Sinnatamby R Niloshini, Dempson J Brian, Power Michael
Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, Canada.
Rapid Commun Mass Spectrom. 2008 Sep;22(18):2773-8. doi: 10.1002/rcm.3674.
Stable isotope signatures were obtained from paired scale and muscle tissue samples from smolt, post-smolt and one-sea-winter adult Atlantic salmon (Salmo salar). Post-smolt and adult scales were separated into central and outer (marine) portions with analyses carried out on the marine growth section of both life-history stages and the central portion for the adult scales. Muscle and scale delta(13)C and delta(15)N signatures were assessed (1) to determine whether a linear relationship exists between tissue types, (2) to determine if a constant offset exists between tissue signatures across all life-history stages, and (3) to evaluate whether underplating imparts a significant bias to life-history scale segments that would preclude their use in retrospective analyses of any ontogenetic dietary changes between life-history stages. Significant correlations were found to exist between muscle and scale stable isotope signatures obtained from smolts (delta(13)C and delta(15)N) and adults (delta(15)N). Both the muscle and the scale signatures captured the dietary shift associated with the transition from freshwater to the marine environment. Post-smolt and adult scales were depleted relative to muscle tissue, which may be attributed to isotopic differences in amino acid composition between muscle and scale tissues. The results suggest that scales may better represent dietary carbon sources because they are not influenced by lipid dynamics. The scale, however, appears less responsive to short-term shifts in diet relative to muscle and, therefore, must be used only to infer seasonally integrated dietary patterns for slow-growing life-history stages.
从银化鲑、后银化鲑和一龄成年大西洋鲑（Salmo salar）的鳞片和肌肉组织配对样本中获取稳定同位素特征。后银化鲑和成年鲑的鳞片被分为中央部分和外部（海洋）部分，对两个生活史阶段的海洋生长部分以及成年鲑鳞片的中央部分进行分析。评估了肌肉和鳞片的δ(13)C和δ(15)N特征，以(1)确定组织类型之间是否存在线性关系，(2)确定所有生活史阶段的组织特征之间是否存在恒定偏移，以及(3)评估底层是否会对生活史鳞片段产生显著偏差，从而排除其在回顾性分析生活史阶段之间个体发育饮食变化中的应用。发现从银化鲑（δ(13)C和δ(15)N）和成年鲑（δ(15)N）获得的肌肉和鳞片稳定同位素特征之间存在显著相关性。肌肉和鳞片特征都捕捉到了与从淡水到海洋环境转变相关的饮食变化。后银化鲑和成年鲑的鳞片相对于肌肉组织贫化，这可能归因于肌肉和鳞片组织之间氨基酸组成的同位素差异。结果表明，鳞片可能更好地代表饮食碳源，因为它们不受脂质动态的影响。然而，相对于肌肉，鳞片对饮食的短期变化反应较小，因此，仅必须用于推断生长缓慢的生活史阶段的季节性综合饮食模式。
