## 5 Discussion
### The MECO CIE Phase (155-167 m): Enhanced Eutrophic Conditions  
This phase corresponds to the main negative excursion of \(\delta^{13}\)C that is coupled with prominent rise in paleotemperatures (Figure 2). The MECO CIE phase is marked by a further increase in bi-triserial benthic foraminifera and a slight reduction in the E/I values (Figure 3). Such changes can be ascribed to enhanced organic matter availability to the seafloor both in terms of quantity and quality and a possible lowering of oxygen availability at the seafloor, as indicated by lowest values of _Nuttalides_ spp. together with two peaks of _Lenticulina_ spp. (Figure 4). This evidence agrees with a more stratified water column and consequent more efficient biological pump, as suggested by lower \(\delta^{13}\)C and higher difference in \(\delta^{18}\)O values between deep and surface dwelling planktic foraminifera [3]. This interval also shows a further decrease of C/A values that would reflect enhanced carbonate dissolution at the sea floor [31] (Figure 3). Planktic foraminiferal assemblages are characterized by a further decrease of large _Azarinina_ and an increase of _Subbotina_. Change in salinity and increase eutrophic conditions related to freshwater input due to enhanced hydrological cycle could have negatively impacted the habitat of the specialized, oligotrophic mixed-layer dwellers acarininids. On the contrary, the eutrophic genus _Subbotina_ may have benefitted by high delivery of food to the thermocline, and this could explain the apparent inconsistency of increase in this cold index. The enhanced hydrological cycle during this warm phase is recorded in the Baskil section through the mineralogical and sedimentological records indicating increasing the nutrient flux from land [32]. Even tough, as an effect of temperature and consumer starvation, the remineralization of organic matter in the water column may have been higher [124; 125; 126; 127], as has been argued for the PETM [128], the nutrient supply at Baskil proved to have been great enough to reach the thermocline habitat of subbotinids and partially the seafloor. A remark concerns the short-term fluctuations in abundance of the planktic foraminiferal genera analyzed. As expected, the transient fluctuations in abundance of the warm indices _Morozovoltaides_ and acarininids that shared the same mixed-layer habitats are generally in phase whereas their fluctuations are out of phase with those of the thermocline cold index _Subbotin_ (Figure 5). The short-term oscillations in abundance of the warm-index symbiont-bearing mixed-layer dweller _Globigerinatheka_ are out of phase with those of subbotinids, as expected, but also with those of acarininids and _Morozovelloides_. A possible competition within the mixed-layer can explain the observed record. Alternatively, different ecological conditions between the upper mixed-layer, inhabited by acarininids and _Morozovelloides_, and the deeper mixed-layer or uppermost thermocline, possibly inhabited by _Globigerinatheka_ in its later stage of life, can justify its variation in abundance out-of-phase with respect to acarininids and _Morozovelloides_. Among the calcareous nannofossil assemblages, the high relative abundance of _D. scrippsae_, already recorded in the upper part of the previous phase, may be the consequence of eutrophic conditions triggered by the great availability of nutrients. Warm and eutrophic conditions could have also stimulated the first common and continuous occurrence of _D. bisectus_ that was only sporadically detected during the time interval below the MECO and recorded as more common at middle latitudes [108; 129]. Although the species _Criborentrum reticulum_ has been considered a temperate and oligotrophic taxon, the increasing trend in abundance observed during this phase in the Baskil section, suggests that this species could have been adapted to eutrophic conditions.