A Ticking Toxic Time Bomb

Microbes under a microscope.

Between 2014 and 2015, a “blob” of record-breaking warm water traversed the west coast of the U.S., gaining media attention as the warm temperatures wreaked havoc on the bottom of the food chain, causing fisheries like sockeye, pink, and coho salmon to collapse and thousands of sea lions and sea birds to starve. However, amid this devastation, one microscopic creature thrived or “bloomed”—a neurotoxin-producing diatom called Pseudo-nitzschia—causing devastating multi-million dollar losses for many West Coast commercial and tribal crab and shellfish fisheries that had to shut down due to the risk of toxin-contaminated seafood. The toxin produced by Pseudo-nitzschia, domoic acid, can cause amnesic shellfish poisoning in humans, with symptoms like vomiting, diarrhea, headache, loss of short-term memory, motor weakness, seizures, and irregular heart rhythms.
Beyond the clear ecological and economic devastation, this 2015 blob-associated harmful algal bloom also left the scientific community in shock. The prevailing understanding was that toxic Pseudo-nitzschia blooms were associated with nutrient-rich, cold-water pulses of water seasonally brought up or “upwelled” from the depths along the Pacific west coast. With the massive hot blob of water hovering over the coastline in 2015, there was little to no upwelling.  So how did a toxic bloom occur during this massive heatwave?

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