The heat wave ravaging British Columbia last week is being blamed for mass death of mussels, clams and other marine animals that live on the beaches of Western Canada.
Christopher Harley, a professor in the zoology department at The University of British Columbia, found countless dead mussels popped open and rotting in their shells on Sunday at Kitsilano Beach in Vancouver.
Harley studies the effects of climate change on the ecology of rocky shores where clams, mussels and sea stars live, so he wanted to see how the intertidal invertebrates were faring in the record heat wave that hit the area on June 26-28.
“I could smell that beach before I got to it, because there was already a lot of dead animals from the previous day, which was not the hottest of three,” he said.
“I started having a look around just on my local beach and thought, ‘Oh, this, this can’t be good.'”
Mussels attach themselves to rocks and other surfaces and are used to being exposed to the air and sunlight during low tide, Harley said, but they generally can’t survive temperatures over 100°F for very long.
Temperatures in downtown Vancouver were 98.6°F on June 26, 99.5°F on the 27th and 101.5°F on the 28th.
Harley and his student used a FLIR thermal imaging camera that found surface temperatures topping 125°F.
At this time of the year, low tide hits at the hottest part of the day in the area, so the animals can’t make it until the tide comes back in, he said.
Climate scientists called the heat wave in British Columbia and the Pacific Northwest in the United States “unprecedented” and warned that climate change would make these events more frequent and intense.
Lytton, British Columbia, broke Canada’s all-time record on June 30 when the temperature topped 121°F. The town was all but destroyed in a deadly wildfire.
There were 719 deaths reported to the province’s coroners between June 25 and July 1, three times as many as would normally occur during that time period.
‘Billion sea animals killed’
Harley said the heat may have killed as many as a billion mussels and other sea creatures in the Salish Sea, which includes the Strait of Georgia, the Puget Sound, and the Strait of Juan de Fuca, but he said that was a very preliminary estimate.
He said that 50 to 100 mussels could live in a spot the size of the palm of your hand and that several thousand could fit in an area the size of a kitchen stovetop.
“There’s 4,000-some miles of shoreline in the Salish Sea, so when you start to scale up from what we’re seeing locally to what we’re expecting, based on what we know where mussels live, you get to some very big numbers very quickly,” he said.
“Then you start adding in all the other species, some of which are even more abundant.”
Brian Helmuth, a marine biology professor at Northeastern University, said death of a mussel bed can cause “a cascading effect” on other species.
“When we see mussel beds disappearing, they’re the main structuring species, so they’re almost like the trees in the forest that are providing a habitat for other species, so it’s really obvious when a mussel bed disappears,” he said.