Controls on barium incorporation into tests of benthic foraminifera from the Aegean Sea (Eastern Mediterranean Sea) – Towards a species-specific Ba/Ca calibration

We have analysed Ba/Ca ratios of live and dead benthic foraminifera ( Uvigerina mediterranea and Melonis affinis ) from core tops of seven sites located in the Aegean Sea by laser ablation ICP-MS. There are no significant Ba/Ca differences in live and dead specimens of U. mediterranea . For M. affinis we apply a threshold criterion for extremely high Ba/Ca in live specimens in order to highlight the overall uniform Ba/Ca signal. The Ba/Ca intra-test variability varies between 16 and 24 % relative standard deviation per specimen. It is attributed to biomineralisation processes i.e., vital effects. The Ba/Ca ratios of M. affinis are significantly higher than those of U. mediterranea throughout most of the sites and their respective samples from different sediment depths. The influence on Ba/Ca of both species by biomineralisation processes and/or microhabitat effects remains open. Linking the Ba/Ca ratios to measured Ba concentration of bottom waters from one of the studied sites, shows partition coefficients of D Ba = 0.34, and D Ba = 0.49 for U. mediterranea and M. affinis , respectively. We could not identify trends of Ba/Ca ratios to observed/ modelled gradients of relevant environmental factors between the seven analysed sites, such as primary productivity and associated C org fluxes or TOC concentrations. Despite the demonstrated limited proxy potential in these parts of the Aegean Sea, we suggest that it is possible to employ Ba/Ca of infaunal benthic species in order to reconstruct export productivity in deep-sea areas with a less complex linkage between primary productivity and nutrient distribution in bottom waters. • Barium incorporation into deep-sea benthic foraminiferal shells is species-specific. • Ba/Ca develops a uniform signal between live and dead specimens. • Melonis affinis is found with higher Ba/Ca ratios than Uvigerina mediterranea. • Ba/Ca intra-test variability of both species is on average 16–24 % RSD per specimen. • D Ba in the Northern Aegean Sea ranges between 0.34 and 0.49.