The ANT-Biofilm research project (PNRA16_00105) concerned the study of microbial colonization processes in coastal environments of Terra Nova Bay (Ross Sea), through the analysis of the microbial biofilm (bacteria, microalgae) and macrobenthic settlement on plastic substrates, with the aim of determining their possible variations caused by natural or anthropogenic disturbances (variations in salinity or the presence of contaminants, respectively). Microbial biofilms, which play a key role as a substrate for larval settlement of many species of invertebrates, constitute hot-spots of microbial diversity; and it is also known that the communities a microbial are capable of responding rapidly to changing environmental conditions, acting as potential "sentinels" of natural or anthropic perturbations that recently are threatening the Antarctic biota. During the first year of activity (XXXIII Italian expedition, November 2017) stainless steel structures were fixed on the seabed of Road Bay and Tethys Bay mounting panels of artificial substrates (Polyvinyl Chloride, PVC and PolyEthylene, PE) for colonization, which during the XXXIV expedition (November 2018) were retrieved in order to study the fouling formation processes at different levels of biological complexity (from microbial community including bacteria and microalgae to benthic invertebrates) and to evaluate their evolution in two coastal sites differently exposed to natural or anthropogenic forcings.

De novo transcriptome analysis of Colobanthus quitensis Antarctic vascular plant grown under condition miming the global warm-up.

Terra Nova Bay (Ross Sea, Antarctica), characterized by a moltitude of ice tongues flowing from land to sea, represents an ideal study site for understanding the complex interaction between relative sea level variations and ice sheet dynamics during the Holocene. The DISGELI project, thanks to the combination of innovative technology and traditional methods for geomorphologic and stratigraphic analysis, aims to: i) reconstruct the local variations of the East Antarctic Ice Sheet after the Last Glacial Maximum; ii) provide a time constrain for the deglaciation processes along the coast; iii) reconstruct, with unprecedent detail, the relative sea level variations during Holocene in the Drygalski basin. The morpho-bathymetric and topographic data obtained through this study will be integrated using digital terrain models based on the analyses of key areas onland, where palaeo-coastlines and sea-level markers have been identified.

Below the results obtained by the HOT ANTARCTICA project are presented. Results regarding geochemistry of crustal melts Main results obtained by the most prominent samples are described separately for each of the investigated terranes (Napier Complex, Lützow Holm Complex, Rauer Islands and Schrimacher Hills). The methodology employed during the work is also listed below: 1) Samples interrogated in this project were previously collected from Napier Complex (provided by the collaboration with Prof. Simon Harley, University of Edinburgh), Lützow Holm Complex (provided by the collaboration with Prof. Satish-Kumar, University of Niigata), Rauer Islands (provided by the collaboration with Prof. Simon Harley, University of Edinburgh and in collaboration with Zhao Liu, Northwest University ,China) and Schrimacher Hills (provided by the Museo Nazionale dell’Antartide, Siena, Italy). 2) Microstructural and petrographic study were done in all samples to identify equilibrium assemblages, melting reaction microstructures and occurrence of nanogranitoids (i.e. crystallized inclusions), melt and fluid inclusions. 3) Microstructural characterization of inclusions using Field Emission-Scanning Electron Microscope (FE-SEM) analyses were done: i) to identify the submicrometric phases within nanogranitoids and ii) to verify the homogeneity of remelted nanogranites and preserved glassy melt inclusions. 4) Experimental remelting of crystallized melt inclusions was performed to overcome the problem of MI decrepitation and volatile loss. The remelting of nanogranitoids was performed at high pressure with a piston cylinder apparatus using a QUICKpress piston cylinder apparatus produced by Depths of the Earth (installed at the Dipartimento di Geoscienze, UniPd). 5) Analysis of the major and trace elements contents of melt inclusions was carried out using i) an electron microprobe at the at University of Milan and ii) a LAICPMS at University of Perugia. 6) Thermodynamic modeling of anatectic conditions: the evaluation of P-T-X parameters and of P-T paths in the different geologic contexts were carried out using the software Perple_X. 7) Micro-Raman spectroscopy: characterization of fluid inclusions coexisting with melt inclusions was done using a HORIBA LabRam HR (high resolution) Raman microspectrometer at the University of Pavia. 8) Cross-comparison of data: during the development of this research project all collected data were analyzed by cross-comparing the information from the different geological contexts, with the aim to highlight similarities and differences. 9) Data discussion and evaluation: all data was analyzed and discussed in tight collaboration with the researchers involved in this project. 10) Synthesis and dissemination of results: dissemination of results was done with oral and poster presentations in several international conferences (see list on the appropriate section - Atti). Presentations include invited keynote presentations by the PI, Bruna Borges Carvalho at Goldschmidt (France, 2023) and Hutton Symposium (Italy, 2023). Invited seminars were also given in several important universities around the world [University of Bern, Switzerland; University of Cambridge, UK; University of Niigata, University of Kyoto, Japan]. Furthermore, a total of two research papers have been published in journals of high impact factor, and other two articles are in preparation. Here we also provide mineral, geochemical and geochronological data of studied areas at Rundvagshetta and Rauer Islands. Preprinted versions of two published article where the data is explained are also provided. Carvalho, B.B., Bartoli, O., Cesare, B., Satish-Kumar, M., Petrelli, M., Kawakami, T., Hokada, T., Gilio, M. (2023). Revealing the link between A-type granites and hottest melts from residual metasedimentary crust. Geology 51, 845-849. https://doi.org/10.1130/G51097.1 Liu, Z., Carvalho, B.B., Li, W., Tong, L., Bartoli, O., Li, C., Chen, L., ,Yan, Q, Wu, H. 2023. Into the high to ultrahigh temperature melting of Earth’s crust: Investigations of melt and fluid inclusions within Mg–rich metapelitic granulites from the Mather Peninsula, East Antarctica. Journal of Petrology 64, egad051. https://doi.org/10.1093/petrology/egad051 Results regarding petrology and geochronology of granulites In northern Victoria Land, the presence of two contrasting P-T paths suggests the possibility that high-grade complexes could have experienced a different metamorphic evolution both in space and time. Geochronological data of the Granite Harbour Intrusives support a prolonged magmatic activity (540-480 Ma), with multiple igneous pulses. This could imply the existence of magmatic underplating triggering the development of monometamorphic granulites during the Ross Orogeny. On the other hand, structural and PT evolution suggest the presence of a polymetamorphic granulitic belt that could be remnant of older orogeny as the Panafrican (ca. 600-500 Ma) (Lombardo et al., 1987; Palmeri, 1997; Talarico and Castelli, 1995). In order to discriminate mono- from poly-metamorphic evolution, metasedimentary granulite complex from the Deep Freeze Range has been investigated. Among all available granulite samples, a detailed petrographical study has been conducted to select the most representative and suitable HT granulite-facies rocks: four samples have been individuated for petrological and geochronological analyses (Opx-Grt and >30 µm Zrn/Mnz bearing), fifteen for geochemistry (absence of leucosome). In the Deep Freeze Range, HT granulites consist of Grt-Opx±Bt±Crd±Spl±Crn gneisses characterized by the presence of numerous Opx±Grt leucocratic segregations. Geochemical results confirm that analyzed granulite protholites have sedimentary origin, being comparable to Post Archean Australian Shale (PAAS; Taylor and McLennan, 1985), and they have been deposited in an orogenic setting (active continental margin). Petrographical, microstructural and mineral chemistry analyses show a metamorphic evolution including three different stages: Pl-Grt1-Spl-Crn-Ilm medium-P granulite facies (M1), Qtz-Pl-Opx-Grt1-Crd-Ilm-Kfs low-P granulite facies (M2), and Qtz-Pl-Grt2-Kfs-Bt-Ath low-P amphibolite (M3). Preliminary petrological results indicate that evolving metamorphic parageneses describe an initial isothermal decompression (exhumation event) followed by isobaric cooling; further thermodynamic modeling by software Perple_X will allow to better define P-T-X conditions. Geochronological studies involved the observation and analysis of monazites and zircons on four selected granulite thin sections. Investigations included X-ray mapping carried out under the electron microscope, CL-BSE imaging (zircons), and trace element analysis and U-Pb dating using LA-ICP-MS. Acquired data are still under review and will have a fundamental role in the reconstruction of the P-T-t path, thus making it possible to discriminate between mono- and poly-metamorphic hypotheses. References Lombardo et al 1987. Memorie della Società Geologica Italiana 33, 99-130. Palmeri R. 1997. Lithos 42, 47-66. Talarico and Castelli D. 1995. Precamb. Res. 75, 157-174. Taylor and McLennan S.M. 1985. Blackwell, Oxford, 312 p.

We will collect skin samples from the volunteers at the Mario Zucchelli Station at different time points, using safe and not harmfull kits. Samples will be analysed by shotgun metagenomic sequencing, considering only the microbial component.

Trophic interactions underlie coexistence mechanisms between species and affect biodiversity and heavy metal bioaccumulation processes. Sea ice dynamics, which at Terra Nova Bay is characterized by an extraordinary seasonality, drives interspecific interactions. Indeed, the activation of the primary production after sea-ice break up opens alternative trophic pathways for consumers. By means of C and N stable isotope analyses, the present project aims at (i) determining food web structure at Terra Nova Bay at different bathymetries and in opposite sea-ice cover conditions; (ii) evaluating heavy metal bioaccumulation in species along food chains, including fish of commercial interests, both in the presence and absence of photosynthetic primary producers. The hypothesis to be tested is if the activation of primary producers following sea-ice break up significantly modifies the food web structure and stability against species loss, as well as heavy metals concentration along food chains. Data on Antarctic food webs are scarce, and even scarcer is our knowledge on mechanisms of primary and secondary biodiversity loss and biomagnification processes in invertebrates and fish. The present research project will shed light on mechanisms underlying biodiversity maintenance in the Antarctic ecosystem and on risks for human health related to heavy metals accumulation in fish species currently or potentially exploited commercially, also in light of expected changes in the extension of sea ice cover. A valuable reference baseline will be established for future studies at the Italian Antarctic Station and for the Marine Protected Area in the Ross Sea.

Concentrations of major, minor and trace elements in particulate matter (PM10) samples, collected at Concordia with monthly time resolution, since January 2018, obtained by PIXE-PIGE and HR-ICP-MS measurements.

Trophic interactions underlie coexistence mechanisms between species, define the functional role of specie within communities, affect biodiversity and bioaccumulation processes of heavy metal. Sea-ice dynamics, which at Terra Nova Bay is characterized by an extraordinary seasonality, drives interspecific interactions and the exchange of materials between ecosystem compartments. Indeed, the activation of the primary production after sea-ice break up opens alternative trophic pathways for consumers. The “next generation SRPs” represent a highly appropriate framework for the present project which follows the results obtained with the previous project ISOBIOTOX (PNRA 2013) and aims at (i) determine topological and functional metrics of sympagic and pelagic food webs at Terra Nova Bay under different conditions of sea-ice coverage along a distance gradient from the nearest open water polynya to areas were the seasonal sea-ice coverage persists longer; (ii) evaluate bioaccumulation and biomagnification of heavy metals in trophic sources at the base of the food web and in target species along food chains, including fishes of commercial interests and top predators, both in the presence and absence of sympagic and pelagic primary producers. High resolution food webs will be reconstructed by means of the simultaneous elemental and isotopic analysis of different elements (C and N) and the bioaccumulation of pollutants. The research program integrates complementary research approaches: (a) Elemental analysis coupled with mass spectrometry for stable isotope analysis (δ13C, δ15N) in animal and vegetal tissues and dead organic matter, (b)analyses of heavy metals accumulation (Chromatography) in the constituent species of the Antarctic food web.

Disdrometric data from an OTT Parsivel with 32 size classes and 32 velocity classes positioned at Mario Zucchelli Station (Antarctica), with monthly spectra and particle size distributions (PSD).

The efficacy and reliability of low-impact technologies were tested to document the occurrence and distribution of Antarctic toothfish in sea-ice covered coastal areas at Terra Nova Bay (Ross Sea). Ancillary information, including main water column parameters (temperature, salinity, density, dissolved oxygen, chlorophyll, and turbidity), was collected at each sampling station.