Budillon, Giorgio

The hydrography of intermediate and deep-water masses in the Northern Ionian Sea (Apulian Plateau) was studied through four quasi-synoptic multidisciplinary surveys carried out in 2004–2006 as an ancillary oceanographic activity in the frame of the APLABES project. This area plays a crucial role for the entire Mediterranean Basin, being influenced by the water outflow of Adriatic origin, which, under severe winter conditions, is a primary source of dense water for the Eastern Mediterranean. At the end of the 1980s such outflow showed a different behavior, and only in the recent years has a gradual re-establishing of the former condition been detected. As such, the Adriatic Sea has regained its role as a main source of the East Mediterranean Deep Water, which was temporarily inhibited during the well-known Eastern Mediterranean Transient which progressively modified the intermediate and deep layers of the Mediterranean Sea. The general structure of water masses was similar through the investigated period, but interesting differences within the bottom layer have been detected. The interaction of the different water types present in the basin is reviewed by means of property–property plots, vertical sections, isopycnal analyses and using an Optimum Multiparameter Analysis (OMP), which is an objective method to measure the mixing of water masses. Due to the lack of any direct information about the dynamics of the water column in the area of the Apulian Plateau during the whole analyzed period, the classical method to infer the baroclinic velocity from the mass field has been applied to hydrographic data. The well-known indeterminacy of this method due to the barotropic component of the velocity field has been resolved using a short time series of current velocities acquired synoptically by a mooring located in the northern part of the studied area. The wavelet transform was adopted for localizing and quantifying the variability of currents simultaneously in both frequency and time domains. The presence of the Adriatic Deep Water close to the bottom was detected on all four surveys, with different signature as underlined by the objectively analysis (with the Optimum Multiparameter Analysis) of the thermohaline field. A core of cold, less-saline and oxygenated water of Adriatic origin coming from the Otranto Channel was identified. This water mass moved in geostrophic balance along the isobaths at 600–1000 m depth at the isopycnal surface of 29.18 kg m−3, not being dense enough to reach the deeper layers of the Ionian Basin, carrying 0.27–0.36 Sv.

We investigated the living (stained) and dead benthic foraminiferal assemblages collected in surface sediment samples (0–1 cm) from two different areas (JOIDES Basin and Mawson Bank) of the Ross Sea (Antarctica). Samples were collected during the BEDROSE oceanographic cruise from January to February 2017. Four living and dead benthic foraminiferal fauna assemblages have been distinguished based on cluster analysis. The differences observed in the living and dead foraminiferal content from the two investigated areas are the result of taphonomic processes induced by the different oceanographic settings and environmental conditions. In the JOIDES Basin, agglutinated taxa Rhabdamminella cylindrica, Lagenammina difflugiformis, Adercotryma glomeratum, Recurvoides contortus, Reophax subfusiformis with high percentages of Trochammina group and Reophax spiculifer associated with the calcareous species Nonionella bradii and Astrononion echolsi characterize the living assemblages. The comparison between living and dead benthic foraminifera reveals considerable similarities in terms of the presence/absence of agglutinated species and differences in relative abundance of calcareous taxa. However, the major influencing factor in foraminiferal preservation appears to be the carbonate dissolution. Results from Mawson Bank show an almost exclusive presence of calcareous taxa with high percentages of Globocassidulina group in both living and dead assemblages. The dead fauna assemblage differs from the corresponding living assemblage by being more diverse documenting high-energy current influence on marine sedimentation.