235 research outputs found
Benthic prokaryotic community dynamics along the Ardencaple Canyon, Western Greenland Sea
No full textThe Ardencaple Canyon, emanating from the Eastern Greenland continental rise over a distance of about 200 km towards the Greenland Basin, was investigated to determine the effect of enhanced down-slope transport mechanisms on deep-sea benthic prokaryotic communities. The concentration of viable bacterial cells (Live/Dead (R) BacLight) and prokaryotic incorporation rates (H-3-thymidine, C-14-leucine) increased with increasing distance from the continental shelf. Multidimensional scaling (MDS) results from terminal restriction fragment length polymorphism (T-RFLP) analysis indicated a spatial coherence between the benthic bacterial community structure, prokaryotic incorporation rates, water content, protein concentration and the total organic matter in the sediments. The community complexity in sediments at 4-5 cm depth was lower in the central parts of the channel compared with the northern and the southern levees, while richness in surface sediments of all stations was similar. Lacking any clear indications for a recent mass sediment transport or funneled shelf drainage flows, high similarities between bacterial assemblages in sediments along the canyon course may thus be governed by a combination of an ice-edge induced particle flux, episodic down-slope and canyon-guided transport mechanisms. (C) 2011 Elsevier B.V. All rights reserved
Bioactivity and Metabolome Mining of Deep-Sea Sediment-Derived Microorganisms Reveal New Hybrid PKS-NRPS Macrolactone from Aspergillus versicolor PS108-62
No full textDespite low temperatures, poor nutrient levels and high pressure, microorganisms thrive in deep-sea environments of polar regions. The adaptability to such extreme environments renders deep-sea microorganisms an encouraging source of novel, bioactive secondary metabolites. In this study, we isolated 77 microorganisms collected by a remotely operated vehicle from the seafloor in the Fram Strait, Arctic Ocean (depth of 2454 m). Thirty-two bacteria and six fungal strains that represented the phylogenetic diversity of the isolates were cultured using an One-Strain-Many-Compounds (OSMAC) approach. The crude EtOAc extracts were tested for antimicrobial and anticancer activities. While antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) and Enterococcus faecium was common for many isolates, only two bacteria displayed anticancer activity, and two fungi inhibited the pathogenic yeast Candida albicans. Due to bioactivity against C. albicans and rich chemical diversity based on molecular network-based untargeted metabolomics, Aspergillus versicolor PS108-62 was selected for an in-depth chemical investigation. A chemical work-up of the SPE-fractions of its dichloromethane subextract led to the isolation of a new PKS-NRPS hybrid macrolactone, versicolide A (1), a new quinazoline (−)-isoversicomide A (3), as well as three known compounds, burnettramic acid A (2), cyclopenol (4) and cyclopenin (5). Their structures were elucidated by a combination of HRMS, NMR, [α]D, FT-IR spectroscopy and computational approaches. Due to the low amounts obtained, only compounds 2 and 4 could be tested for bioactivity, with 2 inhibiting the growth of C. albicans (IC50 7.2 μg/mL). These findings highlight, on the one hand, the vast potential of the genus Aspergillus to produce novel chemistry, particularly from underexplored ecological niches such as the Arctic deep sea, and on the other, the importance of untargeted metabolomics for selection of marine extracts for downstream chemical investigations
Anomalies of oxygen measurements performed with Aanderaa optodes
No full textFour sets of measurements performed between 2005 and 2010 in the deep central
Atlantic, the deep north-western Mediterranean Sea, and in the Arctic Ocean revealed
strange anomalies in the performance of the Aanderaa optode 3830 sensors mounted
on RCM11 current meters in low current regimes (current speeds >10 cm s–1). All
oxygen datasets collected during these deployments showed significant drops of oxygen
(50–100 ìmol) affecting the data stability of the optode sensors in low hydrodynamic
conditions.
High correlations between all acquired parameters (temperature, turbidity, speed and
direction of currents) verified that no unusual event occurred in the mooring areas
during the periods of acquisition, although natural events responsible for such abrupt,
short and intense oxygen variations cannot be easily identified. Despite the well-known
performance of the Aanderaa optodes, these experiments demonstrate that the data
acquired by those installed on RCM11s cannot be always reliable, especially in low
energy systems (typical for the deep ocean), and that current speeds should always be
considered in order to verify the reliability of the data recorded.Published29-391.8. Osservazioni di geofisica ambientaleJCR Journalreserve
Characterization of prokaryotic community dynamics in the sedimentary microenvironment of the demosponge Tentorium semisuberites from Arctic deep waters
No full textThe sedimentary microenvironment of a sessile epibenthic deep-sea species, the small demosponge Tentorium semisuberites, has been investigated to determine its effect on the distribution, physiology and community structure of benthic bacteria and archaea. The upper sediment layers (0 to 2 cm) in the immediate sponge vicinity were characterized by an increased bacterial colonisation with cell abundances on average 3 times higher than those in reference sediments. Similar results were obtained for bacterial secondary production, measured by simultaneous incorporation of the radioactive-labeled substrates 3H-thymidine and 14C-leucine. Our data show a high heterogene-ity of deep-sea sediments with a pronounced patchy distribution of particulate organic carbon (POC), and a significant enrichment of POC in the sediments next to T. semisuberites. Cell-specific 3H-thymidine and 14C-leucine incorporation rates indicate that the quality rather than the quantity of POC around sponges may lead to the observed increase in cell abundances and protein synthesis. Terminal restriction fragment length polymorphism (T-RFLP) analysis revealed that the sponges support a specific benthic bacterial and archaeal community with some unique OTUs (Operational Taxonomic Units), while other OTUs were entirely missing from its surrounding microenvironment. Our data indicate that the small demosponge T. semisuberites causes highly productive patches as hot spots of biochemical cycling, potentially increasing habitat heterogeneity in deep-sea sediments. © Inter-Research 2008.Peer Reviewe
35 - Preliminary results of the oceanographic features of the bottom density-driven currents on the Storfjorden continental slope (Svalbard)
No full textARCA Project - Final Conference, 11 October 2016 Rome - Poster Session - Fjord system - Extended abstract(M. Bensi, V. Kovacevic, M. Rebesco, L. Ursella, D. Deponte, L. Langone, S. Aliani, S. Miserocchi, A. Wåhlin, T. Soltwedel, I. Goszczko, R. Skogseth)</div
Horizontal distribution patterns in arctic macrobenthic communities (Poster)
No full textHorizontal distribution patterns of macrobenthos were studied based on material collected at the deep-sea long-term observatory HAUSGARTEN off West Spitsbergen (79°N) during the RV Polarstern expedition ARK XIX/3c in July-August 2003. Macofauna was obtained at water depths between 2500 and 2600 m. Samples were arranged using a hierarchical approach to analyze benthic fauna distribution at different scales. Three stations were performed along the 26 km transect. Three giant box-corers (0.25 m²) were taken at each station. Five subcores (12.5ґ12.5 cm) were extracted from each box corer. Total macrofauna biomasses varied from 2.31 g ww m2 to 6.41 g ww m2, and densities ranged from 1976 ind. m2 to 3254 ind. m2. Both qualitative and quantitative methods of statistical analysis confirmed that all samples belong to one benthic community with the dominant species complex Tetractinomorpha gen.sp. K_Diastylis K_polaris K_Myriochele K_heeri K_Galathowenia K_fragilis. The inner heterogeneity in species relative abundance and composition was found at a sub-community level. Multivariate analysis showed the division of all samples into two clear groups on the subcore and corer levels. The set of species at the lowest examined level (i.e. in a subcore) allowed the identification of two types of benthic sub-communities. The size of these sub-communities appeared to be not less than several km across. The hierarchical organization of benthic communities on the continental slope off Spitsbergen includes at least two levels: communities, which replace each other along the depth gradient (Wlodarska-Kowalczuk et al. 2004), and sub-communities which make up the orthogonal inner mosaics in each vertical zone. Wlodarska-Kowalczuk, M., M.A. Kendall, J.-M. Weslawski, M. Klages, T. Soltwedel. 2004. Depth gradients of benthic standing stock and diversity on the continental margin at a high latitude ice-free site (off West Spitsbergen, 79°N). Deep-Sea Research I, 51: 1903-1914
Metazoan meiobenthos along continental margins: a review
No full textThe sediment-inhabiting meiofauna is a major component of benthic ecosystems, particularly in the deep sea. Knowledge on the deep-sea meiobenthos has increased considerably during recent decades, and attempts have been made to relate standing stocks with various environmental factors. The flux of organic matter from surface productivity to the seafloor has been proven to exert considerable control on benthic standing stocks. The energy content of sedimentating organic matter generally decreases with water depth due to degradation processes within the water column. Consequently, benthic standing stocks decrease with increasing water depth. Generally enhanced densities of benthic animals are to be expected in areas of increased surface production and subsequently enhanced flux of organic matter to the seafloor. Thus, meiobenthic densities and biomasses should show perceptible differences not only with water depth, but also between areas with different primary productivity in surface layers. The objective of this paper is to condense current information focusing on the abundance of metazoan meiofauna along continental margins, and to compare meiofauna stocks from various climatic regions of the world, representing areas of diverse productivity in the water column. Results clearly demonstrate regional differences on global scale: richer communities were generally found in areas with increased productivity and enhanced input of organic matter to the seafloor
PAH concentrations in the Fram Strait, the Canadian Arctic Archipelago and the lower Great Lakes
No full textThe PEs were deployed at different water depths of deep moorings deployed in the Fram Strait during 2014-2015 (9 samples) and 2018-2019 (22 samples), as well as in surface seawater of the Canadian Arctic Archipelago (6 samples), and in the air (6 samples) and surface water (3 samples) of the lower Great Lakes during 2018-2019. For atmospheric sampling, PEs have deployed at ~1-2 m height and fixed inside two inverted bowls to prevent rainfall and direct solar radiation. For water sampling, PEs were strung on stainless steel wires and attached to stainless steel cages. The surface-water cages were fixed to subsurface floats at ~4-5 m depth, while the deep-water cages were fastened to deep moorings at different depths for ~1 year. PAH concentration data were collected.
Supporting information for "Zhang, L., Ma, Y., Vojta, S., Morales-McDevitt, M., Hoppmann, M., Soltwedel, T., et al. (2023). Presence, Sources and Transport of Polycyclic Aromatic Hydrocarbons in the Arctic Ocean. Geophysical Research Letters, 50, e2022GL101496". https://doi.org/10.1029/2022GL10149
Small benthic size classes along the NW European Continental Margin: spatial and temporal variability in activity and biomass
No full textIn the context of the European OMEX Programme this investigation focused on gradients in the biomass and activity of the small benthic size spectrum along a transect across the Goban Spur from the outer Celtic Sea into Porcupine Abyssal Plain. The effects of food pulses (seasonal, episodic) on this part of the benthic size spectrum were investigated. Sediments sampled during eight expeditions at different seasons covering a range from 200 m to 4800 m water depth were assayed with biochemical bulk measurements: determinations of chloroplastic pigment equivalents (CPE), the sum of chlorophyll a and its breakdown products, provide information concerning the input of phytodetrital matter to the seafloor; phospholipids were analyzed to estimate the total biomass of small benthic organisms (including bacteria, fungi, flagellata, protozoa and small metazoan meiofauna). A new term `small size class biomass' (SSCB) is introduced for the biomass of the smallest size classes of sediment-inhabiting organisms; the reduction of fluorescein-di-acetate (FDA) was determined to evaluate the potential activity of ester-cleaving bacterial exoenzymes in the sediment samples.
At all stations benthic biomass was predominantly composed of the small size spectrum (90% on the shelf; 97–98% in the bathyal and abyssal parts of the transect). Small size class biomass (integrated over a 10 cm sediment column) ranged from 8 g C m−2 on the shelf to 2.1 g C m−2 on the adjacent Porcupine Abyssal Plain, exponentially decreasing with increasing water depth. However, a correlation between water depth and SSCB, macrofauna biomass as well as metazoan meiofauna biomass exhibited a significantly flatter slope for the small size classes in comparison to the larger organisms.
CPE values indicated a pronounced seasonal cycle on the shelf and upper slope with twin peaks of phytodetrital deposition in mid spring and late summer. The deeper stations seem to receive a single annual flux maximum in late summer. SSCB and heterotrophic activity are significantly correlated to the amount of sediment-bound pigments. Seasonality in pigment concentrations is clearly followed by SSCB and activity. In contrast to macro- and megafauna which integrate over larger periods (months/years), the small benthic size classes, namely bacteria and foraminifera, proved to be the most reactive potential of the benthic communities to any perturbations on short time scales (days/weeks). The small size classes, therefore, occupy a key role in early diagenetic processes
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