Chris Harley visited Kitsilano Beach in Vancouver in late June and smelled death.
Tens of thousands of mussels, clams, starfish and snails blanketed the rocks in the sea, giving off a putrid smell that hung in the heat.
“I was pretty dumbfounded,” he recalls.
Harley, a marine biologist at the University of British Columbia, now estimates that last week’s record-breaking heat wave in British Columbia may have killed more than a billion marine animals living along the coast of the Salish Sea.
The results shed light on the seismic effects of the heat wave, which has already been linked to hundreds of human deaths and whose ecological toll continues to be unraveled.
As temperatures reached 40 ° C in Vancouver and several degrees warmer in the interior of British Columbia, the infrared cameras used by Harley’s team recorded temperatures above 50 ° C over rocky coastal habitats. .
Intertidal animals like mussels, which inhabit the area where land and sea meet, can withstand temperatures of up to 30 degrees Celsius for short periods of time, Harley said.
But the scorching heat, combined with the low tides by mid-afternoon, created a dangerous combination for more than six hours straight.
“A mussel on the shore, in some ways, is like a toddler left in a car on a hot day,” Harley said.
“They’re stuck there until the parent comes back, or in this case the tide comes back and there’s not much they can do. They are at the mercy of the environment. And Saturday, Sunday, Monday, during the vague heat, it was so hot that the mussels, there was nothing they could do. ”
Water quality will be impacted
Warned by the Sunday morning scent of the heatwave, Harley and a team of student researchers began surveying several coasts, including those of West Vancouver and the Sunshine Coast.
They discovered endless rows of mussels with dead meat attached to the inside of the shell, as well as other dead creatures like starfish and barnacles.
Harley calculated the number of dead animals found in small areas and multiplied it by the size of habitat in the Salish Sea, which stretches from Campbell River, B.C., to Olympia, N. Washington State.
“You can fit around 2,000 molds in an area the size of your stove,” he said.
“Imagine how many stoves you could put in Stanley Park, then how many Stanley Parks could fit into the Salish Sea. So if you lose a few hundred or a few thousand mussels for each shore, huge numbers. ”
Clearing will temporarily affect water quality as mussels and clams help filter the sea, Harley said.
While the mussel bed will likely recover in a year or two, Harley noted that heat waves will occur more frequently and with greater severity due to climate change.
“At the end of the day, we just won’t be able to keep these filter feeder populations on shore as far as we’re used to,” he said.
Harley said similar finds of dead seashells have already been made in the Strait of Georgia and Washington state. He plans to visit the Gulf Islands and Vancouver Island to confirm seaside deaths in those areas, with the goal of publishing a peer-reviewed article as early as next year.
The deaths, he said, are a reminder that the environment suffers from severe consequences from extreme weather events.
“If we don’t like it, then we have to work harder to reduce emissions and take other steps to reduce the effects of climate change.”