Stable isotope ratios are powerful indicators that facilitate the understanding of the diet shifts and between-habitat migration of aquatic animals. However, isotopic change rate can be variable even between the life stages of a single species, which affects field data interpretation. We conducted diet-switch experiments to compare the δ¹³C and δ¹⁵N changes in multiple tissues between the growing and reproductive stages of ayu fish (Plecoglossus altivelis altivelis). Isotopic changes in the muscle and mucus tissues were faster in the growing stage than in the reproductive stage. Isotopic change in the muscle tissue during the reproductive stage was caused mainly by whole-body growth, whereas allometric growth and/or catabolic turnover rather than whole-body growth accounted more for the isotopic changes in mucus tissue during both stages. Isotopic change was slower in muscle, mucus and ovary tissues, in that order, probably according to the allometric growth and/or catabolic turnover of each tissue. Our investigation showed that the timing of drastic changes differed between the δ¹³C and δ¹⁵N values, as the first report of the isotopic change in the fish ovary tissue, which suggests that the δ¹³C and δ¹⁵N values in the ovary tissue may reflect diets and/or habitats of different time scales. Trophic discrimination factors varied between tissues examined. Our results allowed for accurate applications of multiple-tissue isotope analysis to our target fish over all stages. Such approaches to any fish species are more accurate when considering the variability of isotopic changes between and within stages.

中文翻译：

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通过碳和氮稳定同位素分析确定的多阶段香鱼 (Plecoglossus altivelis altivelis) 肌肉、粘液和卵巢组织的周转率

稳定同位素比率是有助于了解水生动物饮食变化和栖息地间迁移的有力指标。然而，即使在单个物种的生命阶段之间，同位素变化率也可能是可变的，这会影响现场数据解释。我们进行了饮食转换实验，以比较香鱼( Plecoglossus altivelis altivelis)生长和繁殖阶段多个组织中δ ¹³ C 和δ ¹⁵ N 的变化）。肌肉和粘液组织的同位素变化在生长阶段比在生殖阶段更快。生殖阶段肌肉组织的同位素变化主要是由全身生长引起的，而异速生长和/或分解代谢周转而不是全身生长在两个阶段对粘液组织同位素变化的影响更大。肌肉、粘液和卵巢组织中的同位素变化依次较慢，这可能取决于每个组织的异速生长和/或分解代谢周转。我们的调查表明，δ ¹³ C 和δ ¹⁵ N 值发生剧烈变化的时间不同，这是鱼类卵巢组织同位素变化的首次报告，这表明δ卵巢组织中的¹³ C 和δ ¹⁵ N 值可能反映不同时间尺度的饮食和/或栖息地。所检查的组织之间的营养鉴别因子各不相同。我们的结果允许在所有阶段将多组织同位素分析准确应用于我们的目标鱼。在考虑阶段之间和阶段内同位素变化的可变性时，这种对任何鱼类物种的方法更准确。