Chris Harley, a marine biologist at the University of British Columbia, calculated the massive toll on mussels and other marine animals that died in the heat along the Salish Sea off Vancouver. The inland Pacific body of water stretches from the Campbell River north of Vancouver down to Seattle and Olympia in Washington state.
As he discovered endless rows of gaping dead mussels, along with dead clams, snails, sea stars and barnacles on Vancouver’s Kitsilano Beach in late June, Harley said he was “stunned.”
The scientist says mussels are the “poster child” indicator of the heat’s devastation on the ocean. They’re the most vulnerable because they can’t move to cooler water.
“A mussel on the shore in some ways is like a toddler left in a car on a hot day,” Harley told the Canadian Broadcasting Corp. “They are stuck there until the parent comes back or, in this case, the tide comes back in. They’re at the mercy of the environment … during the heat wave, it just got so hot that the mussels, there was nothing they could do.”
Mussels can tolerate temperatures as high as 86 degrees Fahrenheit for short periods of time. But Harley and a colleague using a thermal imaging camera found temperatures as high as 122 degrees along the rocky shoreline of the Salish Sea.
Such a massive die-off has a major effect on the environment. Mussels, which are in the in the middle of the food chain, provide a key transition between shore and ocean. They filter out particles and make water clearer, and they provide important nutrition to other animals, such as starfish and sea ducks.
“They grab plankton that’s floating around in the water and use it to grow, and then they feed other things on the shore so they sort of connect the open water habitat to the shoreline,” Harley explained to the Toronto Star.
Harley said similar discoveries of dead shellfish have already been made in areas of Washington state. He plans to visit the Gulf Islands and Vancouver Island to check seashore deaths from the crushing heat in those areas.
Such deadly heat waves are more likely to happen more frequently and with even more extreme temperatures due to climate change, Harley warned.
“Eventually, we just won’t be able to sustain these populations of filter feeders on the shoreline to be anywhere near the extent that we’re used to,” he said.
The deaths are just the latest dramatic sign that the environment is suffering severe consequences from climate change, Harley said.
“If we don’t like it, then we need to work harder to reduce emissions and take other measures to reduce the effects of climate change,” he told the CBC.
Thousands of mussels cooked to death on a shore in Northern California after record heat in 2019. It was believed to be the worst heat die-off there in 15 years.
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