Benthic foraminiferal stable carbon isotopes as a proxy for organic matter fluxes to the sea floor

我们建议加强海底有孔虫稳定碳同位素记录的适用性，以此作为评估有机质向海底输送的定量指标。我们的目标是开发一种基于地中海未受干扰的表层沉积物中选定的类群的活标本(孟加拉玫瑰染色)的代理。采样站选择在500至1000米之间的狭窄水深区间，并沿地表水生产力和有机质通量的强梯度分布。获得的同位素数据将通过多变量统计分析与特定地点的环境条件和底物的生物地球化学特征相关联。具体地说，我们计划建立一个传递函数，用于评估有机物质向海底的通量速率，该传递函数基于浅海底栖类群Uvilerina Mediterranea和U.peregrina的稳定碳同位素特征。此外，我们还将探索特定营养条件对试验大小与所研究类群的稳定碳同位素信号之间的个体发育关系的潜在影响。随后，传递函数将应用于已公布的地中海晚全新世沉积区间的同位素记录，以重建区域有机质通量和地表水生产力的短期变化。我们的新方法将为验证地中海生物地球化学可变性的模型实验提供数据。

We propose to enhance the applicability of benthic foraminiferal stable carbon isotope records as a quantitative proxy for the assessment of organic matter flux to the sea floor. We aim to develop such a proxy based on living (Rose Bengal stained) specimens of selected taxa from undisturbed surface sediments of the Mediterranean Sea. Sampling stations were selected from a narrow water depth interval between 500 and 1000 m and are located along strong gradients in surface water productivity and organic matter fluxes. The obtained isotope data will be related by multivariate statistical analyses to the site-specific environmental conditions and biogeochemical characteristics of the substrate. Specifically, we plan to establish a transfer function for the assessment of organic matter flux rates to the sea floor based on the stable carbon isotope signature of the shallow infaunal taxa Uvigerina mediterranea and U. peregrina. In addition, we will explore the potential influence of specific trophic conditions on the ontogenetic relation between test size and the stable carbon isotope signal of the studied taxa. Subsequently, the transfer function will be applied to published isotope records from late Holocene sediment intervals of the Mediterranean Sea in order to reconstruct regional short-term changes in organic matter fluxes and surface water productivity. Our new methodological approach will provide data for the validation of model experiments on the biogeochemical variability of the Mediterranean Sea.