*3.1. Sediment Sampling Strategy and Site Selection*

The study is based on the micropaleontological analysis of the distribution abundance pattern and size variability of the planktonic foraminiferal fauna in a series of modern core-tops derived from 17 surface sediment sites across the central Mediterranean Sea. The samples were collected by multicores during various expeditions (POSEIDON cruise "CAPPUCCINO" in June 2006, Meteor cruise M71/3 in January 2007) and cover a latitudinal NW-SE transect from the north Adriatic to the south Ionian Sea, spanning variable sea surface parameters, different productivity regimes, and a wide depth range between 94 and 4088 m (Table 1 and Figure 1). Their chronology is based on <sup>210</sup>Pb and <sup>137</sup>Cs radiometric dating applied on some of the present samples [81] and surrounding core-tops [82,83]. Although generally the core-top samples provide integrated information on a longer time scale (decades, centuries or millennials depending on the sedimentation rate of the selected sites) compared to the water column (e.g., plankton tow, sediment traps) derived samples, the relatively low (0.06–0.91 cm yr−<sup>1</sup> , avg. 0.19 cm yr−<sup>1</sup> ; [77]) sedimentation rates (likely decrease with distance from the shore) in conjunction with the constant sediment accumulation rate over the last century that characterizes the central Mediterranean surface sediments [84] corroborate the recent character of the analyzed samples. Accordingly, all studied core tops are suggested to have a modern age and in accordance with other core-top studies within the Mediterranean Sea [18,20,24,77,85,86]. Thus, our dataset represents an integrated record of some yr to 50 yr or a few 100 yr at most, depending on the core location. The multicore provided topmost (0–1 cm) sediments with an undisturbed sediment–water interface. More explicitly, we use 6 core-top samples along the south Adriatic Sea from the Gargano Promontory to the Strait of Otranto, supplemented by additional 11 samples from the entire Ionian basin (from the Gulf of Taranto to the Mediterranean Ridge offshore Crete Island).

Given the availability of processed sediment samples with well-preserved foraminifera, the analyzed core-tops are further carefully selected based on the major circulation features in Adriatic and Ionian basins as well as the Italian river influences. Therefore, they are strategically positioned to check the sensitivity of environmental parameters and the subsequent planktonic foraminiferal fauna responses by assessing the adaptability of each species, including both species-specific distribution patterns and size variations, to different environmental regimes. For this reason, relative abundances and size offsets have been interpreted in regard to upper water chlorophyll-a (Chl-a) concentrations and mean annual sea surface temperature (SST), salinity (SSS), and density values of the central Mediterranean water masses. SST and SSS data were derived from the Emodnet database (https://portal.emodnet-physics.eu/) (15 December 2020) of the years 1900–2013, while density data obtained from the National oceanic and atmospheric administration dataset (https://www.ncei.noaa.gov/access/world-ocean-atlas-2018/bin/woa18.pl) (15 December 2020) on a 0.1◦ grid resolution. The Chl-a concentrations at each core location were used as satellite data retrieved from OBPG MODIS-Aqua Monthly Global 4 km database (http://oceancolor.gsfc.nasa.gov) (15 December 2020) for the time period 4 September 2002 to 30 June 2020 (Table 1).


**Table 1.** Core-top locations, coordinates, scientific expeditions, seafloor water depths, lithology, and mean annual SST, SSS and density data along with Chl-a concentrations.
