Average shell size of plantkonic foraminifera from 28 stations in the Aegean and the Levantine Sea

For detailed quantitative micropalaeontological analysis, specimens of planktonic foraminifera were picked from about 3g of dry marine sediment, taken from the 1-2 topmost centimeters of the cores. After wet sieving, the dried coarse fraction was sieved through a 125 μm screen and split using an Otto micro-splitter into aliquots of at least 300 planktonic foraminifera specimens. The specimens were orientated and stabilized in separate cells on a Plumer microslide with tragacanth glue for and were photographed for assemblage size analysis. Images were acquired using a modular Leica M165 C fully apochromatic stereo microscope with an integrated 10 megapixel Leica IC90 E color camera (at 2× magnification) and processed using ImageJ software (version 1.50i). The image analysis system determines test 2-D (silhouette) areas and Feret's diameters for each aliquot. Foraminifera shells were positioned to capture the maximum silhouette area of each individual, corresponding to the umbilical or spiral sides, since the difference in average areas for the spiral and umbilical orientations was found for several species to be negligible (Marshall et al., 2013; doi:10.1002/palo.20034). Calibration for the silhouette area and Feret's diameter measurements was performed using a microscale image taken at the same magnification as the foraminiferal images (2×).