A toxic algae called “Heterosigma akashiwo” is blooming in San Francisco Bay, causing the water to look murky and brown and posing a danger to local marine life.
The ongoing bloom could kill fish and shellfish with its toxins, but it does not contain the cyanotoxin that kills dogs and sickens humans, according to the San Francisco Chronicle.
“There are some physical factors that might have sparked this bloom, such as that it’s been relatively clear out, the winds have died down a little bit, we have warmer waters, however, it’s really hard to associate what causes this kind of bloom,” Ian Wren, a scientist with the nonprofit San Francisco Baykeeper, told KGO-TV, a San Francisco ABC affiliate.
The bay has not seen a bloom of this type since 2004. The current “red tide” in the San Francisco Bay is now setting records.
“This is the largest and longest lasting red tide on record for San Francisco Bay,” John Rosenfield, another scientist at the San Francisco Baykeeper, told the San Francisco Examiner.
Authorities are unable to ascertain how long the bloom will linger in the bay.
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“There are so many factors that impact it — in particular, the weather, the tides. So we don’t know. It’s a natural occurrence, and it will naturally go away on its own,” Eileen White with California’s State Water Resources Control Board told the San Francisco Examiner.
Man-caused chemical nutrients from wastewater plants may be the culprit behind the algal resurgence.
“There’s about 40 wastewater treatment plants that discharge a lot of phosphorus and nitrogen into the water. And that’s the building block for algae such as this,” Mr. Wren told KGO-TV.
Although blooms are caused by multiple factors, “there’s obviously not much we can do about wind and wave action. But we can control the amount of nutrients that are in the water,” he also told the San Francisco Chronicle.
For its part, the government has offered a general warning to citizens not to enter the murky, algae-choked water.
“Heterosigma akashiwo … is not known to cause human illness (but it has been documented to contribute to fish kills). A general precaution is for people and their pets to not enter the water during times of any dense blooms or discoloration in the water,” the California Department of Public Health told KGO-TV in a statement.