Cellular look at Pseudo-nitzschia, a harmful algal bloom that is threatening health of humans, marine mammals by creating toxins in filter feeding fish and shellfishNational Journal

Along the Pacific Coast, stretching thousands of miles from Alaska to California, is a massive, record-breaking bloom of toxic algae.

Fueled by unusually warm water in the Pacific, the algae species Pseudo-nitzschia have grown in unprecedented concentrations, casting a brown sheen over the ocean and releasing the neurotoxin domoic acid into the waters.

In June, the National Oceanic and Atmospheric Administration was tipped off that this summer's algae bloom may be intense after finding unusually high concentrations in California's Monterey Bay. "During a normal Pseudo-nitzschia bloom, domoic-acid concentrations of 1,000 nanograms per liter would be considered high," NOAA reported. "However, by mid May concentrations in Monterey Bay reached 10 to 30 times this level."

That was three months ago. Now, as ocean scientist Raphael Kudela explains to CBS news: "It's definitely the largest bloom of this particular algae seen on the West Coast, possibly anywhere, ever."

Pseudo-nitzschia is a type of phytoplankton, a class of microscopic organisms that live near the surface of the ocean and produce half of the world's oxygen. Most phytoplankton don't cause health problems: Only 2 percent of species manufacture toxins.

The problem with the toxic algae isn't that a person may get sick by just swimming in waters. It's that the domoic acid the algae produce accumulates in the food chain. Species of fish and shellfish can handle high concentrations of the acid, but the mammals that feed upon them cannot.

A record-breaking algal bloom continues to expand across the North Pacific reaching as far north as the Aleutian Islands and as far south as Southern California. Average chlorophyll concentrations (milligrams per cubic meter of water) are shown in this image using Suomi NPP VIIRS satellite data from July 2015. (NOAA / NASA)

"In humans the toxin crosses into the brain and interferes with nerve signal transmission," NOAA notes. "People poisoned with very high doses of the toxin can die, while lower doses can cause permanent brain damage (short term memory loss)."

The casualties of the toxin so far have been confined to the animal kingdom: Nine endangered fin whales in Alaska have been found dead, with domoic acid the suspected culprit, and beached sea lions have been acting oddly, possibly poisoned by the toxin.

"California sea lions have been particularly visible victims of domoic acid exposure and toxicosis," researchers at the Marine Mammal Center wrote in a 2011 scientific paper. The toxin appears to damage a region of their brain called the hippocampus, which in humans is a structure associated with memory. When sea lions are poisoned with domoic acid, they act drunk: They become lethargic, disoriented, and sometimes aggressive. Officials at Vandenberg Air Force Base in California had to close beaches twice in July due to erratic sea-lion behavior.

University of California-Santa Cruz scientists note it's unusual for a spring algae bloom to persist so long into the summer, and speculate that unusually warm coastal waters may be fueling their continued growth. (The unusual concentration of warm water in the Pacific has been dubbed "The Blob.").

Officials in California, Oregon, and Washington have implemented warnings or restrictions on fisheries in areas where exposure to domoic acid is high. NOAA estimates that Washington state has lost $9 million in revenue from stymied razor clamming in the state.

The bloom in Pacific is not the only algae problem in the country this summer. Algal blooms are concurrently festering in the nation's freshwater lakes, making them dangerous for swimmers, and threatening municipal water supplies. Blue-green algae, which is also toxic, feeds off of fertilizer runoff, and appears as a film of children's-show green slime on top of the water. On Lake Erie, this summer's bloom could be one of the worst in years, NOAA forecast in July. Lake Erie shines so bright with green algae, it can be seen from space.

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