13C and 15N Natural Abundance in Southern Ocean Biota: An Investigation of Biogeochemistry and Trophic Structure

生物和环境中稳定同位素比值的分析是研究食物网结构和生物地球化学途径性质的重要方法。与南极洲相邻的南大洋浮游生物的13C/12C比率是迄今为止发现的浮游生物中最低的。尽管以前有过一些研究，但南极浮游生物中13C的消耗并没有得到令人满意的解释。这个问题的答案很重要，因为这个同位素异常明确地表明，南大洋的碳生物地球化学一定在某种程度上与现在海洋的其他部分明显不同。南极浮游生物中13C的消耗也可能直接影响到古海洋学对海洋沉积记录中发现的类似消耗的解释。劳和他的合作者建议测量南大西洋、德雷克海峡、斯科舍海和威德尔海的生物群和颗粒有机物中的13C/12C和15N/14N比率。碳同位素测量将解决上述问题；氮同位素测量将提供关于食物网性质的进一步信息，并将有助于检验有关同位素丰度变化原因的假设。该项目的成果将直接补充其他科学家在正在进行的南极冰缘区海洋生态系统研究（AMERIEZ）项目中的工作，并解决极地研究委员会建议特别关注的研究领域。

The analysis of stable isotope ratios in organisms and in the environment is an important method for investigating the structure of food webs and the nature of biogeochemical pathways. Plankton in the Southern Ocean adjacent to Antarctica have the lowest 13C/12C ratios yet found for pelagic organisms. Despite some previous research this depletion of 13C in Antarctic plankton has not been satisfactorily explained. The answer to this question is important because this isotopic anomaly is an unambiguous indication that carbon biogeochemistry in the Southern Ocean must in some way be markedly different from the rest of the present ocean. The 13C depletion in Antarctic plankton could also have a direct bearing on the paleoceanographic interpretation of similar depletions found in the marine sedimentary record. Rau and his collaborators propose to measure 13C/12C and 15N/14N ratios in biota and particulate organic matter in the southern Atlantic Ocean, Drake Passage, Scotia Sea and Weddell Sea. The carbon isotopic measurements will address the problems mentioned above; the nitrogen isotopic measurements will provide further information on the nature of the food web and will facilitate the testing of hypotheses concerning the causes of the variations in isotopic abundances. The results of this project will directly complement the work of other scientists in the ongoing Antarctic Marine Ecosystem Research in the Ice Edge Zone (AMERIEZ) project and address an area of research recommended for special attention by the Polar Research Board.