MUSSELS TESTED FOR TOXINS: QUARANTINE PROLONGED

Written by Adam Spencer, The Triplicate December 21, 2012 02:20 pm

Suzanne Fluharty, of the Yurok Tribe Environmental Program, collects mussels from Wilson Creek Beach to be tested for toxins.
Suzanne Fluharty, of the Yurok Tribe Environmental Program, collects mussels from Wilson Creek Beach to be tested for toxins. Del Norte Triplicate / Bryant Anderson
 Del Norte County’s abundance is delicious. Whether picking mushrooms, huckleberries, or Dungeness crabs from a trap flung from B Street Pier, you don’t have to look far to harvest tasty natural resources.

But not everything natural is safe. Every year, folks who indulge in self-harvested shellfish, particularly mussels, have to pay careful attention to quarantines on harvesting imposed by state agencies because of life-threatening toxins that accumulate in shellfish.

The California statewide quarantine typically ends Oct. 31, but this year the quarantine was extended for Del Norte and Humboldt counties after levels of biotoxins that cause the deadly syndrome Paralytic Shellfish Poisoning (PSP) were detected, including the highest levels ever recorded in Del Norte.  

Recent tests at Point St. George and Wilson Creek Beach show toxin levels are dropping, but the quarantine remains until test results show the toxins have passed.

Clams, oysters and crabs can also
accumulate toxins, but consumption is safe as long as the viscera (like crab butter) is avoided.

A similar quarantine in effect for all of Oregon due to toxin levels above the federal threshold. The highest results were  from Gold Beach, the nearest test location to Del Norte. Eleven Washington counties also extended partial quarantines on sport harvest of shellfish this year due to toxins. In September, a family of seven vacationers were hospitalized after consuming mussels collected from the Puget Sound.

But what exactly are these PSP toxins, sometimes called red tides? How are they produced? And what can be done to protect people from poisoning?

Red tide warnings

 

Red tides and PSP toxins are created by certain types of phytoplankton (single-celled plants that make up the basis of the food chain for all ocean life) called dinoflagellates.  

These organisms are everywhere in the ocean, but they are only visible to the naked eye when they bloom, resulting in millions of cells in each gallon of water.

The red color is produced by pigments in the cell that capture sunlight needed for life, experts said.

Visible red tides, like this one seen south of Crescent City Harbor in November, are similar to but not the same species that produces life-threatening toxins.
Visible red tides, like this one seen south of Crescent City Harbor in November, are similar to but not the same species that produces life-threatening toxins. Courtesy Kenneth Cantrell, Viewpoint Aerial Photography, Lodi
 “Some dinoflagellates can also produce light by a chemical reaction in the cell.  Thus, a bloom can actually light up the ocean waves,” according to a Q-and-A compiled by the California Department of Public Health and researchers at the University of California-Davis.

Aerial photographs of South Beach in Crescent City taken in early November show a visible red tide, although that doesn’t necessarily mean  that PSP toxins are present.

“Here on the West Coast and in California, red tides are perceived by people as these toxic events, but the majority of red tides that are visible to the naked eye are produced by non-toxic dinoflagellates,” said Gregg Langlois, senior environmental scientist at the CDPH and one of the lead experts on shellfish poisoning and red tides. “We’ve had massive red tides along the Sonoma coast and had no PSP toxins present.”

Since the dinoflagellates that produce visible red tides and the ones that produce PSP toxins thrive in similar conditions, however, visible red tides can be a useful warning signal.

Blooms occur with the right conditions controlled by multiple factors including light, temperature, oxygen and nutrients.  A single dinoflagellate cell can divide into several hundred cells within weeks.

When the environment is not ripe for reproduction, dinoflagellates hibernate in cysts, which can lie dormant on the ocean floor, buried in sediment for years, according to experts.

These cysts are transported around the ocean by currents, and when ocean conditions are favorable, the cysts will break open,  dinoflagellates swim out and reproduce rapidly.

 

How toxic is it?

 

The biotoxin found in shellfish that can put a human in the hospital or 6 feet under are called saxitoxins, and it is one of the most poisonous naturally occurring toxins known to man, according to scholary articles published in the National Institutes of Health.

For humans, just 738 micrograms is enough to kill the average person, the equivalent of 10 grains of table salt, according to the Canadian Department of Fisheries and Oceans. 

The highest level recently detected in Del Norte County was  6,394 micrograms per 100 grams of mussel tissue, found in mussels from Wilson Creek Beach on Oct. 29, way above the federal threshold of 80 micrograms per 100 grams of tissue.  A Nov. 25 test from Point St. George showed levels at 828 micrograms per 100 grams. Tests from mussels collected at Wilson Creek Beach on Dec. 10 measured 179 micrograms per 100 grams.

“Since 1927, there have been 542 reported illnesses and 39 deaths attributed to PSP in California,” according to CDPH.

“PSP poisonings have been documented since 1799 when more than 100 Aleut hunters died in Alaska from eating contaminated mussels,” according to the Oregon Department of Fish and Wildlife’s webpage on shellfish toxins.

The CDPH said symptoms of PSP can onset quickly, within a couple minutes or couple hours. It starts with tingling of the lips and tongue, spreading to fingers and toes, eventually leading to loss of control of arms and legs, followed by a difficulty in breathing. Nausea and a sense of floating  can also occur.

“If a person consumes enough toxins, muscles of the chest and abdomen become paralyzed, including muscles used for breathing, and the victim can suffocate. Death from PSP has occurred in less than 30 minutes,” according to CDPH.

There is no known antidote for PSP and cooking shellfish does not kill the toxins.

The last recorded death in California was in the early 1980s, Langlois said, and the lack of more recent deaths may be due in part to monitoring and outreach efforts.

Testing for toxins

 

Amid Del Norte’s geographic isolation, CDPH relies on other agencies and volunteers to collect mussels for testing PSP toxins. 

Members of the Yurok Tribe Environmental Program have rock-hopped during minus tides to collect mussels for testing, efforts called “essential” by CDPH officials.

“To have someone placed locally is a huge help to us,” Langlois said.

Mussel beds are found on the tops of rocks in tidal areas, staying above a distinct line that represents a typical low-tide to avoid predators.

“This is because they can stand being exposed to air and some drying — they just close up their shells tight, but the star fish that normally eat them need to be under water and can only go to the level on the rocks where they can stay submerged,” said Suzanne Fluharty, an environmental specialist for the Yurok Tribe Environmental Program during a recent mussel collecting day. “So those mussels higher up, are safe. Any that grow lower get eaten!” 

Fluharty said that the tribe pays for staff to help with testing, because a significant number of tribal members practice subsistence gathering.  

“Even tribal members who’ve moved away come back during seasonal times to collect traditional foods,” she said.

Mussels are tested at Wilson Creek, because the spot is utilized.

“If our goal in testing is to protect human health, then we prefer to test from sites that are being used,” she said.

After collecting almost 20 mussels with her colleague Joe Hostler (an athletic young adult tribal member who can quickly scurry over slippery tidal rocks), Fluharty will prepare the mussels to be sent to Langlois for testing.

“We need at least one cup of tissue so I’ll go back, shuck them, put them in a special bottle, freeze them and then ship them out to the lab,” she said.

Monitoring like this can be  time consuming, but it is currently one of the only ways the West Coast manages PSP.

Predicting the blooms

 

Instead of simply warning the public after toxins are detected, researchers in Massachusetts are finding ways to predict the blooms before they happen.

Since 2008, scientists have attempted to forecast the location and severity of algal blooms that produce PSP toxins in the Gulf of Maine.

“We’ve been right four out of five times,” said Donald Anderson, director of the U.S. National Office for Harmful Algal Blooms at Woods Hole Oceanographic Institution. During the year they miscalculated,  2010, oceanic conditions were historically unique and hard to predict, but that will only make their predictions better in the future, Anderson said.

Part of the prediction process involves collecting ocean sediment to look for concentrations of cysts of the genus Alexandrium, the genus that produces PSP toxins.

Although Anderson thinks that reproducing his office’s forecast work on the West Coast would be difficult due to the scale of the coast and currents, attempts are being made in Puget Sound.

Stephanie Moore, associate scientist with the National Oceanic and Atmospheric Administration’s Northwest Fisheries Science Center, is paralleling the work on the West Coast pioneered by Anderson on the East Coast.

Moore’s work has been primarily concentrated on Puget Sound, but when testing has occurred on the outer coast of Washington, cysts could not be found although blooms are present.

“This either says to me that we are looking in the wrong places or that these blooms that affect the outer coast are being fueled by areas like Puget Sound,” she said.

Mysteries like that make management of PSP toxins extremely difficult.

“This problem cannot be dealt with regular and traditional monitoring alone. There needs to be some forecasting to predict algal blooms,” Moore said.  

How you can help

 

CDPH’s biotoxin monitoring program welcomes new volunteers to join the shellfish and phytoplankton monitoring programs, especially if they are in an area that needs additional coverage like Del Norte. 

“The ability to protect the public from these dangerous toxins is due in large part to the numerous organizations, and citizen volunteers that contribute their time and effort to provide samples to our program for testing. CDPH can provide the necessary training and equipment for collecting and shipping samples at no cost to the volunteer. Those who want to take part in this valuable program can email This e-mail address is being protected from spam bots, you need JavaScript enabled to view it or call 1-800-553-4133,” the CDPH said in a statement.

 

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