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

点击翻译按钮获取中文摘要

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.