A billion sea animals died during recent West Coast heat waves, including mussels, starfish, crabs

An estimated 1 billion sea creatures died in the heat waves that swept the Western U.S. and Canada over the last few weeks. They couldn’t survive triple-digit temperatures rarely seen in coastal areas and especially in the Pacific Northwest.

Marine biologist Christopher Harley witnessed the massive die-off along the shores of Vancouver, Canada. “The first thing I noticed before I saw anything was the smell. The second thing I noticed was the shoreline crunched when I walked on it, which is not normal. And that's because I was walking over dead mussel after dead mussel in dense beds.”

Harley says the combination of extreme temperatures and low tides prompted their deaths. “On one shore, in an area about the size of a tennis court alone, there were about a million dead mussels. In a similar area, you can fit even more dead barnacles. And once you start adding all those species together, and thinking about how many tennis courts worth of coastline we have in Washington and British Columbia, the numbers become pretty staggering,”

In the long term, Harley says the die-off could impact other animals in the local ecosystem. That includes the surf scoter, a sea duck that migrates to the region for food before flying back to the Arctic. They feed on the mussels, and it’s unclear how many mussels will be left for them to feed on when they return.