Shallow coastal and estuarine habitats function as nurseries for many juvenile fish. In this comparative study, metabolic profiles of two New Zealand finfish, snapper (Chrysophrys auratus) and yellow-eyed mullet—YEM (Aldrichetta forsteri) that as juveniles share the same temperate coastal environments, were examined. Metabolic parameters (routine and maximum metabolic rates, and specific dynamic action—SDA) were investigated at a set of temperatures (13, 17, 21 °C) within the range juveniles both species experience annually. SDA was also determined for a range of different feed rations to investigate the effects of meal size on postprandial metabolic response. Temperature was a strong modulator of snapper and YEM metabolic profile (routine and maximum metabolic rates, and absolute and factorial aerobic scope). Metabolic rates increased with temperature in both species as did absolute scope in YEM, though for snapper, it was only greater at the highest temperature. Factorial scope behaved in the same fashion for the two species, being greatest at 13 °C. Both absolute and factorial scope were ~ twofold greater in YEM than in snapper across the entire temperature range. Temperature also affected SDA response in snapper, while in YEM, SDA parameters were largely unaffected when temperature increased from 17 to 21 °C. Snapper were able to consume a large range of meal sizes (0.5–3.0% body mass—BM) with meal sizes > 1% BM having a pronounced effect on numerous SDA parameters, whereas mullet appeared to consume more limited ration sizes (≤ 1.0% BM). In both species, rations ≤ 1% BM produced similar changes in SDA parameters identifying comparable digestive bio-energetics. Overall, our metabolic characterisations demonstrate that both species can adjust to the variable temperate environmental temperatures and manage the energetic costs of digestion and feed assimilation. Yet, despite these general similarities, YEM’s greater aerobic scope may point to better physiological adaptation to the highly variable temperate coastal environment than were observed in snapper.

中文翻译：

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温度和进料量对两种温带新西兰有鳍鱼 Chrysophrys auratus 和 Aldrichetta forsteri 有氧范围和特定动力作用的影响

浅海和河口栖息地是许多幼鱼的育苗场。在这项比较研究中，研究了两种新西兰有鳍鱼的代谢特征，鲷鱼 (Chrysophrys auratus) 和黄眼鲻鱼 - YEM (Aldrichetta forsteri) 作为幼鱼共享相同的温带沿海环境。代谢参数（常规和最大代谢率，以及特定的动态作用 - SDA）在一组温度（13、17、21°C）下进行了研究，这些温度在两个物种每年都会经历的幼鱼范围内。还确定了一系列不同饲料日粮的 SDA，以研究膳食量对餐后代谢反应的影响。温度是鲷鱼和 YEM 代谢特征（常规和最大代谢率，以及绝对和因子有氧范围）的强大调节剂。两种物种的代谢率都随着温度的升高而增加，YEM 中的绝对范围也是如此，但对于鲷鱼来说，仅在最高温度下代谢率更高。两个物种的因子范围以相同的方式表现，在 13 °C 时最大。在整个温度范围内，YEM 的绝对范围和因子范围都比鲷鱼大两倍。温度也影响鲷鱼的 SDA 响应，而在 YEM 中，当温度从 17 °C 增加到 21 °C 时，SDA 参数基本上不受影响。鲷鱼能够消耗大范围的膳食量（0.5-3.0% 体重 - BM），膳食量 > 1% BM 对许多 SDA 参数有显着影响，而鲻鱼似乎消耗更有限的日粮量（≤ 1.0%） BM）。在这两个物种中，定量≤ 1% BM 在 SDA 参数中产生了类似的变化，从而确定了可比较的消化生物能量学。总体而言，我们的代谢特征表明，这两个物种都可以适应多变的温带环境温度，并管理消化和饲料同化的能量成本。然而，尽管有这些普遍的相似之处，与鲷鱼相比，YEM 更大的有氧范围可能表明对高度多变的温带沿海环境更好的生理适应。