Massive Toxic Algae Blooms May Prove a Sign of Climate Change to Come

The water began turning a barely perceptible brownish-green in early May, a sign that algae were present and growing in the waters of Monterey Bay. By the end of month, Raphael Kudela, a professor of ocean sciences at the University of California, Santa Cruz, and his team, who run a regional algae monitoring project, were measuring some of the highest levels of the neurotoxin domoic acid ever observed in the region.

Although domoic acid, produced by marine diatoms of the genus , is a naturally occurring toxin, during a toxic algal bloom, it accumulates at dangerous levels in shellfish and small fish like sardines and anchovies, which are then eaten by larger marine creatures and humans. Contaminated seafood can cause nausea and vomiting in people. At high levels, the toxin can cause brain damage, memory loss and even death.

Today, the algae bloom observed in Monterey Bay waters has morphed into what some researchers suspect could be the largest ever recorded, stretching from central California all the way up to Alaska. Currently, the bloom is estimated at 40 miles wide and goes 650 feet deep into the Pacific Ocean.

“It’s a pretty massive bloom,” said Kudela, who runs the regional monitoring project with funding from the National Oceanic and Atmospheric Administration’s Ecology and Oceanography of Harmful Algal Blooms program.

“This event may be related to the unusually warm water conditions we’ve been having, and this year that warm water has spread all along the West Coast, from Washington to southern California,” he said in a June  on the university’s news site.

Algae blooms—which can occur in fresh and ocean waters and typically consist of a buildup of microscopic phytoplankton species of algae—are normal occurrences. However, increasingly, scientists have observed an uptick in harmful algal blooms, which produce natural toxins such as domoic acid and can lead to shellfish poisonings and large marine species mortality events.

A view of the future?told Capital Public Radio last week.

In mid-June, a team of NOAA biologists began monitoring the massive algal bloom in conjunction with normal surveying work the researchers carry out to assess West Coast sardine and hake populations from Mexico to Vancouver Island.

Over the course of four trips, researchers on the Bell M. Shimada, a NOAA research vessel, will collect water and algae samples, measure water temperatures and test small fish that feed on plankton. Typically, toxic algae blooms disappear in a matter of weeks, but Trainer said this one may not recede until this fall, when the ocean begins moving again. Part of what this bloom is thriving on are unusually still, warm Pacific waters.

“The fact that we’re seeing multiple toxins at the same time, we’re seeing high levels of domoic acid, and we’re seeing a coastwide bloom—those are indications that this is unprecedented,” she said.

“The blob”—a patch of unseasonably warm water that formed in the northeastern Pacific Ocean late last year—is likely also contributing to the algae bloom, researchers think.

Financial implications for fisheries

Last month, the California Department of Public Health updated its health advisory warning consumers not to eat recreationally harvested mussels and clams, commercially or recreationally caught anchovies and sardines, or commercially or recreationally caught crabs taken from Monterey, Santa Cruz and Santa Barbara counties due to measured “dangerous levels” of domoic acid.

In June, a large Dungeness crab fishery in Washington was shuttered, the first time a crab fishery in Washington has been closed because of domoic acid since 2003. Last month, NOAA gave the state $88,000 in grant money to study the bloom.

Domoic acid outbreaks aren’t unusual in the fall, particularly in razor clams. In the late 1990s and early 2000s, state officials found evidence of the toxin, said Jerry Borchert, a biotoxins specialist for the Washington State Department of Health’s shellfish program.

What is new, he said, is the appearance of high levels of domoic acid in the spring, which is affecting the $84 million crab industry in the state. “This is one of the more intense blooms,” Borchert added. “This is a major economic pain for our industry out here.”

Along all coastal beaches in Washington, officials have prohibited harvesting of razor clams due to high levels of toxins. In the Puget Sound, paralytic shellfish toxins (PSTs) are also causing restrictions for shellfish harvests, he said. PSTs and domoic acid are rarely found in shellfish at the same time, but they have been found together this year.

“Our closures for that [PST] occurred at the beginning of April,” he said, noting that usually, those types of restrictions wouldn’t begin until June. “That’s likely due to elevated water temperatures.” With climate change, water temperatures are predicted to increase, he added.

“That is something we’re thinking about,” he said. “What happens if these happen earlier, last for longer and happen in places that haven’t had them before?”

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