Peering into the whirring machine sitting on a lab bench, it’s hard to imagine the samples now having their atoms blasted were once clams from Samish Bay.
The folks at the Bellingham-based Salish Sea Research Center (SSRC) lab are monitoring marine biotoxins in shellfish. It’s been a longstanding problem for those whose livelihoods and cultures depend on the sea, and experts say it’s here to stay.
[ Read more: Whatcom, Skagit coastal communities show resilience amid expanding biotoxin closures ]
Marine biotoxins are naturally occurring chemicals produced by certain species of phytoplankton: microscopic algae that live in the ocean and photosynthesize like plants. Paralytic shellfish poisoning (PSP), diarrhetic shellfish poisoning (DSP) and amnesic shellfish poisoning (ASP) are all caused by different marine biotoxins.
When humans eat shellfish containing these biotoxins, it puts them at risk for severe illness, or even death. That risk is why local beaches such as Birch Bay, Larrabee and Semiahmoo close to harvesters when high levels of biotoxin are found in their shellfish.
The algae that produce biotoxins are always around in small numbers, but under certain conditions they can multiply quickly, resulting in what’s known as a harmful algal bloom. Most people associate algal blooms with a “red tide,” but not all species will make the water turn color.
Since organisms like clams, oysters and mussels feed on algae and plankton, they can build up harmful levels of biotoxins in their bodies during a bloom event. That’s why biotoxin closures usually start in late spring and fall off toward the cooler months: phytoplankton generally grow faster in warmer weather.
Jerry Borchert, marine biotoxin lead at the Washington Department of Health (DOH), said PSP is the most common type of poisoning in the state. It’s caused by saxitoxins: a group of potent neurotoxins produced by several species of algae.
While death from PSP in Washington is exceedingly rare, saxitoxins are fast-acting and can be deadly in extreme cases. Borchert emphasizes that in a PSP emergency, recognizing the signs (tingling of the lips and extremities) and acting early is key.
“If a person gets this toxin at high levels … eventually they’ll lose the ability to breathe because the diaphragm becomes paralyzed,” Borchert explained. “But if they're given oxygen [fast enough], they can survive.”
Cases of PSP and the other forms of shellfish poisoning remain low in Washington due to vigilant monitoring and testing efforts, but there is widespread concern that the threat from biotoxins will increase in the future due to climate change.
Some recent research suggests that rising ocean temperatures, shifting weather patterns and ocean acidification could favor illness-causing species, but scientific evidence is weak for a global rise in harmful algal blooms. That’s because the conditions required for harmful algae to bloom are complex, and the frequency and timing of blooms varies substantially between even geographically close locations.
“It's not just one or two but multiple things,” Borchert said. “Nutrients, temperature, oxygen, wind, stratified conditions … there's so many things that have to come together just right. And then you have to have the [algae] present to take advantage of those conditions. It’s something we're trying to figure out all the time.”
Researchers and shellfish growers agree, though — the season for harmful algal blooms in Washington has expanded. In past decades, beach closures for paralytic shellfish toxin typically started around June and ended in September. Last year, closures in parts of Whatcom County were in effect until late November, and started again in May of this year.
Luckily, biotoxin monitoring has expanded in recent years as well. DOH tests mussel beds in commercial and recreational harvest areas across the state’s coastline for multiple toxins. Once harvested, the mussels are sent to a laboratory and tested for unsafe levels.
Results for paralytic shellfish toxin are frequently churned out from the DOH lab in a matter of hours. For diarrhetic and amnesic toxins, the samples are run on a machine overnight, with results the next day. The results inform which recreational beaches stay open for collecting and ensure commercial shellfish are safe to ship to market.
Even earlier warning systems are in development by an army of professional and citizen scientists. Michelle Lepori-Bui is the program director of SoundToxins, a network of biologists, shellfish growers, tribes and citizen scientists all focused on identifying the cells of harmful algae species in the waters of Puget Sound. She said in addition to researching harmful algae species, SoundToxins works with the state as a first line of defense against biotoxins.
“It’s like an early warning sign,” Lepori-Bui said. “If you’re monitoring regularly, you’re hopefully seeing those cells before they get ingested by the shellfish. If we see cells in the water, we can let [DOH] know … it can help them prioritize which ones to run first and where to focus their sampling.”
Both SoundToxins and the Salish Sea Research Center are also trying to learn more about the algae itself. Misty Peacock, director of the SSRC, said they are interested in finding out why algae produce biotoxins in the first place, since many harmful species don’t produce toxin all the time. The team is also working alongside other marine monitoring organizations to develop machines that can automate sampling and identify harmful phytoplankton species as they bloom using machine learning.
The new tech is a welcome addition, especially as the future of biotoxins is rife with uncertainty. Emerging biotoxins are a major concern, as ocean conditions change what algae species can thrive where.
Both SoundToxins and the DOH are monitoring Azadinium, a dinoflagellate alga recently detected in Puget Sound whose toxins can cause symptoms similar to that of DSP.
Also of concern are the effects of chronic exposure to low doses of biotoxins. In coastal Indigenous communities where shellfish are a large part of the diet, people can experience adverse health effects over time, even if biotoxin levels are below closure thresholds. One study found that Native Americans who regularly ate razor clams suffered declines in memory and cognitive function, likely due to domoic acid (the biotoxin behind ASP).
For a coastline dependent on shellfish for sustenance, recreation and income, biotoxin research and monitoring is more than just science. It’s an ever-changing battle to preserve many people’s way of life.
Lepori-Bui said that many monitoring programs in the Pacific Northwest were started back in the 1990s when ASP was first detected on the West Coast. People on the coast were initially scared and confused, but it sparked scientists and concerned citizens to fill the knowledge gap.
“I think as a group, the community came together,” Lepori-Bui recalled. “And they said, 'OK, what do we know about this problem, and what can we do to make it better?’”
Ben Long is an environmental/science reporter, placed at CDN through the American Association for the Advancement of Science (AAAS) Mass Media Fellowship. Reach him at benlong@cascadiadaily.com.
