Measuring carbon isotope ratios of microphytobenthos using compound‐specific stable isotope analysis of phytol
Measuring carbon isotope ratios of microphytobenthos using compound‐specific stable isotope analysis of phytol
复制标题
使用植醇化合物特异性稳定同位素分析测量微型底栖植物的碳同位素比
DOI：
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发表时间：
2005
期刊：
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通讯作者：
S. Blackburn
中科院分区：
文献类型：
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作者：
J. Oakes;A. Revill;R. Connolly;S. Blackburn
碳稳定同位素分析是验证微型底栖动物(MPB)在河口食物网中所起作用的理论的最常用方法之一。然而，从沉积物中提取MPB以确定纯同位素特征的困难阻碍了此类研究。我们建立了植醇δ13C(δ13C)的化合物特异性同位素分析方法，作为δ13C的准确替代物。在大多数情况下，MPB是河口沉积物中植物酚的主要来源，特别是在浅水环境中，因此我们的方法避免了提取MPB的需要。我们在实验室中证明了δ13CPhytol和δ13CBulk之间的关系，并可以预测δ13CBulk在中等复制(n=5)时观察值的1.8‰(95%可信区间)内。如果包括水温，δ13CPhytol预测δ13C散装在1.3‰内。对于更大的复制(n=10)，预测非常好(在1.0‰内)。两个来源的混合模型评估了每种评估MPB对消费者营养贡献的方法的有用性。在中等复制情况下(n=5)，对于mpb和另一生产者之间6.0‰的差距，当同时使用δ13CPhytol和温度(95%CI 0.40)而不是仅使用δ13CPhytol(0.46)时，估计更准确(即95%的CI较小)。最大的精度差距是6‰，接近文献中的平均差距(5.5‰)。考虑到从沉积物中提取MPB的困难，对食物网的碳同位素研究可以使用植物酚的CSIA，特别是与简单的水温测量相结合。方法学的进步将使重新评估MPB的营养重要性成为可能。
Carbon stable isotope analysis is one of the most common methods for validating theories about the role microphytobenthos (MPB) plays in estuarine food webs. However, difficulties extracting MPB from sediments to determine a pure isotope signature have hampered such studies. We have developed compound‐specific isotope analysis (CSIA) of phytol δ13C (δ13Cphytol) as an accurate proxy for δ13C of bulk MPB (δ13Cbulk). In most circumstances MPB is the dominant source of phytol in estuarine sediments, particularly in shallow water environments, so our method circumvents the need to extract MPB. We have demonstrated in the laboratory the relationship between δ13Cphytol and δ13Cbulk, and could predict δ13Cbulk within 1.8‰ (95% CI) of observed values at moderate replication (n = 5). If water temperature is included, δ13Cphytol predicts δ13Cbulk within 1.3‰. With greater replication (n = 10), predictions are extremely good (within 1.0‰). A two‐source mixing model assessed the usefulness of each method for estimating MPB contribution to consumer nutrition. At moderate replication (n = 5), for a gap between MPB and another producer of 6.0‰, estimates were more precise (i.e., 95% CIs were smaller) when both δ13Cphytol and temperature were used (95% CI 0.40) rather than only δ13Cphytol (0.46). The greatest difference in precision was for a gap of 6.0‰, close to the average gap in the literature (5.5‰). Given the difficulty of extracting MPB from sediment, carbon isotope studies of food webs could benefit by using CSIA of phytol, especially in conjunction with simple measurements of water temperature. The advance in methodology will allow a reevaluation of the trophic importance of MPB.