Special Edition: Omega-3s

Omega-3 supply: Climate change could threaten global EPA & DHA supply

By Stephen Daniells

- Last updated on GMT

Image: © iStockPhoto tamara_kulikova
Image: © iStockPhoto tamara_kulikova

Related tags: Omega-3 fatty acid, Eicosapentaenoic acid, Epa

Rising ocean temperatures may reduce EPA and DHA production by phytoplankton, with the effects cascading through the world's ecosystems.

According to data published in Global Change Biology​, a 2.5°C increase in water temperature would reduce eicosapentaenoic acid (EPA) by 8.2% and docosahexaenoic acid (DHA) by 27.8% globally.

The ultimate effect may be an overall decline in the global availability of these nutrients for human wellbeing.

“That the global n-3 LC-PUFA [omega-3 long-chain polyunsaturated fatty acid] supply may be threatened in the future adds to a list of serious consequences as a result of climate warming,” ​wrote Stefanie Hixson and Michael Arts from Ryerson University.“While experimental lab studies have shown that changes in FA composition can occur rapidly (< 2 h) in response to temperature, it is the predicted long-term, consistent decrease in n-3 LC-PUFA that may have the most lingering effects on food webs.

“Humans are resourceful and technologically advanced; we will likely create new ways to meet our n-3 LC-PUFA needs (at least for those of us with the means). However, without this advantage, the remaining organisms on the planet, particularly those that normally have access to a significant supply of n-3 LC-PUFA, may have difficulty adapting to reduced levels.

“This could result in lower growth and/or reproduction rates, health issues like lowered immune system function resulting in a higher susceptibility to disease, and impaired cognitive abilities, particularly among top predators for which n-3 LC-PUFA are considered essential nutrients.”

“Climate change is affecting the nutrients that we rely on for our health and survival”

In an interview with Radio Canada International​ Hixson said that the results could potentially damage fish stocks. “We know that EPA in particular is very important for the reproductive health of marine fish and so one might presume that if there is less availability of EPA this may negatively affect reproduction in fish. It’s a possibility.”

Hixson added that there has been a lot of interest in the research, particularly because this is the first study to show such effects. “There is a lot of research into the effects of climate change on phytoplankton but not necessarily on the nutrients they produce, so I think this is a new way of looking how society and other animals may be impacted by climate change: That it is affecting the nutrients that we rely on for our health and survival.”

Omega-3 levels in Plankton Ryerson_Michael_Arts_Stefanie_Hixson
Research co-author Michael Arts (left) and lead author Stefanie Hixson (right). © Brian Bettencourt

Study details

“It is our hope that governments will view this evidence-based research as an accelerated call to action to address the critically urgent issue of climate change,” ​said co-author Professor Michael Arts. “Controlling emissions of greenhouse gases like carbon dioxide, and especially methane, takes on a new urgency when seen in the light of climate warming-induced reductions in the global stockpile of the brain-building nutrient DHA.”

Hixson and Arts compiled data from the literature for EPA and DHA levels in different species of algae from around the world, at specific temperatures, and then used this large data set was then used to predict the levels of these two fatty acids in algae with certain increases in temperature based on climate change models.

They used a linear regression models to predict changes in EPA and DHA levels with changing water temperatures.

“Using a previously published estimate of the global production of EPA by diatoms, which contribute to most of the world's supply of EPA, we predict a loss of 14.2 Mt of EPA annually as a result of ocean warming,” ​they wrote.  

“Our results demonstrate that by the year 2100 EPA and DHA production – and therefore its availability for human consumption – will be very significantly impacted if current trends in global warming continue unabated,”​ explained Hixson in a press release from Ryerson University.

“This is a serious problem, as the current supply of these nutrients has been shown by other researchers to be barely sufficient to meet the nutritional demand of the human population.”

Future research will explore how the potential decrease in DHA production might impact animals in the future, especially with regard to cognitive performance, including intelligence.

Field experiments are also planned to directly test how global warming may be impacting both the production and movement of EPA and DHA through freshwater wetlands and from there onto the land.

Source: Global Change Biology
Published online ahead of print, doi: 10.1111/gcb.13295
“Climate warming is predicted to reduce omega-3, long-chain, polyunsaturated fatty acid production in phytoplankton”
Authors: S.M. Hixson, M.T. Arts

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