Smart responses 
needed for 
marine toxins

Domoic acid doesn't harm razor clams, but can injure and even kill human who eat the clams when toxin levels are too high. Harmful algal blooms like those that produce domoic toxin will have to be managed in smart and innovative ways in this warming century.

Troubled clam season was a sign of more troubles ahead

When the marine toxin domoic acid was first reported in Pacific Northwest waters in 1991, it caused a flurry of public consternation and scientific excitement. Specialist conferences were convened about this new bully on the block, joining older issues like paralytic shellfish poisoning.

PSP hasn’t been a problem since then, but domoic acid — which causes amnesic shellfish poisoning — more than makes up for it. It’s a byproduct produced by a kind of microscopic marine organism. Domoic acid first generated headlines in 1987 after mussels raised on Prince Edward Island in eastern Canada resulted in human deaths and illnesses, including loss of the ability to store short-term memories.

After it appeared here, discussion arose that it could have been around longer, perhaps not causing significant problems. Analysis of old home-canned clams found traces of it from at least a decade earlier. But outbreaks do seem to have become stronger on this coast in the past quarter-century, occasionally killing seabirds and marine mammals from California to Alaska.

Perhaps due to the rich nutrients in the Columbia River plume, Pacific and Grays Harbor counties to the river mouth’s north have the best clamming on the coast in Washington. Clams generate regional tourist revenue in the tens of millions in good years. Dungeness crabs, which eat razor clams and other toxin-impacted prey, can also be contaminated by the toxin during severe outbreaks, threatening the most lucrative commercial fishery in the two states. As we reported last week, Domoic levels seriously impacted 2016-17 clam and crab seasons.

Washington and Oregon both bar recreational and commercial razor clam digging on ocean beaches when the toxin level rises above 19 parts per million in sampled clam flesh. A study last year suggested even this threshold is open to re-examination, since some harm apparently can accumulate from consumption of seafood that passes current standards.

It’s vitally important to better understand exactly what causes spikes in toxin levels. Warmer ocean waters associated with El Niños and the Blob — an unusual mass of warm water in the northeast Pacific — are a strong suspect. Such conditions are virtually sure to become more common as the century continues to warm up. Will this permanently degrade important shellfish industries? It’s possible that after acute recent problems, the domoic-generating algae will go away or quit generating the toxin for years, as it has in the past. But we can’t count on good luck.

Effective monitoring of actual ocean conditions before toxins enter the near-shore food web is essential. In addition, the states must strive for more timely information about clam conditions, and more closely tailor digging times and places to take advantage of clean clams. A new testing system under development promises to deliver toxin results within an hour of sampling, in contrast to as much as a couple days now.

In the past year on the Long Beach Peninsula, digging would have been more-often permissible if authorities had been willing to open miles-long segments of beach where domoic levels were low. State agencies believe this would be difficult to manage, as personnel could have a difficult regulating digging in closed areas when some people walk to the beach through the dunes and wouldn’t see closure signs.

Before domoic levels suddenly when back above 40 ppm, WDFW was prepared this spring to try closing the Peninsula far north end where endangered snowy plovers nest, allowing clamming on the rest for much of May. This would have been a welcome move, as was the daily limit increase to 25 during the last days of clamming.

Ultimately, it may perhaps be possible to bio-engineer the offending algae so it does not produce domoic acid, or to develop other novel solutions to the problem. Without some sort of smart thinking, the warming ocean threatens not only shellfish, but an economy and lifestyle built around them

Economic and environmental harm from marine toxins argues for investment in good science and aggressive follow through.

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