Shellfish, Climate Change & Future Shock


Dungeness crabs for sale at Fisherman’s Wharf in San Francisco. California’s Dungeness crab season was shut down in 2015, when record high ocean temperatures and lingering toxic algae blooms raised the domoic acid in shellfish to unsafe levels. A new study links dangerously high levels of the neurotoxin to warmer ocean temperatures, suggesting such closures could become more common in the future. Eric Risberg/AP

Thanks to the salt folks over at National Public Radio (USA) for one more bit of bad news related to our food preferences and the future as affected by climate change:

Warming Oceans Could Boost Dangerous Toxin In Your Shellfish Dinner


West Coast crab fishermen just ended an 11-day strike over a price dispute. But a more ominous and long-term threat to their livelihood may be on the horizon. A new study in the Proceedings of the National Academy of Sciences has found a link between warming ocean conditions and a dangerous neurotoxin that builds up in sea life: domoic acid.

Seafood lovers got a glimpse of that threat in 2015, when record high ocean temperatures and lingering toxic algae blooms raised the domoic acid in shellfish to unsafe levels, shutting down the West Coast Dungeness crab fishery from Alaska to Southern California for several months. Though less dramatic, the problem emerged again this season, when harvesting was again delayed for portions of the coasts.

Domoic acid is a toxin produced by Pseudo-nitzschia, a micro algae which can accumulate in species like Dungeness crab, clams, mussels and anchovy. It can be harmful to both humans and wildlife, including sea lions and birds. Remember the famous Alfred Hitchcock movie, The Birds? It was inspired by a real-life incident of California seabirds driven into a frenzy by the neurotoxin.

Although we’re starting to hear about domoic acid more often, it’s been on the radar of public health officials since a Canadian outbreak in 1987 killed three and sickened over 100. In mild cases, it can cause vomiting, diarrhea and abdominal cramps. Severe cases can cause trouble breathing, memory loss, and even coma or death.

In the case of Dungeness crabs, the food chain looks like this: The phytoplankton Pseudo-nitzschia produces the toxin domoic acid during an algae bloom. Zooplankton and filter feeders, like clams and mussels, then eat that phytoplankton. (Interestingly, not all shellfish react the same way. Mussels, for example, are able to rid themselves of the toxin within a few weeks, while domoic acid may linger in clams for several months, even up to a year.) Those delicious Dungeness crabs we like so much have a taste for clams, which is where domoic acid can be passed up the food chain to us humans.

Officials are able to test for unsafe levels, keeping tainted seafood out of restaurants and away from seafood counters, but scientists haven’t been able to predict when natural algae blooms may take a toxic turn — until now.

“The record of domoic acid is now 20 years long, allowing us to look at it from a different perspective than anyone has previously,” says Morgaine McKibben, a Ph.D. candidate at Oregon State University and lead author of the new study…

Read the whole story here.


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