Department of Biological and Environmental Sciences, University of Jyväskylä, PB 32, FI-40014 Jyväskylä, Finland.
J Fish Biol. 2010 Jul;77(1):80-97. doi: 10.1111/j.1095-8649.2010.02656.x.
Seasonal and ontogenetic shifts in the diet of Arctic charr Salvelinus alpinus were studied in a deep, ultra-oligotrophic lake in subarctic Finland from both stomach contents and the stable carbon (delta(13)C) and nitrogen (delta(15)N) isotope compositions of muscle and liver tissues. Both diet and isotope results indicated that the S. alpinus population relied mainly on littoral benthic energy sources. The strong littoral reliance appeared largely independent of season or fish size, although the data lacked small (total length, L(T), <130 mm) and young (<3 years) S. alpinus. Liver isotope values of intermediate-sized S. alpinus (200-350 mm), however, suggested exploitation of the increase in the abundance of pelagic zooplankton in the late open-water season. The results suggest that, in general, a strong littoral reliance of fishes can be a feature in subarctic lakes throughout the year. Due to its faster isotopic turnover rate and thus higher resolution for temporal diet changes, liver could be more commonly used in stable-isotope studies of fish trophic niche shifts instead of using only the less responsive muscle tissue.
本研究以生活于北极芬兰亚北极地区一个深而极度寡营养湖中北极红点鲑(Salvelinus alpinus)为对象，通过胃内容物和肌肉及肝脏组织的稳定碳（δ(13)C）和氮（δ(15)N）同位素组成分析，研究了其季节性和发育阶段的食性变化。饮食和同位素结果均表明，北极红点鲑种群主要依赖于沿岸底栖能源。尽管数据缺乏小型（全长，L(T)，<130mm）和年轻(<3 岁)的北极红点鲑，但这种强烈的沿岸依赖性在很大程度上与季节或鱼的大小无关。然而，中等大小（200-350mm）的北极红点鲑的肝脏同位素值表明，它们在开阔水域后期利用了浮游动物丰度增加的优势。研究结果表明，在亚北极地区的湖泊中，鱼类强烈依赖沿岸环境可能是全年的普遍现象。由于肝脏的同位素周转率较快，因此对于时间上的饮食变化分辨率更高，相对于肌肉组织，肝脏可能更常用于稳定同位素研究鱼类营养生态位的变化。
