Biologists advise to use caution in shellfish consumption
On July 16, Alaska Ocean Observing System, UAF Fairbanks and Alaska Sea Grant sponsored a community workshop on Harmful Algal Blooms—certain poisons coming from certain blooms of algae produced by phytoplankton. The group held a second workshop the next day for healthcare professionals.
The group included scientists from National Oceanic Atmospheric Administration, USGS Alaska Science Center, and Joe McLaughlin, Alaska’s head epidemiologist.
Vera Trainer started off the public session telling how the algal toxins affect people and growing organisms, as well as shellfish, seabirds and marine mammals. Trainer, of NOAA Northwest Fisheries Science Center in Seattle, focused her presentation on Alexandrium, a phytoplankton that produces saxitoxin, also known as “Red Tide”, that, if ingested, can lead to Paralytic Shellfish Poisoning, PSP for short.
PSP can occur in humans when they eat shellfish or other organisms that filter seawater for nutrients and store the toxins in their bodies.
Another toxin about which Alaskans should be conscientiously concerned is domoic acid, which can cause permanent brain damage. “We have many, many marine phytoplankton in the ocean out there,” Trainer explained. “If you would take a sample of seawater and look in the microscope, it would just be this beautiful selection of marine plants basically. So every second breath that you take is thanks to the phytoplankton.”
Phytoplankton? Phytoplankton are one-celled plants in the ocean and an important component of the food web.
Most phytoplankton are beneficial to us because they contribute much of the world’s oxygen. However, a very, very small proportion of phytoplankton—less than 1 percent— produce chemicals that are harmful to humans.
The way this works is when shellfish and other filter feeders that strain the waters for small organisms, including some marine mammals, will concentrate toxins in their flesh.
Then when they consume shellfish, they will become sick or in some cases even die, Trainer said. “And when people eat whatever it is, shellfish, fish or perhaps other organisms that have fed upon this plankton, they can have the syndrome called Paralytic Shellfish Poisoning.”
“The symptoms of paralytic shellfish poisoning in people are tingling, numb, blood, numbness, dizziness, vertigo, weakness and paralysis,” Trainer said. “And eventually you’ll have cardiac failure and problems breathing. So it’s quite serious—there is no antidote.”
PSP cannot be cooked out or washed out, aged out or frozen out of shellfish. It is odorless and tasteless. However, a study is underway concerning if you take care of the clam, how your processing of clam may help reduce the risk of ingesting the toxin.
Shellfish for sale commercially for human consumption are inspected for PSP; however, subsistence resources are not monitored, according to Julie Matweyou of UAF and Alaska Sea Grant, stationed in Kodiak.
In Kodiak, a group including Matweyou and Alaska Sea Grant, is working to invent a testing apparatus for use during subsistence harvests for food. There is a test kit on the market for domoic acid toxin, Matweyou reported. Domoic toxin can cause permanent brain damage. Another test has one bring the clams back and test them at home.
The firm Seatox Research Inc. is developing and testing a fluorescence-based method to detect marine neurotoxins that cause paralytic shellfish poisoning and amnesic shellfish poisoning.
A panel of marine scientists gave short presentations on how algal toxins affect marine resources—shellfish, seabirds, marine mammals and humans.
Alaska has 33,000 miles of coastline and many remote small villages, which present obstacles to state monitoring efforts.
“Well, that’s a difficult message for people who harvest shellfish and continue to use these resources as an important economic and cultural component, “ Matweyou said.
Matweyou gets a vital question from the public almost daily. “ Can I eat the shellfish? And I have to walk through all the various components and the data that’s presented from my region and explain to people why I cannot recommend for them to eat shellfish in my region,” Matweyou said. “So when I tell them, no, you cannot eat this shellfish because it’s above regulatory level, they came back to me and they said, ‘I already ate.’
The specter of harmful algal toxins affect harvesters in many different ways–both commercial and subsistence harvesters, Matweyou said.
“We’re primarily talking now about a subsistence harvest and unmonitored subsistence resources, however, PSP does affect the commercial shellfish in our state.” Any shellfish that is going into market is regulated and tested for PSP.
Joe McLaughlin, head epidemiologist and chief of the Alaska Section epidemiology has practical suggestions for those who eat shellfish recreationally or for subsistence: Don’t eat alone. It is a good idea to eat near a medical facility, rather than out on the water or in the wilderness where one is far from help. Report even light cases or in serious cases under medical management, urge medial staff to report cases and symptoms to staff.
McLaughlin describes how the state responds: “Number one, we verify the diagnosis. If a patient is in an emergency department and has consumed shellfish within the last 12 hours and has an illness that is characteristic of PSP and we already went through the symptoms, then what we’ll do is sometimes we’ll actually fly on site depending on the number of patients that are involved in the severity of illness.”
If McLaughlin’s team has several cases that have been reported, they may get a nurse epidemiologist and then may get somebody from the Department of Environmental Conservation, or public health nurse to fly to the community and get a sense for what’s going on.
“You want to make sure that patients are identified, people who have been exposed to mussels or clams have been notified, and anybody who has consumed those mussels or clams that have been implicated in at least one case, a paralytic shellfish poisoning, we will urge them to look for signs or symptoms of paralytic shellfish poisoning if. We advise them to go into an emergency room and get evaluated,” he continued.
So anybody who has signs or symptoms of paralytic shellfish poisoning, McLaughlin encourages them to urgently go in and see an urgent care doctor. And if the symptoms progressed to involve the muscles of respiration or look serious, the patient will likely be hospitalized, maybe intubated or maybe put on mechanical ventilation. Usually the symptoms resolve within a day or two.
Next, the team or ADF&G go into the community to educate about the risks of eating shellfish and post signs.
“One of our key messages is unfortunately, something that people don’t necessarily like to hear from the state, but it is that it’s unsafe to consume, recreationally harvested shellfish,” McLaughlin said.
The severity of the disease is potentially lethal and there is no way for a person to determine, if a shellfish is poisonous unless they had been tested. Unfortunately, there is no field test kit that is FDA approved for people to test their own harvested shellfish and determine whether or not they’re safe to consume.
“So for those who choose to recreationally or subsistence harvest shellfish, our recommendation is number one, never eat shellfish alone,” he said. “I always eat with someone else.”
“We need an inexpensive, reliable field test kit,” McLaughlin said. “That would really turn Alaska around.”
McLaughlin encourages that cases are reported. “The vast majority of cases are mild. People don’t go in to seek medical care and it’s only the more severe cases that people go in to seek medical care. Oftentimes, clinicians forget to report to us.”
The epidemiology department encourages medical staff to go though reportable symptoms, for conditions like PSP and botulism,
Alexandrium, the organism that produces saxitoxin, can be concentrated in shellfish or fish or marine mammals, which we then eat and become sick, he said. “The cell has a resting stage that is called a cyst. And it’s like a seed that’s planted in the ground, but exists in the sediment.” The cysts are resting at ocean bottom, just waiting to emerge from the sediment at just the right time. “We know that these cysts can live for many, many years. It’s not quite clear, but it’s thought even, you know, a hundred or more years,” Trainer said. “We know that amount of sunlight, time of year and water temperature are very important for their existence.”
“So you could imagine as water temperatures continue to increase, this cyst population is just ready to bloom. I’m not saying they’re going to, but they, there are data and they’re also more recent data showing that the numbers are quite high,” Trainer said.
If the Alexandrium cysts are flourishing in the warm water, that doesn’t surprise Rick Thoman, retired from National Weather Service after 30 years. Thoman, of Fairbanks, is with the Alaska Center for Climate Assessment and Policy.
“We’ve had two years in a row of sea ice collapse in the late winter and early spring,” he said. The sun not only melts the ice in the northern Bering Sea but also heats the water. “It is no surprise that the ocean temperatures are extremely high. That’s what you would expect when you take the ice away at least two months early. It could hardly be anything else.”
Thoman said that the Chukchi Sea is also very warm and that is of importance because to get the central Bering Sea to freeze, the Chukchi Sea has to freeze first.
Thoman expects the same for the next season, late freeze-up, early spring, a combination that produces thin ice easily stirred up and broken by the advent of storms, which is repeating the sun’s opportunity to beam down on the dark heat-absorbent surfaces of the arctic iceless seas.