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Faculty of Science

Dwindling DHA availability – New research reveals unseen forces of global warming already in play

Dr. Michael Arts


2030 – That’s the end date a 2018 UN report gives the world to make drastic cuts to carbon emissions. Miss the target and global temperatures could eventually reach 1.5°C above pre-industrial levels. Potential consequences: rising sea levels, floods, drought, food shortages – all the macro effects featured in media. 

Yet, another insidious impact may already be in motion – and it’s happening at minute levels, imperceptible to humans. The story begins with lowly aquatic plants, but by 2100, could see 96% of the world’s population lacking sufficient access to a critical, brain-building, essential fatty acid, docosahexaenoic acid (DHA). Its most prolific producers: algae. 

“96% is a big, scary number,” says Ryerson biology Professor Dr. Michael Arts. So worrisome are the implications that he foresees a large-scale “dampening of human potential.”


Making the global warming connection 

In 2016, Arts demonstrated, in the journal Global Change Biology, how warmer water reduces essential fatty acids in many species of algae. Essential fatty acids are highly retained so the expectation is that reduced DHA in algae will be passed up the food chain to fish.  Arts’ latest research, in collaboration with Dr. Stefanie Colombo, Dalhousie University and, from the University of Toronto, Tim Rodgers, and Drs. Miriam Diamond and Richard Bazinet, extends the scope of this work in a new publication, Ambio.

“We’re the first to make the global climate change connection,” says Arts. “We looked specifically at how warming waters reduce algal DHA production, and how this effect could transfer up the food chain, ultimately impacting humans.”


DHA’s critical role in brain function

DHA is the most abundant long-chain polyunsaturated omega-3 fatty acid in the mammalian brain. Arts explains: “DHA is intimately involved in cell signalling, thoughts, memories and vision.” 

For fetuses and babies, sufficient intake is critical. “Studies show reduced cognitive ability in babies and infants who don’t get enough DHA in their diet,” says Arts.  

Eating fish is currently the leading source of DHA, but global warming now threatens the production of DHA at source.


Temperature-sensitive chemical reactions

As ectotherms, algae’s body temperature mirrors the surrounding environment. When water cools, so do algae. Warmer water = warmer algae. 

“It may seem algae are vulnerable, but they have a trick up their sleeve,” Arts explains. “Algae can protect themselves by altering the chemical composition of their cell membranes.”

In cooler water, algae increase DHA production, combatting rigidity and keeping their membranes flexible. The opposite is now happening. To keep membranes from becoming too fluid, algae decrease DHA production. 

Fish still eat the zooplankton that eat the algae, but with less DHA passed on. To humans the fish filets look no different, but their DHA content may be progressively compromised. 


“Shocked by the numbers”

The researchers expected to find reduced DHA reaching humans, but didn’t know how much. Arts recalls: “After completing our calculations, we were shocked at how big the reduction will be if we continue with business as usual i.e. with no changes to carbon emissions.”

At status quo, 96% of the world will lack sufficient access to DHA by 2100. The impact to collective global brain power has Arts worried. “This will affect cognitive performance of young children and lead to undesirable outcomes in their lives, careers and ability to achieve.” 

Vulnerable populations such as sub-Saharan Africa will be particularly disadvantaged due to limited buying power or access to large freshwater lakes.  


The search for solutions

Research is now under way to ensure adequate future supplies of DHA. “Farming algae is one solution,” says Arts. “It’s expensive, but it’s already happening.”  Arts is also building a mega database of fatty acid profiles in terrestrial plants. But from over 3000 samples so far, he has yet to come across a single species with DHA producing capability. However, genetic engineering to produce algae or terrestrial seed crops with DHA producing ability are other options.

“It’s time to stop talking and start acting. We don’t have time to wait for government feasibility studies,” says Arts, who wages a continual fight to stay optimistic. “We’re playing Russian roulette with a loaded gun, and the average person doesn’t realize just how dangerous this could potentially be. But when I see people, especially young people, across the world genuinely concerned and trying, it’s encouraging.”