Clams, like other bivalve molluscs, may contain high concentrations of domoic acid. (Photo: Stock File)
Study links 'El Niño' with higher shellfish toxicity
Thursday, January 12, 2017, 00:20 (GMT + 9)
A group of researchers discovered that there is a strong correlation between toxic levels of domoic acid in shellfish and the warm-water ocean conditions powered by El Niño events and the Pacific Decadal Oscillation.
The relation was found by scientists at the Oregon State University, the University of Oregon, the National Oceanic and Atmospheric Association (NOAA), and the Oregon Department of Fish and Wildlife.
The work was primarily supported by NOAA, and has been published in the scientific journal Proceedings of the National Academy of Sciences.
The study explains that by using a combination of time-series data spanning two decades, the scientists not only showed a clear link between domoic acid and these larger climatic phenomena, but also developed a new model to predict with some accuracy the timing of domoic acid risks in the Pacific Northwest.
Researchers also pointed out that the findings are particularly timely, given the potential for greater domoic acid outbreak occurrences as oceans continue to warm due to climate change.
Domoic acid is a potent neurotoxin produced by specific types of phytoplankton and ingested by shellfish, can cause serious health effects in humans and some other animals.
In recent years, dangerous levels of these toxins have led to the repeated closure of crab and shellfish harvesting in the Pacific Northwest among others as the problem threatens public health, marine wildlife and can cost millions for coastal economies.
Although it was suspected that these episodes were connected to major climatic forces, it had not been confirmed until now.
The acid is produced by the diatom genus Pseudo-nitzschia, and enters the marine food web when toxic blooms of these micro-algae are ingested by animals such as anchovies and shellfish.
In humans, it is referred to as “amnesic shellfish poisoning,” and symptoms can range from gastrointestinal disturbance to seizures, memory loss or, rarely, death.
Matt Hunter, co-author of the study with the Oregon Department of Fish and Wildlife, explained, “Advance warning of when domoic acid levels are likely to exceed our public health thresholds in shellfish is extremely helpful.”
“Agencies like mine can use this model to anticipate domoic acid risks and prepare for periods of more intensive monitoring and testing, helping to better inform our decisions and ensure the safety of harvested crab and shellfish,” the researcher stressed.