The current algal bloom being experienced along the Pacific coast is far larger than any previously recorded. They are cyclical and occur in the summer. The algae is extremely toxic. According to the National Oceanic and Atmospheric Administration, this bloom stretches from California to Alaska, is 40 miles wide and as much as 650 feet deep. It is believed to be caused by the fact that ocean waters in the northeast Pacific are unusually warm. Researchers are calling it "the blob."
Samples taken from the bloom appear to be made up largely of an algae named Pseudo-nitzschia, of which produces a neurotoxin called domoic acid, which can build up to levels in seafood that are toxic to humans and other animals. Many fisheries have been shut down along the coast, after toxin levels rose to dangerous levels.
While red tides are cyclical, there are indicators that the unusual nature of this event is being influenced by global warming, and researchers are concerned that the current El Niño will trigger a stronger bloom next year. Pat Glibert, professor at Horn Point Laboratory, University of Maryland Center for Environmental Science, says "There’s no question that we’re seeing more algal blooms more often, in more places, when they do occur, they’re lasting longer and often over greater geographical areas. We’re seeing more events than documented decades ago."