An important, but underappreciated, consequence of climate change is the reduction in crucial nutrient production at the base of the marine food chain: the long-chain omega-3 highly unsaturated fatty acids (n-3 HUFA). This can have dramatic consequences on consumers, such as fish as they have limited capacity to synthesise n-3 HUFA de novo. The n-3 HUFA, such as docosahexaenoic acid (DHA, 22:6n-3) and eicosapentaenoic acid (EPA, 20:5n-3), are critical for the structure and function of all biological membranes. There is increasing evidence that fish will be badly affected by reductions in n-3 HUFA dietary availability, however the underlying mechanisms remain obscure. Hypotheses for how mitochondrial function should change with dietary n-3 HUFA availability have generally ignored ATP production, despite its importance to a cell's total energetics capacity, and in turn, whole-animal performance. Here we (i) quantified individual variation in mitochondrial efficiency (ATP/O ratio) of muscle and (ii) examined its relationship with content in EPA and DHA in muscle membrane of a primary consumer fish, the golden grey mullet Chelon auratus, receiving either a high or low n-3 HUFA diet. Mitochondria of fish fed on the low n-3 HUFA diet had higher ATP/O ratio than those of fish maintained on the high n-3 HUFA diet. Yet, mitochondrial efficiency varied up about 2-fold among individuals on the same dietary treatment, resulting in some fish consuming half the oxygen and energy substrate to produce the similar amount of ATP than conspecific on similar diet. This variation in mitochondrial efficiency among individuals from the same diet treatment was related to individual differences in fatty acid composition of the membranes: a high ATP/O ratio was associated with a high content in EPA and DHA in biological membranes. Our results highlight the existence of interindividual differences in mitochondrial efficiency and its potential importance in explaining intraspecific variation in response to food chain changes.

气候变化的一个重要但未被充分认识的结果是，海洋食物链基础上的关键养分生产减少了：长链omega-3高度不饱和脂肪酸（n-3 HUFA）。这可能对消费者产生巨大影响，例如鱼类，因为它们合成n-3 HUFA de novo的能力有限。n-3 HUFA，如二十二碳六烯酸（DHA，22：6n-3）和二十碳五烯酸（EPA，20：5n-3），对于所有生物膜的结构和功能至关重要。越来越多的证据表明，n-3 HUFA饮食供应量的减少将严重影响鱼类，但是其潜在机制仍然不清楚。线粒体功能应如何随着饮食中n-3 HUFA的可用性而改变的假说通常忽略了ATP的产生，尽管它对细胞的总能量学能力以及整个动物的表现都很重要。在这里，我们（i）量化了肌肉线粒体效率（ATP / O比）的个体差异，并且（ii）检查了其与主要食用鱼类金黄色，鱼Chelon auratus肌肉膜中EPA和DHA含量的关系。，接受高或低n-3 HUFA饮食。低n-3 HUFA饮食的鱼的线粒体的ATP / O比高n-3 HUFA饮食的鱼的线粒体的ATP / O比高。但是，在相同的饮食条件下，线粒体效率在个体之间的差异大约是原来的2倍，导致某些鱼类消耗的氧气和能量底物的一半要比相似饮食中的同种酶产生的ATP量高。同一饮食疗法的个体中线粒体效率的这种变化与膜的脂肪酸组成的个体差异有关：高的ATP / O比与生物膜中的EPA和DHA含量高有关。