Trophic position and foraging ecology of Ross, Weddell, and crabeater seals revealed by compound-specific isotope analysis
Trophic position and foraging ecology of Ross, Weddell, and crabeater seals revealed by compound-specific isotope analysis
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DOI：
10.3354/meps12856
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发表时间：
2019-02-14
影响因子：
2.5
通讯作者：
Harding, Karin C.
中科院分区：
文献类型：
--
作者：
Brault, Emily K.;Koch, Paul L.;Harding, Karin C.
罗斯海豹是研究最少的海洋哺乳动物之一，对它们的觅食生态学知之甚少。迄今为止，使用大量稳定同位素分析的研究表明，罗斯海豹的营养地位介于威德尔海豹和食蟹Lobodon carcinophaga海豹之间。然而，消费者批量稳定同位素值不仅反映营养动态，还反映基线同位素值的变化，这种变化可能很大。我们使用特定化合物的氨基酸同位素分析（CSI-AA）分离同位素效应的移动基线与营养结构的觅食生态，这些生态上重要的南极鳍足类。我们发现，罗斯海豹在一个开放的海洋食物网中觅食，而蟹和威德尔海豹在靠近海岸的类似食物网中觅食。然而，同位素证据表明，食蟹海豹很可能是沿着海冰移动的，而威德尔海豹则是以南极洲西部大陆架的生产区为目标。我们的CSI-AA数据表明，罗斯海豹具有较高的营养地位相当于威德尔海豹，相反，从氮同位素结果散装组织先前的结论。CSI-AA表明，螃蟹海豹的营养地位低于罗斯和威德尔海豹，与磷虾为主的饮食一致。我们的研究结果重新定义了罗斯海豹的营养动力学和觅食生态学的观点，也强调了在觅食研究中量化基线同位素变化的重要性。
Ross seals Ommatophoca rossii are one of the least studied marine mammals, with little known about their foraging ecology. Research to date using bulk stable isotope analysis suggests that Ross seals have a trophic position intermediate between that of Weddell Leptonychotes weddellii and crabeater Lobodon carcinophaga seals. However, consumer bulk stable isotope values not only reflect trophic dynamics, but also variations in baseline isotope values, which can be substantial. We used compound-specific isotope analysis of amino acids (CSI-AA) to separate isotopic effects of a shifting baseline versus trophic structure on the foraging ecology of these ecologically important Antarctic pinnipeds. We found that Ross seals forage in an open ocean food web, while crabeater and Weddell seals forage within similar food webs closer to shore. However, isotopic evidence suggests that crabeater seals are likely following sea ice, while Weddell seals target productive areas of the continental shelf of West Antarctica. Our CSI-AA data indicate that Ross seals have a high trophic position equivalent to that of Weddell seals, contrary to prior conclusions from nitrogen isotope results on bulk tissues. CSI-AA indicates that crabeater seals are at a trophic position lower than that of Ross and Weddell seals, consistent with a krill-dominated diet. Our results redefine the view of the trophic dynamics and foraging ecology of the Ross seal, and also highlight the importance of quantifying baseline isotope variations in foraging studies.