Did L.A. wildfire debris worsen this year's toxic algal bloom? Researchers say it's unlikely

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When scores of dead and dying sea animals began washing up on L.A.-area beaches just weeks after January’s devastating fires, the timing seemed suspicious.Harmful algae blooms had sickened marine life in each of the three years prior.

But the especially high number of animal deaths this year prompted several research teams to investigate whether runoff from the fires may have accelerated algae growth to particularly dangerous proportions.The evidence available so far suggests that this year’s algae bloom would have been just as deadly if the catastrophe on land hadn’t happened, multiple scientists said this week.“Some of the fire retardants have nutrients in them, like ammonia or phosphate, that can fuel the growth of phytoplankton and the growth of organisms in the ocean.And we do see some spikes in those nutrients early on, immediately post-fire,” said Noelle Held, a University of Southern California microbiologist and oceanographer who has tested ocean water along L.A.’s coastline regularly since January.

“But those increases are completely dwarfed by the major shift that happened in the ocean between the end of February and the beginning of April — the upwelling event.” Upwellings occur when winds push warmer surface waters from the coastline out to sea, allowing colder, nutrient-rich waters from deeper in the ocean to rise up and take their place.These surges occur naturally in Southern California in winter and spring and contain elements like nitrogen and phosphorus that feed microbes (algae included).

They often precede harmful algae blooms, though scientists are still trying to figure out the precise balance of factors that lead to sudden explosions in toxin-producing algae species.Four different algae species were present in this year’s bloom.

The two most dangerous produce powerful neurotoxins that accumulate in the marine food chain: Alexandrium ...