Jake Slobe | January 25, 2017
A new link between toxic algae and warmer ocean temperatures provides the latest sign that climate change is causing biological disturbances in the oceans. Scientists tracked West Coast outbreaks of the planktonic algae back to 1991, finding a strong correlation with warm phases of ocean cycles.
The new research, published this month in the Proceedings of the National Academy of Sciences, focused on a single-cell species of phytoplankton called Pseudo-nitzschia. The phytoplankton produces domoic acid, which can be fatal to humans if consumed at high levels by eating shellfish. Domoic acid has also been implicated in mass die-offs of marine mammals, including sea lions, sea otters, dolphins and whales.
A 2015 Pseudo-nitzschia bloom from the extending from California coast up to Alaska was the most widespread on record, taking a $100 million bite out of the Dungeness crab industry in Washington, Oregon and California, according to NOAA. Scientists monitor for the toxin and close down fisheries when it reaches dangerous levels. There were unprecedented outbreaks of similar pathogens around the world that year, which was Earth’s warmest on record until 2016.
Researchers have documented the changes to plankton cycles in recent years, including bigger and longer-lasting blooms spreading to new territory. Evidence points to ocean warming as a big part of the problem, with some regional nuances. In 2014, a European Union science report concluded that toxic algae blooms will increase under climate change. Researchers of the new study wrote,
“If these warm ocean regimes become more persistent due to global warming, as some hypothesize, West Coast domoic acid events may also increase in persistence and frequency.”
Since 1900, the average sea surface temperature has increased by 0.85 degrees Celsius. Coastal waters are “very likely to continue to warm in the 21st century, potentially by as much as 4 to 8 degrees Fahrenheit,” according to the EPA, which has warned of increased algae blooms.
Lead author of the new study and oceanographer at Oregon State University, Morgaine McKibben said the scientists compared temperature records from West Coast waters with official reports of elevated toxin levels to find a surprisingly strong correlation between ocean warm phases and outbreaks. She said,
“The warmer the conditions, the bigger the impacts. If it’s a really warm year, it’s going to be a really toxic year.”
The new study looked back 26 years, with the outbreaks spiking during warm phases of the ocean cycle and during El Niño years. While the exact link between climate change and recurring cycles like El Niño has been difficult for scientists to pin down, research shows a clear global warming fingerprint that links greenhouse gas pollution and warmer ocean water off the west coast.