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Integration of foraminiferal and geochemical data (stable isotope and elemental composition) from West Alboran Basin (WAB) ODP Site 976 allowed evaluation of the effects of the initial Mediterranean – Atlantic restriction event preceding the Messinian Salinity Crisis (MSC) in a context of late Miocene cooling and diminishing water – mass exchange close to Gibraltar Strait. At 7.17 Ma a prominent shift in benthic foraminifer abundances from dominantly oxic taxa to species tolerating oxygen deficiency, paired with a drop in δ13C values, suggest that the restriction of the Mediterranean-Atlantic gateways profoundly affected the WAB deep waters. From 7.17 Ma onward, deep-water stagnation increased the bottom water residence time and led to oxygen depletion. Similar changes, already identified in other Mediterranean basins imply that the first signs of Mediterranean-Atlantic restriction significantly predated the onset of the MSC also in the WAB, an area sometimes considered more under the influence of the Atlantic. Simultaneously, a marked amplitude increase of several element-log ratios reveals a clear cyclical pattern related with precession. Together with new δ18O data, the identification of cyclical patterns allowed improving the age model of Site 976 and consequently enabled an accurate correlation with other Mediterranean, mostly land-based sections. Comparing the records, we were able to correlate the event at a basinal scale and to refine thermohaline circulation models of the Mediterranean after 7.17 Ma. Because this Mediterranean-scale change was contemporaneous with the global Late Miocene Carbon Isotope Shift (LMCIS) it was important to discern between global and local effects. Given the synchronicity of the global and local Mediterranean change in the δ13C record, a global effect certainly affected the Mediterranean Basin. However, opposite phase relations of the global and local δ13C signals with orbital parameters, paired with a higher magnitude change identified in our WAB isotope record suggests that the local imprint overruled the global one., The authors appreciate the work of Jose Ignacio Martin Cruz in sample processing and preparation. Furthermore, all fellow ESRs and supervisors from the SALTGIANT project are thanked for their valuable suggestions and discussions. Two anonymous reviewers are gratefully acknowledged for critical reading and detailed comments which were very helpful to improve the original manuscript. This research used data and samples collected through ODP Expedition 161 aboard the Joides Resolution. Geochemical data was acquired at the XRF Core Scanner Lab at the MARUM – Center for Marine Environmental Sciences, University of Bremen, Germany. This research has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement n° 765256 SALTGIANT

Long-chain unsaturated alkenones produced by haptophyte algae are widely used as paleotemperature indicators. The unsaturation relationship to temperature is linear at mid-latitudes, however, non-linear responses detected in subpolar regions of both hemispheres have suggested complicating factors in these environments. To assess the influence of biotic and abiotic factors in alkenone production and preservation in the Subantarctic Zone, alkenone fluxes were quantified in three vertically-moored sediment traps deployed at the SOTS observatory (140°E, 47°S) during a year. Alkenone fluxes were compared with coccolithophore assemblages, satellite measurements and surface-water properties obtained by sensors at SOTS. Alkenone-based temperature reconstructions generally mirrored the seasonal variations of SSTs, except for late winter when significant deviations were observed (3-10 °C). Annual flux-weighted averages in the 3800 m trap returned alkenone-derived temperatures ~1.5 °C warmer than those derived from the 1000 m trap, a distortion attributed to surface production and signal preservation during its transit through the water column. Notably, changes in the relative abundance of E. huxleyi var. huxleyi were positively correlated with temperature deviations between the alkenone-derived temperatures and in situ SSTs (r = 0.6 and 0.7 at 1000 and 2000 m, respectively), while E. huxleyi var. aurorae, displayed an opposite trend. Our results suggest that E. huxleyi var. aurorae produces a higher proportion of C37:3 relative to C37:2 compared to its counterparts. Therefore, the dominance of var. aurorae south of the Subtropical Front could be at least partially responsible for the less accurate alkenone-based SST reconstructions in the Southern Ocean using global calibrations. However, the observed correlations were largely influenced by the samples collected during winter, a period characterized by low particle fluxes and slow sinking rates. Thus, it is likely that other factors such as selective degradation of the most unsaturated alkenones could also account for the deviations of the alkenone paleothermometer., We thank the constructive comments and suggestions of five anonymous reviewers that helped improve and clarify this paper. Cathryn Wynn-Edwards (IMAS) provided support in sample splitting/processing and laboratory analysis. We are grateful to Ivia Closset for helpful comments on interpretation of results and to Erik Behrens for providing data for this research. This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement number 748690 – SONAR-CO2. Australia's Integrated Marine Observing System (IMOS) is enabled by the National Collaborative Research Infrastructure Strategy (NCRIS). It is operated by a consortium of institutions as an unincorporated joint venture, with the University of Tasmania as Lead Agent. This study was supported by the Spanish Ministerio de Economía y Competitividad Project CGL2015-68459-P. The Severo Ochoa Grant CEX2018-000794-S funded by MCIN/AEI/10.13039/501100011033 is likewise acknowledged. This study received Portuguese national funds from FCT - Foundation for Science and Technology through project UIDB/04326/2020, and from the operational programmes CRESC Algarve 2020 and COMPETE 2020 through projects EMBRC.PT ALG-01-0145-FEDER-022121 and EMSO-PT POCI-01-0145-FEDER-022157. Argo data were collected and made freely available by the International Argo Program and the national programmes that contribute to it. (http://www.argo.ucsd.edu, http://argo.jcommops.org). The Argo Program is part of the Global Ocean Observing System. Satellite SST, chlorophyll-a and coccolithophore concentration (NOBM) data sets were produced with the Giovanni online data system, developed and maintained by the NASA GES DISC.