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Vancouver: A year after the heat dome event that killed billions of plants and animals in British Columbia, scientists say ecosystems are recovering, but could be transformed forever if such events become more frequent.
Cold-water marine species could be replaced by warm-water organisms, triggering cascading effects through the environment, said Christopher Harley, a zoology professor at the University of British Columbia.
“If we had another heat wave this summer, it would be a problem,” he said. “An ecosystem might be able to handle a big heat wave once every few decades there’s enough time for recovery but if it starts hitting every four or five years, the species that we’re used to just can no longer persist.”
Dozens of temperature records were set during the heat dome. The high-pressure system settled over Western Canada, acting like a lid to trap a layer of hot air that got progressively hotter for about a week. Three successive Canadian records were set in the town of Lytton, where the temperature topped out at 49.6 C on June 30, the day before fire destroyed most of the village.
The heat caused more than 600 human deaths, the BC Coroners Service reported. It also led to mass mortalities of marine life, reduced crop yields and contributed to wildfires, which later caused devastating landslides last fall.
Diane Srivastava, director of the Canadian Institute for Ecology and Evolution,organized a group of scientists now working to understand the heat dome’s impact on species and ecosystems. She said some were “immediate and obvious” but several years of data is required to “get a full picture of the longer-term effects.”
Harley, a member of the group, said the heat wave caught researchers off guard and they are now “scrambling to understand” what it will mean for the oceanic ecosystem.
“I’m a bit embarrassed to say we don’t know (the ecological consequences) because it hadn’t occurred to us to ask what would happen if it got hot enough to kill billions of marine animals,” he said. “That heat dome was so far outside of what anyone expected.”
Scientists initially estimated more than a billion marine animal died along the Pacific coast. Harley, who has studied shorelines on the West Coast since 1995, said this was an underestimation.
“Easily many billions of animals died,” he said. “It was a perfect storm of a few different things. It was obviously much, much hotter than usual and those high temperatures coincided with very low tides.”
Species with mobility had a higher survival rate than those that anchor to rocks in shallow waters, he explained.
“Mussels aren’t back yet and some of the common seaweeds are not, but baby barnacles are having the time of their lives. They’re all over the place and the first step in recovery is (when) they come in,” he said. “The foundation has now been laid.”
Adam Ford, an assistant professor and Canada Research Chair in Wildlife Restoration Ecology at the University of British Columbia, said the large mammals he studies were far less impacted by the heat than oceanic life.
“We’ve got a couple of years of data under our belt and there wasn’t a bump in mortality or anything during that time.”

By Brieanna Charlebois
The Canadian Press