ALBERT

Beschreibung: There are some active bottom currents on the northern continental slope of the South China Sea (SCS). Reflection seismic profiles show that the bottom current channels occur in the water depth range of 1000 to 2700 m, extending from the NE to the SW, leading to accumulation of discontinuous drifts with higher sedimentation rates on the eastern side of the channel. The stacking pattern of the layers suggests that these drifts propagated southwestward, following the direction of the bottom currents. One sedimentary drift to the southeast of the Dongsha Islands has the highest sedimentation rate of 97cm/ka in the last 12 ka. The sedimentary characteristics of the sediment layers indicate that these bottom currents are most likley caused by the water movement of a branch of the West Pacific Ocean Current, which enters the northern SCS via the Bashi Strait. Once formed, the bottom currents transport sediments along the northern slope of SCS southwestward and finally disappear into the central basin of the SCS. Due to the bottom current activity, the deep-sea sedimentary process in the northern SCS is complex.

Beschreibung: Quantitation of nucleic acids is a fundamental tool in molecular biology that requires accuracy, reliability, and the use of increasingly smaller sample volumes. This unit describes the traditional absorbance measurement at 260 nm and three more sensitive fluorescence techniques, as well as three microvolume methods that use fiber optic technology in specialized cells or instrumentation. These procedures allow quantitation of DNA solutions ranging from 1 pg/µl to 50 mg/ml.

Beschreibung: In contrast to continuum systems where localization or shear banding arises through a bifurcation in a predefined system of differential equations, shear bands emerge in numerical simulations of deforming granular systems with no prescribed mathematical relations other than simple contact forces between particles. Shear bands emerge from the self‐organization of large numbers of particles with long‐range geometrical interactions playing a dominant role; both translation and rotation of particles are important. Granular media therefore deform more like materials with non‐local constitutive relations than materials where only first‐order interactions are relevant. In this paper we adopt a thermo‐mechanical approach and explore the fluxes of energy in the evolving granular system (that has cohesion as well as friction between the particles) as it is loaded through the unstable localization regime, and track the evolution of energy dissipation. As in continua, the sign of the second‐order work defines the emergence of instability in the system. Initially, these instabilities decay into stable configurations of particles but with continued loading, force chains collapse locally to generate geometrically necessary fractures. These zones then propagate to generate localization zones. When these fractures form a continuous network, the system is at the percolation thresh‐hold for broken bonds. However, long before this stage, the second‐order work fluctuates in bursts weakly correlated with bursts in kinetic energy as damage accumulates. This behaviour suggests that any continuum constitutive description of granular media must be (i) non‐local in an anisotropic manner, (ii) micro‐polar, and (iii) involve damage evolution.

Beschreibung: Cold-water coral carbonate mounds, owing their presence mainly to the framework building coral Lophelia pertusa and the activity of associated organisms, are common along the European margin with their spatial distribution allowing them to be divided into a number of mound provinces. Variation in mound attributes are explored via a series of case studies on mound provinces that have been the most intensely investigated: Belgica, Hovland, Pelagia, Logachev and Norwegian Mounds. Morphological variation between mound provinces is discussed under the premise that mound morphology is an expression of the environmental conditions under which mounds are initiated and grow. Cold-water coral carbonate mounds can be divided into those exhibiting “inherited” morphologies (where mound morphology reflects the morphology of the colonised features) and “developed” morphology (where the mounds assume their own gross morphology mainly reflecting dominant hydrodynamic controls). Finer-scale, surface morphological features mainly reflecting biological growth forms are also discussed.

Beschreibung: Sponges of warm- and temperate- but also cold-waters are known to synthesize structurally diverse primary and secondary metabolites. These compounds fulfill a variety of functions including adaptations of the cell membranes to environmental conditions. We show here that boreal sponges of the order Halichondrida are rich sources of brominated lipid fatty acids. The comparison of lipid compositions of halichondrid Demospongiae from boreal and warmer waters indicates an accumulation of brominated fatty acids in sponges from colder settings. Moreover, the spatial distribution of brominated fatty acids in the sponge tissue of one widely distributed sponge of the North-East Atlantic (Phakellia ventilabrum) hints to a function related to membrane fluidity and permeability rather than to defense against predation. However, brominated fatty acids are diagnostic for the presence of bromoperoxidases in sponges and may therefore be potentially useful as markers in a chemical screening for secondary metabolites of pharmacological interest.

Beschreibung: Seasonal (Spring and Summer 2002) concentrations of dissolved (〈0.22 μm) trace metals (Ag, Al, Co, Cu, Mn, Ni, Pb), inorganic nutrients (NO3, PO4, Si), and DOC were determined in groundwater samples from 5 wells aligned along a 30 m shore-normal transect in West Neck Bay, Long Island, NY. Results show that significant, systematic changes in groundwater trace metal and nutrient composition occur along the flowpath from land to sea. While conservative mixing between West Neck Bay water and the groundwaters explains the behavior of Si and DOC, non-conservative inputs for Co and Ni were observed (concentration increases of 10- and 2-fold, respectively) and removal of PO4 and NO3 (decreases to about half) along the transport pathway. Groundwater-associated chemical fluxes from the aquifer to the embayment calculated for constituents not exhibiting conservative behavior can vary by orders of magnitude depending on sampling location and season (e.g. Co, 3.4 × 102– 8.2 × 103 μmol d−1). Using measured values from different wells as being representative of the true groundwater endmember chemical composition also results in calculation of very different fluxes (e.g., Cu, 6.3 × 103 μmol d−1 (inland, freshwater well) vs. 2.1 × 105 μmol d−1(seaward well, S = 17 ppt)). This study suggests that seasonal variability and chemical changes occurring within the subterranean estuary must be taken into account when determining the groundwater flux of dissolved trace metals and nutrients to the coastal ocean.

Beschreibung: A mass balance for the naturally-occurring radium isotopes (224Ra, 223Ra, 228Ra, and 226Ra) in Jamaica Bay, NY, was conducted by directly estimating the individual Ra contributions of wastewater discharge, diffusion from fine-grained subtidal sediments, water percolation through marshes, desorption from resuspended particles, and water exchange at the inlet. The mass balance revealed a major unknown source term accounting for 19–71% of the total Ra input, which could only be resolved by invoking a source from submarine groundwater. Shallow (〈 2 m depth) groundwater from permeable sediments in Jamaica Bay was brackish and enriched in Ra relative to surface bay waters by over two orders of magnitude. To balance Ra fluxes, a submarine groundwater input of 0.8 × 109–9.0 × 109 L d− 1 was required. This flux was similar for all four isotopes, with individual estimates varying by less than a factor of 2. Our calculated groundwater flux was 6- to 70-fold higher than the fresh groundwater discharge to the bay estimated by hydrological methods, but closely matched direct flow rates measured with seepage meters. This suggests that a substantial portion of the discharge consisted of recirculated seawater. The magnitude of submarine groundwater discharge varied seasonally, in the order: summer 〉 autumn 〉 spring. Chemical analyses suggest that the recirculated seawater component of submarine groundwater delivers as much dissolved nitrogen to the bay as the fresh groundwater flux.

Beschreibung: Two new compounds, 2, 3, 5-trimethyl-6-(3-oxobutan-2-yl)-4H-pyran-4-one (1) and (2R)-2, 3-dihydro-7-hydroxy-6, 8-dimethyl-2-[(E)-prop-1-enyl] chromen-4-one (2), together with six known compounds (3–8), were isolated from a deep-sea fungus, identified as Aspergillus sydowi, by a bioassay-guided method. Their structures were elucidated by spectroscopic methods and the cytotoxicities were evaluated by SRB method.

Beschreibung: The genetic paradigm of cancer, focused largely on sequential molecular aberrations and associated biological impact in the neoplastic cell compartment of malignant tumors, has dominated our view of cancer pathogenesis. For the most part, this conceptualization has overlooked the dynamic and complex contributions of the surrounding microenvironment comprised of non-tumor cells (stroma) that may resist, react to, and/or foster tumor development. Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal disease in which a prominent tumor stroma compartment is a defining characteristic. Indeed, the bulk of PDAC tumor volume consists of non-neoplastic fibroblastic, vascular, and inflammatory cells surrounded by immense quantities of extracellular matrix, far exceeding that found in most other tumor types. Remarkably, little is known about the composition and physiology of the PDAC tumor microenvironment, in particular, the role of stroma in tumor initiation and progression. This review attempts to define key challenges, opportunities and state-of-knowledge relating to the PDAC microenvironment research with an emphasis on how inflammatory processes and key cancer pathways may shape the ontogeny of the tumor stroma. Such knowledge may be used to understand the evolution and biology of this lethal cancer and may convert these insights into new points of therapeutic intervention.

Beschreibung: Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) with a bismuth cluster primary ion source was used for analysing microbial lipid biomarkers in 10-µm-thick microscopic cryosections of methanotrophic microbial mats from the Black Sea. Without further sample preparation, archaeal isopranyl glycerol di- and tetraether core lipids, together with their intact diglycoside (gentiobiosyl-) derivatives, were simultaneously identified by exact mass determination. Utilizing the imaging capability of ToF-SIMS, the spatial distributions of these biomarkers were mapped at a lateral resolution of 〈 5 µm in 500 × 500 µm2 areas on the mat sections. Using inline image cluster projectiles in the burst alignment mode, it was possible to reach a lateral resolution of 1 µm on an area of 233 × 233 µm, thus approaching the typical size of microbial cells. The mappings showed different ‘provenances’ within the sections that are distinguished by individual lipid fingerprints, namely (A) the diethers archaeol and hydroxyarchaeol co-occurring with glycerol dialkyl glycerol tetraethers (GDGT), (B) hydroxyarchaeol and dihydroxyarchaeol, and (C) GDGT and gentiobiosyl-GDGT. Because ToF-SIMS is a virtually nondestructive technique affecting only the outermost layers of the sample surface (typically 10–100 nm), it was possible to further examine the studied areas using conventional microscopy, and associate the individual lipid patterns with specific morphological traits. This showed that provenance (B) was frequently associated with irregular, methane-derived CaCO3 crystallites, whereas provenance (C) revealed a population of fluorescent, filamentous microorganisms showing the morphology of known methanotrophic ANME-1 archaea. The direct coupling of imaging mass spectrometry with microscopic techniques reveals interesting perspectives for the in-situ study of lipids in geobiology, microbial ecology, and organic geochemistry. After further developing protocols for handling different kinds of environmental samples, ToF-SIMS could be used as a tool to attack many challenging problems in these fields, such as the attribution of biological source(s) to particular biomarkers in question, or the high-resolution tracking of biogeochemical processes in modern and ancient natural environments.

Beschreibung: The achievable accuracy of bathymetric mapping in the deep ocean using robotic systems is most often limited by the available guidance or navigation information used to combine the measured sonar ranges during the map making process. This paper presents an algorithm designed to mitigate the affects of poor ground referenced navigation by applying the principles of map registration and pose filtering commonly used in simultaneous localization and mapping (SLAM) algorithms. The goal of the algorithm is to produce a self-consistent point cloud representation of the bottom terrain with errors that are on a scale similar to the sonar range resolution rather than any direct positioning measurement. The presented algorithm operates causally and utilizes sensor data that are common to instrumented underwater robotic vehicles used for mapping and scientific explorations. Real world results are shown for data taken on several expeditions with the JASON remotely operated vehicle (ROV). Comparisons are made between more standard mapping approaches and the proposed method is shown to significantly improve the map quality and reveal scene information that would have otherwise been obscured due to poor direct navigation information.

Beschreibung: Chemical investigation of the fungus Trichoderma sp., isolated from the Caribbean sponge Agelas dispar led to four novel sorbicillinoid polyketide derivatives (1–4) with an unprecedented tricyclic ring system. The structures of all compounds, including the absolute configuration, were determined by interpretation of their spectroscopic data (1D and 2D NMR, CD, MS, UV and IR), and molecular modeling calculations.

Beschreibung: Species of the genus Hysterothylacium are among the most common marine nematode fish parasites in the northern Atlantic. Due to recent findings of cryptic speciation in other parasitic ascaridoid nematodes, a similar pattern of sibling species was hypothesized also for Hysterothylacium aduncum. By investigating a 886- to 890-bp-long genomic DNA fragment including ITS-1, 5.8S rDNA and ITS-2 of 40 specimens of H. aduncum of sprat (Sprattus sprattus) of four different biogeographical regions (North Sea, English Channel, Bay of Biscay, Adriatic Sea), we could not detect significant genetic variability and therefore cryptic speciation. Nevertheless, while ITS-1 and 5.8S rDNA sequences were identical for all analysed specimens, ITS-2 sequences showed a population-specific pattern with the differentiation of an English Channel/Bay of Biscay group from a North Sea/Mediterranean Sea group.

Beschreibung: A stable and specific bacterial community was shown to be associated with the Mediterranean sponge Chondrilla nucula. The associated bacterial communities were demonstrated to be highly similar for all studied specimens regardless of sampling time and geographical region. In addition, analysis of 16S rDNA clone libraries revealed three constantly C. nucula-associated bacterial phylotypes belonging to the Acidobacteria, the Gamma- and Deltaproteobacteria present in sponge specimens from two Mediterranean regions with distinct water masses (Ligurian Sea and Adriatic Sea). For the first time, candidate division TM7 bacteria were found in marine sponges. A major part (79%) of the C. nucula-derived 16S rDNA sequences were closely related to other sponge-associated bacteria. Phylogenetic analysis identified 14 16S rRNA gene sequence clusters, seven of which consisted of exclusively sponge-derived sequences, whereas the other seven clusters contained additional environmental sequences. This study adds to a growing database on the stability and variability of microbial consortia associated with marine sponges.

Beschreibung: A liquid chromatograph/mass spectrometry (LC/MS) method was developed for the simultaneous quantitation of seven compounds (safflor yellow A, puerarin, daidzein, ginsenosides (Rg(1), Rb(1), Rd), and notoginsenoside R(1)) in rat plasma samples with sufficient sensitivity to facilitate analysis of samples collected after an intravenous injection of Naodesheng. The plasma samples were subjected to protein precipitation with acetone, and analyzed using negative atmospheric pressure chemical ionization mass spectrometry in selected ion monitoring (SIM) mode with baicalin as an internal standard. Good linearity for all the seven compounds was observed. The intra- and inter-day precision of analysis was 〈15.0% for each compound, and the accuracy ranged from 90.0% to 109.0%. This quantitation method was successfully applied to a pharmacokinetic study of following intravenous injection of rats with Naodesheng

Beschreibung: Mombacho is a deeply dissected volcano belonging to the Quaternary volcanic chain of Nicaragua. The southern, historic collapse crater (El Crater) currently hosts a fumarolic field with a maximum temperature of 121°C. Chemical and isotopic data from five gas-sampling field campaigns carried out in 2002, 2003 and 2005 highlight the presence of high-temperature gas components (e.g. SO2, HCl and HF), which indicate a significant contribution of juvenile magmatic fluids to the hydrothermal system feeding the gas discharges. This is strongly supported by the mantle-derived helium and carbon isotopic signatures, although the latter is partly masked by either a sedimentary subduction-related or a shallow carbonate component. The observed chemical and isotopic composition of the Mombacho fluids seems to indicate that this volcanic system, although it has not experienced eruptive events during the last centuries, can be considered active and possibly dangerous, in agreement with the geophysical data recorded in the region. Systematic geochemical monitoring of the fumarolic gas discharges, coupled with a seismic and ground deformation network, is highly recommended in order to monitor a possible new eruptive phase.

Beschreibung: Centropages typicus is one of the most common, abundant and best studied calanoid copepods in neritic waters of the Mediterranean Sea, which means it can provide useful information about the long-term dynamics of the Mediterranean epipelagic ecosystem. This paper presents the first comparative overview of the seasonal and long-term variability of C. typicus in different Mediterranean regions. This review is based on quantitative information from the published literature and novel data from five ongoing zooplankton time-series carried out in the Mallorca Island (Balearic Sea), the Bay of Villefranche (Ligurian Sea), the Gulf of Naples (Tyrrhenian Sea), the Gulf of Trieste (North Adriatic Sea), and the Saronikos Gulf (Aegean Sea). In most Mediterranean regions, C. typicus has a perennial occurrence, with peaks of abundance that reflect the succession of different generations. Throughout the Mediterranean, the annual cycle of C. typicus is characterized by minima in winter and major peaks in April–June, which is earlier than those observed in European Atlantic waters, where the peaks are more frequently recorded in summer and fall. In the regions investigated, the annual cycle shows remarkable similarities in terms of timing, but notable differences in the peak height; populations are far more abundant in coastal north-western regions and less abundant in the eastern basin. In the long-term, changes in C. typicus phenology observed in the Bay of Villefranche and in the Gulf of Naples are related to the North Atlantic Oscillation (NAO) index. In these two regions, the species responds to climate forcing similarly in terms of average seasonal patterns (bi-modal patterns in years of positive NAO, unimodal patterns in years of negative NAO) but oppositely in terms of quantity, indicating different influence of the NAO on the two regions. At decadal scales, C. typicus populations show high interannual variability with marked geographical differences. In some areas, the patterns are clearly characterized by alternate phases of higher and lower annual abundances, at higher frequency (mainly 1–2 years) in the Gulf of Naples, and lower frequency in the Saronikos Gulf (mainly 4–5 years) and in the Gulf of Trieste (mainly 5–6 years). Synchronous phases of increasing or decreasing abundance are discernable only for a few sites and short periods, for example from 1998 to 2000 in the Gulf of Naples, Gulf of Trieste and Saronikos Gulf. The regional differences observed in the long-term patterns of C. typicus populations suggest that the temporal dynamics of this species are significantly more affected by local conditions than by any possible common driving force acting at basin scale through teleconnections.

Beschreibung: Seven new fungal polyketides possessing linear pentaene structures ending in cyclic moieties were isolated from the mycelium extract of a marine sponge-derived Penicillium rugulosum. Feeding of C-13-labeled acetate and L-methionine was used to verify the polyketide origin of prugosene A1. It could also be shown that prugosenes B1 and C1 were formed from prugosene A1 by hydrolysis and decarboxylation of its oxabicyclo[2.2.1]heptane unit.

Beschreibung: We investigated the effect of commercially available enzymes (α-amylase, α-galactosidase, papain, trypsin, and lipase) as well as proteases from deep-sea bacteria on the larval attachment of the bryozoan Bugula neritina L. The 50% effective concentrations (EC50) of the commercial proteases were 10 times lower than those of other enzymes. Crude proteases from six deep-sea Pseudoalteromonas species significantly decreased larval attachment at concentrations of 0.03 to 1 mIU ml−1. The EC50 of the pure protease from the bacterium Pseudoalteromonas issachenkonii UST041101-043 was close to 1 ng ml−1 (0.1 mIU ml−1). The protease and trypsin individually incorporated in a water-soluble paint matrix inhibited biofouling in a field experiment. There are certain correlations between production of proteases by bacterial films and inhibition of larval attachment. None of the bacteria with biofilms that induced attachment of B. neritina produced proteolytic enzymes, whereas most of the bacteria that formed inhibitive biofilms produced proteases. Our investigation demonstrated the potential use of proteolytic enzymes for antifouling defense.

Beschreibung: We have applied the novel analytical method NanoSIMS to cephalopod statoliths for the first time in order to analyse their chemical microstructure, using a spatial resolution of 400 nm. This technique makes it possible to analyse in situ nano-scale chemical variations between increment layers. In statoliths of the boreoatlantic armhook squid Gonatus fabricii, we found distinct concentration patterns indicating a periodicity in strontium and sodium distributions. Sr and Na show a negative relation, both elements showing alternating patterns where the increments vary in width between approximately 1 and 5 μm. Results suggest, that aragonite deposited during the night is rich in Na and poor in Sr, while aragonite deposited during the day is rich in Sr and poor in Na. This study demonstrates the excellent suitability of NanoSIMS for nano-scale microchemical analyses of aragonite, providing new information on calcification processes and individual life histories. Possible future fields of application include not only cephalopod statoliths, but also virtually all biomineralized tissues in aquatic organisms like fish otoliths, gastropod statoliths, bivalve shells, foraminifers and corals.

Beschreibung: Planktic foraminiferal census data, faunal sea surface temperatures (SSTs) and oxygen isotopic and lithic records from a site in the northeast Atlantic were analyzed to study the interglacial dynamics of Marine Isotope Stage (MIS) 11, a period thought to closely resemble the Holocene on the basis of orbital forcing. Interglacial conditions during MIS 11 persisted for approximately 26 ka. After the main deglacial meltwater processes ceased, a 10- to 12-ka-long transitional period marked by significant water mass circulation changes occurred before surface waters finally reached their thermal maximum. This SST peak occurred between 400 and 397 ka, inferred from the abundance of the most thermophilic foraminiferal species and was coincident with lowest sea level according to benthic isotope values. The ensuing stepwise SST decrease characterizes the overall climate deterioration preceding the increase in global ice volume by ∼ 3 ka. This cooling trend was followed by a more pronounced cold event that began at 388 ka, and that terminated in the recurrence of icebergs at the site around 382 ka. Because the water mass configuration of early MIS 11 evolved quite differently from that of the early Holocene, there is little evidence that MIS 11 can serve as an appropriate analogue for a future Holocene climate, despite the similarity in some orbital parameters.

Beschreibung: Variably altered dacite from the PACMANUS vent field in the eastern Manus back-arc basin, Papua New Guinea, was studied to determine the textural and mineralogical characteristics of hydrothermal alteration taking place in the immediate subsurface of this modern seafloor hydrothermal system. Detailed textural investigations show that fluid flow through the glassy dacite has been strongly controlled by the primary volcanic textures. Quench fractures and networks of interconnected perlitic cracks linking vesicles provided pathways for hydrothermal fluids flowing up to the seafloor. Hydrothermal alteration along these pathways resulted in the formation of pseudoclastic textures. Textural evidence suggests that alteration of the glassy dacite has not been sustained. The samples have been affected by incipient hydrothermal alteration that is typically not preserved in ancient volcanic-rock-hosted massive sulfide deposits. Interaction of the glassy dacite with hydrothermal fluids primarily resulted in the conversion of volcanic glass to dioctahedral smectite. Only minor amounts of trioctahedral smectite were formed. Destruction of the volcanic glass and the formation of smectite caused pronounced changes in the chemistry of the dacite samples, in particular a decrease in the SiO2 whole-rock content and the Na2O/K2O ratio. The two alkali elements behaved differently during hydrothermal alteration due to preferential incorporation of K into the interlayer position of the newly formed dioctahedral smectite. Smectite formation occurred under rock-dominated conditions although the addition of Mg was required to form trioctahedral smectite from the silicic volcanic glass. Primary plagioclase was resistant to hydrothermal alteration highlighting the fact that the destruction of volcanic glass and feldspar are not necessarily contemporaneous in massive sulfide forming hydrothermal systems. Incipient alteration of the glassy dacite close to the seafloor occurred at temperatures below 150 °C in an environment that allowed the development of steep temperature gradients. Comparison of the new data to the findings of deep drilling during ODP Leg 193 suggests that the smectite-rich alteration in the immediate subsurface of the PACMANUS hydrothermal vent field represents the low-temperature equivalent of illite- and chlorite-rich alteration associations forming in the upflow zones of the hydrothermal fluids in the deeper portion of the volcanic sequence.

Beschreibung: An indoor mesocosm system was set up to study the response of phytoplankton and zooplankton spring succession to winter and spring warming of sea surface temperatures. The experimental temperature regimes consisted of the decadal average of the Kiel Bight, Baltic Sea, and three elevated regimes with 2°C, 4°C, and 6°C temperature difference from that at baseline. While the peak of the phytoplankton spring bloom was accelerated only weakly by increasing temperatures (1.4 days per degree Celsius), the subsequent biomass minimum of phytoplankton was accelerated more strongly (4.25 days per degree Celsius). Phytoplankton size structure showed a pronounced response to warming, with large phytoplankton being more dominant in the cooler mesocosms. The first seasonal ciliate peak was accelerated by 2.1 days per degree Celsius and the second one by 2.0 days per degree Celsius. The over-wintering copepod populations declined faster in the warmer mesocosm, and the appearance of nauplii was strongly accelerated by temperature (9.2 days per degree Celsius). The strong difference between the acceleration of the phytoplankton peak and the acceleration of the nauplii could be one of the “Achilles heels” of pelagic systems subject to climate change, because nauplii are the most starvation-sensitive life cycle stage of copepods and the most important food item of first-feeding fish larvae.

Beschreibung: It is widely accepted that climate change constrains biota. Yet, because of the lack of consistent multisite and multitaxon surveys, few studies have addressed general rules about how climate change impacts on structure and diversity of animal communities. Especially, the relative influence of nonclimatic anthropogenic disturbances on this impact is fairly unknown. Here, we present for the first time a meta-analysis assessing the effect of global warming on stream organisms. Fish communities of large rivers in France undergoing various anthropogenic pressures showed significant increase in proportions of warm-water species and of specific richness during the last 15–25 years. Conversely, the equitability decreased, indicating a gradual decrease of the number of dominant species. Finally, the total abundance increased, coupled with rejuvenation and changes in size-structure of the communities. Interestingly, most of these effects were not depressed by the strength of nonclimatic anthropogenic disturbances. Conversely, geographical location of communities and especially closeness of natural barriers to migration could influence their response to climate change. Indeed, increase in the proportion of southern species seemed hindered at sites located close to the southern limit of the European species’ geographical ranges. This work provides new evidence that climate change have deep impacts on communities which, by overtaking the effects of nonclimatic anthropogenic disturbances, could be more substantial than previously thought. Overall, our results stress the importance of considering climate change impacts in studies addressing community dynamics, even in disturbed sites.

Beschreibung: New high resolution carbon isotope stratigraphies from two basinal pelagic carbonate successions in northern Germany (Halle and Oerlinghausen, Münsterland Cretaceous Basin) resolve late Cenomanian to early Mid-Turonian carbon cycle variations at timescales of less than 100 kyr. Beside the major carbon isotope excursion of the late Cenomanian oceanic anoxic event (OAE 2), 11 small-scale distinct features are precisely resolved in the δ13C carbonate curve and related to boreal macrofossil zonations. The small-scale carbon isotope events correspond to secular δ13C carbonate variations identified previously in the English Chalk. The boreal high-resolution δ13C carbonate curve shows a detailed coincidence with two Tethyan δ13C curves from Italy, what demonstrates the interregional significance of the δ13C dates and allows their correlation within error limits of ± 40 kyr. Furthermore, the new δ13C curve enables the calibration of boreal and tethyan macro- and microfossil zonations. Accordingly, the Tethyan calcareous nannoplankton boundary NC13/NC14 corresponds to the boreal FO of C. woollgari, the index taxon for the Lower-Middle Turonian boundary. The cyclic appearance and the temporal spacing of the small-scale carbon isotope events suggest that orbital forcing exerted control on surface water productivity and organic matter preservation at the sea floor.

Beschreibung: Otolith increment width and larval fish data (length and weight) were used to develop an individual-based model (IBM) to describe daily resolved growth rates of North Sea herring (Clupea harengus) larvae (Autumn Spawners) caught during International Herring Larvae Surveys in the ICES area IVa from 1990 to 1998. The model combines sagittal otolith readings (core and individual increment measurements), larval standard length and weight data, and solves an over-determined set of linear system equations for all parameters using the method of least square residuals. The model consists of a matrix, which describes the increment width formation of 119 larvae, a vector containing their length/weight measurements, and a vector describing residuals. The solution vector yields age-dependent maximum somatic growth rates of herring larvae up to an age of 41 days with sizes ranging from 10 to 25 mm. The observed environmental temperature in which larvae dwelled was relatively uniform. Therefore, measured increment width was individually used to determine daily growth from any single larva in relation to their potential maximum growth under optimal feeding conditions. The results are discussed with respect to the spatial and temporal variability of larval occurrence. Finally, an analysis of error estimation of the larval growth characteristics is presented.

Beschreibung: Permeabilities in the subducting slab appear to be too low and dihedral angles between fluid and relevant minerals too high to allow for porous flow, hence fluid channelization is critical for the understanding of subduction zone fluid fluxes. In this review we will outline how fluid channelization controls reaction rates and element redistributions during metamorphism of the subducting plate as well as trace element compositions of subduction-related fluids during flow. Channelized fluid flow predicts that from a rock point of view, most formerly subducted material will show only very limited evidence for fluid flow, consistent with the rarity of observed high fluid fluxes in subduction-related rocks. Aqueous fluid produced by dehydration reactions will not percolate through large rock volumes, but rather will be carried away from the dehydration sites by a veining network. Indeed evidence for significant aqueous-fluid fluxes have been found in high-pressure veins with adjacent selvages. In such selvages, large lithophile elements (LILE's) generally show the highest mobilities, followed by light (L) rare earth elements (REE) and then heavy (H) REE. Compared to high field strength elements (HFSE), even Th shows higher mobilities. From a fluid point of view, equilibrium between aqueous fluid and surrounding rock will only be approached at sites of fluid production and mineral reaction. However, this fluid can be significantly modified while moving upwards through a veining network where the wallrocks are out of equilibrium with the fluid. In a subducting slab, such reactive fluid flow can preferentially dissolve minerals and release their trace elements (e.g. Ba in phengite, Th and La in monazite). The degree of change in aqueous-fluid composition will depend on the amount of fluid–mineral surface interaction. The chemical exchange reactions will not be possible to model by trace element partition coefficients alone, instead future models need to incorporate kinetic parameters such as surface reaction rates.

Beschreibung: Controversy over the oxygen isotope composition of seawater began in the 1950's, since which time there has been no agreement over whether the oxygen isotope composition of the oceans has changed over time. Resolving this uncertainty would allow the δ18O values of demonstrably well preserved marine authigenic precipitates to be used to reconstruct surface climate trends back to early Archean times and would help towards a more quantitative description of Earth's global water cycle on geological time scales. Isotopic studies of marine carbonate and silica reveal a trend of increasing δ18O values with decreasing age since the Archean. This trend has been interpreted by some to reflect a progressive increase in seawater δ18O through time; however, it is generally accepted on the basis of ophiolite studies and theoretical considerations that seawater δ18O cannot change significantly because of the buffering effects of ocean crust alteration at mid-ocean ridges. As a result many alternative interpretations have been proposed, including meteoric alteration; warmer paleoclimates; higher seawater pH; salinity stratification and biased sampling. Here we review these interpretations in the light of an updated compilation of marine carbonate δ18O from around the world, covering the Phanerozoic and Precambrian rock records. Recent models of the geological water cycle demonstrate how long-term trends in chemical weathering and hydrothermal circulation can indeed influence the O-isotope composition of the global ocean to the extent necessary to explain the carbonate δ18O trend, with residual variation attributed to climatic fluctuations and post-depositional alteration. We present the further development of an existing model of the geological water cycle. In the model, seawater δ18O increased from about − 13.3‰ to − 0.3‰ over a period of 3.4 Ga, with average surface temperatures fluctuating between 10 °C to 33 °C, which is consistent with known biological constraints. Similar temperature variations are also obtained, although with higher starting seawater δ18O composition, when more conservative approaches are used that take into account the systematic effects of diagenetic alteration on mean calcite δ18O values. In contrast to much published opinion, the average δ18O value of ocean crust in the model remained relatively unchanged throughout all model runs. Invariable ophiolite δ18O values can, therefore, not be used as a definitive argument against changing seawater δ18O. The most likely explanation for the long-term trend in seawater δ18O invokes two stepwise increases in the ratio of high- to low-temperature fluid/rock interactions. An initial increase may have occurred close to the Archean–Proterozoic boundary, but a possibly more significant increase took place near the Proterozoic–Phanerozoic boundary. Possible explanations for extremely low seawater δ18O during the Archean include higher continental weathering rates caused by a combination of higher atmospheric pCO2 (necessarily combined with high CO2 outgassing rates), a greater abundance of relatively easily weathered volcanic rocks in greenstone belts and partial emergence of spreading ridges. The second increase may have been caused by the suppression of low-temperature overprinting of ocean crust alteration by the formation of a thick sediment cover on ridge flanks due to the emergence of shelly plankton at the beginning of the Phanerozoic. Postulated increases in spreading ridge depths since the Archean would also have enhanced the efficiency of vertical heat flux and changed the depth at which hydrothermal fluids boil, both of which would favour high- over low-temperature interactions with time.

Beschreibung: Stable isotope signatures of primary producers display high inter- and intraspecific variation. This is assigned to species-specific differences in isotope fractionation and variable abiotic conditions, e.g., temperature, and nutrient and light availability. As consumers reflect the isotopic signature of their food source, such variations have direct impacts on the ecological interpretation of stable isotope data. To elucidate the variability of isotope fractionation at the primary producer level and the transfer of the signal through food webs, we used a standardised marine tri-trophic system in which the primary producers were manipulated while the two consumer levels were kept constant. These manipulations were (1) different algal species grown under identical conditions to address interspecific variability and (2) a single algal species cultivated under different nutrient regimes to address nutrient-dependent variability. Our experiments resulted in strong interspecific variation between different algal species (Thalassiosira weissflogii, Dunaliella salina, and Rhodomonas salina) and nutrient-dependent shifts in stable isotope signatures in response to nutrient limitation of R. salina. The trophic enrichment in 15N and 13C of primary and secondary consumers (nauplii of Acartia tonsa and larval herring) showed strong deviations from the postulated degree of 1.0‰ enrichment in δ13C and 3.4‰ enrichment in δ15N. Surprisingly, nauplii of A. tonsa tended to keep “isotopic homeostasis” in terms of δ15N, a pattern not described in the literature so far. Our results suggest that the diets’ nutritional composition and food quality as well as the stoichiometric needs of consumers significantly affect the degree of trophic enrichment and that these mechanisms must be considered in ecological studies, especially when lower trophic levels, where variability is highest, are concerned.

Beschreibung: The active continental margin off south-central Chile (36° to 40°S) is transitional between the tectonically erosive, empty-trench margin north of Juan Fernandez Ridge and the accretionary, trench-filled margin south of the Chile Triple Junction. The small width of the presently active accretionary wedge (maximum width of 25 to 50 km) argues for past phases of tectonic erosion. At present, this sector shows indications of contemporaneous accretion, subduction, and underplating of sediment, as well as readjustment of the slope by various mass-wasting processes. In this context, this study aims to examine the Neogene sedimentary processes on the continental margin from dredge samples recovered during R/V SONNE cruise SO161-5 within this transitional domain using lithology, sandstone petrology, shale mineralogy, and analysis of sedimentary structures. Our results yield that the principal transport of material occurs in high-energy turbidity currents and debris flows via submarine canyons deeply cutting the continental slope, whereas sediment on the shelf is transported by strong coast-parallel bottom currents and trapped by submarine canyons cutting into the shelf. A wide range of mass-wasting processes including slumping, debris flows, evolving to low-density turbidity currents and mud flows, rework the slope sediments. In contrast, thick undisturbed sequences of mostly hemipelagic sediments accumulate in active slope basins, which are largely protected from mass movements. XRD analyses revealed early diagenetic lithification and overall burial depths of up to ∼ 230 mbsf, suggesting a shallow-subsurface cycle of sedimentation, subsidence, diagenesis, uplift, erosion, and resedimentation. The composition of sandstones is dominated by volcanic rock fragments of Andean provenance. Along-strike modal changes reflect a southward increase in glacially denudation and rainfall, the combination of which caused more intense erosion of volcanic rocks and exposure, weathering and, as a result, increased fluvial transport of metamorphic and plutonic rocks to the sea.

Beschreibung: The effects of towed fishing gear on benthic fauna are under intense scrutiny and evidence is growing that trawling may significantly affect benthic communities in the North Sea. Most studies explore the current fauna or compare today’s situation with that of 2 or 3 decades ago, when North Sea-wide information on benthos and fishing became available. However, in the North Sea, extensive mechanised trawling began more than a century ago. This study compared historical and recent records in order to explore potential long-term links between changes in the epibenthos and fishing. Based on reconstructed species lists from museum specimens, we compared epibenthos data from 1902 to 1912 with those from 1982 to 1985 and 2000. We analysed changes in average taxonomic distinctness (AvTD), a biodiversity indicator, and changes in biogeographical species distributions. Landings data were collated for round- and flatfish caught in the northern, central and southern North Sea from 1906 to 2000 as proxies for total otter and beam trawl effort, respectively. These indicate that the southern and much of the central North Sea were fished intensively throughout the 20th century, whilst the northern North Sea was less exploited, especially in earlier decades; exploitation intensified markedly from the 1960s onwards. For epibenthos, the mean AvTD decreased significantly from the 1980s to 2000, when it was below expected values in 4 ICES rectangles, 3 of these located in heavily trawled areas. Biogeographical changes from the beginning to the end of the century occurred in 27 of 48 taxa. In 14 taxa, spatial presence was reduced by 50% or more, most notably in the southern and central North Sea; often these were long-lived, slow-growing species with vulnerable shells or tests. By contrast, 12 taxa doubled their spatial presence throughout the North Sea. Most biogeographical changes had happened by the 1980s. Given that other important environmental changes, including eutrophication and climate change, have gained importance mainly from the 1980s onwards, we have concluded that the changes in epibenthos observed since the beginning of the 20th century have resulted primarily from intensified fisheries.

Beschreibung: The soxB gene encodes the SoxB component of the periplasmic thiosulfate-oxidizing Sox enzyme complex, which has been proposed to be widespread among the various phylogenetic groups of sulfur-oxidizing bacteria (SOB) that convert thiosulfate to sulfate with and without the formation of sulfur globules as intermediate. Indeed, the comprehensive genetic and genomic analyses presented in the present study identified the soxB gene in 121 phylogenetically and physiologically divergent SOB, including several species for which thiosulfate utilization has not been reported yet. In first support of the previously postulated general involvement of components of the Sox enzyme complex in the thiosulfate oxidation process of sulfur-storing SOB, the soxB gene was detected in all investigated photo- and chemotrophic species that form sulfur globules during thiosulfate oxidation (Chromatiaceae, Chlorobiaceae, Ectothiorhodospiraceae, Thiothrix, Beggiatoa, Thiobacillus, invertebrate symbionts and free-living relatives). The SoxB phylogeny reflected the major 16S rRNA gene-based phylogenetic lineages of the investigated SOB, although topological discrepancies indicated several events of lateral soxB gene transfer among the SOB, e.g. its independent acquisition by the anaerobic anoxygenic phototrophic lineages from different chemotrophic donor lineages. A putative scenario for the proteobacterial origin and evolution of the Sox enzyme system in SOB is presented considering the phylogenetic, genomic (sox gene cluster composition) and geochemical data.

Beschreibung: Permafrost environments in the Arctic are characterized by extreme environmental conditions that demand a specific resistance from microorganisms to enable them to survive. In order to understand the carbon dynamics in the climate-sensitive Arctic permafrost environments, the activity and diversity of methanogenic communities were studied in three different permafrost soils of the Siberian Laptev Sea coast. The effect of temperature and the availability of methanogenic substrates on CH4 production was analysed. In addition, the diversity of methanogens was analysed by PCR with specific methanogenic primers and by denaturing gradient gel electrophoresis (DGGE) followed by sequencing of DGGE bands reamplified from the gel. Our results demonstrated methanogenesis with a distinct vertical profile in each investigated permafrost soil. The soils on Samoylov Island showed at least two optima of CH4 production activity, which indicated a shift in the methanogenic community from mesophilic to psychrotolerant methanogens with increasing soil depth. Furthermore, it was shown that CH4 production in permafrost soils is substrate-limited, although these soils are characterized by the accumulation of organic matter. Sequence analyses revealed a distinct diversity of methanogenic archaea affiliated to Methanomicrobiaceae, Methanosarcinaceae and Methanosaetaceae. However, a relationship between the activity and diversity of methanogens in permafrost soils could not be shown.

Beschreibung: Measurements of bromoform (CHBr3), diiodomethane (CH2I2), chloroiodomethane (CH2ICl) and bromoiodomethane (CH2IBr) were made in the water column (5–100 m depth) of the Southern Ocean within 0–40 km of the Antarctic sea ice during the ANTXX1/2 transect of the German R/V Polarstern, at five locations between 70–72°S and 9–11°W in the Antarctic spring/summer of 2003–2004. Some of the profiles exhibited a very pronounced layer of surface sea-ice meltwater, as evidenced by salinity minima and temperature maxima, along with surface maxima in concentrations of CHBr3, CH2I2, CH2ICl and CH2IBr. These results are consistent with in situ surface halocarbon production by ice algae liberated from the sea ice, although production within the sea ice followed by transport cannot be entirely ruled out. Additional sub-surface maxima in halocarbons occurred between 20 and 80 m. At a station further from shore and not affected by surface sea-ice meltwater, surface concentrations of CH2I2 were decreased whereas CH2ICl concentrations were increased compared to the stations influenced by meltwater, consistent with photochemical conversion of CH2I2 to CH2ICl, perhaps during upward mixing from a layer at ∼ 70 m enhanced in iodocarbons. Mean surface (5–10 m) water concentrations of halocarbons in these coastal Antarctic waters were 57 pmol l− 1 CHBr3 (range 44–78 pmol l− 1), 4.2 pmol l− 1 CH2I2 (range 1.7–8.2 pmol l− 1), 0.8 pmol l− 1 CH2IBr (range 0.2–1.4 pmol l− 1), and 0.7 pmol l− 1 CH2ICl (range 0.2–2.4 pmol l− 1). Concurrent measurements in air suggested a sea-air flux of bromoform near the Antarctic coast of between 1 and 100 (mean 32.3, median 10.4) nmol m− 2 day− 1 and saturation anomalies of 557–1082% (mean 783%, median 733%), similar in magnitude to global shelf values. In surface samples affected by meltwater, CH2I2 fluxes ranged from 0.02 to 6.1 nmol m− 2 day− 1, with mean and median values of 1.9 and 1.1 nmol m− 2 day− 1, respectively.

Beschreibung: The methane oxidation potential of active layer profiles of permafrost soils from the Lena Delta, Siberia, was studied with regard to its respond to temperature, and abundance and distribution of type I and type II methanotrophs. Our results indicate vertical shifts within the optimal methane oxidation temperature and within the distribution of type I and type II methanotrophs. In the upper active layer, maximum methane oxidation potentials were detected at 21°C. Deep active layer zones that are constantly exposed to temperatures below 2°C showed a maximum potential to oxidize methane at 4°C. Our results indicate a dominance of psychrophilic methanotrophs close to the permafrost table. Type I methanotrophs dominated throughout the active layer profiles but their number strongly fluctuated with depth. In contrast, type II methanotrophs were constantly abundant through the whole active layer and displaced type I methanotrophs close to the permafrost table. No correlation between in situ temperatures and the distribution of type I and type II methanotrophs was found. However, the distribution of type I and type II methanotrophs correlated significantly with in situ methane concentrations. Beside vertical fluctuations, the abundance of methane oxidizers also fluctuated according to different geomorphic units. Similar methanotroph cell counts were detected in samples of a flood plain and a polygon rim, whereas cell counts in samples of a polygon centre were up to 100 times lower.

Beschreibung: Permafrost environments within the Siberian Arctic are natural sources of the climate relevant trace gas methane. In order to improve our understanding of the present and future carbon dynamics in high latitudes, we studied the methane concentration, the quantity and quality of organic matter, and the activity and biomass of the methanogenic community in permafrost deposits. For these investigations a permafrost core of Holocene age was drilled in the Lena Delta (72°22′N, 126°28′E). The organic carbon of the permafrost sediments varied between 0.6% and 4.9% and was characterized by an increasing humification index with permafrost depth. A high CH4 concentration was found in the upper 4 m of the deposits, which correlates well with the methanogenic activity and archaeal biomass (expressed as PLEL concentration). Even the incubation of core material at −3 and −6°C with and without substrates showed a significant CH4 production (range: 0.04–0.78 nmol CH4 h−1 g−1). The results indicated that the methane in Holocene permafrost deposits of the Lena Delta originated from modern methanogenesis by cold-adapted methanogenic archaea. Microbial generated methane in permafrost sediments is so far an underestimated factor for the future climate development.

Beschreibung: Latent heat polynyas are regions generating strong ice formation, convection and extensive water mass formation. Here we report on the effects of these processes on resuspension of sediments and subsequent methane release from the seafloor and on the resulting excess methane concentration in surface water on a polar shelf during winter. The study is based on measurements of concentration and δ13C values of methane, water temperature, salinity, light transmission and sea ice data collected in March 2003 in Storfjorden, southern Svalbard. In winter, strong and persistent northeasterly winds create polynyas in eastern Storfjorden and cause ice formation. The resulting brine-enriched water cascades from the Storfjordbanken into the central depression thereby enhancing the turbulence near the seafloor. A distinct benthic nepheloid layer was observed reflecting the resuspension of sediments by the cascading dense bottom water. High concentrations of 13C-depleted methane suggest submarine discharge of methane with the resuspended sediments. As the source of the submarine methane, we propose recent bacterial methanogenesis near the sediment surface because of extremely high accumulation rates of organic carbon in Storfjorden. Convective mixing transports newly released methane from the bottom to the sea surface. This eventually results in an excess concentration in surface water with respect to the atmospheric equilibrium, and a sea-air flux of methane during periods of open water. When a new ice cover is formed, methane becomes trapped in the water column and subsequently oxidized. Thus, the residual methane is strongly enriched in 13C in relation to the δ13CCH4δ13CCH4 signature of atmospheric methane. Our results show that latent heat polynyas may induce a direct pathway for biogases like methane from sediments to the atmosphere through coupling of biogeochemical and oceanographic processes. Extrapolating these processes to all Arctic ocean polynyas, we estimate a transfer of CH4 between 0.005 and 0.02 Tg yr−1. This is not a large contribution but the fluxes from the polynyas are 20–200 times larger than the ocean average and the methane evasion process in polynyas is certainly one that can be altered under climate change.

Beschreibung: Comparison of five deep-water coral (DWC)/mound ecosystems along the European Continental Margin shows that suspended particulate organic matter (sPOM), a potential food source, is lipid rich and of high quality. However, there are differences between the sites. The Darwin and Pelagia Mounds (N. Rockall Trough and N. Porcupine Bank, respectively) have higher proportions of labile particulate lipids (including high proportions of polyunsaturated fatty acids) in the benthic boundary layer than Logachev, Hovland and Belgica Mounds (Rockall Bank, S. Porcupine Bank and Porcupine Seabight, respectively). The high quality sPOM could be transported downslope from the euphotic zone. There is some evidence for inter-annual variability at some sites (e.g. Hovland and Logachev Mounds) as large differences in suspended lipid and particulate organic carbon concentrations were observed over the sampling period. Elevated total organic carbon contents of sediments at mound sites, relative to control sites in some cases (particularly Darwin Mounds), probably reflect local hydrodynamic control and the trapping of sPOM by the DWC. Fresh POM can be relatively rapidly transferred to significant depth (up to 8 cm) through bioturbation that is evident at all sites. There is no clear evidence of present day hydrocarbon seepage at any of the sites.

Beschreibung: Physical and chemical properties of the water column, along with meteorological conditions were examined for their relationship with phytoplankton biomass in the Irminger Sea during late autumn and early winter. Data were collected during 2 cruises to the region in November and December 2001 and November 2002. Phytoplankton biomass was approximated by (chl a) concentrations within the water column. When examined during autumn and winter alone, the Irminger Sea was suitably described as one biogeochemical region responding to varying meteorological forcing. Hydrographic differences within the region were not observed to have a significant effect on phytoplankton growth during this period. Strong correlations with latitude were seen in chl a concentrations, physical conditions (including mixed layer depth) and meteorological forcing (including net heat flux). Variability in autumn/winter phytoplankton growth conditions appears to be driven by light limitation modulated by meteorological forcing. The temporal and spatial scales of locations sampled in 2001 represent a progression in the physical and biological conditions from late autumn to early winter. Along this ‘virtual transect’, a baseline value of approximately 0.1 mg m–3 is seen in the mean chl a concentrations within the mixed layer. We postulate that convection provides a mechanism for reduction of net losses of phytoplankton, by helping to keep phytoplankton within the mixed layer. Under such conditions, a deeper and therefore more accurate estimation of the critical depth would be valid. Evidence of the extended maintenance of phytoplankton within the mixed layer is presented in the form of the relative dominances of different phytoplankton groups.

Beschreibung: In spite of the fundamental role the Atlantic Meridional Overturning Circulation (AMOC) plays for global climate stability, no direct current measurement of the Denmark Strait Overflow, which is the densest part of the AMOC, has been available until recently that resolve the cross-stream structure at the sill for long periods. Since 1999, an array of bottom-mounted acoustic instruments measuring current velocity and bottom-to-surface acoustic travel times was deployed at the sill. Here, the optimization of the array configuration based on a numerical overflow model is discussed. The simulation proves that more than 80% of the dense water transport variability is captured by two to three acoustic current profilers (ADCPs). The results are compared with time series from ADCPs and Inverted Echo Sounders deployed from 1999 to 2003, confirming that the dense overflow plume can be reliably measured by bottom-mounted instruments and that the overflow is largely geostrophically balanced at the sill.

Beschreibung: The Sibao Orogen in South China is one of the poorest known Grenville-aged orogenic belts through which the Neoproterozoic supercontinent Rodinia assembled. We report here the first UV laser spot 40Ar/39Ar mica and SHRIMP U–Pb zircon ages from a rare Grenville-aged metamorphic complex, the Tianli Schists, in the eastern Sibao Orogen. Our U–Pb zircon provenance ages indicate that the protolith of the Tianli Schists was a clastic sedimentary succession most likely derived from the Yangtze Block. The depositional age of the protolith is younger than 1530 Ma, as constrained by the youngest detrital zircon grains, but is older than 1040 Ma as constrained by the oldest 40Ar/39Ar muscovite ages. The Yangtze Block provenance for the Tianli Schists suggests that the Sibaoan ophiolitic complexes in northeastern Jiangxi, the ca. 970 Ma Xiwan adakitic granite intrusions, and the ca. 900 Ma(?) Xiwan blueschists, all to the northwest of the study region, were likely formed during the closure of a back-arc basin along the margin of the Yangtze Block. Our in situ UV laser 40Ar/39Ar results from S1 and S2 muscovites suggest that the Tianli Schists underwent metamorphism and deformation at 1042 ± 7 Ma to 1015 ± 4 Ma, the oldest known metamorphic event in the eastern Sibao Orogen. Muscovite/biotite cooling ages of ca. 968 ± 4 and 942 ± 8 Ma are recorded by deformed and recrystallised muscovite and biotite, respectively, indicating tectonic reactivation before 900 Ma, during the later stages of the Sibao Orogeny. Together with previous results from the western Sibao Orogen, our work suggests that the closure of the ocean between the Yangtze and Cathaysia Blocks during the assembly of Rodinia was diachronous: ≥1000 Ma at the western Sibao Orogen and ca. 900 Ma at the eastern Sibao Orogen.

Beschreibung: Annonaceous acetogenins are a large class of naturally occurring polyketides exhibiting potent anticancer activities. Based on our previous discovery of AA005, a multi-ether mimic of natural acetogenins having potent antitumor activities and significant selectivity between normal cells and cancer cells, a new series of mimics containing a terminal lactam were designed, synthesized and evaluated. Bioactivity study against cancer cells shows that the N-methylated lactam-containing compounds 3, 4, and 5 exhibit comparable potencies to that of AA005, as well as the similar selectivity to cancer cells. Hydrocarbon-length effects of N-alkyl were further explored through synthesizing derivatives 24–26, and application of this derivation protocol to the fluorescent labeling was also investigated.

Beschreibung: The experiment IGLOS (Investigation of the Greenland Boundary Layer Over Summit) was conducted in June and July 2002 in the central plateau of the Greenland inland ice. The German research aircraft Polar2, equipped with the turbulence measurement system Meteopod, was used to investigate turbulence and radiation flux profiles near research station “Summit Camp”. Aircraft measurements are combined with measurements of radiation fluxes and turbulent quantities made from a 50 m tower at Summit Camp operated by Eidgenössische Technische Hochschule (ETH) Zürich. During all six flight missions, well-developed stable boundary layers were found. Even in high-wind conditions, the surface inversion thickness did not exceed roughly 100 m. The turbulent height of the stable boundary layer (SBL) was found to be much smaller than the surface inversion thickness. Above the surface layer, significant turbulent fluxes occurred only intermittently in intervals on the order of a few kilometres. Turbulent event fraction in the upper SBL shows the same dependence on gradient Richardson number as reported for near-surface measurements. Clear-air longwave radiation divergence was always found to contribute significantly to the SBL heat budget. In low-wind cases, radiative cooling even turned out to be dominant.

Beschreibung: 1. To study the influence of chironomids on the distribution of pore-water concentrations of phosphate, iron and ammonium, we conducted a laboratory experiment using mesocosms equipped with two-dimensional pore-water samplers, filled with lake sediment and populated with different densities of Chironomus plumosus. 2. Specially designed mesocosms were used in the study. A 6-mm deep space between the front plate and the pore-water sampler at the back plate was just thick enough to allow the chironomids to live undisturbed, yet thin enough to force all the burrows into a two-dimensional plane. 3. The courses of the burrows were observed during the experiment as oxidised zones surrounding them, as well as being identified with an X-ray image taken at the end of the experiment. 4. We investigated the relationship between C. plumosus burrows and spatial patterns of pore-water composition. Concentrations of the three ions were significantly less around ventilated burrows (54% to 24%), as bioirrigation caused a convective exchange of pore-water enriched with dissolved species compared with the overlying water, and also because oxygen imported into the sediment resulting in nitrification of ammonium, oxidation of iron(II) and a co-precipitation of phosphate with Fe(III) oxyhydroxides. 5. In mesocosms with chironomids, new (redox) interfaces occurred with diffusive pore-water gradients perpendicular to the course of burrows and the site of major phosphate, ammonium and iron(II) release shifted from the sediment surface to the burrow walls.

Beschreibung: Samples from the bottom of the sea were used in the exact determination of the crystals structures of naturally occurring hydrocarbon hydrates. The hydrates of methane, ethane, and propane had a cubic structure II with hexakaidecahedral and pentagonal dodecahedral cages occupied by the guest molecules.

Beschreibung: The utility of cuticular autofluorescence for the visualization of copepod morphology by means of confocal laser scanning microscopy (CLSM) was examined. Resulting maximum intensity projections give very accurate information on morphology and show even diminutive structures such as small setae in detail. Furthermore, CLSM enables recognition of internal structures and differences in material composition. Optical sections in all layers and along all axes of the specimens can be obtained by CLSM. The facile and rapid preparation method bears no risk of artefacts or damage occurring to the preparations and the visualized specimens can be used for later analyses allowing for the investigation of irreplaceable type specimens or parts of them. These features make CLSM a very effective tool for both taxonomical and ecological studies in small crustaceans; however, the maximum thickness of the specimens is limited to a few hundred micrometers. Three-dimensional models based on CLSM image stacks allow observation of the preparations from all angles and can permit, improve and speed up studies on functional morphology. The visualization method described has a strong potential to become a future standard technique in aquatic biology due to its advantages over conventional light microscopy and scanning electron microscopy.

Beschreibung: A wide variety of environmental records is necessary for analysing and understanding the complex Late Quaternary dynamics of permafrost-dominated Arctic landscapes. A NE Siberian periglacial key region was studied in detail using sediment records, remote sensing data, and terrain modelling, all incorporated in a geographical information system (GIS). The study area consists of the Bykovsky Peninsula and the adjacent Khorogor Valley in the Kharaulakh Ridge situated a few kilometres southeast of the Lena Delta. In this study a comprehensive cryolithological database containing information from 176 sites was compiled. The information from these sites is based on the review of previously published borehole data, outcrop profiles, surface samples, and our own field data. These archives cover depositional records of three periods: from Pliocene to Early Pleistocene, the Late Pleistocene and the Holocene. The main sediment sequences on the Bykovsky Peninsula consist of up to 50 m thick ice-rich permafrost deposits (Ice Complex) that were accumulated during the Late Pleistocene. They were formed as a result of nival processes around extensive snowfields in the Kharaulakh Ridge, slope processes in these mountains (such as in the Khorogor Valley), and alluvial/proluvial sedimentation in a flat accumulation plain dominated by polygonal tundra in the mountain foreland (Bykovsky Peninsula). During the early to middle Holocene warming, a general landscape transformation occurred from an extensive Late Pleistocene accumulation plain to a strongly thermokarst-dominated relief dissected by numerous depressions. Thermokarst subsidence had an enormous influence on the periglacial hydrological patterns, the sediment deposition, and on the composition and distribution of habitats. Climate deterioration, lake drainage, and talik refreezing occurred during the middle to late Holocene. The investigated region was reached by the post-glacial sea level rise during the middle Holocene, triggering thermo-abrasion of ice-rich coasts and the marine inundation of thermokarst depressions.

Beschreibung: Methanogenic archaea from Siberian permafrost complementary to the already well-studied methanogens from non-permafrost habitats were exposed to simulated Martian conditions. After 22 days of exposure to thermo-physical conditions at Martian low- and mid-latitudes up to 90% of methanogenic archaea from Siberian permafrost survived in pure cultures as well as in environmental samples. In contrast, only 0.3%–5.8% of reference organisms from non-permafrost habitats survived at these conditions. This suggests that methanogens from terrestrial permafrost seem to be remarkably resistant to Martian conditions. Our data also suggest that in scenario of subsurface lithoautotrophic life on Mars, methanogenic archaea from Siberian permafrost could be used as appropriate candidates for the microbial life on Mars.

Beschreibung: Historic data from the Russian-American Hydrochemical Atlas of Arctic Ocean together with data from the TRANSDRIFT II 1994 and TUNDRA 1994 cruises have been used to assess the spatial and inter-annual variability of carbon and nutrient fluxes, as well as air–sea CO2 exchange in the Laptev and western East Siberian Seas during the summer season. Budget computations using summer data of dissolved inorganic phosphate (DIP), dissolved inorganic nitrogen (DIN) and dissolved inorganic carbon (DIC) gives that the Laptev Sea shelf is a net sink of DIP and DIN of 2.5×106, 23.2×106 mol d−1, respectively, while it is a net source of DIC (excluding air–sea exchange) of 1249×106 mol d−1. In the East Siberian Seas the budget computations give 0.5×106, −11.4×106 and −173×106 mol d−1 (minus being a sink) for DIP, DIN, and DIC, respectively. In summers, the Laptev Sea Shelf is net autotrophic while the East-Siberian Sea Shelf is net heterotrophic, and both systems are weak net denitrifying. The Laptev Sea Shelf takes up 2.1 mmol CO2 m−2 d−1 from atmosphere, whereas the western part of the East-Siberian Sea Shelf loose 0.3 mmol CO2 m−2 d−1 to the atmosphere. The variability of DIP, DIN and DIC fluxes during summer in the different regions of the Laptev and East Siberian Seas depends on bottom topography, river runoff, exchange with surrounding seas and wind field.

Beschreibung: In nature, multiple-species rather than single-species microbial associations with plant or animal (including human) hosts are the rule more than the exception. Prominent examples are the microbial consortia of vertebrate intestines and cattle rumen. As many demosponges are associated with enormous amounts of microorganisms, contributing up to 40-60% of the sponge biomass, they are excellent models for marine multi-species, microbe-host associations. Representatives of at least eight different phyla, many of which contain few or no cultivated representatives, have been identified as specific members of the sponge-associated microbiota. Recent studies show that vertical transmission of symbionts through the larval stages rather than horizontal acquisition from seawater appears to be an important mechanism by which the complex and possibly ancient microbial consortia of sponges are formed.

Beschreibung: Many sponge species contain large and diverse communities of microorganisms. Some of these microbes are suggested to be in a mutualistic interaction with their host sponges, but there is little evidence to support these hypotheses. Stable nitrogen isotope ratios of sponges in the Key Largo, Florida (USA) area grouped sponges into species with relatively low δ15N ratios and species with relatively high δ15N ratios. Using samples collected in June 2002 from Three Sisters Reef and Conch Reef in the Key Largo, Florida area, transmission electron microscopy (TEM) and denaturing gradient gel electrophoresis were performed on tissues of the sponges Ircinia felix and Aplysina cauliformis, which are in the low δ15N group, and on tissue of the sponge Niphates erecta, which is in the high δ15N group. Results showed that I. felix and A. cauliformis have large and diverse microbial communities, while N. erecta has a low biomass of one bacterial strain. As the low δ15N ratios indicated a microbial input of nitrogen, these results suggested that I. felix and A. cauliformis were receiving nitrogen from their associated microbial community, while N. erecta was obtaining nitrogen solely from external sources. Sequence analysis of the microbial communities showed a diversity of metabolic capabilities among the microbes of the low δ15N group, which are lacking in the high δ15N group, further supporting metabolic differences between the two groups. This research provides support for hypotheses of mutualisms between sponges and their associated microbial communities.

Beschreibung: The skeleton morphology of the azooxanthellate cold-water coral Lophelia pertusa can be strongly influenced by invasive boring sponges that infest corallites in the still living part of the colony. Atypically swollen corallites of live Lophelia pertusa from the Galway Mound (Belgica Carbonate Mound Province, Porcupine Seabight, NE Atlantic), heavily excavated by boring organisms, have been examined with a wide range of non-destructive and destructive methods: micro-computed tomography, macro- and microscopic observations of the outer coral skeleton, longitudinal and transversal thin sections and SEM analyses of coral skeleton casts. As a result, three excavating sponge species have been distinguished within the coral skeleton: Alectona millari, Spiroxya heteroclita and Aka infesta. Furthermore, four main coral/sponge growth stages have been recognised: (1) cylindrical juvenile corallite/no sponge cavities; (2) flared juvenile corallite/linear sponge cavities (if present); (3) slightly swollen adult corallites/chambered oval sponge cavities; (4) very swollen adult corallites/widespread cavities. The inferred correlation between corallite morphology and boring sponge infestation has been detected in micro-computed tomography (micro-CT) images and confirmed in sponge trace casts and peculiar features of coral skeleton microstructure.

Beschreibung: Cold-water coral carbonate mounds, owing their presence mainly to the framework building coral Lophelia pertusa and the activity of associated organisms, are common along the European margin with their spatial distribution allowing them to be divided into a number of mound provinces. Variation in mound attributes are explored via a series of case studies on mound provinces that have been the most intensely investigated: Belgica, Hovland, Pelagia, Logachev and Norwegian Mounds. Morphological variation between mound provinces is discussed under the premise that mound morphology is an expression of the environmental conditions under which mounds are initiated and grow. Cold-water coral carbonate mounds can be divided into those exhibiting “inherited” morphologies (where mound morphology reflects the morphology of the colonised features) and “developed” morphology (where the mounds assume their own gross morphology mainly reflecting dominant hydrodynamic controls). Finer-scale, surface morphological features mainly reflecting biological growth forms are also discussed.

Beschreibung: Particulate matter in aquatic systems is an important vehicle for the transport of particulate organic carbon (POC). Its accurate measurement is of central importance for the understanding of marine carbon cycling. Previous work has shown that GF/F-filter-based bottle-sample-derived concentration estimates of POC are generally close to or higher than large-volume in-situ-pump-derived values (and in some rare cases in subzero waters are up to two orders of magnitude higher). To further investigate this phenomenon, water samples from the surface and mid-water Northeast Atlantic and the Baltic Sea were analyzed. Our data support a bias of POC concentration estimates caused by adsorption of nitrogen-rich dissolved organic material onto GF/F filters. For surface-ocean samples the mass per unit area of exposed filter and composition of adsorbed material depended on the filtered volume. Amounts of adsorbed OC were enhanced in the surface ocean (typically 0.5 μmol cm− 2 of exposed filter) as compared to the deep ocean (typically 0.2 μmol cm− 2 of exposed filter). These dependencies should be taken into account for future POC methodologies. Bottle/pump differences of samples that were not corrected for adsorption were higher in the deep ocean than in the surface ocean. This discrepancy increased in summer. It is shown that POC concentration estimates that were not corrected for adsorption depend not only on the filtered volume, true POC concentration and mass of adsorbed OC, but also on the filter area. However, in all cases we studied, correction for adsorption was important, but not sufficient, to explain bottle/pump differences. Artificial formation of filterable particles and/or processes leading to filterable material being lost from and/or missed by sample-processing procedures must be considered. It can be deduced that the maximum amounts of POC and particulate organic nitrogen (PON) that can be artificially formed per liter of filtered ocean water are ∼ 3–4 μM OC (5–10% of dissolved OC) and ∼ 0.2–0.5 μM ON (2–10% of dissolved ON), respectively. The relative sensitivities of bottle and pump procedures, and of surface- and deep-ocean material, to artificial particle formation and the missing/losing of material are evaluated. As present procedures do not exist to correct for all possible biasing effects due to artificial particle formation and/or miss/loss of filterable material, uncertainties of filtration-based estimates of POC concentrations need further testing. The challenge now is to further constrain the magnitude of the biasing effects that add to the adsorption effect to reduce the uncertainties of estimates of POC concentrations, inventories and fluxes in the ocean.

Beschreibung: We present a new three-dimensional (3-D) P-wave velocity model for the upper-crustal structure beneath the Strait of Georgia, southwestern British Columbia based on non-linear tomographic inversion of wide-angle seismic refraction data. Our study, part of the Georgia Basin Geohazards Initiative (GBGI) is primarily aimed at mapping the depth of the Cenozoic sedimentary basin and delineating the near-surface crustal faults associated with recent seismic activities (e.g. M = 4.6 in 1997 and M = 5.0 in 1975) in the region. Joint inversion of first-arrival traveltimes from the 1998 Seismic Hazards Investigation in Puget Sound (SHIPS) and the 2002 Georgia Basin experiment provides a high-resolution velocity model of the subsurface to a depth of ???7 km. In the southcentral Georgia Basin, sedimentary rocks of the Cretaceous Nanaimo Group and early Tertiary rocks have seismic velocities between 3.0 and 5.5 km s-1. The basin thickness increases from north to south with a maximum thickness of 7 (??1) km (depth to velocities of 5.5 km s-1) at the southeast end of the strait. The underlying basement rocks, probably representing the Wrangellia terrane, have velocities of 5.5-6.5 km-1 with considerable lateral variation. Our tomographic model reveals that the Strait of Georgia is underlain by a fault-bounded block within the central Georgia Basin. It also shows a correlation between microearthquakes and areas of rapid change in basin thickness. The 1997/1975 earthquakes are located near a northeast-trending hinge line where the thicknesses of sedimentary rocks increase rapidly to the southeast. Given its association with instrumentally recorded, moderate sized earthquakes, we infer that the hinge region is cored by an active fault that we informally name the Gabriola Island fault. A northwest-trending, southwest dipping velocity discontinuity along the eastern side of Vancouver Island correlates spatially with the surface expression of the Outer Island fault. The Outer Island fault as mapped in our seismic tomography model is a thrust fault that projects directly into the Lummi Island fault, suggesting that they are related structures forming a fault system that is continuous for nearly 90 km. Together, these inferred thrust faults may account for at least a portion of the basement uplift at the San Juan Islands. ?? 2007 The Authors Journal compilation ?? 2007 RAS.

Beschreibung: A 1.5 km long, 1 km wide and 70–80 m high carbonate mound was identified on the mid-slope region of the subduction accretionary sedimentary prism offshore Vancouver Island ∼ 3.5 km west of Ocean Drilling Program (ODP) Site 889 and Integrated Ocean Drilling Program (IODP) Site U1327. Seabed-video images show the presence of seafloor carbonate as well as chemosynthetic communities. A high-resolution single channel seismic survey with close line spacing, recording coherent reflectivity down to about 400 m beneath the seafloor, provided acoustic images of this mound and of the gas hydrate bottom-simulating reflector (BSR) beneath it. The mound is interpreted to have developed as a structural topographic high in the hanging wall of a large reverse fault formed at the base of the current seaward slope. The fault zone provides pathways for fluids including gas to migrate to the seafloor where diagenetic carbonate forms and cements the near-surface sediments. To examine the thermal effect of possible upward fluid flow beneath the mound, heat flow at the mound and in the neighbouring region was calculated from the depth of the BSR below the seafloor. These data were combined with heat flow calculated over a broader region from previous multi-channel seismic data. Heat flow within the flattest portion of the surrounding 4 km by 8 km region averages ∼ 74 mW/m2. Taking this value to represent the regional or background heat flow, a simple 2D analytical method was used to calculate theoretical heat flow variations due to topography. Across the mound, most of the variability is explained by topographic effects, including a local 6 mW/m2 negative anomaly over the central mound and a large 20 mW/m2 positive anomaly over the mound steep side slope. However, just south of the mound, there is a 6–7 mW/m2 positive anomaly in a 2-km-long band that has predominantly flat seafloor. Most of this anomaly is probably unrelated to topographic effects, but rather likely due to warm upward fluid flow along faults or fracture zones.

Beschreibung: Sponges (Porifera) are filter feeders that take up microorganisms from seawater and digest them by phagocytosis. At the same time, many sponges are known to harbor massive consortia of symbiotic microorganisms, which are phylogenetically distinct from those in seawater, within the mesohyl matrix. In the present study, feeding experiments were performed to investigate whether phylogenetically different bacterial isolates, hereafter termed “food bacteria,” microbial seawater consortia, and sponge symbiont consortia are taken up and processed differently by the host sponge. Aplysina aerophoba retained high numbers of bacterial isolates and microbial seawater consortia with rates of up to 2.76 × 106 bacteria (g sponge wet weight)–1 h–1, whereas the retention of sponge symbionts was lower by nearly two orders of magnitude [5.37 × 104 bacteria (g sponge wet weight)−1 h–1]. In order to visualize the processing of a food bacterium within sponge tissues, the green fluorescent protein-labeled Vibrio strain MMW1, which had originally been isolated from A. aerophoba, was constructed. Incubation of this strain with A. aerophoba and subsequent visualization in tissue cryosections showed its presence in the choanocytes and/or endopinacocytes lining the canals but, unlike latex beads, not in deeper regions of the mesohyl, which suggests digestion of the bacteria upon contact with the host. Denaturing gradient gel electrophoresis (DGGE) was performed on the incubation seawater to monitor the changes in phylogenetic composition after incubation of the sponge with either seawater or sponge symbiont consortia. However, the DGGE experiment provided no evidence for selective processing of individual lineages by the host sponge. In conclusion, this study extends early studies by Wilkinson et al. (Proc R Soc London B 220:519–528, 1984) that sponges, here A. aerophoba, are able to differentiate between food bacteria and their own bacterial symbionts.

Beschreibung: Bacteria were isolated seasonally from the Mediterranean sponges Chondrilla nucula and Petrosia ficiformis and screened for antibacterial activities. Selected isolates were taxonomically identified by 16S rRNA gene sequencing. A total of 416 different bacterial strains were isolated, 60 (14.4%) of which displayed variable degrees of antimicrobial activity. Of the bioactive strains, 58.3% were able to inhibit Staphylococcus aureus, 6.7% were active against Bacillus subtilis, 11.7% against both Enterococcus faecalis and Escherichia coli, 38.3% against Pseudoalteromonas atlantica and 33.3% against Pseudomonas elongata. 16S rRNA gene sequence analysis showed that 2 isolates, 1 from seawater samples and 1 from P. ficiformis, were most closely related to Bacillus subtilis (99% similarity) and that another isolate from P. ficiformis was most closely related to a previously described sponge-associated Alphaproteobacterium NW001 (98% similarity). Two isolates from C. nucula were most closely related to Brachybacterium paraconglomeratum (99% similarity) and Shewanella algae (89% similarity). The high percentage of bioactive isolates derived from the 2 sponges suggests that marine microorganisms, whether animal-associated or planktonic, are promising sources for drug discovery.

Beschreibung: Numerous marine demosponges serve as habitats to phylogenetically complex microbial communities, with population densities exceeding those of seawater by several orders of magnitude. 16S rRNA gene-based studies have enabled a detailed phylogenetic description of the microorganisms associated with sponges, whereas environmental genomics analyses are beginning to reveal insights into their metabolic and physiological properties. Additionally, metagenomic approaches provide access to functional genes and gene clusters, thereby paving the way for the heterologous expression of novel bioactive substances from microbial symbionts of marine invertebrates.

Beschreibung: The Caribbean sponge, Plakortis simplex, is known to contain a large array of secondary metabolites, including the antimalarial polyketide plakortin, several unusual glycolipids, and some hopanoids, which closely resemble typical bacterial metabolites. The hypothesis that they could be products of bacterial metabolism was tested by localizing specific metabolites in cells using physical separation of sponge cells, bacterial symbionts and supernatant by differential centrifugation. The obtained fractions were analysed separately for the typical P. simplex metabolites by NMR and mass spectrometry, and most of them were shown to be present in the bacterial cells but not in the sponge cells. In addition, PCR screening showed that the biosynthetic pathway for glycosphingolipids was present in the bacterial cells. Isolation of a Sphingomonas strain PS193 from P. simplex and subsequent glycosphingolipid analysis resulted in the detection of a known glycosphingolipid, GSL-1, that did, however, not match the glycosphingolipid profile of P. simplex. Therefore, it is unlikely that Sphingomonas strain PS193 is an abundant member of the microbial community associated with P. simplex. Other glycosphingolipid producing bacteria in P. simplex remain to be identified. In conclusion, this study provides experimental evidence that the glycolipids and hopanoids and possibly also the polyketide plakortin are produced by microbial symbionts rather than the sponge from which the metabolites were originally isolated.

Beschreibung: A method for the quantification of heme b in marine phyto- and bacterioplankton is described. Heme b was extracted from filtered cells using a solution of 2.5% octyl (3-glucopyranoside in 0.02 M ammonium hydroxide. The extract was analysed by high performance liquid chromatography diode array spectrophotometry. Maximum absorbance for heme b was at 400 nm. Heme b was separated from other pigments using a polystyrene divinyl benzene stationary phase and a gradient elution programme with 0.1% (v:v) nonafluoropentanoic acid in water and 50:50 (v:v) isopropanol:acetonitrile as the mobile phases. Heme b was quantified using Fe (III) protoporphyrin IX chloride (hemin) standards. The detection limit, calculated from 3 X s.d. of the lowest standard was 0.08 pmol or 1.57 nM with a 50 mu L injection volume. The first data for heme b in marine phyto- and bacterioplankton are reported. Heme b contents are reported for the eukaryotes Thalassiosira weissflogii, Thalassiosira oceanica, Dunaliella tertiolecta and Emiliania huxleyi, and the prokaryotes Synechococcus WH8102, WH7803, RCC307, Erythrobacter litoralis, Roseobacter denitrificans and Vibrio natriegens. For T. weissflogii, T. oceanica, D. tertiolecta and E. huxleyi cellular heme b concentrations varied between 12 and 60 mu mol L-1 and chlorophyll a to heme b ratios varied between 216 and 309

Beschreibung: The Earth’s crust has played an important role in all aspects of this planet’s evolution. This chapter presents a review of our current understanding of the physical properties of the crust on a global basis. This understanding comes from extensive seismic measurements using many techniques, as well as nonseismic geophysics, including gravity, magnetic, geoelectric, and heat flow measurements. Seismic measurements include those that employ active (man-made) sources and those that use passive (naturally occurring) sources. Deep seismic reflection profiles provide a seismic image of the crust in twodimensions with a high (50–100 m) resolution. Local earthquake tomography can provide three-dimensional (3-D) seismic images at moderate (500–1000 m) resolution and higher, depending on the number and spacing of seismographs. Nonseismic methods provide estimates of crustal density, magnetic properties, conductivity and geotherms (temperature vs depth). The crust in deep ocean basins is 6–7 km thick and has a relatively uniform seismic velocity structure, but there are numerous oceanic regions with anomalous crustal structure, including mid-ocean ridges, trenches, volcanic islands, and oceanic plateaux. Ocean–continent passive margins are also highly variable in structure, and may be classified as volcanic versus nonvolcanic margins. Continental crust ranges in thickness from 16 to 80 km, and has a highly variable seismic velocity and density structure. The proportions of continental crust, by area, are 69% shield and platform (cratons), 15% old and young orogens, 9% extended (stretched) crust, 6 % magmatic arc, and 1% rifts. The weighted mean continental crustal thickness and average crustal velocity are 41 km (SD 6.2 km) and 6.45 km s−1 (SD 0.21 km s−1), respectively. A global geographic distribution of seismic data has made it possible to create global crustal models with cell sizes as small as 2 ° × 2 °. These models provide a complete description of seismic velocities and density within the crust and uppermost mantle, including, where present, ice, water, and sedimentary layers and the crystalline crust (parameterized in three layers, upper, middle and lower crust), and sub-Moho properties. The crust is the most intensely studied region of the Earth’s interior and consequently is the best understood in terms of its structure, composition, and evolution.

Beschreibung: Two single-channel seismic (SCS) data sets collected in 2000 and 2005 were used for a four-dimensional (4D) time-lapse analysis of an active cold vent (Bullseye Vent). The data set acquired in 2000 serves as a reference in the applied processing sequence. The 4D processing sequence utilizes time- and phase-matching, gain adjustments and shaping filters to transform the 2005 data set so that it is most comparable to the conditions under which the 2000 data were acquired. The cold vent is characterized by seismic blanking, which is a result of the presence of gas hydrate in the subsurface either within coarser-grained turbidite sands or in fractures, as well as free gas trapped in these fracture systems. The area of blanking was defined using the seismic attributes instantaneous amplitude and similarity. Several areas were identified where blanking was reduced in 2005 relative to 2000. But most of the centre of Bullseye Vent and the area around it were seen to be characterized by intensified blanking in 2005. Tracing these areas of intensified blanking through the three-dimensional (3D) seismic volume defined several apparent new flow pathways that were not seen in the 2000 data, which are interpreted as newly generated fractures/faults for upward fluid migration. Intensified blanking is interpreted as a result of new formation of gas hydrate in the subsurface along new fracture pathways. Areas with reduced blanking may be zones where formerly plugged fractures that had trapped some free gas may have been opened and free gas was liberated.

Beschreibung: The Mediterranean outflow water (MOW) paleocirculation during the last 50,000 years has been inferred from the grain-size distribution of contourite beds in core MD99-2341 from the Gulf of Cadiz (Southern Iberian Margin–Atlantic Ocean). Three main contourite facies are described. Their vertical succession defines two contourite sequences that reveal past variations of the MOW bottom-current velocity. A comparison of contourite sequences and the planktonic δ18O record of core MD99-2341 with the δ18O record from Greenland Ice Core GISP2 show a close correlation of sea-surface water conditions and deep-sea contouritic sedimentation in the Gulf of Cadiz with Northern Hemisphere climate variability on millennial timescales. A high MOW velocity prevailed during Dansgaard-Oeschger stadials, Heinrich events and the Younger Dryas cold climatic interval. The MOW velocity was comparatively low during the warm Dansgaard-Oeschger interstadials, Bølling-Allerød and the Early Holocene. Rapid sea-level fluctuations on the order of 35 m during Marine Oxygen Isotope Stage 3 are considered to have exerted limiting controls on the MOW volume transport and thus positively modulated the MOW behaviour during the last 50 kyr.

Beschreibung: Determining the movement of marine animals is logistically difficult and is currently primarily based on VHF and satellite-tracking telemetry, GPS, acoustic telemetry, and geolocation, all of which have substantial limitations in accurately locating the fine-scale movements of these animals. A recent development—that of dead-reckoning—is being increasingly used to examine the fine-scale movement of animals underwater. The advantages and drawbacks of this approach are quite different to those incurred by the other methods. This paper considers the advances that deadreckoning can bring to the study of the often cryptic movement and behaviour of marine animals at sea. Methods used in determining position via dead-reckoning are presented and consideration is given to results derived from the use of deadreckoning on cetaceans, pinnipeds, penguins and sea turtles; these are complemented by data on cormorants and albatrosses acquired using GPS systems. Suggestions are made as to how movement data derived from these devices can be analysed using indices that allow interpretation over a large variety of temporal and spatial scales.

Beschreibung: Total alkalinity (TA) is one of the few measurable quantities that can be used together with other quantities to calculate concentrations of species of the carbonate system (CO2, HCO3 −, CO32−, H+, OH−). TA and dissolved inorganic carbon (DIC) are conservative quantities with respect to mixing and changes in temperature and pressure and are, therefore, used in oceanic carbon cycle models. Thus it is important to understand the changes of TA due to various biogeochemical processes such as formation and remineralization of organic matter by microalgae, precipitation and dissolution of calcium carbonate. Unfortunately deriving such changes from the common expression for TA in terms of concentrations of on-conservative chemical species (HCO3 −, CO3 2 −, B(OH)4 −, H+, OH−, etc.) is rarely obvious. Here an expression for TA (TAec) in terms of the total concentrations of certain major ions (Na+, Cl−, Ca2+ etc.) and the total concentrations of various acid-base species (total phosphate etc.) is derived from Dickson's original definition of TA under the constraint of electroneutrality. Changes of TA by various biogeochemical processes are easy to derive from this so-called explicit conservative expression for TA because each term in this expression is independent of changes of temperature or pressure within the ranges normally encountered in the ocean and obeys a linear mixing relation. Further, the constrains of electroneutrality for nutrient uptake by microalgae and photoautotrophs are discussed. A so-called nutrient-H+-compensation principle is proposed. This principle in combination with TAec allows one to make predictions for changes in TA due to uptake of nutrients that are consistent with observations. A new prediction based on this principle is the change in TA due to nitrogen fixation followed by remineralization of organic matter and subsequent nitrification of ammonia which implies a significant sink of TA in tropical and subtropical regions where most of the nitrogen fixation takes place.

Beschreibung: Extreme hydrological events are often triggered by exceptional co-variations of the relevant hydrometeorological processes and in particular by exceptional co-oscillations at various temporal scales. Wavelet and cross wavelet spectral analysis offers promising time-scale resolved analysis methods to detect and analyze such exceptional co-oscillations. This paper presents the state-of-the-art methods of wavelet spectral analysis, discusses related subtleties, potential pitfalls and recently developed solutions to overcome them and shows how wavelet spectral analysis, if combined to a rigorous significance test, can lead to reliable new insights into hydrometeorological processes for real-world applications. The presented methods are applied to detect potentially flood triggering situations in a high Alpine catchment for which a recent re-estimation of design floods encountered significant problems simulating the observed high flows. For this case study, wavelet spectral analysis of precipitation, temperature and discharge offers a powerful tool to help detecting potentially flood producing meteorological situations and to distinguish between different types of floods with respect to the prevailing critical hydrometeorological conditions. This opens very new perspectives for the analysis of model performances focusing on the occurrence and non-occurrence of different types of high flow events. Based on the obtained results, the paper summarizes important recommendations for future applications of wavelet spectral analysis in hydrology.

Beschreibung: The element compositions Si, Ca and Al of up to 2 1.1 ka old sediments in about 10 in long cores from the southern basin of the Shaban and Kebrit deeps in the northern Red Sea allowed a classification of major sediment types in carbonate sands and -muds and siliceous oozes. A FeOOH-enriched sediment horizon and a few samples with high Zn values in the Kebrit core indicate a hydrothermal origin probably near the brine-sea water interface with subsequent transport of hydrothermal compounds into the deep sediments. High organic carbon contents up to 8.4% are positively correlated with the Ba concentrations, which suggests that high bioproductivity, and rapid deposition (C-14 dating suggests a sedimentation rate near 70 cm/ka) led to the formation of sapropelic sediments between 11.8 and 13.6 ka (Younger Dryas). Organic petrological observations showed that the sediment organic material largely consists of 〈20 gm-sized roundish fecal pellets (intimate mixtures of organic matter and inorganic constituents) and bituminite. Terrestrial organic matter (pollens of land plants, fusinite etc.) is very rare in the sediment cores from both deeps. Organic-geochemical investigations of kerogens and organic extracts show that a significant (hydrothermal) hydrocarbon production did not occur in near-surface sediments of the Shaban and Kebrit deeps. Rock Eval pyrolysis of kerogens characterised the organic matter to be of type II quality. The delta C-13 values of the kerogens from the most prominent sapropel in the Shaban deep indicate an enrichment of(C-12-rich) nutrients in the water column during postglacial sapropel formation in the Younger Dryas. The n-alkane spectra are dominated by short chain lengths between n-C-15 and n-C-25 Prevailing n-C-15 to n-C-25 alkanes in low mature sediments are indicative of algal and microbial source. Pristane/phytane ratios are generally low (〈 I to similar to 1) which suggests that anoxic conditions prevailed within the anaerobic brine-filled deeps for the whole time covered by the sediments. This again indicates that sapropel formation was caused by high bioproductivity in the northern Red Sea rather than episodic stagnation with better preservation of the organic matter. Long-chain alkenones and sterols are the dominating compounds of the lipid fraction. Cholesterol contents in the sediment cores reflect phases of eukaryotes production in the water column, whereas the positive correlations of dinosterol with TOC and the amounts of total extract suggests that the major organic carbon source in the northern Red Sea during postglacial high-productivity stages were dinoflagellates. Another important carbon source, however, is indicated by the occurrence of 22,29,30-trisnorhopan-21 -one (TNH). Although the formation of TNH from its precursors is not fully understood, this compound probably results from microbial. degradation of intact bacteriohopanepolyols (BHP), which can be used as indicators for bacterial abundances and phyla. TNH is most likely produced at the brine-sea water interface where sedimenting organic matter accumulates and, if the redoxcline corresponds to the density gradient, the organic matter is subjected to efficient aerobic bacterial degradation processes. However, during high bioproductivity stage (Younger Dryas) the redoxcline was probably higher in the water column and thus, a significant TNH production at the brine-sea water interface did not occur at times of sapropel formation in the northern Red Sea deeps. (C) 2007 Elsevier B.V All rights reserved.

Beschreibung: Two biotic indices, ATZI Marine Biotic Index (AMBI) and Benthic Quality Index (BQI) have been recently introduced within the EC Water Framework Directive to assess the quality of marine habitats: both are based on sensitivity/tolerance classification and quantitative information on the composition of soft-bottom macrofauna. Their performance, especially with regard to sampling effort was assessed based on two data sets collected in Southern Baltic and one from the Gulf of Lions Mediterranean. AMBI was not affected by sampling effort but BQI was. Two modifications were proposed for BQI (i.e., BQI) (1) the removal of the scaling term (i.e., BQIW), and (2) the replacement of the scaling term by different scaling term (i.e., BQIES). Both modified BQIs were largely independent of sampling effort. Variability was slightly lower for BQIW than for BQIES. BQI was highly correlated with BQIW and with BQIES both in the Southern Baltic and in the Gulf of Lions. However, the proportions of stations, which were not attributed the same ecological quality status (EcoQ) when using BQI and its two modified forms were always high. Differences in ecological classification were mostly due to the scales used to infer EcoQ. Based on this study we recommend to use BQIES in future studies because it apparently constitutes the best compromise in (1) being independent of sampling effort, (2) limiting the variability in computation in relation with sampling effort, (3) being correlated with BQI and corresponding EcoQ.

Beschreibung: In this paper it is suggested that a stochastic isotropic diffusive process, representing a spatial first order auto regressive process (AR(1)-process), can be used as a null hypothesis for the spatial structure of climate variability. By comparing the leading empirical orthogonal functions (EOFs) of a fitted null hypothesis with EOF modes of an observed data set, inferences about the nature of the observed modes can be made. The concept and procedure of fitting the null hypothesis to the observed EOFs is in analogy to time analysis, where an AR(1)-process is fitted to the statistics of the time series in order to evaluate the nature of the time scale behavior of the time series. The formulation of a stochastic null hypothesis allows one to define teleconnection patterns as those modes that are most distinguished from the stochastic null hypothesis. The method is applied to several artificial and real data sets including the sea surface temperature of the tropical Pacific and Indian Ocean and the Northern Hemisphere wintertime and tropical sea level pressure.

Beschreibung: Extensive ROV-based sampling and exploration of the seafloor was conducted along an eroded transform-parallel fault scarp on the northeastern side of the Guaymas Basin in the Gulf of California to observe the nature of fluids venting from the seafloor, measure the record left by methane-venting on the carbonates from this area, and determine the association with gas hydrate. One gas vent vigorous enough to generate a water-column gas plume traceable for over 800 m above the seafloor was found to emanate from a ∼10-cm-wide orifice on the eroded scarp face. Sediment temperature measurements and topography on a sub-bottom reflector recorded in a transform-parallel seismic reflection profile identified a subsurface thermal anomaly beneath the gas vent. Active chemosynthetic biological communities (CBCs) and extensive authigenic carbonates that coalesce into distinct chemoherm structures were encountered elsewhere along the eroded transform-parallel scarp. The carbon isotopic composition of methane bubbles flowing vigorously from the gas vent (−53.6±0.8‰ PDB) is comparable to methane found in sediment cores taken within the CBCs distributed along the scarp (−51.9±8.1‰ PDB). However, the δ13C value of the CO2 in the vent gas (+12.4±1.1‰ PDB) is very distinct from those for dissolved inorganic carbon (DIC) (−35.8‰ to −2.9‰ PDB) found elsewhere along the scarp, including underneath CBCs. The δ13C values of the carbonate-rich sediments and rocks exposed on the seafloor today also span an unusually large range (−40.9‰ to +12.9‰ PDB) and suggest two distinct populations of authigenic carbonate materials were sampled. Unconsolidated sediments and some carbonate rocks, which have lithologic evidence for near-seafloor formation, have negative δ13C values, while carbonate rocks that clearly formed in the subsurface have positive δ13C values (up to +23.0‰) close to that measured for CO2 in the vent gas. There appears to be two carbon sources for the authigenic carbonates: (1) deeply-sourced, isotopically heavy CO2 (∼+12‰); and (2) isotopically light DIC derived from local anaerobic oxidation of methane at the sulfate–methane interface in the shallow subsurface. Addition of isotopically light methane-derived carbon at the seafloor may completely mask the isotopically heavy CO2 signature (+12.4‰) in the underlying sediments. Thus, the authigenic carbonates may have formed from the same methane- and carbon dioxide-bearing fluid, but under different migration and alteration conditions, depending on how it migrated through the sediment column.

Beschreibung: We investigated connections between subtropical Atlantic climate variability, atmospheric conditions in the European Alpine region (45 to 47° N and 5 to 8° E) and the interannual variability of the thermal conditions in the largest body of freshwater in Western Europe (Lake Geneva). The long-term water temperature was related to climate variability by means of a multivariate regression model. Results revealed atmospheric connections that have been elusive so far, and showed that over the period from 1959 to 2000, summer thermal conditions in Lake Geneva appear tightly linked to the long-term variability of the subtropical Atlantic climate. The multivariate model revealed high skills and tight correlations, which suggest the possibility of assessing future thermal changes in Lake Geneva from the Atlantic climate variability. The implications of such climatic forcing on the functioning of the pelagic ecosystem in Lake Geneva were illustrated by analysing the long-term changes in abundance of the summer-dominant carnivorous cladocerans Bythotrephes longimanus and Leptodora kindtii during the period 1974 to 2000. Again, the multivariate model revealed high skills and excellent correlations between the interannual changes in abundance of these species and the variability of summer climate. Our approach provides a general understanding of the interrelations between large- and regional-scale climates, local environmental conditions and the ecological responses in Lake Geneva during summer, and is therefore applicable to other retrospective studies.

Beschreibung: A common elemental analyzer system connected to a temperature-controlled gas chromatography (GC) column and coupled to an isotope ratio mass spectrometer was improved to decrease the determination limit for a simultaneous stable isotope ratio measurement of nitrogen and carbon dioxide. The additional use of a special ashtray system to collect the combustion residuals permitted more time-efficient work. These modifications to the elemental analyzer allowed precise measurements to be made down to 1.5 µg nitrogen and 10 µg carbon for stable isotope analysis. Low system background values and an acceptable signal-to-noise ratio have made an additional blank correction for these low sample measurements unnecessary. We provide a precision of this stable isotope analysis for lowest amounts of 1.2–2 µg nitrogen with a standard deviation of ±0.496‰ (n = 27) and for 8.2–15 µg carbon with a standard deviation of ±0.257‰ (n = 31) across different sample runs under stipulated conditions. This application can be established in an automatic mode without cryofocusing procedures.

Beschreibung: Development of a mechanistic understanding and predictions of patterns of biodiversity is a central theme in ecology. One of the most influential theories, the intermediate disturbance hypothesis (IDH), predicts maximum diversity at intermediate levels of disturbance frequency. The dynamic equilibrium model (DEM), an extension of the IDH, predicts that the level of productivity determines at what frequency of disturbance maximum diversity occurs. To test, and contrast, the predictions of these two models, a field experiment on marine hard-substratum assemblages was conducted with seven levels of disturbance frequency and three levels of nutrient availability. Consistent with the IDH, maximum diversity, measured as species richness, was observed at an intermediate frequency of disturbance. Despite documented effects on productivity, the relationship between disturbance and diversity was not altered by the nutrient treatments. Thus, in this system the DEM did not improve the understanding of patterns of diversity compared to the IDH. Furthermore, it is suggested that careful consideration of measurements and practical definitions of productivity in natural assemblages is necessary for a rigorous test of the DEM.

Beschreibung: Future warming is predicted to shift the Earth system into a mode with progressive increase and vigour of extreme climate events possibly stimulating other mechanisms that invigorate global warming. This study provides new data and modelling investigating climatic consequences and biogeochemical feedbacks that happened in a warmer world not, vert, similar 112 Myr ago. Our study focuses on the Cretaceous Oceanic Anoxic Event (OAE) 1b and explores how the Earth system responded to a moderate not, vert, similar 25,000 yr lasting climate perturbation that is modelled to be less than 1 °C in global average temperature. Using a new chronological model for OAE 1b we present high-resolution elemental and bulk carbon isotope records from DSDP Site 545 from Mazagan Plateau off NW Africa and combine this information with a coupled atmosphere–land–ocean model. The simulations suggest that a perturbation at the onset of OAE 1b caused almost instantaneous warming of the atmosphere on the order of 0.3 °C followed by a longer (not, vert, similar 45,000 yr) period of not, vert, similar 0.8 °C cooling. The marine records from DSDP Site 545 support that these moderate swings in global climate had immediate consequences for African continental supply of mineral matter and nutrients (phosphorous), subsequent oxygen availability, and organic carbon burial in the eastern subtropical Atlantic, however, without turning the ocean anoxic. The match between modelling results and stratigraphic isotopic data support previous studies [summarized in Jenkyns, H.C., 2003. Evidence for rapid climate change in the Mesozoic–Palaeogene greenhouse world. The Royal Society, 361: 1885–1916.] in that methane emission from marine hydrates, albeit moderate in dimension, may have been the trigger for OAE 1b, though we can not finally rule out alternative mechanisms. Following the hydrate mechanism a total of 1.15 × 1018 g methane carbon (δ13C = − 60 ‰), equivalent to about 10% to the total modern gas hydrate inventory, generated the δ13Ccarb profile recorded in the section. Modelling suggests a combination of moderate-scale methane pulses supplemented by continuous methane emission at elevated levels over not, vert, similar 25,000 yr. The proposed mechanism, though difficult to finally confirm in the geological past, is arguably more likely to occur in a warmer world and apparently perturbs global climate and ocean chemistry almost instantaneously. This study shows that, once set-off, this mechanism can maintain Earth's climate in a perturbed mode over geological time leading to pronounced changes in regional climate.

Beschreibung: New and published data on the composition of melt inclusions in olivine (Fo73–91) from volcanoes of the Kamchatka and northern Kurile Arc are used 1) to evaluate the combined systematics of volatiles (H2O, S, Cl, F) and incompatible trace elements in their parental magmas and mantle sources, 2) to constrain thermal conditions of mantle melting, and 3) to estimate the composition of slab-derived components. We demonstrate that typical Kamchatkan arc-type magmas originate through 5–14% melting of sources similar or slightly more depleted in HFSE (with up to ∼ 1 wt.% previous melt extraction) compared to MORB-source mantle, but strongly enriched in H2O, B, Be, Li, Cl, F, LILE, LREE, Th and U. Mean H2O in parental melts (1.8–2.6 wt.%) decreases with increasing depth to the subducting slab and correlates negatively with both ‘fluid-immobile’ (e.g. Ti, Na, LREE) and most ‘fluid-mobile’ (e.g. LILE, S, Cl, F) incompatible elements, implying that solubility in hydrous fluids or amount of water does not directly control the abundance of ‘fluid-mobile’ incompatible elements. Strong correlation is observed between H2O/Ce and B/Zr (or B/LREE) ratios. Both, calculated H2O in mantle sources (0.1–0.4%) and degrees of melting (5–14%) decrease with increasing depth to the slab indicating that the ultimate source of water in the sub-arc mantle is the subducting oceanic plate and that water flux (together with mantle temperature) governs the extent of mantle melting beneath Kamchatka. A parameterized hydrous melting model [Katz et al. 2003, G3, 4(9), 1073] is utilized to estimate that mantle melting beneath Kamchatka occurs at or below the dry peridotite solidus (1245–1330 °C at 1.5–2.0 GPa). Relatively high mantle temperatures (yet lower than beneath back-arc basins and ocean ridges) suggest substantial corner flow driven mantle upwelling beneath Kamchatka in agreement with numerical models implying non-isoviscous mantle wedge rheology. Data from Kamchatka, Mexico and Central America indicate that 〈 5% melting would take place beneath continental arcs without water flux from the subducting slab. A broad negative correlation appears to exist between crustal thickness and the temperature of magma generation beneath volcanic arcs with larger amounts of decompression melting occurring beneath thinner arc crust (lithosphere). In agreement with the high mantle temperatures, we observe a systematic change in the composition of slab components with increasing slab depth from solute-poor hydrous fluid beneath the volcanic front to solute-rich hydrous melt or supercritical liquid at deeper depths beneath the rear arc. The solute-rich slab component dominates the budget of LILE, LREE, Th and U in the magmas and originates through wet-melting of subducted sediments and/or altered oceanic crust at ≥ 120 km depth. Melting of the upper parts of subducting plates under water flux from deeper lithosphere (e.g. serpentinites), combined with high temperatures in the mantle wedge, may be a more common process beneath volcanic arcs than has been previously recognized.

Beschreibung: Two newly developed coring devices, the Multi-Autoclave-Corer and the Dynamic Autoclave Piston Corer were deployed in shallow gas hydrate-bearing sediments in the northern Gulf of Mexico during research cruise SO174 (Oct–Nov 2003). For the first time, they enable the retrieval of near-surface sediment cores under ambient pressure. This enables the determination of in situ methane concentrations and amounts of gas hydrate in sediment depths where bottom water temperature and pressure changes most strongly influence gas/hydrate relationships. At seep sites of GC185 (Bush Hill) and the newly discovered sites at GC415, we determined the volume of low-weight hydrocarbons (C1 through C5) from nine pressurized cores via controlled degassing. The resulting in situ methane concentrations vary by two orders of magnitudes between 0.031 and 0.985 mol kg− 1 pore water below the zone of sulfate depletion. This includes dissolved, free, and hydrate-bound CH4. Combined with results from conventional cores, this establishes a variability of methane concentrations in close proximity to seep sites of five orders of magnitude. In total four out of nine pressure cores had CH4 concentrations above equilibrium with gas hydrates. Two of them contain gas hydrate volumes of 15% (GC185) and 18% (GC415) of pore space. The measurements prove that the highest methane concentrations are not necessarily related to the highest advection rates. Brine advection inhibits gas hydrate stability a few centimeters below the sediment surface at the depth of anaerobic oxidation of methane and thus inhibits the storage of enhanced methane volumes. Here, computerized tomography (CT) of the pressure cores detected small amounts of free gas. This finding has major implications for methane distribution, possible consumption, and escape into the bottom water in fluid flow systems related to halokinesis.

Beschreibung: High-resolution multi-frequency and multi-component seismic data were acquired at northern Hydrate Ridge in the accretionary complex of the Cascadia subduction zone to quantify the amount of hydrate and free gas in the sediment. We present a detailed local analysis of four component (4C) ocean bottom seismometer (OBS) data and show the importance of multi-frequency and shear wave data for determining hydrate reservoir properties. A detailed model of the elastic parameters at the bottom simulating reflector (BSR) is developed by using synthetic seismogram modelling. The main focus in this study is an amplitude-versus-offset (AVO) analysis of shear waves, which originate by PS-conversion at the BSR in 73 m below the seafloor (bsf). The AVO analysis enables the determination of the shear wave velocity above the BSR. A velocity of 400 m/s indicates that the presence of gas hydrate in the pore space significantly increases the shear modulus of the sediment above the BSR. Information about the attenuation and the shape of the BSR transition zone is obtained from the frequency-dependent reflection amplitudes of the BSR. The BSR is shown to be a gradual type transition zone of 1.5–2.5 m thickness. Average Q factors of Qp = 150 for P-waves and of Qs = 35 for S-waves are determined within the gas hydrate stability zone (GHSZ). The low Qs factor points to a pronounced attenuation of S-waves in the uppermost sediments. From rock physics modelling, the hydrate concentration is estimated to vary locally between 3–12% of the pore space. Below the BSR, free gas concentrations of 0.5% and 8% are determined for homogeneous and patchy distributed gas, respectively.

Beschreibung: Deposits of coral-bearing, marine shell conglomerate exposed at elevations higher than 20 m above present-day mean sea level (MSL) in Bermuda and the Bahamas have previously been interpreted as relict intertidal deposits formed during marine isotope stage (MIS) 11, ca. 360–420 ka before present. On the strength of this evidence, a sea level highstand more than 20 m higher than present-day MSL was inferred for the MIS 11 interglacial, despite a lack of clear supporting evidence in the oxygen-isotope records of deep-sea sediment cores. We have critically re-examined the elevated marine deposits in Bermuda, and find their geological setting, sedimentary relations, and microfaunal assemblages to be inconsistent with intertidal deposition over an extended period. Rather, these deposits, which comprise a poorly sorted mixture of reef, lagoon and shoreline sediments, appear to have been carried tens of meters inside karst caves, presumably by large waves, at some time earlier than ca. 310–360 ka before present (MIS 9–11). We hypothesize that these deposits are the result of a large tsunami during the mid-Pleistocene, in which Bermuda was impacted by a wave set that carried sediments from the surrounding reef platform and nearshore waters over the eolianite atoll. Likely causes for such a megatsunami are the flank collapse of an Atlantic island volcano, such as the roughly synchronous Julan or Orotava submarine landslides in the Canary Islands, or a giant submarine landslide on the Atlantic continental margin.

Beschreibung: Atmospheric deposition fluxes of soluble nutrients (N, P, Si, Fe, Co, Zn) to the tropical North Atlantic were determined during cruise M55 of the German SOLAS programme. Nutrient fluxes were highest in the east of the section along 10°N, owing to the proximity of source regions in West Africa and Europe, and lowest in the west, for both dry and wet deposition modes. In common with other recent studies, atmospheric P and Si inputs during M55 were strongly depleted relative to the stoichiometry of phytoplankton Fe, N, P and Si requirements. Atmospheric N inputs were equivalent to 0.1–4.7% of observed primary productivity during the cruise. Atmospheric nutrient supply was also compared to observed nitrogen fixation rates during M55. While atmospheric Fe supply may have been sufficient to support N fixation (depending on the relationship between our simple Fe leaching experiment and aerosol Fe dissolution in seawater), atmospheric P supply was well below the required rate. The stable nitrogen isotope composition of nitrate–N in aerosol and rain was also determined. Results of a simple model indicate that atmospheric deposition and nitrogen fixation introduce similar amounts of isotopically light nitrogen into surface waters of the study region. This implies that nitrogen isotope-based methods would overestimate nitrogen fixation here by a factor of 2, if atmospheric inputs were not taken into account.

Beschreibung: Mud volcanism in the Gulf of Cadiz occurs over a large area extending from the shelf to more than 3500 m water depth and is triggered by compressional stress along the European–African plate boundary, affecting a deeply faulted sedimentary sequence of locally more than 5 km thickness. The investigation of six active sites shows that mud volcano (MV) fluids, on average, are highly enriched in CH4, Li, B, and Sr and depleted in Mg, K, and Br. The purity of the fluids is largely controlled by the intensity of upward directed flow. Flow rates could be constrained by numerical modelling and vary between 〈0.05 and 15 cm yr−1. Application of δD–δ18O systematics identifies clay mineral dehydration, most likely within Mesozoic and Tertiary shales and marls, as the major source of fluids. Hence, Cl and Na in the pore fluids are mostly depleted below seawater values, following a general trend of dilution. However, deviations from this trend occur and are likely caused by the dissolution of halite in evaporitic deposits. Other secondary processes overprinting the original fluid composition may occur along the flow path, such as dissolution of anhydrite or gypsum and/or the formation of calcite and dolomite. Different sources of fluids are also indicated by variations in 87Sr/86Sr, which range from 0.7086 to 0.7099 at the different sites. Dehydration may be induced primarily by overburden and tectonic compression; however, very high concentrations of Li and B, specifically at Captain Arutyunov MV (CAMV) indicate additional leaching at temperatures above 150 °C, which could be explained by the injection of hot fluids along deep penetrating, major E–W strike–slip fault systems. This hypothesis is supported by the occurrence of generally thermogenic, but significantly CH4-enriched, light volatile hydrocarbon gases at CAMV which cannot be explained by shallow microbial methanogenesis. Li and Li/B ratios from different types of hot and cold vents are used to infer that high temperature signals seem to be preserved at various cold vent locations and indicate a closer coupling of both systems in continental margin environments than outlined in previous studies.

Beschreibung: Cephalopod beaks retrieved from stomachs of dead emperor penguin chicks at Pointe Géologie, Terre Adélie, provide information on taxonomic and size composition of the penguin’s squid diet, on the trophic range of the squid species preyed upon and on the fractional trophic impact of the penguin on the whole food web. Emperor penguins prey upon four squid species (Psychroteuthis glacialis, Kondakovia longimana, Gonatus antarcticus, Alluroteuthis antarcticus) and do not take squid larger than 480 mm mantle length. Larger squid live either below the penguin’s diving range or are beyond its handling capacity. Nitrogen stable isotope ratios indicate that squids cover a range of about two trophic levels (2.5–8‰ δ15N). The impact of the emperor penguin, however, concentrates on the upper part of this range, about 68% of its squid prey being 〉6‰ δ15N. The principal components of the emperor’s diet, fish, krill and squid, differ distinctly in average trophic level. Consequently the trophic position of the emperor penguin changes accordingly with diet composition and may differ by almost one trophic level between different emperor penguin colonies.

Beschreibung: Complete sediment subduction at the Costa Rica subduction zone makes this convergent margin an ideal place to investigate the effects of tectonic deformation in situ. We present a seismic reflection study along a line located 3 km landward of the Middle American Trench and oriented parallel to the strike of the décollement. The Ocean Bottom Hydrophone (OBH) seismic data include large offsets and incidence angles at the reflectors. We derive the P- and S-waves velocity distribution below the décollement using a P-wave analysis of amplitude with reflection angle. The investigation shows that there are unexpected large lateral velocity variations at a scale of only a few 100 m. The shear wave velocity in the uppermost subducted sediment varies between 300 and 700 m/s, while the variation of the compressional wave velocity is in a range of 1700 to 2000 m/s. The variation of the vP–vS ratio between 2.8 and 5.2 can only be explained by variations of the pore fluid pressure. The modelled velocities correspond to a normalised pore fluid pressure ratio λ* in the range between 0.02 and 0.93. The most reasonable explanation for these observations is the localised presence of fluids, which are released during diagenesis by smectite to illite transformation. During this process, which takes place in three discrete steps, the interlayer water of the smectite is added to the pore fluid and the permeability of the sediment is decreased. Both effects lead to the formation of small, overpressured cells.

Beschreibung: On- and off-mound sediment cores from Propeller Mound (Hovland Mound province, Porcupine Seabight) were analysed to understand better the evolution of a carbonate mound. The evaluation of benthic foraminiferal assemblages from the off-mound position helps to determine the changes of the environmental controls on Propeller Mound in glacial and interglacial times. Two different assemblages describe the Holocene and Marine Isotope Stage (MIS) 2 and late MIS 3 (∼31 kyr BP). The different assemblages are related to changes in oceanographic conditions, surface productivity and the waxing and waning of the British Irish Ice Sheet (BIIS) during the last glacial stages. The interglacial assemblage is related to a higher supply of organic material and stronger current intensities in water depth of recent coral growth. During the last glaciation the benthic faunas showed high abundances of cassidulinid species, implying cold bottom waters and a reduced availability of organic matter. High sedimentation rates and the domination of Elphidium excavatum point to shelf erosion related to sea-level lowering (∼50 m) and the progradation of the BIIS onto the shelf. A different assemblage described for the on-mound core is dominated by Discanomalina coronata, Gavelinopsis translucens, Planulina ariminensis, Cibicides lobatulus and to a lower degree by Hyrrokkin sarcophaga. These species are only found or show significantly higher relative abundances in on-mound samples and their maximum contribution in the lower part of the record indicates a higher coral growth density on Propeller Mound in an earlier period. They are less abundant during the Holocene, however. This dataset portrays the boundary conditions of the habitable range for the cold-water coral Lophelia pertusa, which dominates the deep-water reefal ecosystem on the upper flanks of Propeller Mound. The growth of this ecosystem occurs during interglacial and interstadial periods, whereas a retreat of corals is documented in the absence of glacial sediments on-mound. Glacial conditions with cold intermediate waters, a weak current regime and high sedimentation rates provide an unfavourable environmental setting for Lophelia corals to grow. A Late Pleistocene decrease is observed in the mound growth for Propeller Mound, which might face its complete burial in the future, as it already happened to the buried mounds of the Magellan Mound province further north.

Beschreibung: Bimodal depth distribution patterns observed for sprat Sprattus sprattus larvae in previous field studies conducted in the deep basins of the Baltic Sea have led researchers to hypothesise that larval sprat condition was depth-dependent. We examined this hypothesis by measuring morphological, biochemical and otolith-based proxies for nutritional condition in sprat larvae collected in discrete 5 m depth intervals from the surface to the bottom in the central Bornholm Basin. Similar to earlier studies, larval sprat were most abundant in 2 depth strata (0 to 10 and 65 to 75 m). Their nutritional condition in surface and deep waters was not uniformly expressed by the different indices. For example, sprat larvae from 0 to 10 m could not be distinguished from conspecifics caught at 65 to 75 m by a long-latency condition proxy (otolith-based growth rates). Similarly, a medium-latency proxy (RNA:DNA) did not suggest differences in condition between the depths. However, short-latency proxies (protein:standard length and DNA:dry weight) supported the depth-dependent condition hypothesis. The lack of correspondence and pitfalls associated with the use and interpretation of multiple condition indices (e.g. the influences of temperature and body size) are discussed and recommendations to strengthen these various metrics are provided.

Beschreibung: The occurrence of the ctenophore Mnemiopsis leidyi as a new invasive species in the Baltic Sea and the potential consequences for fish stock recruitment was investigated in spring 2007. The study focused on the Bornholm Basin, which serves as the major spawning ground for cod and sprat, the commercially most important fish stocks in the Baltic. The distribution pattern of M. leidyi revealed a substantial overlap with cod eggs. The observed predation of M. leidyi on eggs has the potential to alter the recruitment success of cod, which is the top predator in the system and, thus, to change the Baltic food-web structure.

Beschreibung: Quorum sensing (QS) signals have been considered to play important roles in biofilm development and in the attractiveness of biofilms to higher organisms in marine ecosystem. In this study, bacterial QS signalsacylated homoserine lactone derivatives (AHLs) were detected in 2-, 4-, and 6-day-old subtidal biofilms by using AHLs reporter strains. N-dodecanoyl-homoserine lactone (C12-HSL) was identified in 6-day-old biofilm at a concentration of 9.04 μg cm−minus;2 (3.36 mmol l−minus;1). To investigate the possible role of AHLs in the consequent eventlarval settlement of the polychaete Hydroides elegans onto subtidal biofilmsseven biofilm-derived bacteria that effectively induced larval settlement of H. elegans, were screened for AHL production. One of them, the Vibrio sp. UST950701-007, produced N-hexanoyl-homoserine lactone (C6-HSL). Larval settlement bioassay showed that C6-HSL, C12-HSL, and 3-oxo-octanoyl-homoserine lactone (3-oxo-C8-HLS) at certain concentrations induced some initial larval settlement behaviors such as reducing swimming speed, crawling on the bottom. However, these AHLs did not effectively induce larval settlement in comparison to the effective settlement inducer 3-isobutyl-1-methylxanthine. The possible chemokinetic mechanism and indirect effects of AHLs on larval settlement are suggested.

Beschreibung: Global Nd–Hf isotope systematics can be mainly described with two linear arrays, the global silicate Earth array (“the terrestrial array”) and the global ferromanganese crust and nodule array (”the seawater array”). The offset between these two arrays provides evidence for the sources and mechanisms by which these elements are added to ocean water. However, the reason for this offset is under debate, with the two preferred hypotheses being (i) incongruent release of Hf during continental weathering and (ii) hydrothermal contribution of Hf to the seawater budget. Here we present new Nd and Hf isotope data on glacio-marine core-top sediments from around the perimeter of the Antarctic continent. The results range from εHf = − 30.0 to εHf = + 3.9 and εNd = − 21.3 to εNd = + 0.9, reflecting the large range of basement ages and lithologies around the Antarctic continent. In Nd–Hf isotope space, they confirm the systematic correlations found in rocks from other parts around the world and provide valuable insights into the previously underrepresented group of sediments with very old provenance. In this paper we revisit the cause for the offset of the seawater array from the terrestrial array using simple mass balance considerations. We use these calculations to test to what degree the seawater array could be a product of preferential weathering of “non-zircon portions” of the upper continental crust, implying retention of zircons in the solid residue of weathering. Lutetium–Hf and Sm–Nd evolution and mixing calculations show that the global seawater array can be generated with continental sources only. On the other hand, a predominantly hydrothermal origin of Hf in the ocean is not possible because the seawater Hf isotopic composition is significantly less radiogenic than hydrothermal sources, and requires a minimum fraction of 50% continental Hf. While hydrothermal sources may contribute some Hf to seawater, continental contributions are required to balance the budget.

Beschreibung: Because of its chemical and radiative properties, atmospheric ozone constitutes a key element of the Earth's climate system. Absorption of sunlight by ozone in the ultraviolet wavelength range is responsible for stratospheric heating, and determines the temperature structure of the middle atmosphere. Changes in middle atmospheric ozone concentrations result in an altered radiative input to the troposphere and to the Earth's surface, with implications on the energy balance and the chemical composition of the lower atmosphere. Although a wide range of ground- and satellite-based measurements of its integrated content and of its vertical distribution have been performed since several decades, a number of uncertainties still remain as to the response of middle atmospheric ozone to changes in solar irradiance over decadal time scales. This paper presents an overview of achieved findings, including a discussion of commonly applied data analysis methods and of their implication for the obtained results. We suggest that because it does not imply least-squares fitting of prescribed periodic or proxy data functions into the considered times series, time-domain analysis provides a more reliable method than multiple regression analysis for extracting decadal-scale signals from observational ozone datasets. Applied to decadal ground-based observations, time-domain analysis indicates an average middle atmospheric ozone increase of the order of 2% from solar minimum to solar maximum, which is in reasonable agreement with model results.

Beschreibung: A synthesis of backscatter imagery coupled with a large 3D seismic dataset in the Lower Congo Basin (LCB) reveals a patchy distribution of features interpreted to be associated with fluid seepage from 300 m to 2500 m water depth. With the exception of one region of anomalous backscatter positive-relief mounds, all inferred seep sites occur in negative-relief pockmarks. The extensive 3D seismic dataset in the LCB offers a unique opportunity to study the plumbing system that is feeding surface cold seep systems, and in general, to reconstruct the relationship between tectonics and fluid flow in continental margins. The fluid seeps in the LCB are associated with morphologically, stratigraphically or tectonically controlled focused fluid flow. The integration of the geophysical datasets, backscatter imagery coupled to 3D seismic, clearly indicates that fluid seeps are not randomly distributed, but their seabed organization reflects 1) the location of the underlying structure (reservoir or trap) where the fluids are coming from, 2) the geometry and morphology of the reservoir/trap, and 3) the discontinuities in the sedimentary column along which fluids have migrated. In the LCB seafloor pockmarks are always associated with underlying tectonic structures (fault zones, salt diapirs, polygonal faults) or buried sedimentary bodies (turbiditic channels, erosional surfaces), whereas they never occur above sub-horizontal parallel-stratified fine-grained sediments. Even if triggering processes can not be clearly defined here, we propose a model of seafloor fluid seep organization, which represents a new tool for identifying the geometry of flow pathways and the underlying buried bodies where the fluids are originating from. This qualitative 3D model provides insight into the geohydrologic processes of continental margins.

Beschreibung: Glaciated continental shelves are characterised by large amphitheatre-like embayments between prominent cross-shelftroughs. The integration of swath bathymetry and high-resolution seismic data (3D, 2D) collected across the western Svalbard continental margin indicates how such embayments form. Although their bathymetric expression resembles headwall scarps of submarine slopefailures, the shelfembayments are the result of the interplay between sediment dynamics and transport underneath fast-moving ice streams in the cross-shelftroughs and the slower-moving parts of the ice sheets on the adjacent shallower shelf banks during full glacial conditions. This is supported by (1) the absence of major landslide deposits at their toe, (2) continuous prograding shelf deposition and (3) absence of landslide-related faulting. Instead, the seismic data suggest a depositional origin of the shelfembayments that is characterised by continuous sediment input at lower rates off a slow-moving ice mass in the centre of the embayment which is fringed by the lateral ice-stream ridges. These findings put into perspective the importance of submarine slopefailure on glaciated margins.

Beschreibung: This study aimed at simulating different degrees of winter warming and at assessing its potential effects on ciliate succession and grazing-related patterns. By using indoor mesocosms filled with unfiltered water from Kiel Bight, natural light and four different temperature regimes, phytoplankton spring blooms were induced and the thermal responses of ciliates were quantified. Two distinct ciliate assemblages, a pre-spring and a spring bloom assemblage, could be detected, while their formation was strongly temperature-dependent. Both assemblages were dominated by Strobilidiids; the pre-spring bloom phase was dominated by the small Strobilidiids Lohmaniella oviformis, and the spring bloom was mainly dominated by large Strobilidiids of the genus Strobilidium. The numerical response of ciliates to increasing food concentrations showed a strong acceleration by temperature. Grazing rates of ciliates and copepods were low during the pre-spring bloom period and high during the bloom ranging from 0.06 (Δ0°C) to 0.23 day−1 (Δ4°C) for ciliates and 0.09 (Δ0°C) to 1.62 day−1 (Δ4°C) for copepods. During the spring bloom ciliates and copepods showed a strong dietary overlap characterized by a wide food spectrum consisting mainly of Chrysochromulina sp., diatom chains and large, single-celled diatoms.

Beschreibung: We assessed the temporal changes in and the relationships between the structures of the macroinvertebrate communities and the environmental conditions of the French Rhône River (the river from Lake Geneva to the Mediterranean Sea) over the last 20 years (1985–2004). Multisite environmental and biological datasets were analysed using multiple CO-inertia analysis (MCOA) and Procrustean analysis. Changes in environmental conditions were mainly marked by an improvement in water quality between 1985 and 1991 and by an increase in water temperature from 1985 onwards due to climate change. Improvement in water quality seemed to delay changes in community structures under global warming. We then observed trends in community structures coupled with high temperatures and a decrease in oxygen content. Interestingly, we observed both gradual changes and rapid switches in community states. These shifts seemed coupled to extreme hydroclimatic events (i.e. pulse disturbances). Floods and the 2003 heatwave enhanced the development of eurytolerant and invasive taxa which were probably able to take advantage of gradual warming environmental conditions. Despite various site-specific “press” constraints (e.g. hydropower schemes, nuclear power plants), similar changes in community structures were observed along the French Rhône River. Such consistency in temporal processes at large geographical scales underlined the strength of hydroclimatic constraints on community dynamics compared to specific local disturbances. Finally, community structures did not show any sign of recovery, and their relative sensitivities to extreme hydroclimatic events seemed to increase with time. Thus, our results suggest that global changes may reduce the resilience of current community states.

Beschreibung: The early diagenesis of trace elements (V, Cr, Co, Cu, Zn, As, Cd, Ba, U) in anoxic sediments of the Achterwasser, a shallow lagoon in the non-tidal Oder estuary in the Baltic Sea, was investigated in the context of pyrite formation. The dissolved major redox parameters show a two-tier distribution with transient signals in the occasionally re-suspended fluid mud layer (FM) and a permanently established diagenetic sequence in the sediment below. Intense microbial respiration leads to rapid depletion of O2 within the uppermost mm of the FM. The reduction zones of Mn, Fe and sulfate overlap in the FM and in the permanently anoxic sediment section which appears to be a typical feature of estuarine sediments, under low-sulfate conditions. Degrees of pyritization (DOP) range from 50% in the FM to remarkably high values 〉 90% at 50 cm depth. Pyrite formation at the sediment surface is attributed to the reaction of Fe-monosulfides with intermediate sulfur species via the polysulfide pathway. By contrast, intense pyritization in the permanently anoxic sediment below is attributed to mineral growth via adsorption of aqueous Fe-sulfide complexes onto pyrite crystals which had originally formed in the surface layer. The studied trace elements show differential behavior patterns which are closely coupled to the diagenetic processes described above: (i) Zn, Cu and Cd are liberated from organic matter in the thin oxic layer of the sediment and diffuse both upwards across the sediment/water boundary and downwards to be trapped as monosulfides, (ii) V, Cr, Co and As are released during reductive dissolution of Mn- and Fe-oxyhydroxides, (iii) U removal from pore water occurs concomitantly to Fe reduction in the FM and is attributed to reduction of U(VI) to U(IV), (iv) the Ba distribution is controlled by reductive dissolution of authigenic barite in the sulfate reduction zone coupled with upward diffusion and re-precipitation. The incorporation of trace elements into pyrite is most intense for Co, Mn and As, intermediate for Cu and Cr and little to negligible for U, Zn, Cd, V and Ba. The observed trend is largely in agreement with previous studies and may be explained with differing rates for ligand exchange. Slow and fast ligand exchange and thus precipitation kinetics are also displayed by downcore increasing (Mn, Cr, Co and As) or constantly low (Zn, Cu, Cd) pore water concentrations. The downward increasing degrees of trace metal pyritization (DTMP) for Co, Cu, Zn and As are, in analogy to pyrite growth, assigned to adsorption of sulfide complexes or As oxyanions onto preexisting pyrite minerals.