Thiamine, a nutrient that most animals rely on, lacks some marine ecosystems and experts are deeply concerned.
In January 2020, the staff of Coleman National Fish Hatchery in California noticed disoriented fish amidst the olive-colored clouds of live fish that were having a tough time swimming. These small fish were observed to roll onto their sides and sink to the bottom of the tank only to spring back upright and roll over again.
Hundreds of mortalities have been reported in facilities that contained millions of fish normally, which tipped experts that something was not right.
Brett Galyean, a manager at California hatchery says that deaths were by the thousands and weren't ceasing any time soon.
Biologists from the California-Nevada Fish Health Center inspected the situation but couldn't make a diagnosis. Hence, samples were sent over to the University of California for further testing.
The team researched the causes of the rapid expiration of fish daily and uncovered a study on nutritional deficiencies of trout from the Great Lakes. Several decades ago, fish in the region were sick and dying and have been found to be deficient in thiamine or vitamin B1.
What is Thiamine?
Thiamine or Vitamin B1 is a water-soluble nutrient that is needed by all living cells. It is essential for at least five life-sustaining enzymes used in metabolism.
Most animals acquire thiamin from their diet. Hence thiamine deficiency arises from thiamine deficient food or prey.
In addition, some prey species produce large quantities of thiaminase that break down thiamine in predators that eat them.
Thiamine originates in the lowest levels of the food web where species of bacteria, fungi, phytoplankton, and plants synthesize the compound which naturally occurs in multiple forms.
When thiamine deficiency occurs, it may lower reproduction, decrease early life viability, immunosuppression, neurological disorders, and in the long-run decline in fish and wildlife populations.
The phenomenon has been observed in reptiles, fish, birds, wild populations, and possibly mammals.
Combating Thiamine Deficiency in Fish
Biologists from the Fish Health Center ran a trial of submerging the fish in water with dissolved thiamine powder. Galyean says it was a success where after several hours, nearly all fish were back to normal behavior.
Coleman and his team decided to scale up the treatment and applied it to roughly a million fry. It solved the short term problems but was not a viable solution for the underlying problems.
Fish acquire thiamine via ingestion of food, while females pass the nutrient to their eggs. The troubling new condition implicated that something is wrong in the Pacific Ocean--the last place the fish eat before entering the hatchery and fresh water to spawn.
In 2016 a paper was published in the journal Nature, that sounded the alarm of the effects of thiamine deficiencies on long-term wildlife population declines.
The paper noted that the marine and the terrestrial vertebrate population dropped by half from 1970-2012. The downside, according to the authors were happening at a much more rapid rate than expected.
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