The Blob That Might Ruin Christmas

For as long as I can remember, every Christmas Eve my family has eaten Dungeness Crab for dinner (with French onion soup, and sourdough bread). It’s a Holiday tradition in many Bay Area households—you can buy these sweet, tangy crustaceans only when they're in season, from late November through the winter.

My dad would drive from our suburban town of Clayton to a live fish market in San Francisco’s Chinatown, where you could buy dozens of different live marine creature—clams, oysters, lobsters, fish, even turtles.

Photo: Sam Breach

He’d bring them home and we’d soak them in a bucket of saltwater until it was time to cook them. We kids learned how to pick one up without getting pinched (you want to grab between their back legs, where the claws can’t reach.)

But there may be no Christmas crab this year because of a giant blob.

No, not that blob; a blob of warm water in the north Pacific Ocean.

(Scientists really do call it "the blob," by the way.) This unusually warm patch of ocean—more than a thousand miles across—has been about 3 or more degrees Fahrenheit (1.5 to 2 degrees Celsius) warmer than normal.

That may not sound horrifying, but in the two years since the blob first appeared, it has played havoc with plankton, those tiny drifting creatures at the base of all the ocean’s food webs.

This year, the warmer water has caused a toxic bloom of billions of microscopic algae shaped like porcupine quills, called Pseudo-nitzschia.

Photo: Exploratorium Living Systems

All along the California coast, these pointy microbes are secreting a neurotoxin—called domoic acid. Crabs, as well as mussels, clams, and other organisms that eat plankton, are absorbing the domoic acid.

The toxin doesn’t kill the crab, but people who eat them would be in for an un-happy holiday. Domoic acid can cause nausea, vomiting, diarrhea, and far more serious symptoms in some cases.

I’ve always thought that thin, pointy Pseudo-nitzschia had a sinister look about them. But scientists say they don’t always produce the toxin.

During our regular weekly plankton net drag at the Exploratorium, we have always found Pseudo-nitzschia happily co-existing with other plankton.

Photo: Exploratorium Living Systems

In addition to toxin laced crustaceans, the blob has caused other problems. Some other types of plankton die off in the blob’s warmer waters. So the many fish species that eat plankton have trouble surviving. With fewer fish, seabirds like the auklet have also been dying in the Pacific northwest. Some scientists also say that sea lion pups are starving because of the lower fish populations.

I had assumed that the blob was linked to climate change, and some scientists think it is. Others say it’s more likely the result of a longer term cycling of ocean temperatures called the Pacific Decadal Oscillation.

Whatever the cause, there’s a chance that conditions will change later on this winter as El Niño kicks in. If so, maybe we’ll be able to eat crab again. But for now, it’s looking like we’ll have to find another main course for Christmas Eve.

Check the California HABMap website for the latest news about harmful algal blooms, such as Pseudo-nitzschia.