By Andrew Freedman From Mashable

A massive toxic algal bloom that ranks as one of the largest ever seen along the West Coast of the U.S. and Canada has spread across the coastal waters of Alaska, British Columbia and south all the way to California. The bloom has forced the shutdown of economically vital fisheries up and down the West Coast.

The bloom has erupted within an area of the northeast Pacific Ocean that has had persistently above average sea surface temperatures for much of the past two years. This warm region is known to many oceanographers and meteorologists as “The Blob.”

This unusual ocean feature, with ocean temperatures nearly 5 degrees Fahrenheit above average, has been present for about two years in the Gulf of Alaska as well as off the coast of California.

It is thought to have played a significant role in triggering California’s worst drought in a millennium, since it has altered atmospheric circulation in ways that steered storms away from the Golden State.

It also may have helped make for ideal conditions for a harmful algal bloom.

Don Boesch, president of the University of Maryland Center for Environmental Science, told Mashable in an interview that the “blob” of warm water may be indicative of a layer of the ocean where little mixing is going on between warm surface waters and cooler subsurface waters. This stagnant ocean structure can favor algal blooms and benefit certain types of algae over others, he said.

“Warmer, more stable water masses could allow this particularly toxic species of algae to gain advantage and grow more abundant than other species,” Boesch said. He has conducted extensive research on algal blooms in the Chesapeake Bay, where the main cause is nutrient runoff from the agricultural sector.

This bloom is different, he said, since it is occurring independent of any local pollution sources

Toxic phytoplankton
Algal blooms in the ocean contain microscopic plants called phytoplankton, which form the base of

the marine food web. Phytoplankton are enormously beneficial — they do, after all, produce the majority of the oxygen we breathe every day.

However, everything has a dark side, even plankton. However, everything has a dark side, even plankton.

Certain phytoplankton, known as Pseudo-nitzschia, produce dangerous neurotoxins that can sicken marine life and humans that consume fish and shellfish.

According to the National Oceanic and Atmospheric Administration (NOAA), the ongoing algae bloom has led to extremely high levels of a particular algal toxin known as domoic acid, which can kill marine life and sicken humans as well.

The high levels of this toxin have led authorities to shut down the razor clam harvest in Oregon and Washington, close much of Washington’s Dungeness crab fishery and take action to limit some sardine and anchovy fishing in California.

In May, when the bloom in the blob was still young, scientists recorded some of the highest domoic acid levels ever observed in Monterey Bay, California. According to a Monterey Bay Aquarium Research Institute press release, domoic acid levels reached 10-to-30 times the levels typically seen during harmful algal blooms observed during the past quarter century.

The acid released by plankton becomes concentrated in small fish and shellfish, which can sicken larger fish and seabirds that consume them. People can be sickened when they eat the larger fish and shellfish.

In this way, harmful algal blooms can reverberate through the food chain.

For example, according to Alaska Dispatch News, at least nine endangered fin whales that died near Kodiak Island in June are suspected to have died from algal bloom-related toxins.

There are other reports of dead or sickened whales, sea lions and other iconic large marine species, though conclusive proof is lacking that algae-related toxins were the cause in each instance. Typically, harmful algal blooms only last a few weeks, but this one has endured far longer, even growing with time since it was spotted in May.

Scientists can monitor the amount and spread of large algal blooms via satellite by measuring chlorophyll concentrations at the surface. Where blooms are present, there are usually higher chlorophyll concentrations. The concentration of microscopic algae has been particularly thick along coastal areas from Alaska’s Aleutian Islands south to Seattle.

There is reason to believe the bloom will reappear, potentially to an even greater extent, next year, too, since a strengthening El Niño event in the tropical Pacific is heating up ocean waters even more.

IMAGES:
IMAGE: WEATHERBELL ANALYTICS
Elephant Seals bask in the sunshine on the beach during their summer migration to San Simeon, California. IMAGE: JOHN PYLE/CAL SPORT MEDIA/ASSOCIATED PRESS
Map of sea surface temperature anomalies on August 7, 2015, with “The Blob” circled in blue.
Chlorophyll levels along the Washington coast and southern Vancouver Island on July 30, 2015. Bright colors indicate higher levels. IMAGE: NASA WORLDVIEW

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