Projected declines in global DHA availability for human consumption as a result of global warming

Abstract

Docosahexaenoic acid (DHA) is an essential, omega-3, long-chain polyunsaturated fatty acid that is a key component of cell membranes and plays a vital role in vertebrate brain function. The capacity to synthesize DHA is limited in mammals, despite its critical role in neurological development and health. For humans, DHA is most commonly obtained by eating fish. Global warming is predicted to reduce the de novo synthesis of DHA by algae, at the base of aquatic food chains, and which is expected to reduce DHA transferred to fish. We estimated the global quantity of DHA (total and per capita) currently available from commercial (wild caught and aquaculture) and recreational fisheries. The potential decrease in the amount of DHA available from fish for human consumption was modeled using the predicted effect of established global warming scenarios on algal DHA production and ensuing transfer to fish. We conclude that an increase in water temperature could result, depending on the climate scenario and location, in a * 10 to 58% loss of globally available DHA by 2100, potentially limiting the availability of this critical nutrient to humans. Inland waters show the greatest potential for climate-warminginduced decreases in DHA available for human consumption. The projected decrease in DHA availability as a result of global warming would disproportionately affect vulnerable populations (e.g., fetuses, infants), especially in inland Africa (due to low reported per capita DHA availability). We estimated, in the worst-case scenario, that DHA availability could decline to levels where 96% of the global population may not have access to sufficient DHA. Keywords Aquaculture Á Climate change Á Docosahexaenoic acid (DHA) Á Fisheries Á Global warming Stefanie M. Colombo and Timothy F. M. Rodgers contributed equally to this project.

Winter in water: differential responses and the maintenance of biodiversity

“…Some evidence has already linked shorter winters with reduced reproductive success of a spring spawning, cool water fish (Farmer et al ). Warmer temperatures could also indirectly affect the ability of fishes to acquire resources necessary for growth and reproduction by altering the production of essential biomolecules at the base of the food web (Colombo et al ). Alternatively, warmer winters might benefit the growth of all fishes if the increase in metabolic demand for resources is met (Brodersen et al ) and, at least temporarily, increase species richness through regional shifts in the species pool (Lancaster et al ).…”

Algae: Critical Sources of Very Long-Chain Polyunsaturated Fatty Acids

“…Thus, there are more and more examples where algae (or new genetically-manipulated agricultural crops) are needed to reduce the current and future projected shortfalls in VLCPUFA. The anticipated shortage of VLCPUFA will only be made worse by climate change [54].…”

“…Given the increasing demand for VLCPUFA, as well as the problems with maintaining fish supplies, it is clear that this is a serious issue, that needs to be addressed urgently. Some calculations about the amounts of EPA and DHA which will be needed in the future [48] and possible shortfalls due to climate change [54] have been made.…”

Oxidation of polyunsaturated fatty acids to produce lipid mediators

“…Instead, the vast majority are synthesised by marine microalgae at the base of the marine food web [77]. Nevertheless, even this supply is currently under threat due to climate change [4,78]. For humans, the precursor essential fatty acids (LA, ALA) can be converted to 20 and 22C PUFA but rather inefficiently [3,54].…”