Browsing by Author "Masotti, Italo"

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    Influence of Estuarine Water on the Microbial Community Structure of Patagonian Fjords
    (2021) Tamayo-Leiva, Javier; Cifuentes-Anticevic, Jeronimo; Aparicio-Rizzo, Pilar; Arroyo, Jose Ignacio; Masotti, Italo; Diez, Beatriz
    Fjords are sensitive areas affected by climate change and can act as a natural laboratory to study microbial ecological processes. The Chilean Patagonian fjords (41-56 degrees S), belonging to the Subantarctic ecosystem (46-60 degrees S), make up one of the world's largest fjord systems. In this region, Estuarine Water (EW) strongly influences oceanographic conditions, generating sharp gradients of oxygen, salinity and nutrients, the effects of which on the microbial community structure are poorly understood. During the spring of 2017 we studied the ecological patterns (dispersal and oceanographic factors) underlying the microbial community distribution in a linear span of 450 km along the estuarine-influenced Chilean Patagonian fjords. Our results show that widespread microbial dispersion existed along the fjords where bacterioplankton exhibited dependence on the eukaryotic phytoplankton community composition. This dependence was particularly observed under the low chlorophyll-a conditions of the Baker Channel area, in which a significant relationship was revealed between SAR11 Clade III and the eukaryotic families Pyrenomonadaceae (Cryptophyte) and Coccomyxaceae (Chlorophyta). Furthermore, dissolved oxygen and salinity were revealed as the main drivers influencing the surface marine microbial communities in these fjords. A strong salinity gradient resulted in the segregation of the Baker Channel prokaryotic communities from the rest of the Patagonian fjords. Likewise, Microbacteriaceae, Burkholderiaceae and SAR11 Clade III, commonly found in freshwater, were strongly associated with EW conditions in these fjords. The direct effect of EW on the microbial community structure and diversity of the fjords exemplifies the significance that climate change and, in particular, deglaciation have on this marine region and its productivity.
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    Summer phyto- and bacterioplankton communities during low and high productivity scenarios in the Western Antarctic Peninsula
    (2019) Fuentes, Sebastián; Arroyo González, José Ignacio; Rodríguez Marconi, Susana; Masotti, Italo; Alarcón Schumacher, Tomás; Polz, Martin F.; Trefault Carrillo, Nicole Natalie; De la Iglesia Cabezas, Rodrigo Alonso; Diez Moreno, Beatriz
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    Vertically distinct sources modulate stable isotope signatures and distribution of Mesozooplankton in central Patagonia: The Golfo de Penas- Baker Channel connection and analogies with the Beagle Channel
    (2024) Castro, Leonardo R.; Soto-Mendoza, Samuel; Riccialdelli, Luciana; Presta, Maria L.; Barrientos, Pamela; Gonzalez, Humberto E.; Daneri, Giovanni; Gutierrez, Marcelo; Montero, Paulina; Masotti, Italo; Diez, Beatriz
    Using hydrographic and zooplankton sampling along with stable isotope analyses, we determined the influence of freshwater input and of oceanic water ingress at the Golfo de Penas to the Baker Channel (47 degrees S), central Patagonia, on the zooplankton community during mid-spring. Our results show that different taxonomic and functional groups occurred within the mesozooplankton community along an offshore-inshore-oriented transect. Some groups occurred mostly offshore (i.e. euphausiids, fish larvae, stomatopods, amphipods), while others occurred in higher abundance inshore (i.e. medusae, chaetognaths, siphonophores, ostracods). Early life stages of ecologically key species, such as Euphausia vallentini and pelagic stages of Munida gregaria, occurred mostly at the Golfo de Penas. Higher trophic positions estimated from delta 15N occurred in mesozooplankton groups inshore (Baker Channel) and lower at the Golfo de Penas, coinciding with the decrease in C:N ratio in zooplankton and with an increase in chlorophyll-a values in the seawater seawards. The delta 13C distribution in the zooplankton groups along the offshore-inshore transect showed a positive gradient from the inshore most stations towards the Baker Channel mouth, suggesting a negative relationship with freshwater carrying terrestrial organic carbon and a positive relationship with seawater. However, from the channel mouth seawards, a decrease in delta 13C in most zooplankton groups occurred. Within the Baker Channel, low delta 13C values occurred in particulate organic matter (POM) at the surface layer, higher values at intermediate depths, and low values at the deepest zones. This uneven distribution of delta 13C values in POM and zooplankton, along with the presence of different water masses at different depths suggest an along-basin transport of organic carbon of different sources at different layers: of terrestrial origin at surface, marine origin at mid depth, and from degraded organic matter from offshore entering at higher depths. Thus, a complex scenario of lateral transport of water of different characteristics modulates the presence of zooplankton in different locations and their food sources along the area. These findings resemble others observed in further south in the Beagle Channel (57 degrees S) also in spring but the relative contribution of different carbon sources may differ between Patagonian systems.