ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    facet.materialart.
    Unknown
    PANGAEA
    In:  Supplement to: Bode, Maya; Hagen, Wilhelm; Schukat, Anna; Teuber, Lena; Fonseca-Batista, Debany; Dehairs, Frank; Auel, Holger (2015): Feeding strategies of tropical and subtropical calanoid copepods throughout the eastern Atlantic Ocean – Latitudinal and bathymetric aspects. Progress in Oceanography, 138, 268-282, https://doi.org/10.1016/j.pocean.2015.10.002
    Publication Date: 2020-01-17
    Description: The majority of global ocean production and total export production is attributed to oligotrophic oceanic regions due to their vast regional expanse. However, energy transfers, food-web structures and trophic relationships in these areas remain largely unknown. Regional and vertical inter- and intra-specific differences in trophic interactions and dietary preferences of calanoid copepods were investigated in four different regions in the open eastern Atlantic Ocean (38°N to 21°S) in October/November 2012 using a combination of fatty acid (FA) and stable isotope (SI) analyses. Mean carnivory indices (CI) based on FA trophic markers generally agreed with trophic positions (TP) derived from d15N analysis. Most copepods were classified as omnivorous (CI ~0.5, TP 1.8 to ~2.5) or carnivorous (CI 〉=0.7, TP 〉=2.9). Herbivorous copepods showed typical CIs of 〈=0.3. Geographical differences in d15N values of epi- (200-0 m) to mesopelagic (1000-200 m) copepods reflected corresponding spatial differences in baseline d15N of particulate organic matter from the upper 100 m. In contrast, species restricted to lower meso- and bathypelagic (2000-1000 m) layers did not show this regional trend. FA compositions were species-specific without distinct intra-specific vertical or spatial variations. Differences were only observed in the southernmost region influenced by the highly productive Benguela Current. Apparently, food availability and dietary composition were widely homogeneous throughout the oligotrophic oceanic regions of the tropical and subtropical Atlantic. Four major species clusters were identified by principal component analysis based on FA compositions. Vertically migrating species clustered with epi- to mesopelagic, non-migrating species, of which only Neocalanus gracilis was moderately enriched in lipids with 16% of dry mass (DM) and stored wax esters (WE) with 37% of total lipid (TL). All other species of this cluster had low lipid contents (〈 10% DM) without WE. Of these, the tropical epipelagic Undinula vulgaris showed highest portions of bacterial markers. Rhincalanus cornutus, R. nasutus and Calanoides carinatus formed three separate clusters with species-specific lipid profiles, high lipid contents (〉=41% DM), mainly accumulated as WE (〉=79% TL). C. carinatus and R. nasutus were primarily herbivorous with almost no bacterial input. Despite deviating feeding strategies, R. nasutus clustered with deep-dwelling, carnivorous species, which had high amounts of lipids (〉=37% DM) and WE (〉=54% TL). Tropical and subtropical calanoid copepods exhibited a wide variety of life strategies, characterized by specialized feeding. This allows them, together with vertical habitat partitioning, to maintain high abundance and diversity in tropical oligotrophic open oceans, where they play an essential role in the energy flux and carbon cycling.
    Type: Dataset
    Format: application/zip, 2 datasets
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    facet.materialart.
    Unknown
    PANGAEA
    In:  Supplement to: Fagel, Nathalie; Dehairs, Frank; André, Luc; Bareille, Gilles F; Monnin, Christophe (2002): Ba distribution in surface Southern Ocean sediments and export production estimates. Paleoceanography, 17(2), 1-20, https://doi.org/10.1029/2000PA000552
    Publication Date: 2020-01-17
    Description: We present excess Ba (Baxs) data (i.e., total Ba corrected for lithogenic Ba) for surface sediments from a north-south transect between the Polar Front Zone and the northern Weddell Gyre in the Atlantic sector and between the Polar Front Zone and the Antarctic continent in the Indian sector. Focus is on two different processes that affect excess Ba accumulation in the sediments: sediment redistribution and excess Ba dissolution. The effect of these processes needs to be corrected for in order to convert accumulation rate into vertical rain rate, the flux component that can be linked to export production. In the Southern Ocean a major process affecting Ba accumulation rate is sediment focusing, which is corrected for using excess 230Th. This correction, however, may not always be straightforward because of boundary scavenging effects. A further major process affecting excess Ba accumulation is barite dissolution during exposure at the sediment-water column interface. Export production estimates derived from excess 230Th and barite dissolution corrected Baxs accumulation rates (i.e., excess Ba vertical rain rates) are of the same magnitude but generally larger than export production estimates based on water column proxies (234Th-deficit in the upper water column; particulate excess Ba enrichment in the mesopelagic water column). We believe export production values based on excess Ba vertical rain rate might be overestimated due to inaccurate assessment of the Baxs preservation rate. Barite dissolution has, in general, been taken into account by relating it to exposure time before burial depending on the rate of sediment accumulation. However, the observed decrease of excess Ba content with increasing water column depth (or increasing hydrostatic pressure) illustrates the dependence of barite preservation on degree of saturation in the deep water column in accordance with available thermodynamic data. Therefore correction for barite dissolution would not be appropriate by considering only exposure time of the barite to some uniformly undersaturated deep water but requires also that regional differences in degree of undersatuation be taken into account.
    Type: Dataset
    Format: application/zip, 2 datasets
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Publication Date: 2019-07-17
    Description: Continental shelves and shelf seas play a central role in the global carbon cycle. However, their importance with respect to trace element and isotope (TEI) inputs to ocean basins is less well understood. Here, we present major findings on shelf TEI biogeochemistry from the GEOTRACES program as well as a proof-of-concept for a new method to estimate shelf TEI fluxes. The case studies focus on advances in our understanding of TEI cycling in the Arctic, transformations within a major river estuary (Amazon), shelf sediment micronutrient fluxes, and basin-scale estimates of submarine groundwater discharge. The proposed shelf flux tracer is 228-radium (T1/2=5.75 y), which is continuously supplied to the shelf from coastal aquifers, sediment porewater exchange, and rivers. Model-derived shelf 228Ra fluxes are combined with TEI/ 228Ra ratios to quantify ocean TEI fluxes from the western North Atlantic margin. The results from this new approach agree well with previous estimates for shelf Co, Fe, Mn, and Zn inputs and exceed published estimates of atmospheric deposition by factors of ~3-23. Lastly, recommendations are made for additional GEOTRACES process studies and coastal margin-focused section cruises that will help refine the model and provide better insight on the mechanisms driving shelf-derived TEI fluxes to the ocean.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    facet.materialart.
    Unknown
    PANGAEA
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: PANGAEA Documentation , NonPeerReviewed
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Publication Date: 2020-01-20
    Type: Dataset
    Format: text/tab-separated-values, 105 data points
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Publication Date: 2020-01-20
    Type: Dataset
    Format: text/tab-separated-values, 98 data points
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Publication Date: 2020-01-20
    Type: Dataset
    Format: text/tab-separated-values, 280 data points
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
  • 9
    Publication Date: 2020-01-20
    Type: Dataset
    Format: text/tab-separated-values, 413 data points
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Publication Date: 2020-01-20
    Type: Dataset
    Format: text/tab-separated-values, 140 data points
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...