More and more fish keep dying due to the ongoing Heterosigma akashiwo algae bloom in Oakland’s downtown lake. This species of algae has produced toxic blooms in other places along the Pacific coast before.
No one’s certain of how a red tide of H. akashiwo kills fish, but a likely theory is that when the billions of algae in Lake Merritt started dying, bacteria that ate the dead algae used up all the oxygen in the water.
Other theories suggest the algae themselves produce toxins such as hydrogen peroxide that interfere with fishes’ breathing.
Whatever the method, the massacre is ongoing and near total; every day more dead fish float to the surface and against the shore of the lake.