Isolation of a Vibrio parahaemolyticus pandemic strain from a marine water sample obtained in the northern Adriatic

n/

The depositional record of the Odyssea drift (Ross Sea, Antarctica)

The Ross Sea is one of the major areas for Antarctic Bottom Water formation (the Ross Sea Bottom Water, RSBW), representing the densest ocean water mass, filling the deepest ocean basins connected to the southern ocean. Peri- odic refill of the RSBW occurs through formation of dense, cold and saline water masses (brine) forming on the shelf at the Ross Sea permanent polynya by freezing and salt rejection (high-salinity shelf water, HSSW). The HSSW periodically overspills the shelf area and descends along the slope. This mechanism represents the engine of the global ocean circulation regulating the climate. The Hillary Canyon, crossing the Ross Sea continental slope, represents one of the main conducts through which the HSSW descends the slope to reach the deeper ocean. On its western levee, there is a mounded depocen- tre that was mapped and ground-sampled during the Italian ITRS17-ODYSSEA expedition on board the RV OGS-Explora (January-February 2017). Geophysical data allowed interpreting such feature as a sediment drift (ODYSSEA Drift), generated by along-slope, contour currents sediment transport and accumulation through sev- eral hundred-thousands years. It was inferred that contour currents transported and deposited the sediments that descent the Hillary Canyon by means of the HSSW. Therefore, the depositional sequence of the ODYSSEA Drift potentially contains the record of the variability of HSSW formation, the along slope current intensity in associa- tion to climate change, and the interplay between the two bottom currents. A multidisciplinary investigation was applied to six gravity cores collected in the proximal and distal area of the ODYSSEA Drift. The cores were analysed to reconstruct the age model combining AMS radiocarbon dating on foraminifera tests, biostratigraphy, and the sediment palaeomagnetic record; the sediment physical properties (wet bulk density, water content and grain size); and compositional characteristics (XRF core scan and geochemistry). Three main lithofacies were distinguished and associated to depositional processes and climatic conditions: 1) finely laminated and bioturbated sediments characterized by a relatively high Ca content with common presence of biogenic component. Such facies was associated to contour current deposition during relatively warm conditions. 2) Bioturbated sediments with abundant, sparse and/or layered Ice Rafted Debris, and high Ca content. The onset of this facies is characterized by a prominent Mn peak that was associated to bottom ocean oxygenation through ice sheet melting/decay. 3) Laminated, barren sediments associated to steady strong bottom currents under harsh climate conditions. Further preliminary data interpretations are discussed

Evolution of a high-latitude sediment drift inside a glacially-carved trough based on high-resolution seismic stratigraphy (Kveithola, NW Barents Sea)

Published version, source at http://doi.org/10.1016/j.quascirev.2016.02.007. License CC BY-NC-ND 4.0.Kveithola is a glacially-carved, E-W trending trough located in the NW Barents Sea, an epicontinental shelf sea of the Arctic Ocean located off northern Norway and Russia. A set of confined sediment drifts (the “Kveithola Drift”) is located in the inner part of the trough. In general, drift deposits are commonly characterized by high lateral continuity, restricted occurrence of hiatuses and relatively high accumulation rates, and thus represent excellent repositories of paleo-environmental information. We provide for the first time a detailed morphological and seismostratigraphic insight into this sediment drift, which is further supported by some preliminary lithological and sedimentological analyses. The complex morphology of the drift, imaged by combining all available multibeam data, includes a main and a minor drift body, two drift lenses in the outer part of the trough, more or less connected drift patches in the innermost part and small perched sediment patches in a structurally-controlled channel to the north. The seismic (PARASOUND) data show that the main and minor drift bodies are mainly well-stratified, characterized by sub-parallel reflections of moderate to high amplitude and good lateral continuity. The reflectors show an abrupt pinch-out on the northern edge where a distinct moat is present, and a gradual tapering to the south. Internally we identify the base of the drift and four internal horizons, which we correlate throughout the drift. Two units display high amplitude reflectors, marked lensoidal character and restricted lateral extent, suggesting the occurrence of more energetic sedimentary conditions. Facies typical for contourite deposition are found in the sediment cores, with strongly bioturbated sediments and abundant silty/sandy mottles that contain shell fragments. These characteristics, along with the morphological and seismic information, suggest a strong control by a bottom current flowing along the moat on the northern edge of the drift. Though both Atlantic and Arctic waters are known to enter the trough, from the west and the north respectively, brine-enriched shelf water (BSW) produced during winter and flowing westward in the moat, is suggested to be responsible for the genesis of the Kveithola Drift. The formation of BSW is inferred to have started around 13 cal ka BP, the onset of drift deposition, suggesting that conditions leading to atmospheric cooling of the surface waters and/or the presence of coastal polynyas and wind or floating ice shelves have persisted on the western Barents Shelf since that time. The units inferred to have been deposited under more energetic sedimentary conditions (tentatively dated to the Younger Dryas and to 8.9–8.2 cal ka BP) are suggestive of stronger BSW formation. In general, we infer that variations in the bottom current regime were mainly related to BSW formation due to atmospheric changes. They could also have been a response to successive episodes of grounded and sea ice retreat that allowed for a first limited, later open shelf current, which progressively established on the western Barents Sea shelf

Geomorphology and development of a high-latitude channel system: the INBIS channel case (NW Barents Sea, Arctic)

This is a post-peer-review, pre-copyedit version of an article published in Arktos. The final authenticated version is available online at: http://dx.doi.org/https://doi.org/10.1007/s41063-019-00065-9 .The INBIS (Interfan Bear Island and Storfjorden) channel system is a rare example of a deep-sea channel on a glaciated margin. The system is located between two trough mouth fans (TMFs) on the continental slope of the NW Barents Sea: the Bear Island and the Storfjorden–Kveithola TMFs. New bathymetric data in the upper part of this channel system show a series of gullies that incise the shelf break and minor tributary channels on the upper part of the continental slope. These gullies and channels appear far more developed than those on the rest of the NW Barents Sea margin, increasing in size downslope and eventually merging into the INBIS channel. Morphological evidence suggests that the Northern part of the INBIS channel system preserved its original morphology over the last glacial maximum (LGM), whereas the Southern part experienced the emplacement of mass transport glacigenic debris that obliterated the original morphology. Radiometric analyses were applied on two sediment cores to estimate the recent (~ 110 years) sedimentation rates. Furthermore, analysis of grain size characteristics and sediment composition of two cores shows evidence of turbidity currents. We associate these turbidity currents with density-driven plumes, linked to the release of meltwater at the ice-sheet grounding line, cascading down the slope. This type of density current would contribute to the erosion and/ or preservation of the gullies’ morphologies during the present interglacial. We infer that Bear Island and the shallow morphology around it prevented the flow of ice streams to the shelf edge in this area, working as a pin (fastener) for the surrounding ice and allowing for the development of the INBIS channel system on the inter-ice stream part of the slope. The INBIS channel system was protected from the burial by high rates of ice-stream derived sedimentation and only partially affected by the local emplacement of glacial debris, which instead dominated on the neighbouring TMF systems

Continental slope and rise geomorphology seaward of the Totten Glacier, East Antarctica (112°E-122°E)

The continental slope and rise seaward of the Totten Glacier and the Sabrina Coast, East Antarctica features continental margin depositional systems with high sediment input and consistent along-slope current activity. Understanding their genesis is a necessary step in interpreting the paleoenvironmental records they contain. Geomorphic mapping using a systematic multibeam survey shows variations in the roles of downslope and along slope sediment transport influenced by broad-scale topography and oceanography. The study area contains two areas with distinct geomorphology. Canyons in the eastern part of the area have concave thalwegs, are linked to the shelf edge and upper slope and show signs of erosion and deposition along their beds suggesting cycles of activity controlled by climate cycles. Ridges between these canyons are asymmetric with crests close to the west bank of adjacent canyons and are mostly formed by westward advection of fine sediment lofted from turbidity currents and deposition of hemipelagic sediment. They can be thought of as giant levee deposits. The ridges in the western part of the area have more gently sloping eastern flanks and rise to shallower depths than those in the east. The major canyon in the western part of the area is unusual in having a convex thalweg; it is likely fed predominantly by mass movement from the flanks of the adjacent ridges with less sediment input from the shelf edge. The western ridges formed by accretion of suspended sediment moving along the margin as a broad plume in response to local oceanography supplemented with detritus originating from the Totten Glacier. This contrasts with interpretations of similar ridges described from other parts of Antarctica which emphasise sediment input from canyons immediately up-current. The overall geomorphology of the Sabrina Coast slope is part of a continuum of mixed contourite-turbidite systems identified on glaciated margins.Australian Government 4333Australian Research Council DP170100557Italian Programma Nazionale di Richerch in Antartide (PNRA)Spanish Government CTM2014-60451-C2-1-P CTM2017-89711-C2-1-

Virulence genes and pathogenicity islands in environmental Vibrio strains nonpathogenic to humans

Most Vibrio species in autochthonous marine microbial communities, such as Vibrio alginolyticus, Vibrio harveyi, Vibrio anguillarum among others, are considered nonpathogenic for humans. However, because many bacterial virulence genes are located in mobile genetic elements, the acquisition of mobile DNA could mediate the appearance of virulent or more virulent strains even in a species defined as nonpathogenic. In this study, we screened a collection of marine nonpathogenic Vibrio strains isolated in the area of the Venetian Lagoon for the presence of virulence and fitness genes usually present in Vibrio cholerae and Vibrio parahaemolyticus clinical isolates. More than one-third of the strains tested positive for the presence of at least one of the potential virulence/ fitness genes with the gene encoding the V. cholerae neuraminidase the most frequently detected. Moreover, 13 of the environmental strains carried modified versions of the V. cholerae pathogenicity island VPI-2, and four of them also contained partial fragments of the V. parahaemolyticus Vp-PAI. The data obtained support the view of nonpathogenic Vibrio strains as a significant reservoir of virulence and fitness genes. The emergence of environmental bacteria with new virulence traits might constitute a direct concern for public health and a risk for human health

Serodiversity and ecological distribution of Vibrio parahaemolyticus in the Venetian Lagoon, Northeast Italy

Vibrio parahaemolyticus is a natural inhabitant of estuarine and marine environments constituting part of the autochthonous microflora. This species is associated with human gastroenteritis caused by ingestion of contaminated water and undercooked seafood. During the past several years, the number of V. parahaemolyticus gastroenteritis cases have increased worldwide, causing over half of all food-poisoning outbreaks of bacterial origin. Vibrio populations in water are known to be influenced by environmental factors. Notably, it has been shown that in different parts of the world the distribution of V. parahaemolyticus in the marine environment is related to the water temperature. In this study, we identified environmental determinants affecting distribution of V. parahaemolyticus in the Venetian Lagoon, in the Italian North Adriatic Sea. Data obtained revealed that sea surface temperature constitutes the key factor influencing occurrence of V. parahaemolyticus, but salinity and chlorophyll concentration are also important. Serotyping of a collection of V. parahaemolyticus environmental isolates revealed high serodiversity, with serotypes O3:KUT and O1:KUT, belonging to the 'pandemic group', occurring with higher frequency. From our results, we conclude that there is no correlation between serotype and specific geographic site or season of the year. However, certain serotypes were isolated in the Lagoon during the entire 18 months of the study, strongly suggesting persistence in this environment

The use of multiple typing methods allows a more accurate molecular characterization of Vibrio parahaemolyticus strains isolated from the Italian Adriatic Sea.

Vibrio parahaemolyticus is a natural inhabitant of marine environments and constitutes part of the autochthonous microbial communities, but is also associated with human gastroenteritis, wound infections and septicemia. Recently, a number of clinical cases of infection due to ingestion of seafood contaminated with V. parahaemolyticus and potentially pandemic marine strains isolated from water and plankton have been reported in Europe. To identify the source of virulent strains and to analyze the possible persistence, in time and space, of particular clones, the molecular typing of Vibrio strains is of high epidemiological interest. In this study, we applied pulsed-field gel electrophoresis and two PCR-based techniques (enterobacterial repetitive intergenic consensus- and repetitive extragenic palindromic-PCR) to establish the DNA fingerprints for the analysis of genetic variability among the environmental V. parahaemolyticus strains isolated in the area of the Venetian Lagoon. A temporal distribution of the environmental strains in the studied geographical area and, in some cases, a strong association between a certain genetic profile and a specific source have been evidenced. A number of genetic clusters/clones seem to persist over time, reappearing in the marine environment for subsequent months and also at a 1-year gap. The use of multiple typing methods allowed a more accurate characterization of the environmental strain genetic profiles and the identification of clones hardly revealed through common techniques