Climate

Toxic Algae Will Thrive As The Planet Warms

CREDIT: AP Photo/Mark Thiessen, File

Last summer, one of the largest toxic algal blooms in recorded history hit the West Coast, shutting down fisheries from California to Washington. Scientists were seeing cells of the toxic bloom as far south as Mexico, and as far north as Homer, Alaska. At the time, Vera Trainer, manager of the Marine Biotoxin Program at NOAA’s Northwest Fisheries Science Center, told ThinkProgress that the bloom was uniquely widespread, “more so than we’ve seen in the past.”

But scientists now are saying that, with climate change, toxic algal blooms like the one seen last summer might become more common along the Pacific coastline, impacting marine communities as far north as Alaska with much more consistency than in the past.

In a new study published in the journal Harmful Algae, researchers from the National Oceanic and Atmospheric Administration (NOAA) found the presence of domoic acid — the same toxic acid that shut down West Coast fisheries last summer — in marine mammals along the Alaskan coastline. This was a surprise, because Alaskan waters were previously thought to be too cold to encourage the growth of domic-producing algal blooms.

Researchers analyzed 13 different species of marine mammals, including sea lions, whales, otters, dolphins, and seals. Altogether, the study looked at 905 samples collected between 2004 and 2013. In all 13 species, researchers found signs of domoic acid. The study also detected the presence of another toxin, known as saxitoxin, in 10 of the 13 marine mammals they analyzed. The presence of these toxins was geographically widespread, ranging from Alaska’s southern coastline to its most northern waters.

“It’s not that we didn’t know that the cells that produce these toxins could be up there,” Kathi Lefebvre, the lead author on the study, told Undark Magazine. “What we didn’t know is they were in high enough levels to be detected in so many marine mammals that high up on the food chain.”

Algal blooms happen when microscopic marine algae proliferate in huge numbers. Not all algal blooms are toxic, but some kinds of algae do produce toxins, such as domoic acid, which is a powerful and fatal neurotoxin. Harmful algal blooms aren’t uncommon for the Pacific, normally occurring during the spring months when the water temperature is at its highest. But as climate change leads to both rapid declines in sea ice and increased ocean temperatures, the geographic range and duration of these toxic algal blooms is expected to increase.

That’s because algae thrive in warmer waters, which both encourage growth in certain kinds of algae and discourage a mixing of ocean waters. Alaskan waters are some of the most rapidly warming waters in the world, having risen by three degrees Celsius in the past decade.

“The waters are warming, the sea ice is melting, and we are getting more light in those waters,” Lefebvre told the Washington Post. “Those conditions, without a doubt, are more favorable for algal growth. With that comes harmful algae.”

Before last summer’s toxic bloom, marine animals suffering from domoic acid poisoning had never been seen north of California. But last summer, scientists observed a sea lion off the coast of Washington suffering from seizures, a sign of domic acid poisoning. The animal eventually had to be euthanized.

Alaska has also seen an increase in marine animal mortalities in recent months. In August, 30 dead whales were observed along the shoreline of the Gulf of Alaska. Months later, scientists were puzzled by the appearance of thousands of dead, seemingly-starved sea birds on Alaska’s coasts. At the time, toxic blooms were not thought to be part of the problem.

But Bruce Wright, senior scientist for the Aleutian and Pribilof Island Association, the federally recognized tribal organization of Alaska's indigenous Aleut citizens, told the Washington Post that he would be surprised if toxic algae did not play a role in the deaths. Toxic algal blooms impact the lowest levels of the food chain first, meaning that toxins often end up in shellfish and feeder fish -- things that larger marine animals feed on. Even if the toxins don't kill the larger marine animals outright, toxic algal blooms can effectively wipe out lower levels of the marine food chain, decimating supplies of food that larger marine animals rely on.

Unusually warm waters fueled by this year's historically strong El Niño pattern is also causing trouble for Chile, which is the world's second-largest exporter of salmon. A toxic algal bloom there has killed nearly 23 million fish, which could end up costing the country nearly $800 million in economic losses.