More than 1 billion marine animals along Canada’s Pacific coast are likely dead from last week’s record heat wave, experts warn, highlighting the vulnerability of ecosystems not accustomed to extreme temperatures.
The “heat dome,” which settled over western Canada and the northwestern United States for five days, pushed temperatures in coastal communities to 40 ° C (1
The intense and tireless heat is believed to have killed as many as 500 people in the province of British Columbia and contributed to the hundreds of forest fires currently burning across the province.
But experts fear it also had a devastating impact on marine life.
Christopher Harley, a marine biologist at the University of British Columbia, has estimated that more than a billion marine animals may have been killed by the unusual heat.
A walk along a beach in the Vancouver area highlighted the magnitude of the devastation caused by the heat wave, he said.
“The coast usually does not shatter when you walk on it. But there were so many empty seashells lying around that you just couldn’t help but step on dead animals while walking around, ”he said.
Harley was struck by the smell of rotting mussels, many of which were actually boiled by the abnormally hot water. Snails, starfish and mussels rotted in the shallow water. “It was an overwhelming, visceral experience,” he said.
While the air around Vancouver hovered around the high 30s (around 100F), Harley and a student used infrared cameras to record temperatures above 50C (122F) along the rocky shore.
“It was so hot when I was out with a student that we gathered data a bit and then retreated to the shade and ate frozen grapes,” Harley said. “But of course the mussels, the starfish and the mussels do not have that opportunity.”
Mussels are hardy shellfish that can withstand temperatures in the high 30s. Barnacles are even more robust and survive the mid-40s (at least 113F) for at least a few hours.
“But when the temperature gets over it, it’s just unsustainable conditions,” he said.
Mass deaths of shellfish would temporarily affect water quality because mussels and clams help filter the ocean, Harley said, keeping it clear enough that sunlight reaches the eelgrass bottoms while creating habitats for other species.
“A square meter of mussel bed could be home to several dozen or even a hundred species,” he said. The closely related way in which mussels live also informed Harley’s calculation of the extent of the loss.
“You can fit thousands in an area the size of a hob. And there are hundreds of miles of pebble beach that are hospitable to mussels. Every time you scale up, the numbers just get bigger and bigger. And it’s just clams. Much marine life would be dead. ”
While mussels can regenerate over a period of two years, a number of starfish and mussels live for decades, and they reproduce more slowly, so their recovery is likely to take longer.
Harley has also received reports from colleagues about dead harbor anemones, stonefish and oysters.
Experts have warned that the province needs to adapt to the reality that sudden and sustained heat waves are likely to become more common as a result of climate change.
Another heat wave is expected to hit the western United States and southwestern Canada in the coming week, highlighting the ruthlessness of the dry summer heat.
“The nerdy ecologist part of me is excited to see what will happen in the coming years,” Harley said. “But most of the rest of me are a little depressed by it. Many species will not be able to keep up with the pace of change. Ecosystems will change in ways that are really difficult to predict. We do not know where the tipping points are. ”