ALBERT

Description: The decadal-scale variability in the tropical Pacific has been analyzed herein by means of observations and numerical model simulations. The two leading modes of the sea surface temperature (SST) variability in the central western Pacific are a decadal mode with a period of about 10 yr and the ENSO mode with a dominant period of about 4 yr. The SST anomaly pattern of the decadal mode is ENSO like. The decadal mode, however, explains most variance in the western equatorial Pacific and off the equator. A simulation with an ocean general circulation model (OGCM) forced by reanalysis data is used to explore the origin of the decadal mode. It is found that the variability of the shallow subtropical–tropical overturning cells is an important factor in driving the decadal mode. This is supported by results from a multicentury integration with a coupled ocean–atmosphere general circulation model (CGCM) that realistically simulates tropical Pacific decadal variability. Finally, the sensitivity of the shallow subtropical–tropical overturning cells to greenhouse warming is discussed by analyzing the results of a scenario integration with the same CGCM.

Description: Carbonate precipitates on mounds and along tectonic scarps off the Costa Rica margin are manifestations of subduction-induced dewatering. The long-term dewatering history is recorded in mineralogical, petrological and isotope signals of carbonates recovered from these sites. The carbonates are strongly depleted in δ13C (−11 to −53‰ PDB) and enriched in δ18O (+4 to +8‰ PDB). Thermogenic methane and biogenic methane were identified as sources of the carbon. Chemoherm carbonates and seepage-associated carbonates formed in a focused flow regime have lighter δ13C values, while others formed in a more diffusive flow regime have slightly enriched C isotope values. Three fluid components were inferred based on the calculation of equilibrium δ18O: clay dehydration water, gas hydrate water and seawater. Calculated equilibrium δ18O values of carbonates from different down-core depths as well as from different precipitation stages show that the δ18O of the precipitating fluid is progressively depleted with time. Dolostones showing a methane-C source and a well constrained O-isotope signature are thought to have formed at depth in the sediment and subsequently became exhumed. Glauconitic sandstones cemented by methane-derived carbonate provide evidence that fluid and solid material have been expelled by the mud volcano.

Description: The current system east of the Grand Banks was intensely observed by World Ocean Circulation Experiment (WOCE) array ACM-6 during 1993–95 with eight moorings, reaching about 500 km out from the shelf edge and covering the water column from about 400-m depth to the bottom. More recently, a reduced array by the Institut für Meerskunde (IfM) at Kiel, Germany, of four moorings was deployed during 1999–2001, focusing on the deep-water flow near the western continental slope. Both sets of moored time series, each about 22 months long, are combined here for a mean current boundary section, and both arrays are analyzed for the variability of currents and transports. A mean hydrographic section is derived from seven ship surveys and is used for geostrophic upper-layer extrapolation and isopycnal subdivision of the mean transports into deep-water classes. The offshore part of the combined section is dominated by the deep-reaching North Atlantic Current (NAC) with currents still at 10 cm s−1 near the bottom and a total northward transport of about 140 Sv (Sv ≡ 106 m3 s−1), with the details depending on the method of surface extrapolation used. The mean flow along the western boundary was southward with the section-mean North Atlantic Deep Water outflow determined to be 12 Sv below the σθ = 27.74 kg m−3 isopycnal. However, east of the deep western boundary current (DWBC), the deep NAC carries a transport of 51 Sv northward below σθ = 27.74 kg m−3, resulting in a large net northward flow in the western part of the basin. From watermass signatures it is concluded that the deep NAC is not a direct recirculation of DWBC water masses. Transport time series for the DWBC variability are derived for both arrays. The variance is concentrated in the period range from 2 weeks to 2 months, but there are also variations at interannual and longer periods, with much of the DWBC variability being related to fluctuations and meandering of the NAC. A significant annual cycle is not recognizable in the combined current and transport time series of both arrays. The moored array results are compared with other evidence on deep outflow and recirculation, including recent models of different types and complexity.

Description: We examined the thermoregulatory behaviour (TRB) of roosting Humboldt penguins (Spheniscus humboldti) in north central Chile during summer and winter, when ambient temperatures (Ta) are most extreme. Each body posture was considered to represent a particular TRB, which was ranked in a sequence that reflected different degrees of thermal load and was assigned an arbitrary thermoregulatory score. During summer, birds exhibited eight different TRBs, mainly oriented to heat dissipation, and experienced a wide range of Ta (from 14 to 31°C), occasionally above their thermoneutral zone (TNZ, from 2 to 30°C), this being evident by observations of extreme thermoregulatory responses such as panting. In winter, birds exhibited only three TRBs, mainly oriented to heat retention, and experienced a smaller range of Ta (from 11 to 18°C), always within the TNZ, even at night. The components of behavioural responses increased directly with the heat load which explains the broader behavioural repertoire observed in summer. Since penguins are primarily adapted in morphology and physiology to cope with low water temperatures, our results suggest that behavioural thermoregulation may be important in the maintenance of the thermal balance in Humboldt penguins while on land.

Description: We quantified the nitrogen and enzyme hydrolyzable amino acid (EHAA) concentrations of sediments prior to and after corals sloughed, ingested, and egested sediments layered onto their surfaces, for the three coral species Siderastrea siderea, Agaricia agaricites, and Porites astreoides in Jamaica. The percent nitrogen of the sediments egested by all three species was lower than in the sediments available to the corals. Additionally, the sediments sloughed (not ingested) by A. agaricites and P. astreoides were lower in percent nitrogen, while the sediments sloughed by S. siderea had the same percent nitrogen as that of the available sediments. The percent nitrogen of the sediments sloughed and egested by P. astreoides showed significant negative and positive relationships, respectively, to increasing sediment loads, while the percent nitrogen of the sediments sloughed and egested by both S. siderea and A. agaricites showed no relationship to sediment load. EHAA concentrations were not significantly different between the sloughed and available sediments but were significantly lower in the sediments egested by S. siderea and A. agaricites (EHAA concentrations were not measured for P. astreodies sediment fractions). Comparisons of the nitrogen and EHAA concentrations in the sloughed and egested sediments to what was available prior to coral processing show that maximum ingestion was between 0.1 and 0.2 µg N µg−1 coral N cm−2 and between 0.5 and 0.6 µg EHAA·cm−2. Maximum assimilation efficiencies were estimated to be 30–60% of the available nitrogen. The data show that corals ingest and alter the nitrogen concentration of particles that land on their surfaces. The corals’ abilities to process these sediments, and the sediments’ possible contributions to coral nutrition, are discussed based on these results.

Description: Simulations and seasonal forecasts of tropical Pacific SST and subsurface fields that are based on the global Consortium for Estimating the Circulation and Climate of the Ocean (ECCO) ocean-state estimation procedure are investigated. As compared to similar results from a traditional ENSO simulation and forecast procedure, the hindcast of the constrained ocean state is significantly closer to observed surface and subsurface conditions. The skill of the 12-month lead SST forecast in the equatorial Pacific is comparable in both approaches. The optimization appears to have better skill in the SST anomaly correlations, suggesting that the initial ocean conditions and forcing corrections calculated by the ocean-state estimation do have a positive impact on the predictive skill. However, the optimized forecast skill is currently limited by the low quality of the statistical atmosphere. Progress is expected from optimizing a coupled model over a longer time interval with the coupling statistics being part of the control vector.

Description: In the eastern South Pacific Ocean, at a depth of about 200 m, a salinity minimum is found. This minimum is associated with a particular water mass, the “Shallow Salinity Minimum Water” (SSMW). SSMW outcrops in a fresh tongue (Smin) centered at about 45°S. The Smin appears to emanate from the eastern boundary, against the mean flow. The watermass transformation that creates SSMW and Smin is investigated here. The Smin and SSMW are transformed from saltier and warmer waters originating from the western South Pacific. The freshening and cooling occur when the water is advected eastward at the poleward side of the subtropical gyre. Sources of freshening and cooling are air–sea exchange and advection of water from south of the subtropical gyre. A freshwater and heat budget for the mixed layer reveals that both sources equally contribute to the watermass transformation in the mixed layer. The freshened and cooled mixed layer water is subducted into the gyre interior along the southern rim of the subtropical gyre. Subduction into the zonal flow restricts the transformation of interior properties to diffusion only. A simple advection/diffusion balance reveals diffusion coefficients of order 2000 m2 s−1. The tongue shape of the Smin is explained from a dynamical viewpoint because no relation to a positive precipitation–evaporation balance was found. Freshest Smin values are found to coincide with slowest eastward mixed layer flow that accumulates the largest amounts of freshwater in the mixed layer and creates the fresh tongue at the sea surface. Although the SSMW is the densest and freshest mode of water subducted along the South American coast, the freshening and cooling in the South Pacific affect a whole range of densities (25.0–26.8 kg m−3). The transformed water turns northward with the gyre circulation and contributes to the hydrographic structure of the gyre farther north. Because the South Pacific provides most of the source waters that upwell along the equatorial Pacific, variability in South Pacific hydrography may influence equatorial Pacific hydrography. Because one-half of the transformation is found to be controlled through Ekman transport, variability in wind forcing at the southern rim of the subtropical gyre may be a source for variability of the equatorial Pacific.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: 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.

Description: Culture pelleting and morphology has a strong influence on process productivity and success for fungal and filamentous bacterial cultures. This impact is particularly evident with early phase secondary metabolite processes with limited process definition. A compilation of factors affecting filamentous or pelleting morphology described in the literature indicates potential leads for developing process-specific control methodologies. An evaluation of the factors mediating citric acid production is one example of an industrially important application of these techniques. For five model fungal and filamentous bacterial processes in an industrial fermentation pilot plant, process development strategies were developed and effectively implemented with the goal of achieving reasonable fermentation titers early in the process development cycle. Examples of approaches included the use of additives to minimize pelleting in inoculum shake flasks, the use of large-volume frozen bagged inoculum obtained from agitated seed fermentors, and variations in production medium composition and fermentor operating conditions. Results were evaluated with respect to productivity of desired secondary metabolites as well as process scalability. On-line measurements were utilized to indirectly evaluate the cultivation impact of changes in medium and process development. Key laboratory to pilot plant scale-up issues also were identified and often addressed in subsequent cultivations.

Description: Hydroacoustic methods are particularly suitable for investigations of the occurrence, cyclicity and amount of bubbles released at cold seeps without disturbing them. Experiments with a horizontally looking single beam transducer (40 and 300 kHz) directed towards artificially produced bubbles show that the backscattering strength of the bubbles increases with the gas flux rate independently of the bubble radii distribution. It is demonstrated that an acoustic system can be calibrated in such a way that gas flux rates of bubble-size spectra, as observed at natural seeps, can be directly related to the echo level of a known, acoustically insonified volume. No system-specific parameters have to be known except the beam width.

Description: Two major water masses dominate the deep layers in the Mariana and Caroline Basins: the Lower Circumpolar Water (LCPW), arriving from the Southern Ocean along the slopes north of the Marshall Islands, and the North Pacific Deep Water (NPDW) reaching the region from the northeastern Pacific Ocean. Hydrographic and moored observations and multibeam echosounding were performed in the East Mariana and the East Caroline Basins to detail watermass distributions and flow paths in the area. The LCPW enters the East Mariana Basin from the east. At about 13°N, however, in the southern part of the basin, a part of this water mass arrives in a southward western boundary flow along the Izu–Ogasawara–Mariana Ridge. Both hydrographic observations and moored current measurements lead to the conclusion that this water not only continues westward to the West Mariana Basin as suggested before, but also provides bottom water to the East Caroline Basin. The critical throughflow regions were identified by multibeam echosounding at the Yap Mariana Junction between the East and West Mariana Basins and at the Caroline Ridge between the East Mariana and East Caroline Basins. The throughflow is steady between the East and West Mariana Basins, whereas more variability is found at the Caroline Ridge. At both locations, throughflow fluctuations are correlated with watermass property variations suggesting layer-thickness changes. The total transport to the two neighboring basins is only about 1 Sverdrup (1Sv ≡ 106 m3 s−1) but has considerable impact on the watermass structure in these basins. Estimates are given for the diapycnal mixing that is required to balance the inflow into the East Caroline Basin. Farther above in the water column, the high-silica tongue of NPDW extends from the east to the far southwestern corner of the East Mariana Basin, with transports being mostly southward across the basin.

Description: The distribution of platinum group elements (PGE) in Cu- and Zn-rich samples from the Roman Ruins and Satanic Mills vent sites in the PACMANUS hydrothermal field (Papua New Guinea) was studied and compared to that from selected ancient volcanogenic massive sulfide (VMS) deposits. Samples from the Satanic Mills site are enriched in Pd and Rh when compared to samples from Roman Ruins and reach highest values in active and inactive Cu-rich black smoker chimneys and chalcopyrite-cemented dacite breccias (up to 356 ppb Pd and up to 145 ppb Rh). A significant positive correlation was established between Cu and Pd and Rh in samples from both vent sites. Comparisons of chondrite normalized patterns and values of Pd/Pt and Pd/Ir ratios in Cu-rich sulfides and probable source rocks (felsic volcanic rocks/MORB) along with the evidence for a magmatic component in the PACMANUS hydrothermal system indicate that leaching of back-arc volcanic rocks together with addition of magmatic volatiles to the convecting hydrothermal system was the most important factor for PGE enrichment at PACMANUS and likely at some PGE-enriched ancient VMS deposits.

Description: The Greens Creek polymetallic massive sulphide deposit is hosted in a typical polyphase deformed lower greenschist facies orogenic setting. The structure of the host rocks is well constrained, exhibiting a series of three superimposed ductile deformations followed by two brittle episodes. The ore is found both in fold hinges where early-formed depositional features are preserved and in fold limbs where primary features are typically strongly modified or obliterated. Samples from both settings have been investigated using electron backscatter diffraction (EBSD) coupled with forescatter orientation contrast (OC) imaging in order to observe the effects of deformation and lower greenschist facies metamorphism on pyrite. Results suggest that colloform pyrite may preserve information relevant to palaeoenvironment, that apparently simple textures are generally more complex, and that pyrite can deform plastically by dislocation glide and creep processes at lower temperatures and/or strain rates than generally accepted. This analysis indicates that EBSD and OC imaging provide powerful tools for observing textural relationships in pyrite that are not shown by more traditional methods. They should become routine tools for pyrite texture analysis.

Description: Sea surface temperature (SST) observations in the North Atlantic indicate the existence of strong multidecadal variability with a unique spatial structure. It is shown by means of a new global climate model, which does not employ flux adjustments, that the multidecadal SST variability is closely related to variations in the North Atlantic thermohaline circulation (THC). The close correspondence between the North Atlantic SST and THC variabilities allows, in conjunction with the dynamical inertia of the THC, for the prediction of the slowly varying component of the North Atlantic climate system. It is shown additionally that past variations of the North Atlantic THC can be reconstructed from a simple North Atlantic SST index and that future, anthropogenically forced changes in the THC can be easily monitored by observing SSTs. The latter is confirmed by another state-of-the-art global climate model. Finally, the strong multidecadal variability may mask an anthropogenic signal in the North Atlantic for some decades.

Description: Pelado, Guespalapa, and Chichinautzin monogenetic scoria cones located within the Sierra del Chichinautzin Volcanic Field (SCVF) at the southern margin of Mexico City were dated by the radiocarbon method at 10,000, 2,800–4,700, and 1,835 years b.p., respectively. Most previous research in this area was concentrated on Xitle scoria cone, whose lavas destroyed and buried the pre-Hispanic town of Cuicuilco around 1,665±35 years b.p. The new dates indicate that the recurrence interval for monogenetic eruptions in the central part of the SCVF and close to the vicinity of Mexico City is 〈2,500 years. If the entire SCVF is considered, the recurrence interval is 〈1,700 years. Based on fieldwork and Landsat imagery interpretation a geologic map was produced, morphometric parameters characterizing the cones and lava flows determined, and the areal extent and volumes of erupted products estimated. The longest lava flow was produced by Guespalapa and reached 24 km from its source; total areas covered by lava flows from each eruption range between 54 (Chichinautzin) and 80 km2 (Pelado); and total erupted volumes range between 1 and 2 km3/cone. An average eruption rate for the entire SCVF was estimated at 0.6 km3/1,000 years. These findings are of importance for archaeological as well as volcanic hazards studies in this heavily populated region.

Description: Several epibiotic species reduce starfish (Asterias rubens) preference for the blue mussel Mytilus edulis in the Baltic. The aim of this study was to reveal whether this associational resistance was caused by structural or chemical aspects of the different epibionts. To assess structural epibiont effects, an in situ experiment was conducted with unfouled mussels and mussels equipped with artificial epibionts ('dummies') exposed to natural predation by A. rubens. The chemically inert dummies closely matched the structural properties of the locally common epibionts Balanus improvisus (barnacle), Ceramium strictum (red alga), Halichondria panicea (sponge), and Laomedea flexuosa (hydrozoan). Starfish fed indiscriminately in all treatments. Chemical effects of epibionts on the attractiveness of mussels for A. rubens were investigated by incorporating freeze-dried epibionts or mussel tissue into Phytagel pellets at natural concentrations. Starfish were allowed to choose among these structurally similar but chemically different prey items in an in vitro experiment. The predators exhibited significant preferences among the food pellets, which closely matched their preferences for corresponding natural mussel-epibiont associations. Thus, chemical aspects of epibionts appear to play a larger role in this associational resistance than do structural aspects. Implications of these indirect interactions for benthic communities are discussed.

Description: A systematic modular approach to investigate the respective roles of the ocean and atmosphere in setting El Niño characteristics in coupled general circulation models is presented. Several state-of-the-art coupled models sharing either the same atmosphere or the same ocean are compared. Major results include 1) the dominant role of the atmosphere model in setting El Niño characteristics (periodicity and base amplitude) and errors (regularity) and 2) the considerable improvement of simulated El Niño power spectratoward lower frequencywhen the atmosphere resolution is significantly increased. Likely reasons for such behavior are briefly discussed. It is argued that this new modular strategy represents a generic approach to identifying the source of both coupled mechanisms and model error and will provide a methodology for guiding model improvement.

Description: Late Holocene volcanic activity at Ruapehu has been characterizedby the generation of small (〈105 m3) to very large (〉107 m3) lahars and repeated,small to medium (VEI 1-3) tephra-producing eruptions. The Onetapu Formation groupsall lahar deposits that accumulated during the last 2,000 years on the southeastern Ruapehu ring plain. The andesitic tephras are grouped within the Tufa Trig Formation and are intercalated within the laharic sequence. By correlating these two formations with new radiocarbon ages obtained on interbedded paleosols, we reconstruct a detailed volcanic history of Ruapehu for this period. Clast assemblages identified in the laharic sequences record thelithologies of synchronous tephras and rocks within the source region. These assemblages suggest a strong genetic link between the development of Crater Lake, the variation in eruptivestyles, and the production of lahars. Lahar-triggering mechanisms include: (1) flank collapse ofhydrothermally altered and unstable portions of the cone; (2) phreatic and phreatomagmatic eruptions favoring the generation of snow-rich slurries and hyperconcentrated stream flows; (3) suddenCrater Lake rim collapse, releasing large amounts of water inducing debris flows; and (4) eruptions that generate large volumes of tephra on snow-covered slopes, later remobilized by heavy rain. Two major lahars in the Onetapu sequence had a volume≥ 4 × 107 m3, roughly 1 to 2 orders of magnitude larger than the 1953event leading to the Tangiwai disaster (151 casualties). One of these lahars crossed over a lowinterfluve currently separating the Whangaehu River from a stream feeding the Tongariro River,sometime since peat accumulated between AD 1400 and AD 1660. A repetition of such a large-scaleevent would have devastating consequences on the infrastructure, economy and environment withinthe distal areas of the two catchments. The 1995–1996 eruptions were a timely reminder ofthe hazards posed by the volcano.

Description: The Indonesian Throughflow (ITF) spreading pathways and time scales in the Indian Ocean are investigated using both observational data and two numerical tracer experiments, one being a three-dimensional Lagrangian trajectory experiment and the other a transit-time probability density function (PDF) tracer experiment, in an ocean general circulation model. The model climatology is in agreement with observations and other model results except that speeds of boundary currents are lower. Upon reaching the western boundary within the South Equatorial Current (SEC), the trajectories of the ITF tracers within the thermocline exhibit bifurcation. The Lagrangian trajectory experiment shows that at the western boundary about 38%±5% thermocline ITF water flows southward to join the Agulhas Current, consequently exiting the Indian Ocean, and the rest, about 62%±5%, flows northward to the north of SEC. In boreal summer, ITF water penetrates into the Northern Hemisphere within the Somali Current. The primary spreading pathway of the thermocline ITF water north of SEC is upwelling to the surface layer with subsequent advection southward within the surface Ekman layer toward the southern Indian Ocean subtropics. There it is subducted and advected northward in the upper thermocline to rejoin the SEC. Both the observations and the trajectory experiment suggest that the upwelling occurs mainly along the coast of Somalia during boreal summer and in the open ocean within a cyclonic gyre in the Tropics south of the equator throughout the year. All the ITF water eventually exits the Indian Ocean along the western boundary within the Mozambique Channel and the east coast of Madagascar and, farther south, the Agulhas Current region. The advective spreading time scales, represented by the elapsed time corresponding to the maximum of transit- time PDF, show that in the upper thermocline the ITF crosses the Indian Ocean, from the Makassar Strait to the east coast of the African continent, on a time scale of about 10 yr and reaches the Arabian Sea on a time scale of over 20 yr.

Description: Polymetallic sulfide-sulfate mineralization enriched in Pb-Ag-As-Sb-Hg occurs in the Bransfield Strait, a late Tertiary-Quaternary marginal basin close to the Antarctic Peninsula. The mineralization is associated with bimodal volcanism and pelagic and volcaniclastic sediment in rifted continental crust. Hydrothermal precipitates have been recovered from two shallow (1,050–1,000 m water depth) submarine volcanoes (Hook Ridge and Three Sisters) in the Central Bransfield Strait. Mineralization at Hook Ridge consists of polymetallic sulfides, massive barite, and pyrite and marcasite crusts in semilithified pelagic and volcaniclastic sediment. Native sulfur commonly infills void space and cements the volcaniclastic sediment. The polymetallic sulfides are dominated by sphalerite with minor galena, enargite, tetrahedrite-tennantite, pyrite, chalcopyrite, and traces of orpiment cemented by barite and opal-A. The presence of enargite at Hook Ridge, the abundance of native sulfur, and the low Fe content of sphalerite indicate a high sulfur activity of the hydrothermal fluids responsible for mineralization. The sulfur isotopic composition of Hook Ridge precipitates documents the complexity of the sulfur sources in this hydrothermal system with variable influence of biological activity and possibly magmatic contributions. Homogenization temperatures and salinities of fluid inclusions in barite and opal-A suggest that boiling may have affected the hydrothermal fluids during their ascent. The discovery of massive barite-silica precipitates at another shallow marine volcano (Three Sisters volcano) attests to the potential for hydrothermal mineralization at other volcanic edifices in the area. The characteristics of the mineralization in the Bransfield Strait with rifting of continental crust, the presence of bimodal volcanism, including highly evolved felsic volcanic rocks, the association with sediments, and the Pb-Ag-As-Sb-Hg enrichment are similar to the setting of massive sulfide deposits in the Okinawa Trough, and distinct from those of sediment-dominated hydrothermal systems such as Escanaba Trough, Middle Valley, and Guaymas Basin. The geological setting of the Bransfield Strait is also broadly similar to that of some of the largest volcanogenic massive sulfide deposits in the ancient record, such as the Iberian Pyrite Belt.

Description: We present evidence for the origin of the Lyngen Gabbro of the Ordovician Lyngen Magmatic Complex in Troms, Northern Norway. The two magmatic suites of the Lyngen Gabbro strike parallel NNE-SSW, and have distinct magmatic signatures. We define these signatures by using major and trace-element analyses together with selected major- and trace-element mineral analyses and 143Nd/144Nd-isotope whole-rock analyses of gabbroic to tonalitic plutonic rocks from seven detailed cross-sections from this large gabbro-complex. The Western suite of the Lyngen Gabbro precipitated from magma that may have been derived from the same system as the associated volcanic rocks. The gabbros have high An-content (An〉90) of their plagioclases relative to co-existing mafic minerals. Together with somewhat high ɛNd(t) values (+6), this implies that the parental magmas were hydrous tholeiites similar to those found in back arc basins today. The Eastern suite, on the other hand, consist of cumulates that were precipitated from melts resembling those of ultra-depleted high-Ca boninitic magmas found in fore-arcs. Extremely high-An plagioclases (An〉95) co-exist with evolved mafic minerals and oxides, and the ɛNd(t) values are lower (+4) than in the Western suite. The Eastern suite has no volcanic counterpart, but dikes intersecting the suites have compositions that possibly represent its parental magma. The oceanic Rypdalen Shear Zone generally separates the two suites in the north, but several non-tectonic transitions from boninitic to tholeiitic signatures southwards advocate that the magmatism happened concurrently. The magmatic proximity between the suites, the hydrous magmatism and the absence of a silicic or calc-alkaline mature arc section, suggests that the Lyngen Gabbro formed in the Iapetus Ocean under conditions presently found in incipient arcs later emplaced as outer arc highs.

Description: Rising atmospheric CO2 and deliberate CO2 sequestration in the ocean change seawater carbonate chemistry in a similar way, lowering seawater pH, carbonate ion concentration and carbonate saturation state and increasing dissolved CO2 concentration. These changes affect marine plankton in various ways. On the organismal level, a moderate increase in CO2 facilitates photosynthetic carbon fixation of some phytoplankton groups. It also enhances the release of dissolved carbohydrates, most notably during the decline of nutrient-limited phytoplankton blooms. A decrease in the carbonate saturation state represses biogenic calcification of the predominant marine calcifying organisms, foraminifera and coccolithophorids. On the ecosystem level these responses influence phytoplankton species composition and succession, favouring algal species which predominantly rely on CO2 utilization. Increased phytoplankton exudation promotes particle aggregation and marine snow formation, enhancing the vertical flux of biogenic material. A decrease in calcification may affect the competitive advantage of calcifying organisms, with possible impacts on their distribution and abundance. On the biogeochemical level, biological responses to CO2 enrichment and the related changes in carbonate chemistry can strongly alter the cycling of carbon and other bio-active elements in the ocean. Both decreasing calcification and enhanced carbon overproduction due to release of extracellular carbohydrates have the potential to increase the CO2 storage capacity of the ocean. Although the significance of such biological responses to CO2 enrichment becomes increasingly evident, our ability to make reliable predictions of their future developments and to quantify their potential ecological and biogeochemical impacts is still in its infancy.

Description: Aspects of the sea level changes in the western Mediterranean Sea are investigated using a numerical tidal model of the Strait of Gibraltar. As a prerequisite, the performance of this model, that is, a two-dimensional, nonlinear, two-layer, boundary-fitted coordinate numerical model based on the hydrostatic approximation on an f plane, is assessed in the simulation of mean and tidal circulation of the Strait of Gibraltar. The model is forced by imposing mean interface and surface displacements as well as M2, S2, O1, and K1 tidal components along the Atlantic and Mediterranean model open boundaries. Model results are compared with observations and with results obtained from a tidal inverse model for the eastern entrance of the Strait of Gibraltar. In general, good agreement is found. A sensitivity study performed by varying different model parameters shows that the model behaves reasonably well in the simulation of the averaged circulation. The model is then used to investigate the climatological sensitivity of the simulated dynamics in the Strait of Gibraltar to changes in the density difference between Atlantic and Mediterranean waters. For this purpose, given a certain density difference between Atlantic and Mediterranean waters, the authors iteratively searched for that sea level drop between the Atlantic and the Mediterranean that fulfills the mass balance of the Mediterranean. It is found that an increase of the density difference leads to an increase of the exchange flow and to an increase of the sea level drop between the two basins. A trend in the sea level drop of O(1 cm yr−1), such as the one observed between 1994 and 1997, is explained by the model as the result of a trend of O(10−4 yr−1) in the relative density difference between the Mediterranean and Atlantic waters. The observed north–south asymmetry in this trend is also captured by the model, and it is found to arise from changes in the along-strait velocity. Results suggest that the dynamics within the Strait of Gibraltar cannot be neglected when sea level changes in the western Mediterranean basin are investigated.

Description: The most important archive of Earth’s climate change through geologic history is the sedimentary rock record. Rhythmic sedimentary alternations are usually interpreted as a consequence of periodic variations in the orbital parameters of the Earth. This interpretation enables the application of cyclostratigraphy as a very precise chronometer, when based on the assumption that orbital frequencies are faithfully recorded in the sedimentary archive. However, there are numerous uncertainties with the application of this concept. Particularly in carbonates, sediment properties such as mineralogical composition and fossil associations are severely altered during post-depositional alteration (diagenesis). We here point out that the assumption of a 1:1 recording of orbital signals in many cases is questionable for carbonate rhythmites. We use computer simulations to show the effect of diagenetic overprint on records of orbital signals in the carbonate record. Such orbital signals may be distorted in terms of frequency, amplitude, and phase by diagenetic processes, and cycles not present in the insolation record may emerge. This questions the routine use of carbonate rhythmites for chronostratigraphic dating

Description: Copepoda (Calanus finmarchicus n=1,722, Paraeuchaeta norvegica n=1,955), Hyperiidae (n=3,019), Euphausiacea (Meganyctiphanes norvegica n=4,780), and the fishes Maurolicus muelleri (n=500) and Pollachius virens (n=33) were collected in the Norwegian Deep (northern North Sea) during summer 2001 to examine the importance of pelagic invertebrates and vertebrates as hosts of Anisakis simplex and their roles in the transfer of this nematode to its final hosts (Cetaceans). Third stage larvae (L3) of A. simplex were found in P. norvegica, M. muelleri and P. virens. The prevalence of A. simplex in dissected P. norvegica was 0.26%, with an intensity of 1. Prevalences in M. muelleri and P. virens were 49.6% and 100.0%, with mean intensities of 1.1–2.6 (total fish length ≥6.0–7.2) and 193.6, respectively. All specimens of C. finmarchicus and M. norvegica examined were free of anisakid nematode species and no other parasites were detected. P. norvegica, which harboured the third stage larvae, is the obligatory first intermediate host of A. simplex in the investigated area. Though there was no apparent development of larvae in M. muelleri, this fish can be considered as the obligatory second intermediate host of A. simplex in the Norwegian Deep. However, it is unlikely that the larva from P. norvegica can be successfully transmitted into the cetacean or pinniped final hosts, where they reach the adult stage. An additional growth phase and a second intermediate host is the next phase in the life cycle. Larger predators such as P. virens serve as paratenic hosts, accumulating the already infective stage from M. muelleri. The oceanic life cycle of A. simplex in the Norwegian Deep is very different in terms of hosts and proposed life cycle patterns of A. simplex from other regions, involving only a few intermediate hosts. In contrast to earlier suggestions, euphausiids have no importance at all for the successful transmission of A. simplex in the Norwegian Deep. This demonstrates that this nematode is able to select definite host species depending on the locality, apparently having a very low level of host specificity. This could explain the wide range of different hosts that have been recorded for this species, and can be seen as the reason for the success of this parasite in reaching its marine mammal final hosts in an oceanic environment.

Description: Participatory rural appraisal (PRA) methods and philosophies were trialed in a volcanic risk management planning and awareness activity for Savo Island, a historically highly destructive volcano in the Solomon Islands. Through a combination of methods we tried to combine the roles of facilitators and educators, and to involve the input of all stakeholders (from community to national government) in the process of volcanic risk management. The PRA approach was an ideal way to address the fundamental differences in outlook, education, needs, and roles of individuals and groups involved or affected. It was also an important catalyst to Savo island- or community-based planning initiatives, which are arguably the most important step toward the preparedness of the 2500 inhabitants of the island for any future destructive volcanic activity. We adapted almost every tenet of the PRA philosophy through inexperience, self-perceived importance and desire to combine both scientific and traditional views for Savo volcanic risk management planning. Nevertheless, what emerged from our experiences was an idea of how fundamentally well suited many PRA approaches are to initiating dialogue within diverse stakeholder groups, and deriving combined scientific/geologic and local/community risk assessments and mitigation action plans. The main challenge remaining includes increasing the involvement or voice of less powerful community members (women, youth, non-landowners) in risk management decision-making in such male-dominated hierarchical societies.

Description: A planar problem of nonlinear transverse oscillations of the surface (warm) front of a finite width is considered within the framework of a reduced-gravity model of the ocean. The source of oscillations is the departure of the front from its geostrophic equilibrium. When the current velocity is linear in the horizontal coordinate and the front's depth is quadratic in this coordinate, the problem is reduced to a system of four ordinary differential equations in time. As a result, the solution is obtained in a weakly nonlinear approximation and strongly nonlinear oscillations of the front are studied by numerically solving this system of equations by the Runge-Kutta method. The front's oscillations are always superinertial. Nonlinearity can lead to a decrease or increase in the oscillation frequency in comparison with the linear case. The oscillations are most intense when the current velocity is disturbed in the direction of the front's axis. A weakly nonlinear solution of the second order describes the oscillations very accurately even for initial velocity disturbances reaching 50% of its geostrophic value. An increase in the background-current shear leads to the damping of oscillations of the front's boundary. The amplitude of oscillations of the current velocity increases as the intensity of disturbances increases, and it is relatively small if background-current shears are small or large.

Description: Coccolithophores first became significant participants in the carbonate cycle in the Jurassic, but throughout the Jurassic they were largely restricted to shelf and epeiric sea environments. They spread into the open ocean in the Cretaceous, and with this became a major factor in governing the carbonate cycle in the sea. With the development of dissolution-resistant forms, such as Watznaueria barnesae, the coccolithophores perturbed the carbonate system and switched the major site of carbonate deposition from shallow seas to the deep ocean. Several major evolutionary steps in the development of the coccolithophores have forced further changes in the carbon cycle, favoring the deep sea as a site of carbonate deposition. Samples of recent coccolith assemblages from bottom sediments differ from those of living coccolithophores in surface waters. Many of the coccoliths of more delicate species, particularly holococcoliths, are dissolved in the water column or at the sediment surface and are only rarely preserved as fossils. They, along with the pteropods, form an important part of the shallow carbonate cycle. There appears to be a continuous gradation in the level of susceptibility of coccoliths to dissolution, from forms that dissolve in the near-saturated waters of the surface ocean to those that are among the most dissolution-resistant forms of calcite. This continuous dissolution spectrum is in contrast to the planktic foraminifera, in which dissolution of the tests also occurs in a sequence, but through a much more restricted depth range, the lysocline. Whereas the order of dissolution of planktic foraminifera follows their habitat, with warm-water species being most susceptible and cold-water forms most resistant to dissolution, the order of dissolution of coccoliths appears to be related to phylogeny. The steepness of the coccolith carbonate dissolution gradient appears to have changed over time. In the Oligocene almost pure nannofossil carbonate oozes devoid of terrigenous material were widespread, perhaps reflecting unusual climatic conditions on land. The overall effect of coccolithophore evolution has been to move carbonate deposition to the deep sea, where coccolith oozes accumulate on ocean crust and will ultimately be subducted. Only a fraction of the carbon in the subducted carbonate is returned to the surface through volcanic activity. If their activity were to continue for several hundreds of millions of years the coccolithophores would remove much of the carbon from the surface of the Earth to be emplaced in the mantle.

Description: Gas emissions from mud volcanoes on Sakhalin Island and water-column gas flares arising from cold seeps in the Okhotsk Sea appear to be related. They are likely activated by tectonic movements along the transform plate boundary separating the Okhotsk Sea Plate from the Eurasian and Amur plates. Gas vents (flares) and methane anomalies occur in the waters offshore Sakhalin Island, along with NE-SW-trending mounds and fluid escape structures on the seafloor. The intersection of the NE-striking transverse faults on land with the Central Sakhalin and Hokkaido-Sakhalin shear zones apparently determines the sites of mud volcanoes, a pattern that continues offshore where the intersection with the East Sakhalin and West Derugin shear zones determines the sites of the submarine gas vents.

Description: The bifurcation behavior of a conceptual heat–salt oscillator model is analyzed by means of numerical continuation methods. A global (homoclinic) bifurcation acts as an organizing center for the dynamics of the simplified convective model. It originates from a codimension-2 bifurcation in an extended parameter space. Comparison with earlier work by Cessi shows that the intriguing stochastic thermohaline excitability can be understood from the bifurcation structure of the model. It is argued that global bifurcations may play a crucial role in determining long-term variability of the thermohaline circulation.

Description: A method is presented to reconstruct decadal variations of the North Atlantic Oscillation (NAO). The spectral characteristics of the NAO on time scales of decades and longer are of particular interest for the understanding of North Atlantic ocean–atmosphere interactions. The reconstruction is based on a transfer model calibration that uses bandpass-filtered time series. The maximum overlap discrete wavelet transform (MODWT) is applied for decomposing the time series variance into different time scales. A total of 43 proxies, including Greenland ice cores and European tree-ring chronologies, are selected and regionally grouped providing four independent reconstructions for the period 1700–1978. The mean reconstruction agrees well with two recently published reconstructions during most of the time period. However, there are considerable differences in the earliest part before 1750. Running correlations between the reconstructions indicate that time-dependent relations exist among the different NAO reconstructions. The results suggest that the geographical distribution of proxies strongly affects the reconstruction and could explain some of the apparent discrepancies among the reconstructions recently published in literature. In the early eighteenth century, external forcing (solar, volcanic) seems to mask the NAO signature within the proxies

Description: The deep circulation and related transports of the southern Labrador Sea are determined from direct current observations from ship surveys and a moored current-meter array. The measurements covered a time span from summer 1997 to 1999 and show a well-defined deep boundary current extending approximately out to the 3300-m depth contour and weak reverse currents farther offshore. The flow has a strong barotropic component, and significant baroclinic flow is only found in the shallow Labrador Current at the shelf break and associated with a deep core of Denmark Strait Overflow Water. The total deep-water transport below σΘ = 27.74 kg m−3 was 26 ± 5 Sv (Sv ≡ 106 m3 s−1) comprising Labrador Sea Water (LSW), Gibbs Fracture Zone Water (GFZW), and Denmark Strait Overflow Water (DSOW). Intraseasonal variability of the flow and transport was high, ranging from 15 to 35 Sv, and the annual means differed by 17%. A seasonal cycle is confined to the shallow Labrador Current; in its deeper part, where the mean flow is still strong, no obvious seasonality could be detected. The transport of the interior anticyclonic recirculation was estimated from lowered acoustic Doppler current profiler stations and geostrophy, yielding about 9 Sv. Thus, the net deep-water outflow from the Labrador Sea was about 17 Sv. The baroclinic transport of GFZW and DSOW referenced to the depth of the isopycnal σΘ = 27.80 kg m−3 is only about one-third of the total transport in these layers. Longer-term variations of the total transports are not represented well by the baroclinic contribution.

Description: Methane investigations carried out in the Okhotsk Sea show that the methane flux from the earth’s interior into the water column increased during periods of seismo-tectonic activity between 1988 and 2002. In this case, methane gas hydrates found on the northeast Sakhalin slope may have decomposed due to a reactivation of fault zones. Methane emissions in the Okhotsk Sea generally can be divided into two forms. Firstly, methane vents from decomposing gas hydrates and/or free gas exist below gas hydrate saturated sediments via fault zones, venting into the water column with high bubble concentrations that were recorded by echosounding. These hydro-acoustic anomalies were named “flares”. Methane concentration inside these flares reached 10,000–20,000 nl/l (background methane concentrations in the Okhotsk Sea are less than 90–100 nl/l). Secondly, methane migrates as seepage into the water column from oil- and gas-bearing sedimentary source rocks on the eastern Sakhalin shelf, without showing acoustic anomalies in the water column, probably by filtration and diffusion processes. In these areas methane concentration reached 500–3,000 nl/l. In seismo-tectonically active regions, like the northwestern part of the Okhotsk Sea, many new flares were observed. Their distribution and orientation are usually controlled by fault zones (East Sakhalin Shear Zone in the Okhotsk Sea).

Description: The ingestion of two size classes of natural particulate matter (PM) and the uptake of the associated nitrogen by four species of scleractinian corals was measured using the stable isotopic tracer 15N. PM collected in sediment traps was split into 〈63 and 〉105 µm size fractions and labeled with (15N-NH4)2SO4. Siderastrea radians, Montastrea franksi, Diploria strigosa, and Madracis mirabilis were incubated in flow chambers with the labeled PM in suspension (〈63 µm), or deposited onto coral surfaces (〉105 µm). Ingestion was detected for all four species (98–600 µg Dry wt. cm–2 h–1), but only for D. strigosa was any difference detected between suspended and deposited PM. Only the three mounding species, S. radians, M. franksi, and D. strigosa showed uptake of suspended and deposited particulate nitrogen (PN); whereas, the branched coral M. mirabilis had no measurable PN uptake. Only coral host tissues were enriched with 15N, with no tracer detected in the symbiotic zooxanthellae. Uptake rates ranged from as low as 0.80 µg PN cm–2 h–1 in S. radians to as high as 13 µg PN cm–2 h–1 in M. franksi. M. franksi had significantly higher uptake rates than S. radians (ANOVA, p〈0.05), while D. strigosa had a statistically similar uptake rate compared to both species. These results are the first to compare scleractinian ingestion of nitrogen associated with suspended and deposited particulate matter, and demonstrate that the use of PM as a nitrogen source varies with species and colony morphology.

Description: As part of an ongoing research program aiming at monitoring molecular changes in the tissues and metabolite trafficking in the hydrosphere of algae subjected to chemical stresses, we are discussing the various analytical techniques that have been employed to characterize, and sometimes to quantity these metabolites. High-field multinuclear and solid-state nuclear magnetic resonance (NMR) spectroscopies are powerful tools for metabolite characterization from extracts and in vivo, but quantification and kinetic aspects show some limitations. Modern MS (mass spectrometry) is extremely useful for fingerprinting samples against databases and when dealing with very low concentrations of metabolites, the limitations being set by the type of chromatographic separation and mode of detection coupled with the mass spectrometer. Regarding chemical communication, optimization in terms of resolution and efficiency of hydrosphere chemical analysis can theoretically be achieved in a system which integrates (i) a multiparametric incubation chamber, (ii) a gasphase or a liquid-phase separation system and (iii) mass spectrometer(s) equipped with one or two detectors responding to the analytical and quantitative needs. This text reviews some of the techniques that have been employed in various types of plant metabolic studies, which may serve as a basis towards an integrative analytical strategy directly applicable to the metabolomics of selected marine macrophytes.

Description: Instrumental climate records are too short to resolve the full range of decadal- to multidecadal-scale natural climate variability. Massive annually banded corals from the tropical and subtropical oceans provide a paleoclimatic archive with a clear seasonal resolution, documenting past variations in water temperature, hydrologic balance, and ocean circulation. Recent coral-based paleoclimatic research has focused mainly on the tropics, providing important implications on the past variability of the El Niño—Southern Oscillation phenomenon and decadal tropical climate variability. New records from some of the rare subtropical/mid-latitude locations of coral growth were shown to reflect aspects of dominant modes of Northern Hemisphere climate variability, e.g., the North Atlantic Oscillation/Arctic Oscillation. These natural climatic modes have important socio-economic impacts owing to their large-scale modulation of droughts, floods, storms, snowfall, and fish stocks. Coral records from key locations provide the opportunity to assess recent shifts of these modes with respect to the natural climate variability of the pre-instrumental period. Providing a better understanding of their dynamics, coral records, together with records derived from other paleoclimatic archives, are essential for a better predictability of future climate.

Description: The bioavailability of nutrients represents one of the most important factors controlling the strength of the biological carbon pump and ultimately the impact of ocean biology on atmospheric CO2. Among those nutrients, the macro-nutrients nitrate (NO 2 - ) and phosphate (PO 4 -3 ) play a particularly important role in limiting biological productivity as evidenced by their often near complete exhaustion in surface waters. As near surface NO 2 - concentrations are generally somewhat lower than those of PO 4 -3 relative to the demand by phytoplankton, biological oceanographers have argued historically that NO 2 - rather than PO 4 -3 is the primary macro-nutrient controlling phytoplankton productivity[Smith, 1984; Codispoti, 1989; Tyrrell, 1999] . Geologists, in contrast, regarded PO 4 -3 as the primary controlling macronutrient[Codispoti, 1989]. They argued that while NO 2 - may indeed be the limiting factor at any given location and time, PO 4 -3 is truly the limiting factor on geological time-scales, because the biologically mediated fixation of the much more abundant dinitrogen gas (N2) into organic nitrogen is alleviating the scarcity of bioavailable nitrogen (Figure 1). Phosphate on the other hand, does not have such a biologically mediated source (Figure 1). It is therefore the geologically controlled balance between the riverine (and atmospheric) input of PO 4 -3 and its burial on the sea-floor that ultimately controls marine biological productivity. Tyrrell [ 1999] provided a synthesis of these two views by identifying NO 2 - as the proximate nutrient, while giving PO 4 -3 the role of being the ultimate nutrient.

Description: Changes in the protein, lipid, glycogen, cholesterol and energy contents, total amino acid and fatty acid profiles of Octopus vulgaris and O. defilippi tissues (gonad, digestive gland and muscle) during sexual maturation (spermatogenesis and oogenesis) were investigated. Both species showed an increase of amino acids and protein content in the gonad throughout sexual maturation (namely in oogenesis), but allocation of these nitrogen compounds from the digestive gland and muscle was not evident. The major essential amino acids in the three tissues were leucine, lysine and arginine. The major non-essential amino acids were glutamic acid, aspartic acid and alanine. With respect to carbon compounds, a significant increasing trend (P〈0.05) in the lipid and fatty acid contents in the three tissues was observed, and, consequently, there was also little evidence of accumulated lipid storage reserves being used for egg production. It seems that for egg production both Octopus species use energy directly from food, rather than from stored products. This direct acquisition model contrasts with the previous model for Octopus vulgaris proposed by O’Dor and Wells (1978: J Exp Biol 77:15–31). Most of saturated fatty acid content of the three tissues was presented as 16:0 and 18:0, monounsaturated fatty acid content as 18:1 and 20:1 and polyunsaturated fatty acid content as arachidonic acid (20:4n-6), eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3). Though cholesterol is an important precursor of steroid hormones, this sterol content exhibited variations that do not seem to be related with the maturation process. Moreover, significant differences (P〈0.05) were obtained between genders, suggesting that perhaps there is a greater physiological demand for cholesterol during spermatogenesis than oogenesis. If the component sterols of octopus are of a dietary origin, considerable variation in the cholesterol content between species might be expected on the basis of the sterol composition of their prey. The glycogen reserves increased significantly in the gonad and decreased significantly (P〈0.05) in the digestive gland and muscle of O. vulgaris (these trends were not evident in O. defilippi). Glycogen may play an important role in the maturation process and embryogenesis of these organisms, because carbohydrates are precursors of metabolic intermediates in the production of energy. It was evident that sexual maturation had a significant effect upon the gonad energy content, but the non-significant energy variation (P〉0.05) in the digestive gland and muscle revealed no evidence that storage reserves are transferred from tissue to tissue. The biochemical composition of digestive gland and muscle may not be influenced by sexual maturation, but rather by other biotic factors, such as feeding activity, food availability, spawning and brooding.

Description: Benthic divers are dependent on local resources and may therefore adopt different foraging strategies to cope with their energetic requirements in varying situations. We investigated the diet of gentoo penguins (Pygoscelis papua) at Kerguelen Islands, comparing its spatial and temporal variations with the general prey distribution. The study was conducted at four sites over 2 years. In total, 212 stomach contents were collected over the entire breeding season. The diet was composed mainly of neritic fish and crustaceans, with important spatial and seasonal variations. Fish dominated the diet at localities facing the open sea (from 38.0% to 94.6% by mass), whereas crustaceans dominated at the more protected site (84.3% by mass). Fish were more abundant in the winter diet and Euphausia vallentini, the major crustacean species, was more abundant in the summer diet. No inter-year variations were detected. These results are consistent with local prey availability, and highlight the large plasticity of the gentoo penguin diet and foraging behaviour.

Description: Within the Southern Ocean, Patagonian toothfish (Dissostichus eleginoides Smitt) and southern elephant seals (Mirounga leonina Linnaeus) forage mainly on fish and cephalopods. From what is known of their diets, the proportion of fish is greatest in toothfish diet. When foraging at-sea for squid, elephant seals and toothfish most often co-occur over continental shelves and submarine plateaux surrounding sub-Antarctic land masses within the Southern Ocean. I used traditional (non-molecular) techniques to compare the squid diet of these two predators. Of the 21 squid species identified, 10 were common to the diets of both predators. One species, Gonatus antarcticus, dominated (61%) the biomass of squid consumed by toothfish, but was of little importance to the elephant seals (2.3%). By contrast, Martialia hyadesi was the most important single species to the elephant seals’ diet (29%), but it contributed 1% to the toothfish diet. Onychoteuthids (Kondakovia longimana, Moroteuthis ingens and Morotenthis knipovitchi) were important to both predators’ diets. The median sizes of five cephalopod species (Slosarczykovia circumantarctica, Galiteuthis glacialis, Gonatus antarcticus, Moroteuthis ingens and Moroteuthis knipovitchi) which were common to both the seal and toothfish diets, were significantly larger in the toothfish stomachs than in the elephant-seal stomachs. Percent similarity indices for the squids that overlapped both diets were in some cases as high as 100%. However, after between-species differences in prey size consumption were accounted for, the similarities fell to between 20 and 50%. These results indicate that the strength of the trophic interaction between the seals and the fish might be weaker than previously thought. The consumption of significantly different-sized squid can also be used to suggest spatial (vertical) foraging separation of these two predators because there is evidence for ontogenetic change in the size of squid species with depth; older, and thus larger, squids live deeper than smaller individuals of the same species.

Description: Recent evidence suggests that, contrary to what was believed previously, most Loligo spp. females spawn multiple times and do not die immediately following a single spawning event. The present study used sustained focal observations of male/female pairs of the opalescent inshore squid Loligo opalescens Berry to examine the structure and behavior of near-bottom spawning groups. The study was carried out in a small area (10 km2) of Monterey Bay, California (36°36.1′N; 121°53.4′W), at depths of 25–45 m, using video cameras mounted on remotely operated vehicles. Behavioral observations were made primarily during daylight hours over known spawning beds in April and November 2000, and August 2001. Squid formed large aggregations in the water column where pairing occurred. Most commonly, only small numbers of active spawners were found at the substrate depositing egg capsules, and the mean operational sex ratio in the spawning groups was 1.87 males:1 female (range=1.0–8.5), although the ratio fluctuated rapidly as roving lone males joined and departed from the small spawning groups. On average, females (n=40) deposited 2.67 capsules (range 2–7) per focal observation at an average interval of 8.47 min between depositions (n=67). Following deposition of the capsules, females broke away from their consort males and jetted upwards to rejoin large schools located many meters above the substrate. Egg-capsule deposition was often interrupted by lone males seeking a mate, or by the approach of predators including fish and marine mammals. The results suggest that most of the communal egg beds in southern Monterey Bay are built up slowly through daily intermittent spawning, not in large “big bang” reproductive events as often depicted for L. opalescens.

Description: This study examined the diet of Antarctic fur seals, Arctocephalus gazella, from an active breeding colony at Cape Shirreff (62°28′S, 60°48′W), Livingston Island, South Shetland Archipelago, Antarctica. It analysed faecal samples from five consecutive years (1997–2001) and length distribution of krill taken by trawl nets in the vicinity of Livingston Island. Antarctic krill, Euphausia superba, was the most frequent prey item, followed by several myctophid species (Gymnoscopelus nicholsi, Electrona antarctica and Electrona carlsbergi), squid and penguin remains. From 1998 to 2001, a modal progression in krill size was evident, suggesting that A. gazella was depending on a strong krill cohort, at least over the study period. Analysis of size distribution and size selectivity of krill preyed upon by fur seals suggests a preference for larger krill (〉34 mm), despite the broader size range of preys items available.

Description: The age and habitat of the giant squid, Architeuthis sanctipauli Velain, 1877, were determined based on isotopic analyses of the statoliths of three female specimens captured off Tasmania, Australia, between January and March 1996. Assuming that the aragonite of the statoliths formed in equilibrium with seawater, δ18O analyses indicated that the squid lived at temperatures of 10.5–12.9°C, corresponding to average depths of 125–250 m and maximum depths of 500 m. The capture records indicated that these squid may have occasionally ranged still deeper, to as much as 1000 m. All the statoliths were labeled with bomb 14C (Δ14C=+22.9‰ to +44.6‰), consistent with the depths inferred from δ18O. A thin section through one of the statoliths revealed 351 growth increments grouped into check-ring structures every 10–16 increments. A model for statolith growth and the pattern of temporal change in Δ14C in the water column was used to estimate the ages of the three specimens. These estimates were very sensitive to the choice of depth range over which Δ14C values were integrated. Assuming that the capture depths represented the maximum habitat depths of these individuals, the calculations suggested an age of 14 years or less. More refined age estimates require a better understanding of the variation of Δ14C and temperature with depth in the areas in which the squids live.

Description: The size selectivity of a trammel net for herded oval squid Sepioteuthis lessoniana in Tateyama Bay, Chiba Prefecture, was estimated by comparison between the mantle length frequency distributions of oval squid caught by a trammel net and by a set net. The measured mesh sizes of the inner net of the trammel net and of the final section of the set net were 85.3 and 11.3 mm, respectively. In the trammel net fishery where oval squid are herded into the net, most of the oval squid are caught in the bag-shaped inner net. Hence, the logistic function was employed for the size selectivity curve of the trammel net. The ‘share each length's catch total’ (SELECT) model was implemented for the estimation of the selectivity curve. The size selectivity r(l) of the trammel net for the oval squid was expressed as a logistic function of the mantle length l: r(l)=exp (-18.57+0.88 l)/[1+exp (-18.57+0.88 l)]. From these logistic parameter estimates, the 50% selection mantle length and selection range (L75-L25) were calculated as 21.07 and 2.49 cm, respectively. The selection probability of oval squid whose mantle girth was equivalent to the mesh perimeter of the inner net was 0.09. Accordingly, oval squid of a girth smaller than the mesh perimeter were likely to pass through the mesh to escape from the net.

Description: In an enclosure study in Schöhsee, a small mesotrophic lake in Northern Germany, the impact of copepods and daphniids on the seston community was studied. In general, these two guilds differ in their feeding behaviour. Copepods actively select their food, with a preference for larger particles, whereas most cladocerans are unselective filter-feeders. In this study we investigate how the impact of the two different grazers affects zooplankton growth. We combine results obtained in the laboratory with results measured in situ in the enclosures. Copepods and cladocerans were cultured on seston from enclosures that were inhabited by density gradients of copepods or daphniids. We observed that Daphnia grew faster on seston that was pre-handled by copepods than on seston that was pre-handled by daphniids, and that somatic growth decreased with increasing densities of daphniids in the enclosures. In contrast, we observed no differences in development rates for copepods grown on the different media. The population growth rates of Daphnia in the Daphnia treatments were determined in the enclosures. Growth differences in both somatic- and population growth of Daphnia were correlated to food quality aspects of the seston. In the laboratory we found that Daphnia growth was correlated with several fatty acids. The strongest regression was with the concentration of 20:4ω3 (r2= 0.37). This particular fatty acid also showed the highest correlation with growth after normalisation of the fatty acids to the carbon content of the enclosures (r2= 0.33). On the other hand, in the enclosure the population growth correlated most to the particulate nitrogen content (r2= 0.78) and only to the N:C ratio, when normalised to carbon (r2= 0.51).

Description: On seasonal time scales, ENSO prediction has become feasible in an operational framework in recent years. On decadal to multidecadal time scales, the variability of the oceanic circulation is assumed to provide a potential for climate prediction. To investigate the decadal predictability of the coupled atmosphere–ocean general circulation model (AOGCM) European Centre-Hamburg model version 5/Max Planck Institute Ocean Model (ECHAM5/MPI-OM), a 500-yr-long control integration and “perfect model” predictability experiments are analyzed. The results show that the sea surface temperatures (SSTs) of the North Atlantic, Nordic Seas, and Southern Ocean exhibit predictability on multidecadal time scales. Over the ocean, the predictability of surface air temperature (SAT) is very similar to that of SST. Over land, there is little evidence of decadal predictability of SAT except for some small maritime-influenced regions of Europe. The AOGCM produces predictable signals in lower-tropospheric temperature and precipitation over the North Atlantic, but not in sea level pressure.

Description: Ambae Island is the largest of Vanuatu’s active volcanoes. It is also one of the nation’s potentially most dangerous, with 60 million m3 of lake-water perched at over 1340 m in the summit caldera and over the active vent. In 1995, small phreatic explosions, earthquake swarms and heightened gas release led to calls for evacuation preparation and community volcanic hazard awareness programs for the ~9500 inhabitants. Differences in perspective or world-view between the island dwellers adhering to traditional beliefs (Kastom) and external scientists and emergency managers led to a climate of distrust following this crisis. In an attempt to address these issues, rebuild dialogue and respect between communities, outside scientists and administrators, and move forward in volcanic hazard education and planning for Ambae, we adapted and applied Participatory Rural Appraisal (PRA) approaches. Initial gender-segregated PRA exercises from two representative communities provided a mechanism for cataloguing local traditional viewpoints and hazard perceptions. Ultimately, by combining elements of these viewpoints and perceptions with science-based management structures, we derived volcanic hazard management guidelines, supported by an alert system and map that were more readily accepted by the test communities than the earlier “top-down” plans imposed by outside governmental and scientific agencies. The strength of PRA approaches is that they permit scientists to understand important local perspective issues, including visualisations of volcanic hazards, weaknesses in internal and external communication systems, and gender and hierarchy conflicts, all of which can hinder community emergency management. The approach we describe has much to offer both developing and industrialised communities that wish to improve their awareness programs and mitigative planning. This approach should also enhance communication and understanding between volcanologists and the communities they serve.

Description: Concentrations of a cyanobacterial toxin, nodularin, were measured in the Baltic Sea in 1998 and 1999. Statistical associations of nodularin concentrations with environmental factors were tested by multiple regression analysis. To reveal the toxin-producing organism, colonies of Aphanizomenon and filaments of Nodularia were picked and analyzed for peptide toxins. It was also investigated whether there was an association with zooplankton and Nodularia. All the measured seston samples contained nodularin, but other toxins were not detected by the HPLC analysis. In both years, the highest nodularin concentrations were found at the surface water layer. The nodularin concentrations were positively correlated with silicate concentrations in water. High concentrations of silica in surface water may indicate recent upwelling, which in turn renders surface water rich in nutrients. This upwelling is likely to intensify cyanobacterial growth and toxin production, which may explain this rather unexpected result. The picked Aphanizomenon colonies did not contain nodularin and the dissolved nodularin concentrations were below detection limit. Thus it was concluded that most of the nodularin was bound to Nodularia cells. The abundances of zooplankton (copepods, rotifers, and cladocerans) were unrelated to Nodularia, but were positively associated with Aphanizomenon.

Description: A system is presented which uses a Hall sensor and an adjacent magnet, attached close to the cloaca of penguins, to record defecation, respiration and heart rates for both free-living birds and those in captivity. The output of the Hall sensor depends on a magnetic field, the strength of which is influenced in the presented scenario by the proximity of the magnet, which varies with movement of the cloaca. The elasticity of the cloaca results in minute, but perceptible, movements associated with the heart, respiration and defecation, although placement of the magnet and sensor is critical, and not all parameters can be measured all of the time. The system, incorporating a logger that can record at frequencies of 50 Hz, was tested on 17 captive and 4 freeliving Magellanic penguins, Spheniscus magellanicus, in Argentina. It showed increased defecation rate associated with feeding, the expected trends in bradycardia and tachycardia associated with diving, and appeared to record some movement of air sacs associated with breathing. The concept of measuring minute changes in relative exterior body positions as a cue to internal processes may be important in future studies for both free-living and captive animals, particularly since it is non-invasive and relatively easy to deploy.

Description: In the literature, an inconsistency exists between estimates of biotically-effected carbon export inferred from large-scale geochemical studies (Jenkins 1982; 47 gC m−2 a−1) and local measurements of turbulent nutrient supply (Lewis et al. 1986; 4 gC m−2 a−1) in the eastern subtropical North Atlantic. Nutrient supply to the upper ocean by turbulent mixing is reexamined using local standard oceanographic measurements and high-resolution vertical profiles of nutrients averaged over a large region directly comparable to that investigated by Jenkins (1982).

Description: The marine microcopepod family Oncaeidae in the Red Sea has been the subject of comprehensive ecological studies over the past 15 years, providing for the first time insights into their community structure, vertical distribution and feeding ecology. Owing to taxonomic problems in species identification, however, many of the earlier ecological results were based on provisionally named species or morphotypes. A recent, ongoing taxonomic study of Red Sea Oncaeidae resulted in a considerable increase in the estimated numbers of species, since many of the species had not been described before. The present paper focuses on the potential significance of an improved taxonomic resolution of oncaeids with respect to various ecological aspects in this area, such as indicator species, community analysis and vertical distribution. The progress in our knowledge of the diversity of Red Sea Oncaeidae is summarized, including latest findings on the taxonomy and zoogeography of very small species (〈0.5 mm), and the importance of sibling species in the family is pointed out. The south–north gradient in species diversity of Oncaeidae within the Red Sea appears to be greater than previously assumed, since several of the newly described species were restricted to the southern part. The number of endemic species among Red Sea oncaeids is very low, however, most of the new species being also recorded outside the Red Sea. New quantitative data on the abundance and vertical distribution of selected oncaeid siblings obtained during a recent cruise in the northern Red Sea are provided to exemplify the changes in the knowledge of oncaeid community structure attributable to the improved taxonomic resolution. The potential ecological importance of a more differentiated consideration of oncaeid species in marine microcopepod communities is discussed

Description: Based on coupled modelling evidence we argue that topographically-induced modifications of the large-scale atmospheric circulation during the last glacial maximum may have led to a reduction of the westerlies, and a slowdown of the Pacific subtropical gyre as well as to an intensification of the Pacific subtropical cell. These oceanic circulation changes generate an eastern North Pacific warming, an associated cooling in the Kuroshio area, as well as a cooling of the tropical oceans, respectively. The tropical cooling pattern resembles a permanent La Niña state which in turn forces atmospheric teleconnection patterns that lead to an enhancement of the subtropical warming by reduced latent and sensible cooling of the ocean. In addition, the radiative cooling due to atmospheric CO2 and water vapor reductions imposes a cooling tendency in the tropics and subtropics, thereby intensifying the permanent La Niña conditions. The remote North Pacific response results in a warming tendency of the eastern North Pacific which may level off the effect of the local radiative cooling. Hence, a delicate balance between oceanic circulation changes, remotely induced atmospheric flux anomalies as well local radiative cooling is established which controls the tropical and North Pacific temperature anomalies during the last glacial maximum. Furthermore, we discuss how the aftermath of a Heinrich event may have affected glacial temperatures in the Pacific Ocean.

Description: The huge warming of the Arctic that started in the early 1920s and lasted for almost two decades is one of the most spectacular climate events of the twentieth century. During the peak period 1930–40, the annually averaged temperature anomaly for the area 60°–90°N amounted to some 1.7°C. Whether this event is an example of an internal climate mode or is externally forced, such as by enhanced solar effects, is presently under debate. This study suggests that natural variability is a likely cause, with reduced sea ice cover being crucial for the warming. A robust sea ice–air temperature relationship was demonstrated by a set of four simulations with the atmospheric ECHAM model forced with observed SST and sea ice concentrations. An analysis of the spatial characteristics of the observed early twentieth-century surface air temperature anomaly revealed that it was associated with similar sea ice variations. Further investigation of the variability of Arctic surface temperature and sea ice cover was performed by analyzing data from a coupled ocean–atmosphere model. By analyzing climate anomalies in the model that are similar to those that occurred in the early twentieth century, it was found that the simulated temperature increase in the Arctic was related to enhanced wind-driven oceanic inflow into the Barents Sea with an associated sea ice retreat. The magnitude of the inflow is linked to the strength of westerlies into the Barents Sea. This study proposes a mechanism sustaining the enhanced westerly winds by a cyclonic atmospheric circulation in the Barents Sea region created by a strong surface heat flux over the ice-free areas. Observational data suggest a similar series of events during the early twentieth-century Arctic warming, including increasing westerly winds between Spitsbergen and Norway, reduced sea ice, and enhanced cyclonic circulation over the Barents Sea. At the same time, the North Atlantic Oscillation was weakening.

Description: Oceanic ecosystems altered by interdecadal climate variability may provide a feedback to the physical climate by phytoplankton affecting heat fluxes into the upper ocean and dimethylsulfide fluxes into the atmosphere

Description: Stratigraphy is the fundament for the establishment and clarification of numerous questions in geology. The problem of the stratification of fossil sediments played a decisive role in the past, and continues to do so today. If one wishes to gain insight regarding the nature of the formation of today’s deposits, and avoid serious errors in the comparison of the same, one must, of necessity, first concern oneself with the sequence of recent sediment layers.

Description: Intrinsic oscillations of stable geophysical surface frontal currents of the unsteady, nonlinear, reduced-gravity shallow-water equations on an f plane are investigated analytically and numerically. For frictional (Rayleigh) currents characterized by linear horizontal velocity components and parabolic cross sections, the primitive equations are reduced to a set of coupled nonlinear ordinary differential equations. In the inviscid case, two periodic analytical solutions of the nonlinear problem describing 1) the inertially reversing horizontal displacement of a surface frontal current having a fixed parabolic cross section and 2) the cross-front pulsation of a coastal current emerging from a motionless surface frontal layer are presented. In a linear and in a weakly nonlinear context, analytical expressions for field oscillations and their frequency shift relative to the inertial frequency are presented. For the fully nonlinear problem, solutions referring to a surface frontal coastal current are obtained analytically and numerically. These solutions show that the currents oscillate always superinertially, the frequency and the amplitude of their oscillations depending on the magnitude of the initial disturbance and on the squared current Rossby number. In a linear framework, it is shown that disturbances superimposed on the surface frontal current are standing waves within the bounded region, the frequencies of which are inertial/superinertial for the first mode/higher modes. In the same frame, a zeroth mode, which could be interpreted as the superposition of an inertial wave on a background vorticity field, would formally yield subinertial frequencies. For surface frontal currents affected by Rayleigh friction, it is shown that the magnitude of the mean current decays according to a power law and that the oscillations decay faster, because this decay follows an exponential law. Implications of the intrinsic oscillations and of their rapid dissipation for the near-inertial motion in an active ambient ocean are discussed.

Description: Aspects of the dynamics of warm-core eddies evolving in a deep ocean are investigated using the results of laboratory experiments and numerical simulations. The vortices, produced experimentally in a system brought to solid body rotation by rapidly lifting a bottomless cylinder containing freshwater immersed in a salty ambient fluid, show clearly the presence of inertial oscillations: deepenings and contractions, shoalings and expansions, alternate during an exact inertial period. These pulsations, though predicted analytically and simulated numerically, had never been measured before for surface eddies having aspect ratios, as well as Rossby and Burger numbers, typical of geophysical warm-core eddies. The spatial structure of the vortex radial and tangential velocity components is analyzed using the experimental results and numerical simulations carried out by means of a layered, nonlinear, reduced-gravity frontal model. It is found that, while the dependence of the vortex radial velocity on the vortex radius evolves toward linearity as time elapses, different spatial structures seem to be possible for the vortex tangential velocity dependence. This behavior, which strongly differs from the “pulson” dynamics, is instead consistent with recently found analytical solutions of the nonlinear, reduced-gravity shallow-water equations describing the dynamics of warm-core eddies on an f plane.

Description: The REE-Ti silicate chevkinite has been recognised previously in Miocene ignimbrites from Gran Canaria, and in correlative offshore syn-ignimbrite turbidites. We have estimated the partition coefficients of REE, Y, Zr and Nb for chevkinite and co-existing peralkaline rhyolitic (comendite) glass using synchrotron-XRF-probe analyses (SYXRF) in order to evaluate the role of this mineral in the REE budget of felsic peralkaline magmas. The Zr/Nb ratio of the chevkinite is 1.55–1.7, strongly contrasting with Zr/Nb of 6.5 in the associated glass. Zr shows a three-fold enrichment in chevkinite relative to the residual melt, whereas Nb is enriched by a factor 〉10. The enrichment of Ce and La in chevkinite is even more significant, namely 19 wt(%) Ce and 12 wt(%) La, compared to 236 ppm Ce and 119 ppm La in the glass. Chevkinite/glass ratios are 988±30 for La, 806±30 for Ce, 626±30 for Pr, 615±40 for Nd, 392±50 for Sm, 225±30 for Eu, 142±25 for Gd, 72±20 for Dy. For trace elements, we derived KdTE of 74±25 for Y, 〉8 for Hf, 〉50 for Th, 15±5 for Nb and 3.55±0.4 for Zr. Mineral/glass ratios for co-existing titanite are 28±10 for La, 86±20 for Ce, 98±30 for Pr, 134±35 for Nd, 240±50 for Sm, 50±20 for Eu, 96±25 for Gd, 82±25 for Dy, 99±30 for Y, 45±10 for Nb and 3±0.5 for Zr. Based on these data, the removal of only 0.05 wt% of chevkinite from a magma with initially 300 ppm Ce would deplete the melt by 93 ppm to yield 207 ppm Ce in the residual liquid. Chevkinite thus appears, when present, to be the controlling mineral within the LREE budget of evolved peralkaline magmas.

Description: Two large-scale free-drifting isobaric-floats experiments, “SOFARGOS”/Marine Science and Technology Programme, phase 2 (MAST2) and Mass Transfer and Ecosystem Response (MATER)/MAST3, undertaken in 1994–95 in the northwestern Mediterranean Sea and in 1997–98 in the Algerian Basin, respectively, have revealed for the first time that Western Mediterranean Deep Water, newly formed by deep convection in the Gulf of Lion (the so-called Medoc site), can be advected several hundreds of kilometers away from the formation area by anticyclonic submesoscale coherent vortices (SCVs). This behavior implies that SCVs participate actively in the large-scale thermohaline circulation and deep ventilation of the western Mediterranean Sea. These SCVs are characterized by small radius (5 km), very low potential vorticity, high aspect ratio (0.1), and extended lifetime (〉0.5 yr).

Description: Savo Island is the 6-km-diameter emergent summit of an andesitic-dacitic stratovolcano, rising from the Iron Bottom Sound, 35 km NW of Honiara, Solomon Islands. Savo has erupted at least three times within recorded history and the 3,000 inhabitants maintain extensive oral traditions of past events. Through description and interpretation of the volcaniclastic sequences on the island, in conjunction with historical accounts and oral traditions, we reconstruct the eruptive processes on Savo. Block-and-ash flow (BAF) deposits are volumetrically dominant on the island within three main depositional environments: near-vent sequences, thick medial channel sequences and distal fan sequences. The deposits comprise universally non-vesicular and highly porphyritic (40–70% phenocrysts), high-silica andesite and dacite clasts. These appear to have been derived from collapsing lava domes during an 1560–1570 a.d. eruption. However, eyewitness descriptions and crater morphology suggest that similar deposits formed from dome explosions or collapses of eruption columns during later eruptions (1830–1840a.d.).Thehigh-sodiummagmas(ca.5–7wt% Na2O) apparently crystallised and strongly degassed prior to eruption. Shallow explosions were possibly caused by entrapment of magmatic gases beneath a dome or conduit plug of highly crystalline, near solid magma. Repeated sealing of the vent may have been due to inward collapse of the highly altered rocks of the surrounding hydrothermal system; these rocks probably were saturated due to contemporaneous high intensity rainfall events. BAFs were hot enough to char vegetation and attain aligned clast TRM (thermal remnant magnetism) up to 3 km from the vent, many being accompanied by ash-cloud surges. Changes with distance in the BAF deposits appear mostly dependent on flow confinement and are limited to an overall decrease in thickness and maximum clast size, and an increased definition of weak planar fabrics. In distal fan sequences, there is strong evidence for syn- and posteruptive redeposition of primary deposits. Since the Savo population is concentrated on coastal volcaniclastic fans, we consider the greatest volcanic risk to life is from BAFs, associated ash-cloud surges and lahars. Hence, the main channels and fans are designated as the highest of three relative hazard zones on a simple map prepared to aid local education and planning initiatives on Savo.

Description: Tephra fallout layers and volcaniclastic deposits, derived from volcanic sources around and on the Papuan Peninsula, form a substantial part of the Woodlark Basin marine sedimentary succession. Sampling by the Ocean Drilling Program Leg 180 in the western Woodlark Basin provides the opportunity to document the distribution of the volcanically-derived components as well as to evaluate their chronology, chemistry, and isotope compositions in order to gain information on the volcanic sources and original magmatic systems. Glass shards selected from 57 volcanogenic layers within the sampled Pliocene–Pleistocene sedimentary sequence show predominantly rhyolitic compositions, with subordinate basaltic andesites, basaltic trachy-andesites, andesites, trachy-andesites, dacites, and phonolites. It was possible to correlate only a few of the volcanogenic layers between sites using geochemical and age information apparently because of the formation of strongly compartmentalised sedimentary realms on this actively rifting margin. In many cases it was possible to correlate Leg 180 volcanic components with their eruption source areas based on chemical and isotope compositions. Likely sources for a considerable number of the volcanogenic deposits are Moresby and Dawson Strait volcanoes (D’Entrecasteaux Islands region) for high-K calc-alkaline glasses. The Dawson Strait volcanoes appear to represent the source for five peralkaline tephra layers. One basaltic andesitic volcaniclastic layer shows affinities to basaltic andesites from the Woodlark spreading tip and Cheshire Seamount. For other layers, a clear identification of the sources proved impossible, although their isotope and chemical signatures suggest similarities to south-west Pacific subduction volcanism, e.g. New Britain and Tonga– Kermadec island arcs. Volcanic islands in the Trobriand Arc (for example, Woodlark Island Amphlett Islands and/ or Egum Atoll) are probable sources for several volcaniclastic layers with ages between 1.5 to 3 Ma. The Lusancay Islands can be excluded as a source for the volcanogenic layers found during Leg 180. Generally, the volcanogenic layers indicate much calc-alkaline rhyolitic volcanism in eastern Papua since 3.8 Ma. Starting at 135 ka, however, peralkaline tephra layers appear. This geochemical change in source characteristics might reflect the onset of a change in geotectonic regime, from crustal subduction to spreading, affecting the D’Entrecasteaux Islands region. Initial 143Nd/144Nd ratios as low as 0.5121 and 0.5127 for two of the tephra layers are interpreted as indicating that D’Entrecasteaux Islands volcanism younger than 2.9 Ma occasionally interacted with the Late Archean basement, possibly reflecting the mobilisation of the deep continental crust during active rift propagation.

Description: Bulk properties of the Denmark Strait overflow (DSO) plume observed in velocity and hydrography surveys undertaken in 1997 and 1998 are described. Despite the presence of considerable short-term variability, it is found that the pathway and evolution of the plume density anomaly are remarkably steady. Bottom stress measurements show that the pathway of the plume core matches well with a rate of descent controlled by friction. The estimated entrainment rate diagnosed from the rate of plume dilution with distance shows a marked increase in entrainment at approximately 125 km from the sill, leading to a net dilution consistent with previous reports of a doubling of overflow transport measured by current meter arrays. The entrainment rate increase is likely related to the increased topographic slopes in the region, compounded by a decrease in interface stratification as the plume is diluted and enters a denser background.

Description: This chapter deals with the discovery of sorbicillactone A, as an illustrative example of the fruitful cooperation within BIOTECmarin — its isolation and chemical characterization, and its biological activities. Sorbicillactone A was isolated from a strain of Penicillium chrysogenum cultured from a sample of the Mediterranean sponge Ircinia fasciculata; it possesses a unique bicyclic lactone structure, seemingly derived from sorbicillin. Among the numerous known sorbicillin-derived structures, it is the first found to contain nitrogen and thus the first representative of a novel type of ‘sorbicillin alkaloids’, apparently originating from a likewise remarkable biosynthesis. Furthermore, the compound exhibits promising activities in several mammalian and viral test systems, in particular a highly selective cytostatic activity against murine leukemic lymphoblasts (L5178y) and the ability to protect human T cells against the cytopathic effects of HIV-1. These properties qualify sorbicillactone A or one of its derivatives for animal and (hopefully) also future therapeutic human trials.

Description: The recent application of molecular microbial ecology tools to sponge-microbe associations has revealed a glimpse into the biodiversity of these microbial communities, that is considered just ‘the tip of the iceberg’. This chapter provides an overview over these new findings with regard to identity, diversity and distribution patterns of sponge-associated microbial consortia. The sponges Aplysina aerophoba (Verongida), Rhopaloeides odorabile (Dicytoceratida) and Theonella swinhoei (Lithistida) were chosen as model systems for this review because they have been subject to both, cultivation-dependent and cultivation-independent approaches. A discussion of the microbial assemblages of Halichondria panicea is presented in the accompanying chapter by Imhoff and Stöhr. Considering that a large fraction of sponge-associated microbes is not yet amenable to cultivation, an emphasis has been placed on the techniques centering around the 16S rRNA gene. A section has been included that covers the potential of sponge microbial communities for drug discovery. Finally, a ‘sponge-microbe interaction model’ is presented that summarizes our current understanding of the processes that might have shaped the community structure of the microbial assemblages within sponges.

Description: The aim of this study was to isolate bacteria that are resistant to the strong antimicrobial metabolites characteristic of Aplysina aerophoba. For this purpose, bacterial isolation was performed on agar plates to which sponge tissue extract had been added. Following screening for antifungal and antimicrobial activities, 5 strains were chosen for more detailed analyses. 16S ribosomal DNA sequencing revealed that all isolates belonged to the genus Bacillus, specifically B. subtilis and B. pumilus. Using a combination of matrix-assisted laser desorption/ ionization mass spectrometry typing of whole cells and antimicrobial bioassays against selected reference strains, the bioactive metabolites were identified as lipopeptides.

Description: In order to assess the stability of the microbial community of the sponge Aplysina cavernicola under in situ conditions, sponges were transplanted from their original location (〉40 m depth) to shallower, more light-exposed sites (7–15 m depth). Transmission electron microscopy revealed that the microbial community remained visually unchanged and free of cyanobacteria over the experimental time period of 3 months. Denaturing gradient gel electrophoresis (DGGE) of PCR-amplified partial 16S rRNA gene sequences allowed a distinction between the variable and permanent fraction of the bacterial community. Comparative sequence analysis of four variable DGGE bands revealed high sequence similarity to representatives of the Alpha- and Gammaproteobacteria and the phylum Bacteroidetes, which have been recovered previously from Mediterranean seawater as clone sequences or by cultivation. Seven (out of 12) permanent DGGE bands showed high sequence similarity to a sponge-specific, monophyletic 16S rRNA gene sequence cluster within the Acidobacteria division, and to a sequence cluster of uncertain affiliation. These sequence clusters represent members of a common microbial community that is shared among distantly related sponges from different, non-overlapping geographic regions. Four additional permanent DGGE bands showed high sequence similarity to a Betaproteobacterium, Burkholderia cepacia, which is not typically known as a marine bacterium. High-performance liquid chromatography analyses of sponge tissues revealed no changes in metabolite pattern, indicating that these compounds are expressed constitutively irrespective of the variations resulting from the transplantation experiment.

Description: A new shipboard current profiler, a 75-kHz ocean surveyor, was operationally used during two research cruises in the tropical Atlantic and the subpolar North Atlantic, respectively. Here, a report is presented on the first experience with this instrument in two very different current regimes, in the Tropics with large vertical shears, and in the subpolar regime with mainly barotropic flow. The ocean surveyor continuously measured currents in the upper ocean from near the surface to about 500–700-m depth. The measurement range showed a dependence on the regional and temporal variations of scattering particles and on the intensity of swell and wind waves. Statistical comparisons are performed with on-station lowered acoustic Doppler current profiler (LADCP) profiles and underway measurements by classic shipboard acoustic Doppler current profiler (ADCP) measurements. Accuracy estimates for hourly averaged ocean surveyor currents result in errors of about 1 cm s–1 for on-station data and of 2–4 cm s–1 for underway measurements, depending on the regional abundance of scatterers and on the weather conditions encountered.

Description: A new mechanism is proposed that explains two key features of the observed El Niño–Southern Oscillation (ENSO) phenomenon—its irregularity and decadal amplitude changes. Using a low-order ENSO model, the authors show that the nonlinearities in the tropical heat budget can lead to bursting behavior characterized by decadal occurrences of strong El Niño events. La Niña events are not affected, a feature that is also seen in ENSO observations. One key result of this analysis is that decadal variability in the Tropics can be generated without invoking extratropical processes or stochastic forcing. The El Niño bursting behavior simulated by the low-order ENSO model can be understood in terms of the concept of homoclinic and heteroclinic connections. It is shown that this new model for ENSO amplitude modulations and irregularity, although difficult to prove, might explain some features of ENSO dynamics seen in more complex climate models and the observations.

Description: We present new data on mineralogical, major and trace element compositions of lavas from the northernmost segment of the Kolbeinsey Ridge (North Kolbeinsey Ridge, NKR). The incompatible element enriched North Kolbeinsey basalts lie on a crystal fractionation trend which differs from that of the other Kolbeinsey segments, most likely due to higher water contents (~0.2%) in the NKR basalts. The most evolved NKR magmas erupt close to the Jan Mayen Fracture Zone, implying increased cooling and fractionation of the ascending magmas. Mainly incompatible element-enriched basalts, as well as some slightly depleted lavas, erupt on the NKR. They show evidence for mixing between different mantle sources and magma mixing. North Kolbeinsey Ridge magmas probably formed by similar degrees of melting to other Kolbeinsey basalts, implying that no lateral variation in mantle potential temperature occurs on the spreading axis north of the Iceland plume and that the Jan Mayen Fracture Zone does not have a cooling effect on the mantle. Residual garnet from deep melting in garnet peridotite or from enriched garnet pyroxenite veins does not play a role. The incompatible element-enriched source has high Ba/La and Nb/Zr, but must be depleted in iron. The iron-depleted mantle is less dense than surrounding mantle and leads to the formation of the North Kolbeinsey segment and its shallow bathymetry. The enriched NKR source formed from a relatively refractory mantle, enriched by a small degree melt rather than by recycling of enriched basaltic crust. The depleted mantle source resembles the mantle of the Middle Kolbeinsey segment with a depletion in incompatible elements, but a fertile major element composition.

Description: Processes that influence the volume and heat transport across the Greenland–Scotland Ridge system are investigated in a numerical model with ° horizontal resolution. The focus is on the sensitivity of cross-ridge transports and the reaction of the subpolar North Atlantic Ocean circulation to changes in wind stress and buoyancy forcing on seasonal to interannual timescales. A general relation between changes in wind stress or cross-ridge density contrasts and the overturning transport of Greenland–Iceland–Norwegian Seas source water is established from a series of idealized experiments. The relation is used subsequently to interpret changes in an experiment over the years 1992–97 with realistic forcing. On seasonal and interannual timescales there is a clear correlation between heat flux and wind stress curl variability. The realistic model suggests a steady decrease in the strength of the cyclonic subpolar gyre of the North Atlantic with a corresponding decrease in heat transport during the 1990s

Description: Geochemical properties of gas hydrate accumulation associated with an active gas vent on the continental slope offshore northeast Sakhalin Island in the Sea of Okhotsk have been investigated. The pore water chemistry data suggest that the gas hydrates (GHs) were formed in an environment of upward-migrating fluid combined with a mechanism of pore water segregation. The upward infiltration of water enriched mainly by Cl− and K+ species appears to occur on the background of earlier diagenesis processes within the gas vent sediments. The GHs were formed from water with chlorinity ranging from 530 to 570 mM. The δ18O and δD of GH water varied from −1.4 to −1.8‰ and from −13 to −18‰, respectively, representing a mix of seawater and infiltrating fluid water. A complex interaction of pore water, water of ascending fluid and segregated pore water during hydrate formation is also supported by water content measurements and observed gas hydrate structure. The direction of segregated water is opposite to upward fluid migration. Decreasing activity of the gas vent is inferred by comparing the present top of the recovered hydrate layer with previous observations.

Description: The role of mean and stochastic freshwater forcing on the generation of millennial-scale climate variability in the North Atlantic is studied using a low-order coupled atmosphere–ocean–sea ice model. It is shown that millennial-scale oscillations can be excited stochastically, when the North Atlantic Ocean is fresh enough. This finding is used in order to interpret the aftermath of massive iceberg surges (Heinrich events) in the glacial North Atlantic, which are characterized by an excitation of Dansgaard–Oeschger events. Based on model results, it is hypothesized that Heinrich events trigger Dansgaard–Oeschger cycles and that furthermore the occurrence of Heinrich events is dependent on the accumulated climatic effect of a series of Dansgaard–Oeschger events. This scenario leads to a coupled ocean–ice sheet oscillation that shares many similarities with the Bond cycle. Further sensitivity experiments reveal that the timescale of the oscillations can be decomposed into stochastic, linear, and nonlinear deterministic components. A schematic bifurcation diagram is used to compare theoretical results with paleoclimatic data.

Description: The metazoan parasites and stomach contents of the small-sized demersal fishes Agonus cataphractus, Buglossidium luteum, Callionymus lyra and Rhinonemus cimbrius were studied and analysed. The fishes were captured using various sampling gears at 12 stations in the central North Sea. A total of 16 metazoan parasite species were isolated: six adult Digenea, three larval and adult Cestoda, four larval and adult Nematoda and three larval and adult Crustacea. With nine parasites species each, A. cataphractus and R. cimbrius harboured the highest parasite diversity, while B. luteum and C. lyra hosted only six and five parasite species, respectively. Eighteen new hosts and four new locality records were established. No Myxozoa, Monogenea or Acanthocephala were found. Most of the detected parasites showed a wide geographical range and a low host-specificity. The composition of the parasite fauna differed between the fish species, in accordance with their different feeding behaviours. The diet of bentho-pelagic feeders ( A. cataphractus, R. cimbrius) was more diverse in comparison with the more specialised benthic feeders ( C. lyra, B. luteum). This correlated with the lower diversity of heteroxenic parasites within both small-sized benthic fish species.

Description: Triassic calciturbidites were studied in a 100-m long core and nearby outcrops of the basinal Buchenstein Formation to determine composition and thickness variations. The quantity of recognized turbidite sediment relative to background sediment changes from 15% (by volume) in the lower part to 60% in the upper part, reflecting the steady progradation of nearby platforms. The composition of the sand fraction of 214 turbidites was point-counted in thin sections. Micrite peloids (average 23%) and lithoclasts (16%) are by far the most dominant constituents. They are interpreted as two different varieties of in-situ precipitated micrite (automicrite), which probably formed under the influence of microbes and constitute the principal building material of the adjacent platforms. Platform-derived skeletal grains amount to only 0.5%. Variations in turbidite composition were quantified using Spearman's rank correlation and cluster analysis. The most significant compositional variations seem to be related to hydrodynamic sorting in the turbidity currents and to the gradual shift from distal to more proximal turbidites in the core as the platforms prograded basinward. Cluster analysis of the 214 samples shows a major subdivision into micrite and sparite dominated turbidites. Clusters associated with micrite-dominated turbidites are enriched in Radiolaria and thin-shelled bivalves, whereas the clusters related to sparite-dominated turbidites show an abundance of lithoclasts. This subdivision seems strongly related to sorting effects in a turbidity current. Point-counting of turbidites in nearby outcrops revealed a lateral variation in composition. Proximal turbidites are sparite-dominated and enriched in lithoclasts, distal portions are chiefly micrite with an open-ocean biota (thin-shelled bivalves, Radiolaria). This differentiation resembles the vertical change in composition of thick turbidite beds, and is attributed to different settling rates of the various grains in the turbidity current. There is no indication that turbidite composition fluctuated significantly under the influence of sea-level fluctuations. This is not surprising because the dominant automicrite facies of the platforms only migrates laterally, but does not change much during sea-level cycles.

Description: Recent studies have suggested that sea surface temperature (SST) is an important source of variability of the North Atlantic Oscillation (NAO). Here, we deal with four basic aspects contributing to this issue: (1) we investigate the characteristic time scales of this oceanic influence; (2) quantify the scale-dependent hindcast potential of the NAO during the twentieth century as derived from SST-driven atmospheric general circulation model (AGCM) ensembles; (3) the relevant oceanic regions are identified, corresponding SST indices are defined and their relationship to the NAO are evaluated by means of cross spectral analysis and (4) our results are compared with long-term coupled control experiments with different ocean models in order to ensure whether the spectral relationship between the SST regions and the NAO is an intrinsic mode of the coupled climate system, involving the deep ocean circulation, rather than an artefact of the unilateral SST forcing. The observed year-to-year NAO fluctuations are barely influenced by the SST. On the decadal time scales the major swings of the observed NAO are well reproduced by various ensembles from the middle of the twentieth century onward, including the negative state in the 1960s and part of the positive trend afterwards. A six-member ECHAM4-T42 ensemble reveals that the SST boundary condition affects 25% of total decadal-mean and interdecadal-trend NAO variability throughout the twentieth century. The most coherent NAO-related SST feature is the well-known North Atlantic tripole. Additional contributions may arise from the southern Pacific and the low-latitude Indian Ocean. The coupled climate model control runs suggest only the North Atlantic SST-NAO relationship as being a true characteristic of the coupled climate system. The coherence and phase spectra of observations and coupled simulations are in excellent agreement, confirming the robustness of this decadal-scale North Atlantic air–sea coupled mode.

Description: In this study, progradation and the subsequent retrogradation of a late Paleocene isolated carbonate platform (Galala Mountains, Eastern Desert, Egypt) is demonstrated by variations of distinct facies associations from the platform margin in the north to the hemipelagic basin in the south. A combination of a sea-level drop and tectonic uplift at around 59 Ma (calcareous nannofossil biozone NP5) favored the initiation of the carbonate platform. From this time onwards, the facies distribution along the platform–basin transect can be subdivided into five facies belts comprising nine different facies associations. Their internal relationships and specific depositional settings are strongly coupled with the Maastrichtian–Paleocene seafloor topography, which resulted from local tectonic movements. Patch reefs and reef debris were deposited at the platform margin and the horizontally bedded limestones on the upper slope. Slumps and debris flows were stored on the lower slope. In the subhorizontal toe-of-slope facies belt, mass-flow deposits pass into calciturbidites. Further southwards in the basin, only hemipelagic marls were deposited. Between 59 and 56.2 Ma (NP5–NP8), the overall carbonate platform system prograded in several pulses. Distinct changes in facies associations from 56.2 to 55.5 Ma (NP9) resulted from rotational block movements. They led to increased subsidence at the platform margin and a coeval uplift in the toe-of-slope areas. This resulted in the retrogradation of the carbonate platform. Furthermore the patch-reef and reef-debris facies associations were substituted by the larger foraminifera shoal association. The retrogradation is also documented by a significant decrease in slump and debris-flow deposits on the slope and calciturbidites at the toe of slope.

Description: Synoptic-scale variability in the air–sea turbulent fluxes in the areas of midlatitudinal western boundary currents is analyzed. In the Gulf Stream area, ocean–atmosphere fluxes on synoptic time- and space scales are clearly coordinated with the propagating synoptic-scale atmospheric transients. The statistical analysis of 6-hourly resolution sea level pressure and surface turbulent fluxes from the NCEP–NCAR reanalysis for the period from 1948 to 2000 in the area of strong sea surface temperature gradients in the Gulf Stream gives strong proof for the association between the propagating cyclones and synoptic patterns of surface turbulent fluxes. It is shown that sea–air interaction in this area is controlled by the sharpness of surface temperature gradients in the ocean and by the intensity of the advection of the air masses in different parts of cyclones during the cold-air and warm-air outbreaks. A simple parameter based on the joint consideration of the characteristics of sea surface temperature and sea level pressure fields is used to characterize the synoptic variability of air–sea turbulent fluxes. The effectiveness of the relationship between surface temperature and surface pressure on one side and air–sea flux anomalies on the other vary from year to year in phase with variability in the frequencies of deep atmospheric cyclones in the Gulf Stream area. The limits of applicability of the approach, its sensitivity to higher-resolution sea surface temperature data, and the possibility of its further applications are discussed.

Description: A total of 37 juvenile Etmopterus spinax from the Norwegian Deep were examined for stomach contents and metazoan ecto- and endoparasites. These squaliform elasmobranchs were caught by benthopelagic net in May 2001 at a depth of 194–214 m. The euphausiid Meganyctiphanes norvegica and the teleost Maurolicus muelleri were the principal prey organisms. With increasing total length of E. spinax, the frequency of Meganyctiphanes norvegica prey decreased and that of M. muelleri increased. Seven different metazoan parasite species were found: adult Monogenea (2), larval and adult Cestoda (3), and larval Nematoda (2). The predominant parasites were an unidentified monocotylid monogenean and the cestode Aporhynchus norvegicus, with respective prevalences of infestation of 83.8% and 81.1%. The sites of infestation were the gills (Squalonchocotyle spinacis, Monogenea), nasal cavities (Monocotylidae indet.), body cavity (Lacistorhynchus tenuis, Cestoda), stomach wall and organs of the body cavity (Anisakis simplex, Nematoda), and stomach and spiral valve (A. norvegicus and Pseudophyllidea indet., Cestoda; Hysterothylacium aduncum, Nematoda). No other metazoan parasite taxa were found, and the musculature was free of parasites. Five new host and three new locality records were established. M. muelleri seems to be an important intermediate host for the endoparasitic nematodes which were found, with E. spinax serving as a paratenic host. E. spinax also serves as an intermediate host for the trypanorhynch cestode L. tenuis, and as the definitive host for the two monogeneans and the trypanorhynch A. norvegicus. The latter uses Meganyctiphanes norvegica as the second intermediate host in the Norwegian Deep. The relationship between the feeding ecology, habitat, and vagility of E. spinax and the resulting parasite fauna is discussed.

Description: Volcanic gases such as SO2, H2S, HCl and COS emitted during explosive eruptions significantly affect atmospheric chemistry and therefore the Earth's climate. We have evaluated the dependence of volcanic gas emission into the atmosphere on altitude, latitude, and tectonic setting of volcanoes and on the season in which eruptions occurred. These parameters markedly influence final stratospheric gas loading. The latitudes and altitudes of 360 active volcanoes were compared to the height of the tropopause to calculate the potential quantity of volcanic gases injected into the stratosphere. We calculated a possible stratospheric gas loading based on different volcanic plume heights (6, 10, and 15 km) generated by moderate-scale explosive eruptions to show the importance of the actual plume height and volcano location. At a plume height of 15 km for moderate-scale explosive eruptions, a volcano at sea level can cause stratospheric gas loading because the maximum distance to the tropopause is 15–16 km in the equatorial region (0–30°). Eruptions in the tropics have to be more powerful to inject gas into the stratosphere than eruptions at high latitudes because the tropopause rises from ca. 9–11 km at the poles to 15–16 km in the equatorial region (0–30°N and S). The equatorial region is important for stratospheric gas injection because it is the area with the highest frequency of eruptions. Gas injected into the stratosphere in equatorial areas may spread globally into both hemispheres.