Department of Renewable Resources, University of Alberta, Edmonton, Alberta, Canada.
Canadian Rivers Institute, Biology Department, University of New Brunswick, Fredericton, New Brunswick, Canada.
J Fish Biol. 2022 Jan;100(1):229-241. doi: 10.1111/jfb.14939. Epub 2021 Nov 23.
The field of stable isotope ecology is moving away from lethal sampling (internal organs and muscle) towards non-lethal sampling (fins, scales and epidermal mucus). Lethally and non-lethally sampled tissues often differ in their stable isotope ratios due to differences in metabolic turnover rate and isotopic routing. If not accounted for when using non-lethal tissues, these differences may result in inaccurate estimates of resource use and trophic position derived from stable isotopes. To address this, the authors tested whether tissue type, season and their interaction influence the carbon and nitrogen stable isotope ratios of fishes and whether estimates of species trophic position and resource use are affected by tissue type, season and their interaction. This study developed linear conversion relationships between two fin types and dorsal muscle, accounting for seasonal variation. The authors focused on three common temperate freshwater fishes: northern pike Esox lucius, yellow perch Perca flavescens and lake whitefish Coregonus clupeaformis. They found that fins were enriched in C and depleted in N compared to muscle in all three species, but the effect of season and the interaction between tissue type and season were species and isotope dependent. The estimates of littoral resource use based on fin isotope ratios were between 13% and 36% greater than those based on muscle across species. Season affected this difference for some species, suggesting the potential importance of using season-specific conversions when working with non-lethal tissues. Fin and muscle stable isotopes produced similar estimates of trophic position for northern pike and yellow perch, but fin-based estimates were 0.2-0.4 trophic positions higher than muscle-based estimates for lake whitefish. The effect of season was negligible for estimates of trophic position in all species. Strong correlations existed between fin and muscle δ C and δ N values for all three species; thus, linear conversion relationships were developed. The results of this study support the use of non-lethal sampling in stable isotope studies of fishes. The authors suggest that researchers use tissue conversion relationships and account for seasonal variation in these relationships when differences between non-lethal tissues and muscle, and seasonal effects on those differences, are large relative to the scale of isotope values under investigation and/or the trophic discrimination factors under use.
稳定同位素生态学领域正逐渐从致死采样（内部器官和肌肉）转向非致死采样（鳍、鳞片和表皮黏液）。由于代谢周转率和同位素路径的差异，致死和非致死采样组织的稳定同位素比值往往不同。如果在使用非致死组织时不考虑这些差异，可能会导致基于稳定同位素的资源利用和营养位置的估计不准确。为了解决这个问题，作者测试了组织类型、季节及其相互作用是否影响鱼类的碳和氮稳定同位素比值，以及物种营养位置和资源利用的估计是否受组织类型、季节及其相互作用的影响。本研究建立了两种鳍型与背肌之间的线性转换关系，以解释季节变化。作者以三种常见的温带淡水鱼类为研究对象：北方狗鱼 Esox lucius、黄鲈 Perca flavescens 和湖白鲑 Coregonus clupeaformis。结果表明，在所有三种鱼类中，鳍的 C 富集而 N 亏损，与肌肉相比，但季节的影响以及组织类型与季节之间的相互作用是物种和同位素依赖性的。基于鳍同位素比值的沿岸资源利用估计值比基于肌肉的估计值高 13%至 36%，跨越物种。对于某些物种，季节会影响这种差异，这表明在使用非致死组织时，使用特定季节的转换可能很重要。鳍和肌肉稳定同位素对北方狗鱼和黄鲈的营养位置估计相似，但对于湖白鲑，鳍基估计比肌肉基估计高 0.2-0.4 营养位置。季节对所有物种的营养位置估计的影响可以忽略不计。对于所有三种鱼类，鳍和肌肉的 δ C 和 δ N 值之间存在很强的相关性；因此，建立了线性转换关系。本研究结果支持在鱼类稳定同位素研究中使用非致死采样。作者建议研究人员在使用组织转换关系时，考虑这些关系中的季节性变化，当非致死组织与肌肉之间的差异以及季节对这些差异的影响相对于所研究的同位素值的范围和/或所使用的营养鉴别因子较大时。
