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Ozeanographie

Die Ozeanographie umfasst viele verschiedene Disziplinen, die sich mit den physikalischen, chemischen und biologischen Prozessen beschäftigen, die sich in den Ozeanen der Erde abspielen. Die Stabilisotopenanalyse ist ein leistungsfähiges Mittel, um diese Prozesse nachzuverfolgen, sowohl in der Gegenwart als auch in der Vergangenheit. Die Paläoozeanographie nutzt stabile Sauerstoffisotopensignaturen von Materialien, die in Eiskernen oder Sedimenten konserviert wurden, um die Geschichte der Meeresoberflächen- oder Tiefseetemperaturen nachzuvollziehen. Die Stabilisotopenanalyse von Sauerstoff und Wasserstoff kann auch die Hydrologie von ozeanischen Gewässern enthüllen, indem die Bewegung und Zirkulation von Gewässern, evaporitische Prozesse und meteorologische Einflüsse auf lokaler, regionaler und globaler Ebene verfolgt werden.

Nährstoffkreislauf und Ökologie der Weltmeere sind ebenfalls von Interesse; stabile Kohlenstoff-, Stickstoff- und Schwefelisotope sind leistungsfähige Werkzeuge, die eingesetzt werden, um Algenaktivität, Struktur von Nahrungsketten in oberflächlichen oder benthischen Gemeinschaften und Nährstoffflüsse während der Jahreszeiten zu untersuchen. Besonders nützlich ist die Stabilisotopenanalyse, um ungewöhnliche Grenzen von tiefen, hydrothermalen Systemen zu erforschen, wo ungewöhnliche chemosynthetische Organismen die Basis der Gemeinschaften sind, die unter diesen extremen Bedingungen gedeihen.

Publikationen zum Thema Ozeanographie mit unseren Geräten

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83 Ergebnisse:

Feeding patterns of two sympatric shark predators in coastal ecosystems of an oceanic island
Canadian Journal of Fisheries and Aquatic Sciences (2016)
Clément Trystram, Karyne Rogers, Marc Soria, Sébastien Jaquemet

Stomach contents and stable carbon and nitrogen isotope analyses (δ13C and δ15N) were used to investigate the trophic ecology of two apex predators, tiger sharks (Galeocerdo cuvier) and bull sharks (Carcharhinus leucas), from Reunion Island to describe their dietary habits at both the population and individual levels. In this oceanic island, the tiger and bull sharks were more piscivorous and teutophagous than noted in previous research from other localities. The δ13C values suggested that bull sharks depended on more neritic organic matter sources than tiger sharks, confirming a coastal habitat preference for bull sharks. Moreover, the total length of the bull shark influenced δ13C values, with smaller individuals being more coastal than larger individuals. All indicators suggest that there is a higher degree of similarity between individual tiger sharks compared with the more heterogeneous bull shark population, which is composed of individuals who specialize on different prey. These results suggest tha...
Schlagworte: carbon , nitrogen , ecol , ocea , elem

One-century decline of mollusk diversity as consequence of accumulative anthropogenic disturbance in a tropical estuary (Cuban Archipelago)
Marine Pollution Bulletin (2016)
Maickel Armenteros, Misael Díaz-Asencio, Raúl Fernández-Garcés, Carlos Alonso Hernández, Yusmila Helguera-Pedraza, Yoelvis Bolaños-Alvarez, Claudia Agraz-Hernández, Joan-Albert Sanchez-Cabeza

In order to infer changes in sediments and mollusk assemblages for the last century, we used biogeochemical data from two 210Pb dated cores collected in Sagua La Grande estuary, Cuban Archipelago. We found evidences of cumulative anthropogenic disturbance during the last century, causing considerable depletion of mollusk assemblage diversity and enhancement of the dominance of deposit feeding species. The sequence of impacts assessed was i) eutrophication due to nutrient releases from urban settlements, ii) habitat alteration due to water channeling and damming, and iii) mercury pollution. These successive impacts caused a steady diversity depletion from ca. 70 mollusk species in 1900 to less than five in 2010. Only two species persisted in the estuary: Nuculana acuta and Finella dubia. Hurricanes did not impact the molluscan fauna in the long term. The effects of the anthropogenic impacts suggest that the resilience of this estuarine system is compromised.
Schlagworte: carbon , nitrogen , ocea , poll , elem

Evidence of Anomalously Low δ13C of Marine Organic Matter in an Arctic Fjord
Scientific Reports, Published online: 9 November 2016; | doi:10.1038/srep36192 (2016)
Vikash Kumar, Manish Tiwari, Siddhesh Nagoji, Shubham Tripathi, F. Joos, M. J. Prather, C. D. Holmes, J. Hsu, P. Ciais, W. M. Sackett, P. A. Meyers, P. A. Meyers, P. A. Meyers, C. J. Schubert, S. E. Calvert, K. Fahl, R. Stein, K. E. Peters, J. I. Hedges,

Accurate estimation of relative carbon deposition (marine vs. terrestrial) is required for understanding the global carbon budget, particularly in the Arctic region, which holds disproportionate importance with respect to global carbon cycling. Although the sedimentary organic matter (SOM) concentration and its isotopic composition are important tools for such calculations, uncertainties loom over estimates provided by organic-geochemical bulk parameters. We report carbon and nitrogen concentrations and isotopes (δ13C and δ15N) of SOM at an Arctic fjord namely Kongsfjorden. We find that the bound inorganic nitrogen (ammonium attached to the clay minerals) forms a significant proportion of total nitrogen concentration (~77% in the inner fjord to ~24% in the outer part). On removing the bound nitrogen, the C/N ratio shows that the SOM in the inner fjord is made up of terrestrial carbon while the outer fjord shows mixed marine-terrestrial signal. We further show that the marine organic matter is unusually more depleted in 13C (~−24‰) than the terrestrial organic matter (~−22.5‰). This particular finding also helps explain high δ13C values of SOM as noted by earlier studies in central Arctic sediments despite a high terrestrial contribution.
Schlagworte: carbon , nitrogen , ocea , elem

Stable isotopes in deep-sea living (stained) foraminifera from the Mozambique Channel (eastern Africa): multispecies signatures and paleoenvironmental application
Journal of Oceanography (2016)
Christophe Fontanier, Saburo Sakai, Takashi Toyofuku, Eline Garnier, Christophe Brandily, Thibaut Eugene, Bruno Deflandre

Oxygen and carbon isotopes (δ18O and δ13C) have been investigated in carbonate tests of deep-sea foraminifera living in the Mozambique Channel (eastern Africa) to understand how environmental constraints (e.g., organic matter, oxygenation) control the intra- and interspecific variability of isotopic signatures. 197 living individuals, including eight different species, from various microhabitats within the sediment were sorted from sediment samples gathered at two stations on the Malagasy upper slope. Results show that the δ18O values of foraminiferal taxa were not controlled by microhabitat pattern. They presented tremendous and intriguing intraspecific variability that is not explained by the classical ontogenetic effect. The δ13C values of infaunal foraminiferal taxa do not show a 1:1 relationship with the bottom water δ13C DIC and do not present a constant offset from it; instead, they appear to be mainly controlled by a microhabitat effect. The lower δ13C values of shallow, intermediate, and deep infaunal taxa at the deeper station compared to those seen at the shallower station reflect the enhanced exportation of sedimentary organic matter at the sediment–water interface, and its related mineralization within the upper sediments. The ∆δ13C between shallow/very shallow infaunal species (i.e., Hoeglundina elegans, Uvigerina hispida) and intermediate/deep infaunal species (i.e., Melonis barleeanus, Globobulimina barbata) permits insight into (1) the exportation of organic matter to the seafloor and (2) the various degradation pathways for organic detritus in the benthic environments off NW Madagascar.
Schlagworte: carbon , oxygen , ecol , ocea , mulitcarb

Applicability of Perinereis aibuhitensis Grube for fish waste removal from fish cages in Sanggou Bay, P. R. China
Journal of Ocean University of China (2016)
Jinghui Fang, Zengjie Jiang, Henrice M. Jansen, Fawen Hu, Jianguang Fang, Yi Liu, Yaping Gao, Meirong Du

The present study investigated the applicability of integrated polychaete-fish culture for fish waste removal to offset negative impact induced by organic benthic enrichment. A field study demonstrated that deposition rate was significantly higher underneath the fish farm than that in control area. The material settling under the farm was characterized by a high amount of fish feces (45%) and uneaten feed (27%). Both feeding rate (FR) and apparent digestibility rate (ADR) increased with decreasing body weight, as was indicated by significantly a higher rate observed for the groups containing smaller individuals in a lab study. The nutrient in fresh deposited material (De) was higher than that in sediments collected under the farm (Se), resulting in lower feces production but higher apparent digestibility rate for the De group as feeding rate was similar. Consequently, higher nutrient removal efficiency was observed in the De group. A mass balance approach indicated that approximately 400–500 individuals m−2 is required for removing all waste materials deposited underneath the fish farm, whereas abundance can be lower (about 300–350 individuals m−2) when only the fish waste needs to be removed. The results showed that a significant amount of waste had been accumulated in the fish cages in Sanggou Bay. The integration of fish with P. aibuhitensis seems promising for preventing organic pollution in the sediment and therefore is an effective strategy for mitigating negative effect of fish farms. Thus such integration can become a new IMTA (integrated multi-trophic aquaculture) model in Sanggou Bay.
Schlagworte: carbon , nitrogen , ecol , ocea , elem

Disentangling the record of diagenesis, local redox conditions, and global seawater chemistry during the latest Ordovician glaciation
Earth and Planetary Science Letters (2016)
Anne-Sofie C. Ahm, Christian J. Bjerrum, Emma U. Hammarlund

The Late Ordovician stratigraphic record integrates glacio-eustatic processes, water-column redox conditions and carbon cycle dynamics. This complex stratigraphic record, however, is dominated by deposits from epeiric seas that are susceptible to local physical and chemical processes decoupled from the open ocean. This study contributes a unique deep water basinal perspective to the Late Ordovician (Hirnantian) glacial record and the perturbations in seawater chemistry that may have contributed to the Hirnantian mass extinction event. We analyze recently drilled cores and outcrop samples from the upper Vinini Formation in central Nevada and report combined trace- and major element geochemistry, Fe speciation (FePy/FeHR and FeHR/FeT), and stable isotope chemostratigraphy (δ13COrg and δ34SPy). Measurements of paired samples from outcrop and core reveal that reactive Fe is preserved mainly as pyrite in core samples, while outcrop samples have been significantly altered as pyrite has been oxidized and remobilized by modern weathering processes. Fe speciation in the more pristine core samples indicates persistent deep water anoxia, at least locally through the Late Ordovician, in contrast to the prevailing interpretation of increased Hirnantian water column oxygenation in shallower environments. Deep water redox conditions were likely decoupled from shallower environments by a basinal shift in organic matter export driven by decreasing rates of organic matter degradation and decreasing shelf areas. The variable magnitude in the record of the Hirnantian carbon isotope excursion may be explained by this increased storage of isotopically light carbon in the deep ocean which, in combination with increased glacio-eustatic restriction, would strengthen lateral- and vertical gradients in seawater chemistry. We adopt multivariate statistical methods to deconstruct the spatial and temporal re-organization of seawater chemistry during the Hirnantian glaciation and attempt to isolate the latent magnitude and global perturbation in the carbon cycle. We speculate, using a two component mixing model and residual estimates from principal component analysis, that the secular open ocean Hirnantian C isotope excursion possibly amounts to only ∼ +1.5‰. Such an increase could be mechanistically driven by the combination of sea-level fall, persistent deep water anoxia, and cooler glacial temperatures that increased the organic carbon burial efficiency in the deeper basins.
Schlagworte: carbon , sulfur , ocea , elem

Sediment characteristics and microbial mats in a marine mangrove, Manche-à-eau lagoon (Guadeloupe)
Journal of Soils and Sediments (2016)
Swanne Gontharet, Antoine Crémière, Marie-Madeleine Blanc-Valleron, Mathieu Sebilo, Olivier Gros, Anniet M. Laverman, David Dessailly

Purpose Marine mangrove sediments in the Manche-à-Eau lagoon (Guadeloupe, Caribbean Sea) harbor locally extensive, white microbial mats. These mats cover the surface of reduced sediments near the roots of red mangrove trees, Rhizophora mangle, and are mainly composed of sulfur-oxidizing bacteria belonging to the Beggiatoaceae family, with some filamentous cyanobacteria. The goal of this study was to investigate the possible influence of sediment characteristics on the presence of these microbial mats. Materials and methods Four push cores were collected in April 2013, two from zones with microbial mats and two from zones without mats. Sediment characteristics (grain-size distribution, mineralogy, total organic carbon (TOC) and total nitrogen (TN) contents, atomic TOC/TN ratios, and organic matter (OM) δ13C values) were compared for all four cores. Results and discussion Significant differences were observed between sediments below microbial mats and those without mats. Sediments with microbial mats contained greater amounts of clay, and higher TOC, TN, and TOC/TN ratios, with lower total carbonate content and δ13C values. The higher clay content most likely results from lower fluid flow velocity near to mangrove roots, while higher TOC/TN ratios and lower δ13C values indicate higher inputs of OM from mangrove trees. These results are consistent with the fact that microbial mats were observed near the roots of mangrove trees, which trap OM from terrestrial vegetation and fine sediments. Conclusions The grain-size distribution of sediment particles, the total carbonate content, and the δ13C values are the main parameters discriminating between zones with microbial mats and those without mats. Variations in total carbonate content, which is mainly of biogenic origin, result from conditions that are more favorable for benthic organisms in zones without microbial mats. Variations of the TOC/TN ratios are controlled by the presence of a non-negligible amount of inorganic nitrogen bound to surface clay mineral particles and/or by microbial processes.
Schlagworte: carbon , ocea , elem

H + -driven increase in CO 2 uptake and decrease in HCO3− uptake explain coccolithophores' acclimation responses to ocean acidification
Limnology and Oceanography (2016)
Dorothee M. Kottmeier, Sebastian D. Rokitta, Björn Rost

Recent ocean acidification (OA) studies revealed that seawater [H1] rather than [CO2] or [HCO2 3 ] regulate short-term responses in carbon fluxes of Emiliania huxleyi. Here, we investigated whether acclimation to altered carbonate chemistry modulates this regulation pattern and how the carbon supply for calcification is affected by carbonate chemistry. We acclimated E. huxleyi to present-day (ambient [CO2], [HCO2 3 ], and pH) and OA conditions (high [CO2], ambient [HCO2 3 ], low pH). To differentiate between the CO2 and pH/H1 effects, we also acclimated cells to carbonation (high [CO2] and [HCO2 3 ], ambient pH) and acidification (ambient [CO2], low [HCO2 3 ], and pH). Under these conditions, growth, production of particulate inorganic and organic carbon, as well as carbon and oxygen fluxes were measured. Under carbonation, photosynthesis and calcification were stimulated due to additional HCO2 3 uptake, whereas growth was unaffected. Such stimulatory effects are not apparent after short-term carbonation, indicating that cells adjusted their carbon acquisition during acclimation. Being driven by [HCO2 3 ], these regulations can, however, not explain typical OA effects. Under acidi- fication and OA, photosynthesis stayed constant, whereas calcification and growth decreased. Similar to the short-term responses toward high [H1], CO2 uptake significantly increased, but HCO2 3 uptake decreased. This antagonistic regulation in CO2 and HCO2 3 uptake can explain why photosynthesis, being able to use CO2 and HCO2 3 , often benefits from OA, whereas calcification, being mostly dependent on HCO2 3 , often decreases. We identified H1 as prime driver of coccolithophores’ acclimation responses toward OA. Acidified conditions seem to put metabolic burdens on the cells that result in decreased growth.

Carbon-13 labelling shows no effect of ocean acidification on carbon transfer in Mediterranean plankton communities
Estuarine, Coastal and Shelf Science (2015)
L. Maugendre, J.-P. Gattuso, A. de Kluijver, K. Soetaert, D. van Oevelen, J.J. Middelburg, F. Gazeau

Despite an increasing number of experiments, no consensus has emerged on the effect of ocean acidification on plankton communities and carbon flow. During two experiments, performed in the Bay of Calvi (France, Corsica; summer 2012) and the Bay of Villefranche (France; winter 2013), nine off-shore mesocosms (∼50 m3) were deployed among which three served as controls and six were enriched with CO2 to reach partial pressure of CO2 (pCO2) levels from 450 to 1350 μatm and 350–1250 μatm in the Bay of Calvi and the Bay of Villefranche, respectively. In each mesocosm, inorganic 13C was added in order to follow carbon transfer from inorganic via bulk particulate organic carbon and phytoplankton to bacteria by means of biomarkers as well as to zooplankton and settling particles. Despite very low plankton biomasses, labelled carbon was clearly transferred through plankton communities. Incorporation rates in the various plankton compartments suggested a slow-growing community based on regenerated production in the Bay of Calvi while in the Bay of Villefranche, fast-growing species were clearly dominating community production at the start with a shift toward slow-growing species during the experiment due to nutrient limitation. Both bulk and group-specific productions rates did not respond to increasing pCO2 levels. These experiments were the first conducted in the Mediterranean Sea under low nutrient concentrations and phytoplankton biomasses and suggest that ocean acidification may not significantly impact plankton carbon flows in low nutrient low chlorophyll (LNLC) areas.

Dependence of pH in coastal waters on the adsorption of protons onto sediment minerals
Limnology and Oceanography (2015)
Junghyun Lee, Guebuem Kim

We measured pH, total alkalinity (TAlk), dissolved inorganic carbon (DIC), and δ13C-DIC in groundwater of a subterranean estuary in Hwasun Bay in the volcanic island of Jeju, Korea. In the sandy aquifer, the pH values (7.4 ± 0.2) of fresh groundwater increased sharply to ∼ 10 and then behaved conservatively in the mixing zone between alkalified fresh groundwater and seawater. The distributions of δ13C-DIC, Ca2+, and Mg2+ in coastal groundwater, along with the results from lab experiments on sediment columns, suggest that the increase of pH in this subterranean estuary is associated with the adsorption of protons (protonation) onto sandy sediments, rather than other geochemical processes. Our lab experiments showed that the protonation (1) occurs commonly for various sediments of Jeju Island, (2) increases pH effectively for low-salinity (salinity < 10) groundwater, and (3) depends on the relative amount of transition metal (i.e., Fe, Ti, and Mn) oxides. The chamber experiments at the interface of seawater and groundwater indicate the direct seepage of high pH water into the ocean. This increase in pH leads to corresponding uptake of CO2 from the atmosphere. Thus, our result suggests that the reaction between groundwater and coastal sediments should be considered as an important driver of pH change that regulates the magnitude of chemical species in coastal groundwater seeping into the ocean at the volcanic island, Jeju, Korea.
Schlagworte: carbon , geol , ocea