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Group reports of December sea lion rescue from Cerrito Creek

From the December e-newsletter of Friends of 5 Creeks:

(Sick) Sea Lion on tidal Cerrito Creek

On Saturday, Dec. 21, the Marine Mammal Center rescued a disoriented sea lion that had swum up tidal Cerrito Creek to Pacific East Mall, at the foot of Albany Hill. Most wildlife sightings are exciting: River otters are making their way into cities; F5C members recently enjoyed watching a great horned owl on the edge of Codornices Creek.

This sighting, however, was not good news. The young male sea lion was sick from domoic acid. This deadly toxin is produced by so-called “red tide” algae, and accumulates in shellfish and other prey that birds and mammals eat. Blooms of these toxic algae seem to be becoming more common in San Francisco Bay.

The likely reason seems surprising: The Bay is becoming clearer. Our cities discharge massive amounts of nutrients to the Bay in treated sewage. But a muddy bay kept sunlight from stimulating growth. Today, though, dams trap mountain erosion that formerly washed downstream. Mud washed down by hydraulic mining over a century ago is dwindling. The Bay’s hardened shorelines can’t erode. And recent lack of rain and storms means little new erosion or disturbance.

Our Cerrito Creek sea lion — still being cared for at the Marine Mammal Center as this is written — is not proof of anything. But life really is a web. Even lowly mud, or lack of it, has far-reaching effects. Our Feb. 3 Bay Currents talk, Mud Matters, will explore these fascinating interconnections, as well as some hopeful ways that mud may help us protect and revitalize the Bay. Please join us!

Chris Treadway