Short‐term starvation affects fatty acid metabolism of Daphnia magna neonates and juveniles

Abstract

As fatty acids are one of the most crucial biomolecules transferred across the aquatic food webs, they are claimed to be bioindicators of stressors. Among the various environmental stressors, food shortage is of prime importance. Lower food availability can affect fatty acid metabolism of organisms. We investigated the effects of short-term starvation on fatty acid metabolism of Daphnia magna neonates and juveniles. The results revealed that the total fatty acid content in neonates and juveniles of daphnids both rapidly declined within 24 h of starvation, and it remained constant after the following 24 h of starvation. In addition, the fatty acid profiles in neonates or juveniles fed for 24 h were not significantly different from that in the fasting individuals, while the feeding daphnids presented notably higher fatty acid saturation and lower unsaturation in relative to the fasting daphnids within the next 24 h. D. magna neonate increased its special need for C16:1n7 over food transformation, and its C16:1n7 content was elevated the most when fed for 48 h, much higher than the other fatty acids. Time-course changes in fatty acid content in starved D. magna showed that the dietary polyunsaturated α-linolenic acid, i.e. C18:3n3, could be considered as the potential biomarker in either neonates or juveniles to respond to the abiotic food shortage. This study could offer insights into the assessment of food-deprived stress in terms of fatty acid metabolism for distinct ages of cladocerans.