Biological Sciences, University of Canterbury, Ilam, Christchurch, 8041, New Zealand.
Seafood Production Group, The New Zealand Institute for Plant and Food Research Limited, 293-297 Akersten Street, Port Nelson, 7043, New Zealand.
J Comp Physiol B. 2020 Mar;190(2):169-183. doi: 10.1007/s00360-020-01258-5. Epub 2020 Jan 29.
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.
浅海和河口生境是许多幼鱼的育幼场。在这项比较研究中，研究了两种新西兰鱼类（Chrysophrys auratus 鲈鱼和 Aldrichetta forsteri 黄眼鲻鱼）的代谢特征，这两种鱼类的幼鱼在温带沿海环境中共同生活。在幼鱼每年经历的一系列温度（13、17、21°C）下，研究了代谢参数（常规和最大代谢率以及比能消耗-SDA）。为了研究餐量对餐后代谢反应的影响，还确定了一系列不同的饲料量的 SDA。温度是鲈鱼和鲻鱼代谢特征（常规和最大代谢率以及绝对和因子有氧范围）的强烈调节剂。在这两个物种中，代谢率随着温度的升高而升高，YEM 的绝对范围也是如此，尽管对于鲈鱼，只有在最高温度下才更高。对于两个物种，因子范围的行为方式相同，在 13°C 时最大。在整个温度范围内，YEM 的绝对和因子范围比鲈鱼高两倍。温度也影响了鲈鱼的 SDA 反应，而在 YEM 中，当温度从 17°C 升高到 21°C 时，SDA 参数基本不受影响。鲈鱼能够消耗大量的餐量（0.5-3.0% 体重-BM），餐量大于 1% BM 对许多 SDA 参数有明显影响，而鲻鱼似乎只能消耗更有限的口粮量（≤1.0% BM）。在这两个物种中，1% BM 以下的口粮量产生了类似的 SDA 参数变化，表明消化生物能量学具有可比性。总的来说，我们的代谢特征表明，这两个物种都可以适应变化的温带环境温度，并管理消化和饲料同化的能量成本。然而，尽管有这些共同之处，YEM 更大的有氧范围可能表明其对高度变化的温带沿海环境的生理适应能力比鲈鱼更好。
