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ArticleBacterioplankton diversity and distribution in relation to phytoplankton community structure in the Ross Sea surface waters(Frontiers Media, 2022-01-27) Cordone, Angelina ; d'Errico, Giuseppe ; Magliulo, Maria ; Bolinesi, Francesco ; Selci, Matteo ; Basili, Marco ; de Marco, Rocco ; Saggiomo, Maria ; Rivaro, Paola ; Giovannelli, Donato ; Mangoni, OlgaPrimary productivity in the Ross Sea region is characterized by intense phytoplankton blooms whose temporal and spatial distribution are driven by changes in environmental conditions as well as interactions with the bacterioplankton community. However, the number of studies reporting the simultaneous diversity of the phytoplankton and bacterioplankton in Antarctic waters are limited. Here, we report data on the bacterial diversity in relation to phytoplankton community structure in the surface waters of the Ross Sea during the Austral summer 2017. Our results show partially overlapping bacterioplankton communities between the stations located in the Terra Nova Bay (TNB) coastal waters and the Ross Sea Open Waters (RSOWs), with a dominance of members belonging to the bacterial phyla Bacteroidetes and Proteobacteria. In the TNB coastal area, microbial communities were characterized by a higher abundance of sequences related to heterotrophic bacterial genera such as Polaribacter spp., together with higher phytoplankton biomass and higher relative abundance of diatoms. On the contrary, the phytoplankton biomass in the RSOW were lower, with relatively higher contribution of haptophytes and a higher abundance of sequences related to oligotrophic and mixothrophic bacterial groups like the Oligotrophic Marine Gammaproteobacteria (OMG) group and SAR11. We show that the rate of diversity change between the two locations is influenced by both abiotic (salinity and the nitrogen to phosphorus ratio) and biotic (phytoplankton community structure) factors. Our data provide new insight into the coexistence of the bacterioplankton and phytoplankton in Antarctic waters, suggesting that specific rather than random interaction contribute to the organic matter cycling in the Southern Ocean.
ArticleSurface bacterioplankton community structure crossing the Antarctic Circumpolar Current Fronts(MDPI, 2023-03-09) Cordone, Angelina ; Selci, Matteo ; Barosa, Bernardo ; Bastianoni, Alessia ; Bastoni, Deborah ; Bolinesi, Francesco ; Capuozzo, Rosaria ; Cascone, Martina ; Correggia, Monica ; Corso, Davide ; Di Iorio, Luciano ; Misic, Cristina ; Montemagno, Francesco ; Ricciardelli, Annarita ; Saggiomo, Maria ; Tonietti, Luca ; Mangoni, Olga ; Giovannelli, DonatoThe Antarctic Circumpolar Current (ACC) is the major current in the Southern Ocean, isolating the warm stratified subtropical waters from the more homogeneous cold polar waters. The ACC flows from west to east around Antarctica and generates an overturning circulation by fostering deep-cold water upwelling and the formation of new water masses, thus affecting the Earth's heat balance and the global distribution of carbon. The ACC is characterized by several water mass boundaries or fronts, known as the Subtropical Front (STF), Subantarctic Front (SAF), Polar Front (PF), and South Antarctic Circumpolar Current Front (SACCF), identified by typical physical and chemical properties. While the physical characteristics of these fronts have been characterized, there is still poor information regarding the microbial diversity of this area. Here we present the surface water bacterioplankton community structure based on 16S rRNA sequencing from 13 stations sampled in 2017 between New Zealand to the Ross Sea crossing the ACC Fronts. Our results show a distinct succession in the dominant bacterial phylotypes present in the different water masses and suggest a strong role of sea surface temperatures and the availability of Carbon and Nitrogen in controlling community composition. This work represents an important baseline for future studies on the response of Southern Ocean epipelagic microbial communities to climate change.