ALBERT

Beschreibung: Four in situ experiments were conducted to examine the potential top-down and bottom-up control of epibenthic ciliate communities. The experiments were run in the littoral of Lake Erken and at a brackish water site on the island of Väddö on the Baltic coast of Sweden, during the spring of 2000. The experimental manipulations were the presence/absence of the natural macrozoobenthos grazer community, cross-classified with the presence/absence of additional nutrients. Epibenthic ciliates responded to both manipulation of grazers and resources, but the response was group specific. Total ciliate abundance decreased when macrozoobenthos (largely chironomids, gastropods, trichopteran larvae, isopods and amphipods) were removed, thus excluding a direct predation effect of the macrozoobenthos community on ciliates. Total ciliate biomass, but not abundance, tended to increase in the presence of additional nutrients; an effect weakly dependent on season and site. The disparity between effects of nutrients on biomass and abundance was due to effects on heterotrichs, a group of large but relatively rare algivorous ciliates. The manipulations altered the ciliate community composition, and between lakes there were differences in species richness and diversity and experiments. However, neither the removal of macrozoobenthos nor the addition of nutrients changed species richness or diversity. This runs counter to work with other taxonomic groups, which shows maximal diversity at an intermediate level of resources or predation. This can only be partially explained by the lack of direct predation effects and the open nature of the experimental system.

Beschreibung: An analytical model is developed to study the tidally induced mean circulation in the frontal zone. Four distinct forcing mechanisms are identified, which result in the generation of the counterclockwise Bernoulli cell, the clockwise Ekman cell, the clockwise frontal cell, and the Stokes drift (facing in the direction with the shallow water to the left). The decomposition of the cross-frontal circulation provides a dynamical framework for interpreting and understanding its complex structure. To illustrate the underlying physics, three model configurations are considered pertaining to a homogenous ocean and winter and summer fronts. For a homogeneous ocean, the circulation is dominated by three cells; for the winter front, the offshore Bernoulli cell is strengthened; and for the summer front, two counterrotating cells are found in the vertical direction, associated with the two branches of the front. The dependence of the cell structure on the Ekman, Burger, and other dimensionless numbers is examined.

Beschreibung: Here, we present a new technique for the direct measurement of 44Ca/40Ca isotope ratios on a Multicollector Inductively Coupled Plasma Mass Spectrometer (MC–ICP–MS, AXIOM) using the “cool plasma” technique. By reducing the plasma energy to about 400 W, the isobaric effect resulting from 40Ar+ can be significantly reduced, enabling the simultaneous and precise measurement of 44Ca and 40Ca beam intensities in different Faraday cups. In contrast to the TIMS technique requiring a 43Ca/48Ca double spike, the isotope measurements on MC–ICP–MS can be performed by bracketing standards. We express the calcium isotope variation relative to NIST SRM 915a (δ44/40Ca [‰]=[((44Ca/40Ca)sample/(44Ca/40Ca)NIST SRM 915a)−1]*1000). Isobaric effects of 24Mg16O+ and 23Na16OH+ interfering with 40Ca and 26Mg16OH2+ with 44Ca can be neglected by measuring calcium isotopes near the low-mass edge of the peaks. No influence of 87Sr2+ monitored on 43.5 atomic mass units (amu) was found. Repeated measurements of two Johnson Matthey CaCO3 standards (lot No. 4064 and lot No. 9912) revealed values of about −11.29 (‰ SRM 915a) and 0.57 (‰ SRM 915a). These values are in accordance with previous values published by Russell et al. [Geochim. Cosmochim. Acta 42 (1978) 1075], Heuser et al. [Int. J. Mass Spectrom. 220 (2002) 385], Hippler et al. [Geostand. Newsl. 27 (2003) 267] and Schmitt et al. [Geochim. Cosmochim. Acta 67 (2003) 2607]. Repeated measurement of the NIST SRM 915a CaCO3 standard showed that the variance of a single δ44/40Ca measurement is about 0.14‰ RSD being comparable with TIMS. MC–ICP–MS-based δ44/40Ca values measured on inorganically precipitated aragonite samples are indistinguishable from earlier measurements based on TIMS, confirming the positive correlation of δ44/40Ca and temperature. MC–ICP–MS-based δ44/40Ca measurements on cultured Orbulina universa showed a slope of about 0.026‰/°C being similar to the TIMS-based δ44/40Ca measurements showing a slope of about 0.019‰/°C. The large offset of about 5‰ between the two techniques is shown to be caused by a “matrix” effect, indicating that any δ44/40Ca measurements on MC–ICP–MS are sensitively controlled by the Ca concentration and the acidity of the solution. Our study demonstrates the possibility to measure the whole dispersion of calcium isotopes with MC–ICP–MS, showing that 40Ca can be used for normalization of 44Ca.

Beschreibung: The objective of the project entitled “Operational Radar and Optical Mapping in monitoring hydrodynamic, morphodynamic and environmental parameters for coastal management (OROMA)” within the Fifth Framework Programme of the European Commission (EC) is to improve the effectiveness of monitoring technologies in coastal waters. The Research Vessel (R.V.) Ludwig Prandtl of the GKSS research centre was equipped with special sensors and instruments to measure the position of the ship, the water depth, the salinity, the water temperature, the current speed and direction, the modulation characteristics of short-wave energies, and relevant air-sea interaction parameters due to the presence of submarine sand waves. The first experiment of the OROMA project on 5-16 August 2002 took place in the Lister Tief, a tidal inlet of the German Bight in the North Sea. The seabed morphology of the Lister Tief reveals a complex configuration of different bedforms which is four-dimensional in space and time. A significant upward orientated component uvert of the three-dimensional current velocity field was observed. Marked vertically so-called waterspouts of uvert above the crests of sand waves have been measured by the Acoustic Doppler Current Profiler (ADCP) as straight lines. They cause water upwelling with turbulence patterns at the water surface affecting the Normalized Radar Cross Section (NRCS) modulation. A first impression of expected NRCS modulation signatures of sea bottom topography detected by the GKSS shipborne X-band radar are presented as an uncalibrated composite of five single sea clutter images acquired in the Lister Tief on 22 November 1990.

Beschreibung: A multi-model ensemble-based system for seasonal-to-interannual prediction has been developed in a joint European project known as DEMETER (Development of a European Multimodel Ensemble Prediction System for Seasonal to Interannual Prediction). The DEMETER system comprises seven global atmosphere–ocean coupled models, each running from an ensemble of initial conditions. Comprehensive hindcast evaluation demonstrates the enhanced reliability and skill of the multimodel ensemble over a more conventional single-model ensemble approach. In addition, innovative examples of the application of seasonal ensemble forecasts in malaria and crop yield prediction are discussed. The strategy followed in DEMETER deals with important problems such as communication across disciplines, downscaling of climate simulations, and use of probabilistic forecast information in the applications sector, illustrating the economic value of seasonal-to-interannual prediction for society as a whole.

Beschreibung: The contribution of the marine biota to air-sea fluxes of CO2 and O2 is often described in terms of biological production concepts, such as new production, export production, and net community production. We evaluate these three quantities using a basin-scale ecosystem-circulation model of the North Atlantic Ocean based on Redfield stoichiometry into which we introduce an artificial tracer which records the biotic contribution to air-sea exchange of gases like O2 and CO2. It is found that on average the biological production rates overestimate the biotically effected air-sea flux by some 20% and, in some regions, even predict the wrong direction. With primary production restricted to the euphotic zone, but respiration extending to farther below, the discrepancy can largely be attributed to the different integration depths used in the different concepts (euphotic zone, surface mixed layer), and on annual and longer timescales, all rates converge when using the base of the winter mixed layer rather than that of the euphotic zone as the reference depth. For the surface carbon budget, which ultimately controls air-sea exchange of CO2, it is irrelevant whether carbon atoms cross this boundary in organic or inorganic speciation. Hence the transports of biotically generated surpluses or deficits of dissolved inorganic matter must also be accounted for. While their contribution amounts to only a few percent on the basin scale, the subduction of newly remineralized inorganic matter can locally account for about half of the biotically effected air-sea flux, for example, in regions of mode-water formation.

Beschreibung: Climate variability in the northeast Atlantic was investigated on glacial–interglacial and millennial time scales during the last 200 000 years, using sea surface temperature (SST) records derived from planktonic foraminiferal diversities and from Mg/Ca measurements on Globigerina bulloides. Paleoceanographical interpretations are supported by species composition analyses, benthic and planktonic isotopic data as well as records of iceberg-rafted debris (IRD). Differences of climate development are recognized for both interglacial and glacial periods. Temperature estimates indicate slightly warmer conditions (up to 2°C) during marine oxygen isotope stage (MIS) 5e than during the Holocene. In contrast to the last glaciation, when the SST minimum coincided with a minimum in solar insolation immediately before Termination I, during the penultimate glaciation a long SST minimum occurred at times of intermediate solar insolation well preceding the onset of Termination II. This discrepancy between two glacial terminations may be explained by an inherently different orbital configuration characteristic for each glacial interval. Despite these differences between the two glacial trends, the superimposed shorter-lived climatic events reveal the same order of principal steps, implying their common causal nature. A direct comparison of faunal SSTs with those retrieved from Mg/Ca analysis shows that Mg/Ca-derived temperatures follow the general glacial–interglacial trend; however, the latter appear to be largely overestimated. Supported by δ18O data in G. bulloides, which show little response to millennial-scale variability, there seems to be a need for species-dependent calibration experiments that also consider the different oceanographic settings this particular species can live in.

Beschreibung: New seismic and geodetic data from Costa Rica provide insight into seismogenic zone processes in Central America, where the Cocos and Caribbean plates converge. Seismic data are from combined land and ocean bottom deployments in the Nicoya peninsula in northern Costa Rica and near the Osa peninsula in southern Costa Rica. In Nicoya, inversion of GPS data suggests two locked patches centered at 14 ± 2 and 39 ± 6 km depth. Interplate microseismicity is concentrated in the more freely slipping intermediate zone, suggesting that small interseismic earthquakes may not accurately outline the updip limit of the seismogenic zone, the rupture zone for future large earthquakes, at least over the short (∼1 year) observation period. We also estimate northwest motion of a coastal “sliver block” at 8 ± 3 mm/yr, probably related to oblique convergence. In the Osa region to the south, convergence is orthogonal to the trench. Cocos-Caribbean relative motion is partitioned here, with ∼8 cm/yr on the Cocos-Panama block boundary (including a component of permanent shortening across the Fila Costeña fold and thrust belt) and ∼1 cm/yr on the Panama block–Caribbean boundary. The GPS data suggest that the Cocos plate–Panama block boundary is completely locked from ∼10–50 km depth. This large locked zone, as well as associated forearc and back-arc deformation, may be related to subduction of the shallow Cocos Ridge and/or younger lithosphere compared to Nicoya, with consequent higher coupling and compressive stress in the direction of plate convergence.

Beschreibung: This study focuses on an important aspect of air–sea interaction in models, namely, large-scale, spurious heat fluxes due to false pathways of the Gulf Stream and North Atlantic Current (NAC) in the “storm formation region” south and east of Newfoundland. Although high-resolution eddy-resolving models show some improvement in this respect, results are sensitive to poorly understood, subgrid-scale processes for which there is currently no complete, physically based parameterization. A simple method to correct an ocean general circulation model (OGCM), acting as a practical substitute for a physically based parameterization, is explored: the recently proposed “semiprognostic method,” a technique for adiabatically adjusting flow properties of a hydrostatic OGCM. The authors show that application of the method to an eddy-permitting model of the North Atlantic Ocean yields more realistic flow patterns and watermass characteristics in the Gulf Stream and NAC regions; in particular, spurious surface heat fluxes are reduced. Four simple modifications to the method are proposed, and their benefits are demonstrated. The modifications successfully account for three drawbacks of the original method: reduced geostrophic wave speeds, damped mesoscale eddy activity, and spurious interaction with topography. It is argued that use of a corrected (eddy permitting) OGCM in a coupled modeling system for simulating present climate (as now becomes possible because of increasing computer power) should lead to a more realistic simulation in regions of strong air–sea interaction as compared with that obtained with an uncorrected model. The method is also well suited for the simulation of the uptake and transport of passive tracers, such as anthropogenic carbon dioxide or components of ecosystem models.

Beschreibung: A numerical model of the Atlantic Ocean was used to study the low-frequency variability of meridional transports in the North Atlantic. The model shows a behaviour similar to those used in previous studies, and the temporal variability of certain variables compares favourably to observed time series. By changing the depth and width of the sills between the subpolar North Atlantic and the Nordic Seas, the mean horizontal and overturning circulation as well as some water mass properties are modified significantly. The reaction of meridional oceanic transports to atmospheric forcing fluctuations remains, however, unchanged. The critical role of the surface heat flux retroaction term for the meridional heat transport in stand-alone ocean models is discussed. The experiments underline the role of atmospheric variability for fluctuations of the large-scale ocean circulation on time scales from years to decades, and they support the hypothesis that the mean overturning strength is controlled by the model representation of the density of the overflow water masses.

Beschreibung: Seismic reflection data document for the first time the existence of a BSR in a limited area west of the Dnieper Canyon in the northwestern Black Sea. Seismic wide-angle data suggest that gas hydrates occupy in average 15±2% of the pore space in a zone of 100 m in thickness. A conservative quantification of the amount of methane associated with this gas hydrate occurrence is about 12±3×1011 m3 (0.6±0.2 Gt of methane carbon). Conductive heat flow deduced from the BSR depth is in the range of 21±6 to 55±15 mW m−2.

Beschreibung: An 8 million year record of subtropical and midlatitude shelf-sea temperatures, derived from oxygen isotopes of well-preserved brachiopods from a variety of European sections, demonstrates a long-term Cenomanian temperature rise (16–20°C, midlatitudes) that reached its maximum early in the late Turonian (23°C, midlatitudes). Superimposed on the long-term trend, shelf-sea temperatures vary at shorter timescales in relation to global carbon cycle perturbations. In the mid-Cenomanian and the late Turonian, two minor shelf-sea cooling events (2–3°C) coincide with carbon cycle perturbations and times of high-amplitude sea level falls. Although this evidence supports the hypothesis of potential glacioeustatic effects on Cretaceous sea level, the occurrence of minimum shelf-sea temperatures within transgressive beds argues for regional changes in shelf-sea circulation as the most plausible mechanism. The major carbon cycle event in the latest Cenomanian (oceanic anoxic event 2) is accompanied by a substantial increase in shelf-sea temperatures (4–5°C) that occurred ∼150 kyr after the commencement of the δ13C excursion and is related to the spread of oceanic conditions in western European shelf-sea basins. Our oxygen isotope record and published δ18O data of pristinely preserved foraminifera allow the consideration of North Atlantic surface water properties in the Cenomanian along a transect from the tropics to the midlatitudes. On the basis of fossil-derived δ18O, estimated δw ranges, and modeled salinities, temperature-salinity-density ranges were estimated for tropical, subtropical, and midlatitude surface waters. Accordingly, the Cenomanian temperate shelf-seas waters have potentially the highest surface water density and could have contributed to North Atlantic intermediate to deep waters in the preopening stage of the equatorial Atlantic gateway.

Beschreibung: European colonization of North America severely altered terrestrial and aquatic ecosystems alike. Here, we integrate archaeological, historical, and recent data to derive the ecological history of the Quoddy Region, Bay of Fundy, Canada, an upwelling region rich in marine diversity and productivity. We document successive changes on all trophic levels from primary producers to top predators over the last centuries. Our objectives were to (1) construct a baseline of "what was natural in the coastal ocean," and (2) analyze the sequence and potential interaction of multiple human impacts. Archaeological records highlight the abundance and diversity of marine species used by indigenous people over the last 2000-3000 years. Europeans colonized the area in the late 1700s and rapidly transformed the environment by multiple "top-down" (exploitation), "bottom-up" (nutrient loading), and "side-in" (habitat destruction, pollution) impacts. Most large vertebrates were severely overexploited by 1900, leading .to the extinction of three mammal and six bird species. Diadromous fish dramatically declined after river dam- ming in the early 1800s, and recovery was prevented by subsequent river pollution. Over- fishing of groundfish stocks started in the late 1800s, gradually leading to a final collapse in the 1970s. In the 20th century, decline of traditional fisheries induced a shift to low trophic level harvesting and aquaculture, which increased exponentially over the past 20 years. Eutrophication caused shifts in seaweed and phytoplankton communities: Some long- lived rockweeds were replaced by annual bloom-forming algae, and diatoms were replaced by dinoflagellates. Today, the once unique Quoddy Region shows the most common signs of degradation found in highly impacted coastal areas worldwide. Multiple human influences have altered abundance and composition of every trophic level in the food web and reduced upper trophic levels by at least one order of magnitude. We highlight cumulative and indirect effects that impair the ability to predict and manage highly impacted coastal ecosystems. On the other hand, simple protection and restoration measures in the 20th century led to the recovery of some species. It is these successes that provide guidance for a more sus- tainable interaction of humans with their marine environment.

Beschreibung: Wetland soils affected by permafrost are extensive in subarctic and arctic tundra. However, this fact does not imply these soils have been sufficiently investigated. In particular, studies of element translocation processes are scarce. This study was conducted (i) to determine the relationship between water and redox regimes in wetland soils in the Siberian tundra, and (ii) to investigate their influence on the distribution of redox sensitive and associate elements (Mn, Fe, P). Major geomorphic units were chosen (microhigh, polygon rim and slope; microlow, polygon center) from two low-centered polygons in the Lena Delta. Within polygons, redox potential, permafrost, and water level were measured during summer in 1999 and 2000 and (related) compared with element distribution. Manganese, Fe, and P accumulations were preferentially observed in aerobic microhighs. Anaerobic conditions in the microlows lead to a mobilization of Mn, Fe, and P. The elements migrate via water and are immobilized at the microhigh, which acts as an oxidative barrier. The element pattern, indicating an upward flux via water along redox gradients, is explained by higher evapotranspiration from soils and vegetation of the microhighs (Typic Aquiturbel) compared with soils and vegetation of the microlows (Typic Historthel). However, in further research this upward transport should be validated using labeled elements.

Beschreibung: The consistency of long-term yearly precipitation and runoff trends over the largest Arctic watersheds (Ob, Yenisei and Lena Rivers) is examined. Three gridded precipitation datasets (Climatic Research Unit, University of Delaware, NCEP) are used for comparative analyses with runoff data collected at basin outlets. The results generally demonstrate inconsistency in long-term changes of basin precipitation and runoff. The Yenisei River runoff increases significantly, while precipitation data show mostly negative trends. The Ob River does not show any significant trend either in precipitation or runoff. Positive trend in the Lena River runoff is accompanied by a weak precipitation increase; however, the precipitation increase is not strong enough to support the observed runoff change. The inconsistency identified in basin precipitation and runoff trends suggests uncertainty in both the quality of basin precipitation and runoff datasets, as well as the perceived hydrologic factors impacting runoff change.

Beschreibung: Introduction Active-layer thickness is a major factor for all physical and biological processes in permafrost soils. It is closely related to the fluxes of energy, water and carbon between permafrost landscapes and the atmosphere. Active-layer thickness is mainly driven by air temperature, but also influenced by snow cover, summer rainfall, soil properties and vegetation characteristics (Nelson et al., 1998). The typical polygonal tundra of the Lena Delta is characterised by a pronounced microrelief, which causes a high small-scale heterogeneity of soil and vegetation properties. Consequently, also the active-layer thickness varies substantially across small lateral distances of decimetres to metres. In order to up-scale results of process studies to the landscape scale, a quantification of the heterogeneity of active-layer thickness is of great interest.

Beschreibung: In this paper, we summarize data on terrigenous sediment supply in the Kara Sea and its accumulation and spatial and temporal variability during Holocene times. Sedimentological, organic-geochemical, and micropaleontological proxies determined in surface sediments allow to characterize the modern (riverine) terrigenous sediment input. AMS-14C dated sediment cores from the Ob and Yenisei estuaries and the adjacent inner Kara Sea were investigated to determine the terrigenous sediment fluxes and their relationship to paleoenvironmental changes. The variability of sediment fluxes during Holocene times is related to the post-glacial sea-level rise and changes in river discharge and coastal erosion input. Whereas during the late/middle Holocene most of the terrigenous sediments were deposited in the estuaries and the areas directly off the estuaries, huge amounts of sediments accumulated on the Kara Sea shelf farther north during the early Holocene before about 9 Cal. kyr BP. The maximum accumulation at that time is related to the lowered sea level, increased coastal erosion, and increased river discharge. Based on sediment thickness charts, echograph profiles and sediment core data, we estimate an average Holocene (0–11 Cal. kyr BP) annual accumulation of 194×106 t yr−1 of total sediment for the whole Kara Sea. Based on late Holocene (modern) sediment accumulation in the estuaries, probably 12×106 t yr−1 of riverine suspended matter (i.e., about 30% of the input) may escape the marginal filter on a geological time scale and is transported onto the open Kara Sea shelf. The high-resolution magnetic susceptibility record of a Yenisei core suggests a short-term variability in Siberian climate and river discharge on a frequency of 300–700 yr. This variability may reflect natural cyclic climate variations to be seen in context with the interannual and interdecadal environmental changes recorded in the High Northern Latitudes over the last decades, such as the NAO/AO pattern. A major decrease in MS values starting near 2.5 Cal. kyr BP, being more pronounced during the last about 2 Cal. kyr BP, correlates with a cooling trend over Greenland as indicated in the GISP-2 Ice Core, extended sea-ice cover in the North Atlantic, and advances of glaciers in western Norway. Our still preliminary interpretation of the MS variability has to be proven by further MS records from additional cores as well as other high-resolution multi-proxy Arctic climate records.

Beschreibung: The expedition ARK XIX/3 with the German icebreaking RV "Polarstern" was jointly organized between the Alfred Wegener Institute for Polar and Marine Research (AWI) and the Institut Français de Recherche pour l'Exploitation de la mer (IFREMER), the latter providing the unmanned deep-sea submersible "Victor 6000". AWI and IFREMER offered this unique combination of infrastructure in 2003 to European scientists to permit access on advanced technology in marine research to a broader community. Therefore, this cruise was not only a milestone in the Franco-German cooperation but also an important contribution to the European marine research initiatives. All still pictures and videos taken with "Victor 6000" during the expedition "VICTOR IN THE NORTH" are joint property of AWI and IFREMER with copyright by IFREMER. This material can be used for scientific purposes with the indication of IFREMER's copyright. It would be very much appreciated if the joint effort of AWI and IFREMER in organising the cruise ARK XIX/3 would be mentioned in the acknowledgements of any future publication written on the basis of material collected during the expedition. Any commercial or other than scientific use of either pictures or videos collected with "Victor 6000" needs the written formal approval of IFREMER. The entire cruise report is also available in digital format on a CD-ROM attached to this booklet because many of the pictures and graphs are in colour. All hand written dive log files are permanently stored at the AWI. For a certain period of time the cruise diary will be still accessible via the internet at www.polarstern-victor.de.

Beschreibung: Erosion by high stress abrasion of convergent margins from horsts and grabens on the subducting plate is not shown in seismic images. In a proposed model, the frontal sediment prism is a dynamic mass that elevates pore-fluid pressure. Overpressured fluid invades fractures in the upper plate and separates fragments that are dragged into a subduction channel along the plate interface. Removed fragments are smaller than surface ship seismic techniques have resolved and beyond the reach of past scientific ocean drilling; however, current drill capability and downhole geophysics can test the model.

Beschreibung: Sponges (phylum Porifera) are sessile marine filter feeders that have developed efficient defense mechanisms against foreign attackers such as viruses, bacteria, or eukaryotic organisms. Protected by a highly complex immune system, as well as by the capacity to produce efficient antiviral compounds (e.g., nucleoside analogues), antimicrobial compounds (e.g., polyketides), and cytostatic compounds (e.g., avarol), they have not become extinct during the last 600 million years. It can be assumed that during this long period of time, bacteria and microorganisms coevolved with sponges, and thus acquired a complex common metabolism. It is suggested that (at least) some of the bioactive secondary metabolites isolated from sponges are produced by functional enzyme clusters, which originated from the sponges and their associated microorganisms. As a consequence, both the host cells and the microorganisms lost the ability to grow independently from each other. Therefore, it was—until recently—impossible to culture sponge cells in vitro. Also the predominant number of “symbiotic bacteria” proved to be nonculturable. In order to exploit the bioactive potential of both the sponge and the “symbionts,” a 3D-aggregate primmorph culture system was established; also it was proved that one bioactive compound, avarol/avarone, is produced by the sponge Dysidea avara. Another promising way to utilize the bioactive potential of the microorganisms is the cloning and heterologous expression of enzymes involved in secondary metabolism, such as the polyketide synthases.

Beschreibung: Single grains of detrital white mica from two different synorogenic sediments in the Southern Urals were analysed using the in situ ultraviolet laser ablation Ar–Ar dating technique to discriminate between age signatures associated with a high-pressure signal (phengites) from those related to muscovite only. Two disparately aged sandstone formations of Neoproterozoic (Upper Vendian) and Upper Devonian (Famennian) age were formed by the erosion of high-relief source areas with contemporaneously exhumed high-pressure rocks. A bimodal distribution of ages and chemical compositions can be detected in the two detrital populations. There is no age overlap between the two populations, reflecting completely different source areas containing high-pressure rocks of different ages.Within the Upper Vendian sandstones, detrital white mica from a 571–609 Ma age group is phengitic in composition (Si 3.3–3.41 per formula unit), while an older 645–732 Ma age group is comprised of muscovite composition grains only. The first group is compatible with the time of late exhumation and emplacement of a source area containing high-pressure rocks, the Neoproterozoic Beloretzk terrane. The older age range is compatible with a long history of cooling and the allochthonous nature of this terrane. Detrital white mica from the Famennian sandstones(Zilair Formation) comprises one age group (342–421 Ma) containing phengite (Si 3.21–3.39 per formula unit) and muscovite, and a second group (446–496 Ma) containing muscovite only. While the derivation of the second group cannot be correlated with any as yet known regional data, the first age group indicates the earliest arrival of high-pressure rocks at the surface along the suture zone after Late Devonian arc–continent collision.

Beschreibung: Polyclonal antibodies that recognize the two subunits AmoA and AmoB of the ammonia monooxygenase (AMO) were applied to identify ammonia-oxidizing bacteria by immunofluorescence (IF) labeling in pure, mixed, and enriched cultures. The antibodies against the AmoA were produced using a synthetic peptide of the AmoA of Nitrosomonas eutropha, whereas the antibodies against the AmoB had been developed previously is against the whole B-subunit of the AMO [Pinck et al. (2001) Appl Environ Microbiol 67:118–124]. Using IF labeling, the AmoA antibodies were specific for the detection of all species of the genus Nitrosomonas. In contrast, the antiserum against AmoB labeled all genera of ammonia oxidizers of the β-subclass of Proteobacteria (Nitrosomonas, Nitrosospira, Nitrosolobus, and Nitrosovibrio). The fluorescence signals of the AmoA antibodies were spread all over the cells, whereas the signals of the AmoB antibodies were associated with the cytoplasmic membranes. The specificity of the reactions of the antisera with ammonia oxidizers were proven in pure and mixed cultures, and the characteristic IF labeling and the morphology of the cells enabled their identification at the genus level. The genus-specific IF labeling could be used to identify ammonia oxidizers enriched from various habitats. In enrichment cultures of natural sandstone, cells of the genera Nitrosomonas, Nitrosovibrio, and Nitrosospira were detected. Members of the genus Nitrosovibrio and Nitrosolobus were most prominent in enriched garden soil samples, whereas members of the genus Nitrosomonas dominated in enriched activated sludge. The antibodies caused only slight background fluorescence on sandstone and soil particles compared to oligonucleotide probes, which could not be used to detect ammonia oxidizers on these materials because of strong nonspecific fluorescence.

Beschreibung: In the past decade, within the framework of joint Russian–German marine and terrestrial studies on the Arctic shelf, New Siberian Islands, and coastal lowlands of the Laptev and East Siberian seas, fundamentally new data have been obtained on terrestrial and offshore permafrost in this area. Field and laboratory investigations supplemented with numerical modeling and generalization of the results of numerous geological surveys, exploratory works, and scientific researches performed in previous years have made it possible to revise existing knowledge about the distribution, thickness, physical state, and history of development of terrestrial and offshore permafrost in the East Siberian part of the Arctic. The main results of these studies and their interpretation are discussed in this paper.

Beschreibung: This paper summarizes the results of studies of the Late Weichselian periglacial environments carried out in key areas of northern Eurasia by several QUEEN teams (European Science Foundation (ESF) programme: “Quaternary Environment of the Eurasian North”). The palaeoglaciological boundary conditions are defined by geological data on timing and extent of the last glaciation obtained in the course of the EU funded project “Eurasian Ice Sheets”. These data prove beyond any doubt, that with the exception of the northwestern fringe of the Taymyr Peninsula, the rest of the Eurasian mainland and Severnaya Zemlya were not affected by the Barents–Kara Sea Ice Sheet during the Last Glacial Maximum (LGM). Inversed modelling based on these results shows that a progressive cooling which started around 30 ka BP, caused ice growth in Scandinavia and the northwestern areas of the Barents–Kara Sea shelf, due to a maritime climate with relatively high precipitation along the western flank of the developing ice sheets. In the rest of the Eurasian Arctic extremely low precipitation rates (less than 50 mm yr−1), did not allow ice sheet growth in spite of the very cold temperatures. Palaeoclimatic and palaeoenvironmental conditions for the time prior to, during, and after the LGM have been reconstructed for the non-glaciated areas around the LGM ice sheet with the use of faunal and vegetation records, permafrost, eolian sediments, alluvial deposits and other evidences. The changing environment, from interstadial conditions around 30 ka BP to a much colder and drier environment at the culmination of the LGM at 20–15 ka BP, and the beginning of warming around 15 ka BP have been elaborated from the field data, which fits well with the modelling results.

Beschreibung: The bacterial community composition of the active layer (0–45 cm) of a permafrost-affected tundra soil was analysed by fluorescence in situ hybridisation (FISH). Arctic tundra soils contain large amounts of organic carbon, accumulated in thick soil layers and are known as a major sink of atmospheric CO2. These soils are totally frozen throughout the year and only a thin active layer is unfrozen and shows biological activity during the short summer. To improve the understanding of how the carbon fluxes in the active layer are controlled, detailed analysis of composition, functionality and interaction of soil microorganisms was done. The FISH analyses of the active layer showed large variations in absolute cell numbers and in the composition of the active microbial community between the different horizons, which is caused by the different environmental conditions (e.g., soil temperature, amount of organic matter, aeration) in this vertically structured ecosystem. Universal protein stain 5-(4,6-dichlorotriazin-2-yl)aminofluorescein (DTAF) showed an exponential decrease of total cell counts from the top to the bottom of the active layer (2.3 × 109–1.2 × 108 cells per gram dry soil). Using FISH, up to 59% of the DTAF-detected cells could be detected in the surface horizon, and up to 84% of these FISH-detected cells could be affiliated to a known phylogenetic group. The amount of FISH-detectable cells decreased with increasing depth and so did the diversity of ascertained phylogenetic groups.

Beschreibung: Durch Vermittlung von Jörn Thiede gelangte das Geologenarchiv in den Besitz eines Videobands von einem Fernsehinterview mit Rosenqvist (auch gelegentlich Rosenquist), das Elen Roaldset (E.R.) im Geologischen Institut der Universität Oslo am 8.September 1988 führen konnte. Es umfasst den gesamten Lebenslauf und die wichtigsten wissenschaflichen Leistungen dieses aussergewöhnlichen Geologen und Mineralogen. Er wurde in Wien am 17. Mai 1916 geboren, kam aber mit seinen Eltern schon 1917 nach Oslo, wo er am 8. Oktober 1994 starb (K. Bjørlykke 1995). Im Folgenden sollen aus dem Interview nur seine wegweisenden Untersuchungen der Quicktone, seine fachliche Vielseitigkeit, sein gesellschaftliches Engagement und seine schwierigen Erfahrungen mit Deutschland herausgegriffen werden. Das in der Landessprache geführte Gespräch wurde von Geir Ebelfoff und Lars Erik Kastilan ins Deutsche transkribiert.

Beschreibung: Despite increased paleoenvironmental studies in Northern Yakutia (ANDREEV et al. 2002 and references therein), little is known of past climatic and environmental fluctuations during the Middle and Late Weichselian (Karginsky interstadial and Sartan stage). New pollen and radiocarbon data from the Verkhoyansk Mountains document the Late Pleistocene and early Holocene environmental history of the area.The climate of the region is extreme continental and arid. In Yakutsk the absolute minimum temperature reaches -64°C, absolute maximum +38°C, and annual precipitation is 180-250 mm. But more than 350-400 mm vapors from June to September (GAVRILOVA 1973). Today larch (Larix dahurica) forest (taiga) with herbs dominate the vegetation. Few other trees (Betula pendula, Pinus sylvestris, Picea obovata) and shrubs (Alnus fruticosa, Pinus pumila, Betula nana) also grow in the area. The samples came from a site at the Tumara River valley (63N, 130W).The pollen spectra show that open tundra-like Poaceae and Cyperaceae associations with some other herbs (Caryophyllaceae, Ranunculaceae, and Asteraceae) dominated the area about 50-40 14C ka ago. Steppe-like communities with Artemisia, Cichoriaceae, Thalictrum, and rare shrubby tundra communities with Salix and Betula sect. Nanae were also present in the vegetation cover. An increase of Chenopodiaceae pollen and Equisetum spore contents, which are mainly pioneer species on disturbed soils, and the presence of charcoal particles in the sediments dated ca 48-50 14C ka most likely reflect fire activity at that time.Higher content of Salix pollen, Polypodiaceae and Lycopodium spores during ca 48-30 14C ka may reflect climate conditions warmer and wetter than during the previous interval. A find of Linum perenne pollen grains indicate the existence of dry steppe habitats in the area as well. The presence of this species reflects that temperatures were at least 12.5°C during the growing season. This relatively warm interval corresponds well with the Karginsky Interstadial (Stage 3) recorded in Siberia.Spores of Selaginella rupestris, an indicator of very dry environment, are common in the spectra at around 23 14C ka. A decrease of pollen and spores concentration reflects further deterioration of environmental conditions. A decrease of Salix pollen content and the presence of Artemisia, Cichoriaceae, Thalictrum pollen and an increase of the charcoal particle content also point to rather dry climate conditions. This relatively cold and dry interval corresponds well with the Sartan stadial (Stage 2) recorded in Northern Eurasia. During the Last Glacial Maximum (14C dated at about 19 ka BP) pollen concentration significantly decreased. Many pollen taxa completely disappeared from the spectra pointing to an extremely severe environment.Higher tree pollen contents (mostly Salix and Betula sect. Albae) at the Late Glacial/early Holocene transition (10-9 14C ka) reflect rather favorable climate conditions for the development of taiga vegetation during that interval. This data are in good agreement with other early Holocene pollen records from Northern Yakutia (e.g. PISARIC 2001, ANDREEV 2002).

Beschreibung: The Space Information Laboratory (SIL) of the Tropical Center for Earth and Space Studies of the University of Puerto Rico at Mayagu¨ ez (UPRM) has been collecting and processing satellite data since December of 1996. Satellite imagery from the Advanced Very High Resolution Radiometer (AVHRR) and the Sea viewing Wide Field of view Sensor (SeaWiFS) provides us with a new understanding of phytoplankton dynamics in the Caribbean region. SeaWiFS shows the intrusion of waters into the eastern Caribbean Sea from the Orinoco River during fall and from the Amazon River during spring–summer. Strong coastal upwelling in Venezuela produced by the trade winds during winter– spring is detected with the AVHRR. The satellite data suggest that these seasonal events may play an important role in phytoplankton fertilization of the eastern Caribbean Sea. SeaWiFS and hydrological data are also combined to evaluate the impact of hurricanes on phytoplankton distribution. The development of models for estimation of ocean primary productivity using SeaWiFS and AVHRR data is now in progress.

Beschreibung: Testate amoebae (Protozoa: Testacea) were studied in the Late Quaternary permafrost deposits in the Siberian Arctic (Bykovsky Peninsula of the Laptev Sea coast, 71°40′ –71°80′ N and 129°–129°30′ E). The Testacea associations studied reflect specific environmental conditions in paleocryosols, which were controlled by the local micro-relief as well as by regional climate conditions. In total, 86 species, varieties, and forms of testate amoebae were found in 38 Pleistocene and Holocene samples. The rhizopods indicate that soil conditions at ca. 53,000 14C years BP were probably rather similar to the modern cold and wet arctic tundra environment. More moisture and warmer soil conditions were relatively favorable for rhizopods ca. 45,300–43,000 14C years BP, but it was significantly drier at about 42,000 14C years BP. Drier and colder environmental conditions were also present about 39,300–35,000 14C years BP. The Late Pleistocene samples, radiocarbon dated to 33,000–12,000 years BP, are characterized by a low species diversity and density indicating that this period may have been extremely cold and dry. This conjecture is also supported by the polymorphism of some species. Hydrophilic Difflugia species (mostly obligate hydrobiotes) are broadly represented in the studied Holocene samples. The species composition and density of rhizopods in the majority of Holocene samples suggest wet and relatively warm conditions. Changes in rhizopod assemblages during the last 53,000 years were not very dramatic, mostly consisting of rare species and changes in the dominant species complexes during the Pleistocene and Holocene. However, these changes were more drastic during the Pleistocene. They were probably at least partly responsible for the disappearance of some rare testacean species such as Argynnia sp.

Beschreibung: Was hat der Untergang der TITANIC mit Kiel zu tun? Das Unglück brachte einen Kieler Forscher dazu, sich intensiv mit der Ausbreitung von Schallwellen unter Wasser zu beschäftigen. Eine Ausstellung zeichnet seinen Weg jetzt nach.

Beschreibung: Horizontal gene transfer is an important mechanism for the evolution of microbial genomes. Pathogenicity islands — mobile genetic elements that contribute to rapid changes in virulence potential — are known to have contributed to genome evolution by horizontal gene transfer in many bacterial pathogens. Increasing evidence indicates that equivalent elements in non-pathogenic species — genomic islands — are important in the evolution of these bacteria, influencing traits such as antibiotic resistance, symbiosis and fitness, and adaptation in general. This review discusses the recent lessons that have been learned from pathogenicity islands in pathogenic microorganisms and how they apply to the role of genomic islands in commensal, symbiotic and environmental bacteria.

Beschreibung: Marine sponges (Porifera) harbor large amounts of commensal microbial communities within the sponge mesohyl. We employed 16S rRNA gene library construction using specific PCR primers to provide insights into the phylogenetic identity of an abundant sponge-associated bacterium that is morphologically characterized by the presence of a membrane-bound nucleoid. In this study, we report the presence of a previously unrecognized evolutionary lineage branching deeply in the domain Bacteria that is moderately related to the Planctomycetes, Verrucomicrobia, and Chlamydia lines of decent. Because members of this lineage showed 〈75% 16S rRNA gene sequence similarity to known bacterial phyla, we suggest the status of a new candidate phylum, named “Poribacteria”, to acknowledge the affiliation of the new bacterium with sponges. The affiliation of the morphologically conspicuous sponge bacterium with the novel phylogenetic lineage was confirmed by fluorescence in situ hybridization with newly designed probes targeting different sites of the poribacterial 16S rRNA. Consistent with electron microscopic observations of cell compartmentalization, the fluorescence signals appeared in a ring-shaped manner. PCR screening with “Poribacteria”-specific primers gave positive results for several other sponge species, while samples taken from the environment (seawater, sediments, and a filter-feeding tunicate) were PCR negative. In addition to a report for Planctomycetes, this is the second report of cell compartmentalization, a feature that was considered exclusive to the eukaryotic domain, in prokaryotes.

Beschreibung: Portable and automated field screening equipment would be very effective in assessing contamination due to explosives at many defense sites. A droplet based microfluidic lab-on-a-chip utilizing electrowetting has been presented for fully automated detection of TNT. Microliter droplets of TNT in DMSO and KOH in water are reacted on a chip in a programmed way. The same platform has integrated colorimetric detection. The detection of TNT is linear in the range of 12.5–50 µg/mL.

Beschreibung: Log and core data document gas saturations as high as 90% in a coarse-grained turbidite sequence beneath the gas hydrate stability zone (GHSZ) at south Hydrate Ridge, in the Cascadia accretionary complex. The geometry of this gas-saturated bed is defined by a strong, negative-polarity reflection in 3D seismic data. Because of the gas buoyancy, gas pressure equals or exceeds the overburden stress immediately beneath the GHSZ at the summit. We conclude that gas is focused into the coarse-grained sequence from a large volume of the accretionary complex and is trapped until high gas pressure forces the gas to migrate through the GHSZ to seafloor vents. This focused flow provides methane to the GHSZ in excess of its proportion in gas hydrate, thus providing a mechanism to explain the observed coexistence of massive gas hydrate, saline pore water and free gas near the summit.

Beschreibung: 16S rDNA library construction revealed a uniform microbial community in sponges that were collected from different oceans. Altogether 14 monophyletic, sponge-specific sequence clusters were identified that belong to at least seven different bacterial divisions. By definition, the sequences of each cluster are more closely related to each other than to a sequence from non-sponge sources. These monophyletic clusters comprise 70 % of all publicly available, sponge-derived 16S rDNA sequences reflecting the generality of the observed phenomenon. This shared microbial fraction represents the ‘smallest common denominator’ of the sponges investigated in this study. Bacteria that are exclusively found in certain host species or that occur only transiently would have been missed. A picture emerges where sponges can be viewed as highly concentrated reservoirs of so far uncultured, elusive and possibly evolutionarily ancient marine microorganisms

Beschreibung: A sediment core recovered in Lake Lyadhej-To at the northwestern edge of the Ural Mountains reflects the complete Holocene environmental history from ∼11,000 cal. yr B.P. Five limnological episodes are identified in the diatom and geochemical records. The initial lake stage, Episode I (∼11,000–10,850 cal. yr B.P.) is characterized by the absence of biogenic production and a high influx of clastic sediments. Episode II (∼10,850–8650 cal. yr B.P.) is characterized by ice-free conditions during summer, highest bioproductivity, strong growth of planktic diatoms and anoxic bottom waters. This period represents the Holocene climatic optimum. Deterioration of climatic conditions commenced in Episode III (∼8650–7000 cal. yr B.P.) as indicated by distinctly lower bioproductivity and longer persistence of winter ice on the lake. During Episode IV (∼7000–2500 cal. yr B.P.), the diatom and pollen records indicate that temperatures were cool and the growing season was short. Finally, in Episode V (∼2500 cal. yr B.P. to present), limnological conditions, indicated by increased organic carbon and diatom deposition, initially suggest improved conditions followed by a return to modern conditions beginning ∼500 cal. yr B.P. The pollen stratigraphy from Lake Lyadhej-To is consistent with other paleoclimatic records from northern Eurasia, confirming rapid postglacial warming, the presence of dense tree forests during the climatic optimum, and finally a gradual southward retreat of the treeline towards its modern location.

Beschreibung: In July 2001, samples of surface suspended particulate material (SPM) of the Irtysh river in its middle and lower reaches (from Omsk City to the confluence with the Ob river) and its main tributaries were collected (18 stations along 1834 km). The SPM samples were analyzed for major and trace element composition. The results show that the geochemistry of Irtysh river SPM is related to landscape and geochemical peculiarities of the river basin on one hand and to industrial activities within the drainage area on the other hand. In the upper basin polymetallic and cinnabar deposits and phosphorite deposits with high As content are widespread. The open-cut mining and developed oil-refining, power plants and other industries lead to the contamination of the environment by heavy metals and other contaminants. The territory of the West Siberian lowland, especially the Ob-Irtysh interfluve, is characterized by the occurrence of swamps and peat-bogs. Tributaries of the Irtysh river originating in this region, have a brown color and the chemical composition of the SPM is specific for stagnant water. In the first 500–700 km downstream from Omsk City the Irtysh river has the typical Al–Si-rich suspended matter composition. After the inflow of the tributaries with brown water the SPM composition is significantly changed: an increase of POC, Fe, P, Ca, Sr, Ba and As concentrations and a strong decrease of the lithogenic elements Al, Mg, K, Na, Ti, Zr can be observed. The data show that Fe-organic components (Fe-humic amorphous compounds, which contribute ca. 75–85% to the total Fe) play a very important role in SPM of the tributaries with brown water and in the Irtysh river in its lower reaches. Among the trace metals significant enrichments relative to the average for global river SPM could only be observed for As and Cd (coefficient of enrichment up to 16 for As and 3–3.5 for Cd). It can be shown that the enrichment of As in the SPM is related to natural processes, i.e. the weathering of phosphate containing deposits with high As concentrations in the upper Irtysh basin and the high As–P affinity in the swamp peaty soil. Dissolved P and As are absorbed by amorphous organic C/Fe oxyhydroxide components which act as carriers during the transport to the main stream of the Irtysh river. The role of anthropogenic factors is probably insignificant for As. In contrast, the enrichment of Cd is mainly related to anthropogenic input. The threefold enrichment of Cd in the SPM just below Omsk City and its continuous decrease down to background level at a distance of 500–700 km downstream points quite definitely to the municipal and industrial sewage of Omsk City as the main source of Cd in the SPM of the Irtysh river.

Beschreibung: The spatio-temporal pattern of peak Holocene warmth (Holocene thermal maximum, HTM) is traced over 140 sites across the Western Hemisphere of the Arctic (0–180°W; north of ∼60°N). Paleoclimate inferences based on a wide variety of proxy indicators provide clear evidence for warmer-than-present conditions at 120 of these sites. At the 16 terrestrial sites where quantitative estimates have been obtained, local HTM temperatures (primarily summer estimates) were on average 1.6±0.8°C higher than present (approximate average of the 20th century), but the warming was time-transgressive across the western Arctic. As the precession-driven summer insolation anomaly peaked 12–10 ka (thousands of calendar years ago), warming was concentrated in northwest North America, while cool conditions lingered in the northeast. Alaska and northwest Canada experienced the HTM between ca 11 and 9 ka, about 4000 yr prior to the HTM in northeast Canada. The delayed warming in Quebec and Labrador was linked to the residual Laurentide Ice Sheet, which chilled the region through its impact on surface energy balance and ocean circulation. The lingering ice also attests to the inherent asymmetry of atmospheric and oceanic circulation that predisposes the region to glaciation and modulates the pattern of climatic change. The spatial asymmetry of warming during the HTM resembles the pattern of warming observed in the Arctic over the last several decades. Although the two warmings are described at different temporal scales, and the HTM was additionally affected by the residual Laurentide ice, the similarities suggest there might be a preferred mode of variability in the atmospheric circulation that generates a recurrent pattern of warming under positive radiative forcing. Unlike the HTM, however, future warming will not be counterbalanced by the cooling effect of a residual North American ice sheet.

Beschreibung: Thermoterraces in syngenetic ice complexes are widespread along the erosion-dominated shores of the Yakutia Arctic coast. Thermoterraces progressively record quantitative information about their existence which may be used to determine the mean shore retreat rate during the time they are present. Initial measurements of four thermoterraces were carried out by the authors on the south coast of the Dmitry Laptev Strait in 2002, and shore retreat rates were calculated. Comparison of erosion rates obtained using thermoterrace dimensions and geodetic survey results with rates determined using aerial photographs showed that the erosion rate values obtained in these two ways are approximately of the same order.

Beschreibung: The effect of microrelief and vegetation on methane (CH4) emission was investigated in a wet polygonal tundra of the Lena Delta, Northern Siberia (72.37N, 126.47E). Total and plant-mediated CH4 fluxes were measured by closed-chamber techniques at two typical sites within a low-centred polygon. During the study period, total CH4 flux averaged 28.0 ± 5.4 mg m−2 d−1 in the depressed polygon centre and only 4.3 ± 0.8 mg m−2 d−1 at the elevated polygon rim. This substantial small-scale spatial variability of CH4 emission was caused by strong differences of hydrologic conditions within the microrelief of the polygon, which affected aeration status and organic matter content of the soils as well as the vegetation cover. Beside water table position, the vegetation cover was a major factor controlling CH4 emission from polygonal tundra. It was shown that the dominant vascular plant of the study area, Carex aquatilis, possesses large aerenchyma, which serve as pathways for substantial plant-mediated CH4 transport. The importance of plant-mediated CH4 flux was strongly influenced by the position of the water table relative to the main root horizon. Plant-mediated CH4 transport accounted for about two-thirds of the total flux in the wet polygon centre and for less than one-third of the total flux at the moist polygon rim. A clipping experiment and microscopic-anatomical studies suggested that plant-mediated CH4 transport via C. aquatilis plants is driven only by diffusion and is limited by the high diffusion resistance of the dense root exodermes.

Beschreibung: Diatom assemblages and organic carbon records from two sediment cores located within an estuarian bay of the inner Kara Sea trace changes in Yenisei River runoff and postglacial depositional environments. Paleosalinity and sea-ice reconstructions are based on modern relationships of local diatom assemblages and summer surface-water salinity. Approximately 15,500 cal yr B.P., rivers and bogs characterized the study area. When sea level reached the 38- to 40-m paleo-isobath approximately 9300 cal yr B.P., the coring site was flooded. From 9300–9100 cal yr B.P., estuarine conditions occurred proximal to the depocenter of fluvially derived material, and salinity was 〈7–8. Paleosalinity increased to 11–13 by 7500 cal yr B.P., following postglacial sea-level rise and the southward shift of the Siberian coast. Sharp decreases in diatom accumulation rates, total sediment, and organic carbon also occurred, suggesting the presence of brackish conditions and greater distance between the coast and study site. Maximum paleosalinity (up to 13) was recorded between 7500 and 6000 cal yr B.P., which was likely caused by the enhanced penetration of Atlantic waters to the Kara Sea. Stepwise decreases to modern salinity levels happened over the last 6000 cal yr.

Beschreibung: Beginning: When Jules Verne made his imaginary journey of exploration to the centre of the earth through the vents in an Icelandic volcano over a hundred years ago, he assumed that all volcanoes are interlinked in a subterranean system. But even his imagination failed to visualise the world-wide system of submarine volcanoes that extends over a distance of over 60,000 kilometres and only breaks the surface of the ocean at Iceland. This mid-oceanic ridge, which spans the entire world ocean, has evolved along the boundaries between the tectonic plates of the Earth’s crust. Gakkel Ridge, in the central eastern Arctic Ocean is the northern most spur of the plate boundary between Eurasia and North America, and at the same time the most slowly opening ridge segment in the world, opening only a few millimetres each year.

Beschreibung: From cell cultures of Suberites domuncula was isolated a bacterial strain, SDC-1, which was identified by 16S ribosomal RNA sequence analysis as an α-Proteobacterium of the genus Ruegeria. The occurrence of the strain in sponge cell culture could be explained by its resistance to the antibiotics used in the isolation of sponge cell cultures or by the preservation of SDC-1 by host sponge cells. The fatty acid composition of SDC-1 is characterized by branched C-12 methyl fatty acids. Two new and 8 known cyclic dipeptides were isolated and characterized from the fermentation broth of SDC-1. Cyclodipeptides are one of the families of cell-cell signaling compounds and may have some role to play in sponge-bacteria interactions.

Beschreibung: Maintaining deep sea animals in in situ conditions has always been technically difficult because of the high-pressure requirements. Even more difficult are any attempts in manipulating or sampling these organisms while keeping them alive in high-pressure aquaria. We present a technique to withdraw blood samples by vascular catheterization which allows withdrawal of samples of during maintenance of specimens under high-pressure conditions. We have developed this technique to answer a long debated question, how carbon dioxide is transported from the ambient sea water to the bacterial symbionts inside the trophosome of the hydrothermal vent tubeworm Riftia pachyptila. Our results indicate that the carbon supply to the symbionts is mainly through inorganic CO2 while its incorporation into malate and succinate may serve storage functions at periods of low CO2 availability in the environment.