Red Tide Muddies the Waters



For the past few days, the media have been running scary stories about an algae bloom which has caused a red tide offshore and in parts of San Francisco Bay. The red tide results from a higher-than-normal concentration of a microscopic algae (plantlike organism) known as Heterosigma akashiwo, which SF Baykeeper, the San Francisco Estuary Institute and the Aquatic Science Center have been tracking since it appeared in the last month. So far, the toxic bloom has killed large quantities of fish all around San Francisco Bay and Lake Merritt.

The red tide is different than domoic acid, which can infect sea lions, other marine mammals and even Dungeness crabs in local waters. Domoic acid is produced by a single-celled plant called Pseudo-nitzschia. Blooms of these tiny organisms seem to occur when water warms, and in the presence of agricultural runoff. The Marine Mammal Center reports no cases of red tide affecting marine mammals as of Monday, August 29.

Jim Malcolm, harbormaster of the Richardson Bay Regional Agency, told the Floating Times: “I am seeing signs of it in Richardson Bay; it is present through discoloration of the water in that the water takes on a brown color.” Malcolm has no knowledge of dead fish in Richardson’s Bay so far, thankfully.  As the accompanying video shows, there are plenty of live fish right off our docks.

While the algae isn’t toxic to humans, reports SF Gate, “it can cause skin and eye irritation, according to the San Francisco Bay Regional Water Quality Control Board. [The board] is recommending people stay out of any water that looks reddish–brown—and keep their pets out, too.” And, of course, don’t eat dead fish.

Video (shot August 29) and post by Larry Clinton