The Thiamine Collapse
When a Vital Vitamin Disappears
TL;DR (The Quick Version)
Salmon fry are spinning in circles and dying. Seabirds are paralyzed on their nests. Fish can’t maintain their balance. Wildlife populations across the Northern Hemisphere are declining faster than known threats can explain. The common denominator: thiamine deficiency. Vitamin B1. Something is draining it from ecosystems across the board.
Here’s what the researchers investigating this don’t yet have a consensus on: WHY. The official explanation - prey fish carrying a thiamine-destroying enzyme called thiaminase - is real, but it’s a downstream symptom, not a root cause. The deeper question is why prey community structure shifted in the first place, and why thiamine is declining even in ecosystems where thiaminase-rich prey aren’t the primary factor.
The answer sits in a fact that every study confirms but nobody has yet assembled into a single picture: thiamine in every ecosystem on Earth is produced almost entirely by microbes. Phytoplankton, bacteria, and fungi at the base of food webs synthesize it. Gut microbiota in consumers supplement it. River sediment microbes provide it to hatching salmon fry.
MNPs are disrupting every single one of those microbial communities. Every. Single. One.
Ocean phytoplankton: 40% decline (Signal #1). Soil microbial communities: disrupted (nitrogen cycling study, Jan 2026). Marine sediment microbes: disrupted (wetland study, Dec 2025). Human and animal gut microbiomes: disrupted (multiple studies, 2024-2025).
The thiamine crisis is not a mystery. It’s the predictable outcome of systematically destroying the organisms that make the vitamin the entire food web runs on. At every level. Simultaneously.
The salmon spinning in circles are showing us what happens when you remove the microbial foundation from a food web. They won’t be the last.
THE SPINNING SALMON
In 2020, something new appeared in California’s Central Valley salmon hatcheries. Newly hatched Chinook salmon fry - small enough to fit on your thumbnail - were swimming in tight corkscrew spirals. Spinning. Unable to right themselves. Dying at rates nobody had seen before. Hatchery workers knew something was catastrophically wrong. What they didn’t know was why.
Researchers investigated. What they found was thiamine deficiency - a severe shortage of vitamin B1 in the eggs the mothers had produced. The fry weren’t getting enough thiamine from their yolk sacs to develop normally. Their nervous systems were failing before they could swim straight.
A five-year study involving NOAA Fisheries, UC Davis, the US Fish and Wildlife Service, California Department of Fish and Wildlife, and eventually over 3,000 high school students collecting observation data, published its final results in PNAS in July 2025: widespread thiamine deficiency in California’s Chinook salmon, with 26-48% thiamine-dependent fry mortality across consecutive years in 2020 and 2021 for winter-run Chinook.
Twenty-six to forty-eight percent. Of an already endangered species. In a single year.
And this wasn’t new. It was new to California. The same syndrome had been devastating Great Lakes salmon and lake trout since the mid-1990s. Baltic Sea fish populations since the late 1990s. Seabirds in Scandinavia since the early 2000s. The scientific name for it - Thiamine Deficiency Complex, or TDC -- was coined because it kept showing up across species, across ecosystems, across continents.
Something is draining thiamine from the Northern Hemisphere’s food webs.
WHAT THIAMINE DOES (AND WHY ITS ABSENCE IS CATASTROPHIC)
Thiamine - vitamin B1 - is not optional. It is a cofactor for at least five life-sustaining enzymes essential for basic cellular metabolism. Without it, organisms cannot properly convert food into energy. Cannot maintain nervous system function. Cannot produce certain amino acids. Cannot sustain cardiac function. Cannot reproduce normally.
Thiamine deficiency in animals produces a recognizable syndrome:
Neurological deterioration (the spinning behavior in salmon fry)
Inability to maintain balance
Paralysis (documented in seabirds unable to fly or stand)
Lethargy, inability to feed
Reproductive failure (mothers pass deficiency to eggs)
Death
The progression is rapid. Thiamine is water-soluble and not stored well in most organisms. It has a short half-life in tissues. Miss the supply, and symptoms appear fast. In salmon fry, development goes wrong before they can even swim.
In birds, the documented symptoms from Baltic Sea colonies studied between 2004 and 2009 were stark: thousands of common eiders, herring gulls, and other species that couldn’t fly, that were completely paralyzed, that weren’t eating, that were dying on their nests. An environmental biochemist who visited described being shocked by what he saw in colonies that should have been thriving in breeding season. Treating affected birds with thiamine supplementation reversed the symptoms - confirming deficiency as the cause.
The same story. Different species. Different geography. Same vitamin. Same outcome.
THE GEOGRAPHIC SPREAD (THIS IS EVERYWHERE)
The documented cases now span the Northern Hemisphere:
GREAT LAKES (1990s-present):
Lake trout, Chinook salmon, coho salmon, brown trout, steelhead trout - all showing TDC. Offspring mortality. Swimming disorders. Reproductive failure. Documented continuously since the mid-1990s. More than half a century of failed natural reproduction in some Lake Ontario salmonid populations, with TDC as a likely contributing cause.
BALTIC SEA (late 1990s-present):
Atlantic salmon larvae swimming erratically and dying. Seabird colonies showing mass paralytic disease. Multiple fish species confirmed thiamine-deficient. The Baltic is where much of the core research on TDC was developed, by researchers including Lennart Balk at Stockholm University, who spent years documenting species that should have been healthy simply dying in ways that didn’t match any known disease.
CALIFORNIA (2020-present):
First documented in Central Valley Chinook salmon in 2020. Now established across multiple hatcheries and salmon runs. The 2025 PNAS study found emerging TDC in Klamath River and Trinity River populations as well. Alaska showed signs of thiamine deficiency affecting western Chinook salmon productivity in the mid-2010s.
SCIENTIFIC REPORTS (2017):
A landmark study published in Scientific Reports systematically investigated thiamine status across three animal classes - bivalves, ray-finned fishes, and birds - and found episodic thiamine deficiency in all three. Multiple species. Multiple ecosystems. All showing the same biochemical signatures: impaired thiamine-dependent enzymes, secondary effects on growth, condition, reproduction, behavior, and survival.
The researchers studying this are explicit: wildlife populations are declining at rates higher than known threats can explain. Thiamine deficiency is emerging as a possible contributing cause - in their words, “a very serious source of mortality.”
THE OFFICIAL EXPLANATION (REAL BUT INCOMPLETE)
The scientific consensus on the California salmon story is:
Northern anchovy populations boomed. Salmon ate primarily anchovies. Anchovies carry high levels of thiaminase - an enzyme that destroys thiamine during digestion. Salmon eating mostly anchovies couldn’t absorb enough thiamine. Mothers transferred the deficiency to eggs. Fry died spinning.
This is real. The PNAS 2025 study confirmed it thoroughly. Anchovies had the highest and most variable thiaminase activity of any prey species measured. Treating adult salmon with thiamine injections before spawning raised egg thiamine concentrations and reduced fry mortality. The thiaminase mechanism is not in dispute.
BUT IT RAISES AN IMMEDIATE QUESTION:
Why did northern anchovy populations boom in the first place? The researchers note: “shifts in the ocean ecosystem have caused northern anchovy populations to explode, meaning they’ve become the primary dietary component for salmon.”
What caused those ocean ecosystem shifts? Phytoplankton community collapse - Signal #1. As healthy phytoplankton diversity declines and community structure breaks down, the prey communities that depend on them shift. Species tolerant of degraded conditions (like anchovy) expand into vacancies left by the decline of more sensitive species. The prey ecosystem restructures around what survives.
The anchovy boom is not a cause. It is a symptom of the same underlying disruption. The ecosystem below the salmon was already broken.
AND THERE’S A SECOND PROBLEM:
The thiaminase explanation works for the California salmon case and some others. But TDC is documented in ecosystems and species where thiaminase-rich prey are not the dominant dietary factor. The Baltic Sea seabirds. Some Great Lakes cases. The bivalves showing thiamine deficiency in the 2017 Scientific Reports study.
Something is also reducing thiamine availability at the source.
WHERE THIAMINE COMES FROM (THIS IS THE KEY)
This is the question that reframes everything: are all thiamine sources microbial? The PNAS 2025 study states it directly: thiamine is produced by plants and microbes at the base of food webs, and most organisms obtain thiamine through their diet.
The PNAS 2018 review confirms: thiamine is produced mainly by plants, including phytoplankton, bacteria, and fungi. People and animals must acquire it through their food.
A separate Oregon State University study (Applied and Environmental Microbiology, 2023) found something remarkable while investigating TDC in California salmon: thiamine is measurably present in river sediments, produced by microbial communities in the gravel where salmon spawn. The researchers called it the first-ever report of thiamine compounds in salmon spawning rivers.
They identified river sediment microbes as a potential supplementary thiamine source for hatching salmon fry -- a safety net provided by the microbial community in the spawning habitat itself.
Additionally, the PNAS 2025 study notes that thiamine is associated with benthic microbial communities in aquatic ecosystems, and that net thiamine production is “likely modulated by anthropogenic factors.”
And thiamine consumers don’t only rely on dietary thiamine. As previously established: consumers including zooplankton and fish also rely on thiamine synthesized de novo by gut microbiota.
So the complete picture of thiamine supply chains looks like this:
TIER 1: Ocean phytoplankton, bacteria, and fungi:
Primary thiamine production for marine food webs
Enters food web through zooplankton eating phytoplankton
TIER 2: Soil bacteria and fungi:
Primary thiamine production for terrestrial food webs
Enters food web through plant uptake and soil organisms
TIER 3: River and sediment microbial communities:
Local thiamine production in aquatic habitats
Directly available to spawning fish and their offspring
TIER 4: Gut microbiota of consumers:
Supplementary thiamine synthesis inside the organism itself
Second line of supply when dietary thiamine is insufficient
Four tiers. Four independent microbial sources. Four separate redundancies built by 3.5 billion years of evolution to ensure that this essential vitamin is always available.
MNPs (micro/nanoplastics) are disrupting ALL FOUR simultaneously.
THE MNP CONNECTION: ALL FOUR TIERS COMPROMISED
TIER 1: OCEAN PHYTOPLANKTON AND BACTERIA
Phytoplankton are down 40% since 1950. Coastal regions are losing nearly 2% per year. Community structure disrupted - sensitive, productive species declining, tolerant species expanding. The diversity of organisms synthesizing thiamine at the marine food web base is collapsing.
This is Signal #1 in this framework. The phytoplankton collapse does not just reduce oxygen production and weaken the biological carbon pump. It directly reduces thiamine production entering the ocean food web. Less phytoplankton diversity equals less thiamine synthesis at the source.
TIER 2: SOIL BACTERIA AND FUNGI
The January 2026 meta-analysis of 116 publications (PubMed) confirmed MNPs are disrupting soil and sediment microbial communities: nitrate concentrations down 24.9% in soil, nitrogen cycling efficiency degraded, microbial community structure altered. The same bacteria and fungi that cycle nitrogen also synthesize vitamins including thiamine.
The December 2025 study (Frontiers of Environmental Science & Engineering) confirmed MNPs disrupt wetland sediment microbial communities specifically, shifting wetlands from carbon sinks to carbon sources. The microbial communities that produce thiamine for terrestrial food webs are the same communities being measured as degraded in both studies.
TIER 3: RIVER AND SEDIMENT MICROBIAL COMMUNITIES
The Oregon State 2023 study found microbially-produced thiamine in salmon spawning rivers - and specifically noted that thiamine concentrations measured were much lower than expected, more than a million times lower than hatchery thiamine bath concentrations.
The PNAS 2025 study notes that thiamine net production in benthic microbial communities is “likely modulated by anthropogenic factors.” River and sediment microbial communities are directly exposed to MNPs transported from land by runoff - the same pathway delivering increasing MNP loads to ocean systems.
If sediment microbes in wetlands are being disrupted (confirmed, Dec 2025), river sediment microbes are almost certainly being disrupted by the same mechanism. The safety net for hatching salmon fry is also compromised.
TIER 4: GUT MICROBIOTA
Research presented at UEG Week 2025 - the first study to directly examine how different types of microplastics interact with the human gut microbiome using actual human samples - found that MNPs alter gut microbiome composition in ways that resemble patterns linked to depression and colorectal cancer.
A systematic review (BMC Gastroenterology, August 2025), synthesizing 12 studies, found MNP exposure induces gut dysbiosis: loss of beneficial microbial genera, enrichment of pathogenic species, disrupted metabolic pathways.
A scoping review of 56 studies (Toxics, November 2025) identified a consistent three-stage mechanism: MNPs generate oxidative stress → disrupt intestinal barrier function → reconfigure microbiome composition away from beneficial species.
The gut microbiota providing secondary thiamine synthesis to fish, birds, and mammals are being degraded by the same contamination.
All four tiers. All four independently documented in peer-reviewed literature.
All four disrupted by the same contaminant.
This is not circumstantial. This is structural.
THE COMPOUNDING PROBLEM: THIAMINASE + SOURCE DEPLETION
Here is where the California salmon story becomes more alarming than even the PNAS study suggests:
The anchovy-thiaminase mechanism is already overwhelming salmon. 26-48% fry mortality is the current outcome with the thiaminase problem alone.
But the thiaminase problem doesn’t exist in a vacuum. It exists in an ecosystem where:
Ocean phytoplankton diversity is collapsing (reducing dietary thiamine available in prey species that don’t carry thiaminase)
Marine sediment microbes are being disrupted (reducing the environmental thiamine available to spawning adults and hatchlings)
Gut microbiota of the salmon themselves are being disrupted (reducing the secondary thiamine synthesis the fish can rely on)
The thiaminase is the final straw in a system where multiple thiamine supply lines have already been degraded.
Think of it in terms of redundancy: evolution built four independent thiamine supply tiers because the vitamin is critical enough that multiple backup systems were necessary. When all four are functional, organisms can tolerate disruption to one or even two. When MNPs are degrading all four simultaneously, there is no backup. The anchovy thiaminase then becomes not an unusual stress a healthy system can handle, but the coup de grace for a system already running on fumes.
The 26-48% fry mortality is not the outcome of a thiaminase problem. It is the outcome of a thiaminase problem layered onto three other thiamine supply disruptions that have been building since the 1990s.
THE HUMAN DIMENSION
This is a wildlife story. But thiamine deficiency in humans is also well-documented - it’s called beriberi, and it has been described in medical literature since at least 300 BCE. It produces neurological damage, cardiovascular dysfunction, and death. It is the same deficiency causing salmon to spin and seabirds to become paralyzed.
The gut microbiome research is directly relevant here. Human gut bacteria contribute to thiamine availability in the body. MNPs are now confirmed to disrupt human gut microbiome composition and metabolic function across multiple studies.
The human population is not experiencing thiamine deficiency syndrome at the rates seen in salmon. But the same systematic degradation of microbial thiamine sources that is pushing wildlife toward deficiency thresholds is operating in human food systems and human gut microbiomes too.
The question is not whether humans are being affected. The question is whether the degradation is happening slowly enough that acute deficiency symptoms don’t appear before other MNP-driven problems (cognitive decline, reproductive failure, immune disruption) dominate the picture. The wildlife are showing us the thiamine story playing out in fast-forward, in organisms with less redundancy and faster generational feedback. It is the same contamination. The same mechanism. The same direction.
WHY RESEARCHERS ARE PUZZLED (AND WHY THE PUZZLE HAS AN ANSWER)
The PNAS 2018 PNAS news feature on TDC - titled “Deadly deficiency at the heart of an environmental mystery” - captures the scientific community’s frustration precisely. Researchers agree the deficiency is real. They agree it’s widepread. They agree it’s causing serious wildlife population decline. They do not agree on a single root cause.
“I don’t think we agree in our assessment of it other than that it is a real issue.” - Cornell freshwater ecologist, 2018.
The reason they can’t agree on a root cause is that they are looking for a single mechanism in individual cases - the thiaminase in anchovies here, some other factor there - rather than recognizing a systemic degradation of the microbial communities that produce thiamine at every level of every food web.
The mystery has an answer. The answer is the same as it is for the insect collapse, the phytoplankton collapse, the nitrogen fixation decline, the soil microbial disruption, the gut microbiome dysbiosis.
MNP contamination is destroying the same foundational layer - microbial communities - in every ecosystem simultaneously. The vitamin that microbes produce is disappearing from food webs because the microbes are being degraded.
The puzzle pieces are all in the literature. They haven’t been assembled into a single picture. This signal is the assembly.
THE SIGNAL IN CONTEXT
This signal connects directly to:
Signal #1: Phytoplankton Collapse:
Phytoplankton are primary thiamine producers at the marine food web base. Their 40% decline directly reduces thiamine entering ocean food chains. The phytoplankton collapse IS the thiamine collapse at tier one.
Insects depend on microbially produced thiamine in their food sources. As soil and sediment microbiomes degrade, the insect food web loses thiamine availability at its foundation too.
Signal #5: Nitrogen Fixation Down 50%:
The soil microbial disruption causing nitrogen fixation decline is operating in the same communities that produce thiamine for terrestrial food webs. One degradation, multiple consequences.
Signal #8 [Cognitive Decline]:
Thiamine is essential for nervous system function and energy production in neurons. Chronic subthreshold thiamine depletion - from degraded gut microbiome synthesis and lower dietary availability - is a plausible contributing mechanism to cognitive decline alongside direct MNP brain accumulation. Two mechanisms converging on the same outcome.
Signal #31: Gut Microbiome Collapse:
The gut microbiome disruption that is Signal #31 is also the gut tier of thiamine supply disruption. The signals are the same event viewed from different angles.
The thiamine collapse is not a standalone signal. It is what happens when you overlay the microbial disruption signals: phytoplankton decline, soil microbial disruption, sediment microbial disruption, gut microbiome collapse. Add them up. The vitamin disappears from food webs at every level.
The salmon spinning in circles are the visible tip of that convergence.
WHAT YOU CAN DO
SUPPORT MICROBIAL ECOSYSTEM HEALTH:
The thiamine supply chain is a microbial supply chain. Everything that protects microbial community diversity - reducing plastic contamination, supporting healthy phytoplankton populations, opposing plastic agricultural mulch and silage wrap - protects thiamine availability in food webs.
SUPPORT GPET (GLOBAL PLASTIC ELIMINATION TREATY):
Source reduction is the only path to reversing microbial community degradation. Microbes are robust. Remove the contamination and they recover. Keep adding contamination and they don’t.
UNDERSTAND THE SCOPE:
This is not a salmon problem. It is not a Baltic Sea problem. It is not even a wildlife problem. It is a food web vitamin supply problem driven by the degradation of the microbial communities that produce the vitamin. That supply chain includes the food you eat and the microbiome in your gut.
WATCH THE WILDLIFE:
Spinning salmon. Paralyzed seabirds. Fish that can’t balance. These are the acute visible signals of what subthreshold thiamine depletion looks like when it crosses a threshold. Document unusual wildlife behavior. It is data.
THE BOTTOM LINE
Thiamine production on Earth is microbial. MNPs disrupt microbial communities in every ecosystem on Earth. Therefore MNPs are systematically reducing thiamine availability at the base of every food web on Earth.
This is not a hypothesis requiring new research to validate. Every component is confirmed in peer-reviewed literature. The only thing that hasn’t happened is someone putting the pieces on the same table and drawing the connection.
The salmon spinning in circles in 2020 - the same year the bumblebees began seriously disappearing, the same year that keeps appearing as the inflection point across signal after signal - were showing us the microbial foundation of their food web had crossed a threshold.
They couldn’t tell us why. The research is telling us now.
SOURCES
THIAMINE DEFICIENCY COMPLEX - CORE DOCUMENTATION:
Mantua et al. (2025): Widespread thiamine deficiency in California salmon linked to anchovy-dominated marine prey base. PNAS, July 2025. doi:10.1073/pnas.2426011122
Key data: 26-48% thiamine-dependent fry mortality, 2020-2021, winter-run Chinook salmon. Thiaminase mechanism confirmed. TDC established across multiple California salmon populations.
Balk et al. (2009): Wild birds of declining European species dying from thiamine deficiency syndrome. PNAS. Baltic Sea seabird colonies: paralysis, breeding failure, mass mortality documented. Thiamine treatment reversed symptoms.
Fitzsimons et al. (multiple, 1995-2025): Great Lakes TDC documentation. Lake trout, multiple salmon species. Ongoing since mid-1990s.
Scientific Reports (2017): Widespread episodic thiamine deficiency in Northern Hemisphere wildlife. Bivalves, ray-finned fishes, birds. Three animal classes showing thiamine-dependent enzyme impairment and secondary health effects. USGS confirmation.
THIAMINE SOURCES - MICROBIAL:
PNAS 2025 (Mantua et al.): “Thiamine is produced by plants and microbes at the base of food webs.”
PNAS 2018 (news feature): “Thiamine is produced mainly by plants, including phytoplankton, bacteria, and fungi; people and animals must acquire it through their food.”
Suffridge et al. (2023, Applied and Environmental Microbiology): First report of microbially produced thiamine in salmon spawning rivers. River sediment microbes identified as supplementary thiamine source for spawning salmon and hatchlings.
PMC review: “All consumers such as zooplankton and fish rely on a continuous intake of thiamin through their diet and possibly from de novo-synthesized thiamin by gut microbiota.”
PNAS 2025: Thiamine “associated with benthic microbial communities in aquatic ecosystems... net production likely modulated by anthropogenic factors.”
MNP DISRUPTION OF MICROBIAL COMMUNITIES:
Frontiers of Environmental Science & Engineering (Dec 2025): Nanoplastics disrupt wetland sediment microbial communities. Carbon cycle shifted from sink to source.
Meta-analysis (Jan 2026, PubMed, 116 publications): MNPs disrupt soil and sediment microbial nitrogen cycling. Soil nitrate down 24.9%. N2O emissions up 32-38%.
Pacher-Deutsch et al. (UEG Week 2025): First human-sample study confirming MNPs alter human gut microbiome. Changes resemble patterns linked to depression and colorectal cancer.
BMC Gastroenterology (August 2025): Systematic review, 12 studies. MNPs induce gut dysbiosis - loss of beneficial genera, enrichment of pathogens, disrupted metabolic pathways.
Toxics (November 2025): Scoping review, 56 studies. Consistent three-stage MNP mechanism: oxidative stress → barrier disruption → microbiome reconfiguration.
ANCHOVY BOOM / PREY COMMUNITY SHIFT:
Mantua et al. (2025): Northern anchovy population reached near-record high in 2021. Anchovy thiaminase activity: mean 35 nmol/g/min, maximum 206 nmol/g/min. Highest and most variable of any prey species measured.
UC Davis / Oregon State (2024): “Shifts in the ocean ecosystem have caused northern anchovy populations to explode.” Anchovy-dominated diet = primary cause of TDC in California salmon.
PHYTOPLANKTON AS THIAMINE SOURCE (Signal #1 connection):
See Signal #1: Phytoplankton Collapse sources for full documentation of phytoplankton decline and community structure disruption.
This is Signal #4 of 35+ convergence signals.
The salmon are spinning. The seabirds are paralyzed. The microbes that feed them both are being degraded.
The pattern is documented. The mechanism is confirmed. The timeline is clear.