TY - GEN A1 - Kiene, Marvin A1 - Wacker, Alexander A1 - Martin-Creuzburg, Dominik T1 - Omega-3 versus Omega-6: Are We Underestimating the Ecological Significance of Arachidonic Acid in Aquatic Systems? T2 - Biomolecules N2 - The long-chain polyunsaturated fatty acids (PUFA) eicosapentaenoic acid (EPA, ω-3, or n-3) and arachidonic acid (ARA, ω-6 or n-6) are known to have distinct physiological functions, yet can both support growth and reproduction of consumers, raising the question of whether EPA and ARA are ecologically substitutable dietary resources. We explored the relative importance of EPA and ARA for the growth and reproduction of the freshwater keystone herbivore Daphnia in a life-history experiment. Both PUFA were supplemented in a concentration-dependent manner to a PUFA-free diet, separately and in combination (50% EPA: 50% ARA mixture). The growth-response curves obtained with EPA, ARA, and the mixture were virtually congruent and the thresholds for PUFA limitation did not differ, indicating that EPA (n-3) and ARA (n-6) were substitutable dietary resources under the applied experimental conditions. The actual requirements for EPA and ARA might change with growth conditions, e.g., under the influence of parasites or pathogens. The higher retention of ARA in Daphnia suggests that EPA and ARA are subject to different turnover rates, which also implies different physiological functions. Studies on the ARA requirements of Daphnia could provide valuable information on the presumably underestimated ecological importance of ARA in freshwater food webs. KW - arachidonic acid KW - eicosapentaenoic acid KW - polyunsaturated fatty acids KW - membrane lipids KW - eicosanoids KW - co-limitation KW - Daphnia KW - freshwater food webs KW - limitation KW - ecology Y1 - 2023 UR - https://opus4.kobv.de/opus4-UBICO/frontdoor/index/index/docId/31022 SN - 2218-273X VL - 13 IS - 5 ER -