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首页> 外文期刊>Paleoceanography >Combined carbonate carbon isotopic and cellular ultrastructural studies of individual benthic foraminifera: 2. Toward an understanding of apparent disequilibrium in hydrocarbon seeps
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Combined carbonate carbon isotopic and cellular ultrastructural studies of individual benthic foraminifera: 2. Toward an understanding of apparent disequilibrium in hydrocarbon seeps

机译：单个底栖有孔虫碳酸盐碳同位素和细胞超微结构的组合研究：2.理解烃渗流中的表观不平衡

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Numerous previous studies show disequilibrium between stable carbon isotope ratios of foraminiferal calcite and pore water dissolved inorganic carbon in hydrocarbon seeps, calling into question the utility of this widely used paleoceanographic tracer as a proxy. We use a recently developed method to compare stable carbon isotope ratios of foraminiferal carbonate with cell ultrastructural observations from individual benthic foraminifera from seep (under chemosynthetic bivalves) and nonseep habitats in Monterey Bay, California, to better understand control(s) of benthic foraminiferal carbon isotope ratios. Two attributes previously proposed to cause the isotopic offsets are diet and symbionts. Ultrastructural analysis shows that positive staining with Rose Bengal indicates presence of foraminiferal cytoplasm, bacterial biomass, or a combination of both and, thus, is not an unequivocal indicator of viability. We also show for the first time that some living seep foraminifera have endobionts. Results from our unique, yet limited, data set are consistent with suggestions that, in our sites, several foraminiferal species collected from seep clam beds may not survive there, diet and symbiont presence do not appear to be major contributors to disequilibrium, little calcification of seep-tolerant foraminiferal species occurs while seep conditions prevail, and microscale variability in habitats could influence δ13C of benthic foraminiferal carbonate. Results further suggest that our knowledge of benthic foraminiferal ecology and biomineralization, especially in extreme habitats such as seeps, must be bolstered before we fully understand the fidelity of paleoenvironmental records derived from benthic foraminiferal test δ13C data.
机译：先前的许多研究表明，有孔虫方解石的稳定碳同位素比与烃渗流中孔隙水溶解的无机碳之间的不平衡，使人们广泛质疑这种广泛使用的古海洋示踪剂是否可以替代。我们使用一种最新开发的方法来比较有孔虫碳酸盐的稳定碳同位素比与来自加利福尼亚州蒙特雷湾的渗水（在化学合成双壳类下）的单个底栖有孔虫和非深栖生境的细胞超微结构观察结果，以更好地了解对底栖有孔虫碳的控制同位素比。先前提出的引起同位素偏移的两个属性是饮食和共生。超微结构分析表明，玫瑰红的阳性染色表明有孔虫细胞质，细菌生物量或两者的结合存在，因此，这并不是生存力的明确指标。我们还首次显示一些活的有孔虫有内生菌。来自我们独特但有限的数据集的结果与以下建议相一致：在我们的站点中，从渗水蛤beds床上收集的一些有孔虫可能无法在那里生存，饮食和共生体的存在似乎不是造成不平衡的主要因素，钙的钙化很少。在渗水条件普遍存在的情况下，会出现耐渗水的有孔虫物种，并且生境的微观变化会影响底栖有孔虫碳酸盐的δ13C。结果进一步表明，必须充分了解底栖有孔虫生态学和生物矿化的知识，尤其是在诸如渗水等极端生境中，才能充分了解由底栖有孔虫测试δ13C数据得出的古环境记录的保真度。

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