Heat Wave may have Killed a Billion Sea Animals

July 8, 2021

A thermal image of recently killed mussels in Lighthouse Park in West Vancouver, B.C., captured on June 28. The scale bar on the right shows the hottest and coolest temperatures recorded in the image.  (Chris Harley/University of British Columbia)

In our conversations about “building resilience” against heat waves, I can’t stop thinking about the creatures we’re not able to protect.


Chris Harley walked on to Vancouver’s Kitsilano Beach in late June and smelled death. 

Carpeting the sea rocks were tens of thousands of mussels, clams, sea stars and snails, emitting a putrid odour that hung thick in the heat. 

“I was pretty stunned,” he recalled. 

Harley, a marine biologist at the University of British Columbia, now estimates that last week’s record-breaking heat wave in B.C. may have killed more than one billion seashore animals living along the Salish Sea coastline. 

The findings shine a 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 unravelled.

As temperatures cracked 40 C in Vancouver, and several degrees higher in B.C.’s Interior, infrared cameras used by Harley’s team recorded temperatures above 50 C on rocky shoreline habitats. (122 F)

Intertidal animals like mussels, which inhabit the area where land and sea meet, can endure temperatures in the high 30s for short periods of time, Harley said. 

But the scorching heat, combined with low tides in the middle of the afternoon, created a dangerous combination for more than six hours at a time.

“A mussel on the shore in some ways is like a toddler left in a car on a hot day,” Harley said.

“They are stuck there until the parent comes back, or in this case, the tide comes back in and there’s very little they can do. They’re at the mercy of the environment. And on Saturday, Sunday, Monday, during the heat wave, it just got so hot that the mussels, there was nothing they could do.” 

Tipped off by the smell on the Sunday morning of the heat wave, Harley and a team of student researchers began to canvas multiple coastlines, including those in West Vancouver and on the Sunshine Coast. 

They discovered endless rows of mussels with dead meat attached inside the shell, along with other dead creatures like sea stars and barnacles. 

Harley calculated the number of dead animals found in small areas and multiplied it by the habitat size in the Salish Sea, which spans from Campbell River, B.C., to Olympia, Wash. 

“You can fit about 2,000 mussels in an area the size of your stovetop,” he said. 

“Imagine how many stovetops you could fit into Stanley Park, and then how many Stanley Parks fit into the Salish Sea. So if you’re losing a few hundred or a few thousand mussels for every major shoreline, that quickly scales up to a very, very large number.” 

The wipe-out 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 happen more frequently and with greater severity due to climate change.

“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. 

Harley said similar discoveries of dead shellfish have already been made in the Strait of Georgia and Washington state. He plans to visit the Gulf Islands and Vancouver Island to confirm seashore deaths in those areas, with the aim of publishing a peer-reviewed paper as early as next year.

The deaths, he said, are a reminder that the environment is suffering severe consequences from extreme weather events. 

“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.” 


8 Responses to “Heat Wave may have Killed a Billion Sea Animals”

  1. rhymeswithgoalie Says:

    “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.”

    There’s conflation of a lot of concepts in the term “reduce emissions” (reducing CO2 or all GHGs means lower temperatures, but reducing aerosols would increase temperatures).

    Zeke Hausfather discusses the issue (includes interactive graphs):

  2. J4Zonian Says:

    Regardless of the quality of the science here, the inevitable implications drawn by the lunatic right wing are bullshit.

    Net zero is bullshit; it’s nothing but a way for industry and both US parties’ right wing government to delay. Carbon capture doesn’t exist. Hydrogen is a fossil fuel scam. Offsets (Joe Romm calls them ripoffsets) are things that were already being done, or trading not cutting some trees for cutting other trees. The only way to fix that is to drastically reduce the amount of wood being used and forest being cleared for meat, other ag, and development—globally—and turn deforestation into reforestation. Probably the only way to deal with it in the countries where it’s happening most is to drastically reduce both local and global inequality and autocratic rule.

    The right wing continues to increase both, and stymie the energy transformation that has to happen to avoid the collapse of global civilization and nature. Hundreds of clean safe renewable energy projects are being held up by intransigent officials of one variety or another.

    [D]isinformation Fueled Ohio Bill Restricting Renewable Energy
    Right wing government up to it’s usual tricks—lies, manipulation, corruption.
    Four (hundred thousand) dead in Ohio.


    Yes, decreasing coal burning while replacing any part of it with gas is the second worst thing we can do about energy; it will release warming being masked by aerosols while allowing equal warming from gas to continue. The answer is to reduce energy use through efficiency, wiser lives, and electrification, while replacing all fossil fuels with clean safe renewable energy as fast as humanly possible. Clearly, Republicans and oligarchic Democrats are not interested and states are either not interested or not up to it, so we need a progressive US government to declare a climate and inequality emergency, ditch the filibuster, expand the court(s), get statehood for DC, PR, and the other territories, clear the hurdles and get renewable energy projects operating now. Winning slowly is the same as losing. Whatever it takes.

    • John Swallow Says:

      Everything is fine for these hypocrites as long as its in someone else’s back yard.
      “Kennedy tries to halt windmills
      Mr. Kennedy, a staunch environmentalist, opposes the Cape Wind project, which will place windmills in the sound’s shallows to create electricity for customers in Cape Cod, Martha’s Vineyard and Nantucket.”

      • J4Zonian Says:

        Utterly irrelevant. Swallows needs to stop muddying the waters.

        While s/he’s at it, s/he should stop lying about climate.

        The Earth is warming.
        It’s caused by humans’ fossil fuel burning, use of land, and industrial chemicals.
        If not stopped it will destroy civilization and most life on Earth.
        We can still save some of what we love if we act radically and massively, now.

        We need to replace fossil fuels with efficiency, wiser lives, and clean safe renewable energy, transform chemical-industrial agriculture to small-scale low-meat organic permaculture, stop deforestation and transform extractive forestry with regenerative methods, stop synthesizing harmful industrial chemicals, radically equalize economically and politically, and do a bunch of other things, all in the next 9 years.

        • J4Zonian Says:

          PS The Washington Times is a right wing piece of garbage founded by Sun Myung Moon and still owned by the Moonies. Any citation of it is an admission that there are no credible arguments on one’s side, and that all rationality opposes everything one says.

          The article Swallows cites is from 2006, a lifetime ago in clean safe renewable energy years, when the Kennedies and Kochs were aligned in their elitist opposition to needed wind power near their enormous compounds

  3. redskylite Says:

    Not only sea animals, there’s no a/c under water:

    River temperatures reaching and surpassing 70 degrees Fahrenheit (21 Celsius) pose a threat by depleting oxygen levels and possibly feeding algae blooms. Rainbow and brown trout in the Colorado River, which thrive in temperatures between 50 and 60 F (10 and 16 C), become lethargic and often stop feeding, Duncan said, and wildlife officials have seen evidence of the fish dying in parts of the river.


  4. indy222 Says:

    I’m seeing lots of weakened and torn-off mussel clusters locally in Central California, and dead mussels as well. The clusters still attached are thinning out. It’s been a slowly on-going thing for the past few years.

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