mussel beds could recover.

“What worries me is that if you start having heat waves like this, every 10 years instead of every 1,000 years, or every five years … you are getting hit too hard, too fast to recover,” Harley said. And he explained that, in that case, the ecosystem will look “very different.”