On the enigmatic ‘flying potato’, neither plant nor animal, that caused the Bay’s biggest harmful algal bloom in history

Author: Mukta Patel, Bay Nature
September 21, 2022
Heterosigma akashiwo cells under a microscope
Photo Credit: William Cochlan

At times this summer, the shores of San Francisco Bay looked like a piscine battlefront — strewn with dead white and green sturgeon, leopard sharks, striped bass, bat rays, smelt, anchovies, and other fish. It started in late July in Alameda and expanded throughout the entire Bay. By late August, some 10,000 fish had reportedly died at Oakland’s Lake Merritt alone. Where the killer algae bloomed, the water was dull and rust-colored. One resident was quoted saying“the end was near”. A local scientist called the event a “wildfire in the water”. The murk came from the sheer density of the culprit, which was multiplying in the millions: a miniscule organism called Heterosigma akashiwo — akashiwo means “red tide” in Japanese. This wasn’t H. akashiwo’s first star turn.

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