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Toxic red tide algae bloom cited for fish die-off

September 4, 2022

San Francisco Bay Area affected since late July

Environmental scientists are investigating an ongoing harmful algal bloom (HAB) and the extent of the ecological damage as cities have been busy with shoreline cleanups of ‘thousands’ of dead fish and other marine life, reports Associated Press.

California Fish and Wildlife Department spokesperson Jordan Traverso said an “estimated 10,000 yellowfin gobies died … as well as hundreds of striped bass and hundreds of sturgeon.”

She added that dissolved oxygen levels and/or toxins produced by the algae are probably impacting all aquatic species in the area “to some degree.” Wildlife staff are sampling strategic locations to “verify the extent of the harm to fish and aquatic species.”

Algae blooms and dead fish were reported not only along the Oakland and Lake Merritt shorelines, but also “for many miles to the north and south along the coastline,” reads City of Oakland’s 9/1/2022 community update reads.

The bloom was detected in late July in the Oakland and Alameda area according to Eileen White, executive officer of the San Francisco Bay Regional Water Quality Control Board. She mentioned this bloom is unusually “large” and its toxicity widespread.

Contra Costa, Marin and San Mateo counties also have reported algae blooms.

The City of Oakland’s public works department and water board has posted signs warning lake visitors not touch the water, in the event that toxins are present and can cause skin and eye irritation. The water control board discourages people and pets from touching any water “reddish-brown” in color.

The microorganism Heterosigma akashiwo is considered the cause. It was first spotted in the Alameda Estuary. While it is always present in the bay, scientists are studying “what caused it to spread so far and wide and for so many weeks,” reports Associated Press.

Algae are a natural part of the ecosystem, especially during the summer season, but an overabundance of the compounds they release can accumulate to levels harmful to wildlife and people advises the California Water Quality Monitoring Council.