Led by a consortium of researchers from the CNRS, IRD, Ifremer and UBO, among others, the OMEGA research programme is exploring the consequences of climate change on the availability of long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFAs), commonly known as omega-3.These essential nutrients, mainly provided by small pelagic fish (SPF) such as sardines and anchovies, are crucial for human health and the proper functioning of marine ecosystems. The combination of global warming and increasing global demand poses a risk to their availability by 2040.
by Laurie Henry et Carole Saout-Grit
Cover photo: a basket of sardines, rich in omega-3
Availability threatened by climate change
Although they only account for around 1% of the ocean surface, upwelling systems are responsible for around 20% of global fish catches due to their high nutrient content. These zones, known as the Canary Current, Benguela Current, Humboldt Current and California Current, are essential for the production of long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFAs), in particular eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). EPA and DHA are poorly synthesised by animals, including small pelagic fish (SPF) and humans.
SPF such as sardines and anchovies are the main vectors of these essential fatty acids to humans, which they accumulate through their consumption of phytoplankton, the first link in the trophic chain where these lipids are synthesised. These molecules are crucial for the health of organisms, particularly for the functioning of the brain, the cardiovascular system and the immune system. In humans, they have been shown to play a role in the prevention of neurodegenerative and cardiovascular diseases.
However, climate change is likely to disrupt this dynamic by changing the composition of phytoplankton communities. Rising temperatures and other aspects of climate change are likely to favour phytoplankton species that are lower in omega-3, leading to a decrease in their concentration throughout the food web. At the same time, the exploitation of PPP stocks and the increase in demand for omega-3, due to strong demographic growth and the development of aquaculture, are accentuating the pressure on this resource.
A decline in the availability of omega-3 could therefore have direct repercussions on the nutritional state of fish, but also on the quality of human food. Aquaculture depends largely on fish oil for the manufacture of meal and oils rich in EPA and DHA. If these trends continue, they could ultimately affect public health, particularly in regions where fish consumption is a key source of omega-3. By 2040, the global supply of omega-3 could thus become insufficient to meet food and industrial needs. This issue is still not fully integrated into marine resource management strategies.
An interdisciplinary approach to anticipate the future
Faced with this threat, the OMEGA project uses an interdisciplinary scientific approach that combines in situ observations, experiments, modelling, economics and sociological analyses to assess the influence of omega-3 supply and demand on small pelagic populations in a context of climate change. Using the Bay of Biscay as a reference study site, the scientists are developing an innovative methodology that will then be applied to the main upwelling systems (Humboldt, Benguela, Canary Islands, California).
The aim is 1) to analyse the spatio-temporal variability of the omega-3 content of several species of small pelagics, 2) to understand how environmental changes influence their physiology and behaviour, 3) to anticipate the impacts on stocks and the supply of omega-3 for humans, 4) exploring the effects of fishing and processing methods on the quality of omega-3, by studying the impact of fishing gear, the season, the duration of the tides, storage and the place of landing and finally 5) completing the study with a sociological component to analyse the perception of fishermen and consumers, particularly on the relationship between environmental changes and the consumption of omega-3.
Research method and focus © Omega
A project with multiple challenges for the future
The OMEGA programme, thanks to an interdisciplinary approach, aims to anticipate fluctuations in stocks of small pelagic fish and their nutritional value. By combining ecological studies, biochemical analyses and predictive modelling, researchers are developing indicators to better understand the evolution of sardine and anchovy populations, but also to evaluate the quality of the fatty acids they contain.
The results of the project were presented at the TRANSPEL symposium, during which 17 papers were based in whole or in part on the OMEGA project.
© Zhan Zhang/ Unsplash
Find out more on video (by IRD Le Mag ‘) : https://www.youtube.com/watch?v=IQ6yIyPLOao&t=3s and https://www.youtube.com/watch?v=un5LGi0iyh4