Researcher explains why thousands of dead mussels line coast of Bodega Bay

BODEGA BAY, Calif. (KGO) -- The particular splendor of low tide along Northern California's Coast...

A sliver of low-lying summertime fog, year-round tranquility, and predictability---or maybe not for Jackie Sones, a researcher at the Bodega Marin Lab.

She had been out on the rocks one afternoon last month when she noticed a distinct change.

"Normally the mussel beds are dark and tight. It looks like a carpet," she said.

But, not that day. Not with bleached, dried out, empty mussel shells cracking beneath her shoes.

They stretched as far as Jackie could see. "We're talking tens of thousands of mussels."

It's what scientists call a mass mortality event, or die-off.

Since the initial discovery, we now know that it extends as far north as Fort Bragg, with climate change as the likely cause.

"We have seen smaller die-offs, but never a die-off to this extent," said Sones.

It is the largest event like this in fifteen years.

Researchers blame a confluence of factors that should never happen in June; a three-day heatwave combined with low tides.

The mussels never had a chance.

They thrive in temperatures around 50 degrees and can survive in rare temperatures approaching the low 90's.

But that day, in the heat wave, their environment hit three digits.

"In essence, they were cooked," said Sones.

It matters because mussels are foundational in these waters. Other species depend on them for survival. Think biological dominoes.

"So if we see more events like this more frequently we will be more concerned about the mussel bed and their ecosystem as a whole."

What began with a pleasant walk, now interpreted as a warning shot.

"I hope to not see a surprise like this again," said Jackie Sones.