ALBERT

Description: The volcanic arc of the Hellenic subduction zone with its four volcanic centers is of major relevance when evaluating the seismovolcanic hazard for the Aegean region. We present results from a 22-station temporary seismic network (CYCNET) in the central Hellenic Volcanic Arc (HVA). CYCNET recordings allow to analyze the level and spatio-temporal evolution of microseismic activity in this region for the first time. A total of 2175 events recorded between September 2002 and July 2004 are analyzed using statistical methods, cluster analysis and relative relocation techniques. We identify distinct regions with significantly varying spatiotemporal behavior of microseismicity. A large portion of the seismic activity within the upper crust is associated with the presence of islands representing horst structures that were generated during the major Oligocene extensional phase. In contrast, the central part of the Cyclades metamorphic core complex remains aseismic considering our magnitude threshold of 1.8 except one spot where events occur swarm-like and with highly similar waveforms. The highest activity in the study area was identified along the SW–NE striking Santorini–Amorgos zone. Within this zone the submarine Columbo volcano exhibits strong temporal variations of seismic activity on a high background level. This activity is interpreted to be directly linked to the magma reservoir and therein the migration of magma and fluids towards the surface. NE of Columbo where no volcanic activity has yet been reported we observe a similar seismicity pattern with small-scaled activity spots that might represent local pathways of upward migrating fluids or even developing volcanic activity within this zone of crustal weakness. In contrast, the Santorini and Milos volcanic complexes do not show significant temporal variations and low to moderate background activity, respectively. Relating our results to the distribution of historical earthquakes and the GPS-derived horizontal velocity field we conclude that the Santorini–Amorgos zone is presently in the state of right-lateral transtension reflecting a major structural boundary of the volcanic arc subdividing it into a seismically and volcanically quiet western and an active eastern part.

Description: There is growing concern about the transfer of methane originating from water bodies to the atmosphere. Methane from sediments can reach the atmosphere directly via bubbles or indirectly via vertical turbulent transport. This work quantifies methane gas bubble dissolution using a combination of bubble modeling and acoustic observations of rising bubbles to determine what fraction of the methane transported by bubbles will reach the atmosphere. The bubble model predicts the evolving bubble size, gas composition, and rise distance and is suitable for almost all aquatic environments. The model was validated using methane and argon bubble dissolution measurements obtained from the literature for deep, oxic, saline water with excellent results. Methane bubbles from within the hydrate stability zone (typically below 500 m water depth in the ocean) are believed to form an outer hydrate rim. To explain the subsequent slow dissolution, a model calibration was performed using bubble dissolution data from the literature measured within the hydrate stability zone. The calibrated model explains the impressively tall flares (〉1300 m) observed in the hydrate stability zone of the Black Sea. This study suggests that only a small amount of methane reaches the surface at active seep sites in the Black Sea, and this only from very shallow water areas (〈100 m). Clearly, the Black Sea and the ocean are rather effective barriers against the transfer of bubble methane to the atmosphere, although substantial amounts of methane may reach the surface in shallow lakes and reservoirs.

Description: Structure-based inhibitor design has led to the discovery of a number of potent inhibitors of glycogen phosphorylase b (GPb), N-acyl derivatives of β-d-glucopyranosylamine, that bind at the catalytic site of the enzyme. The first good inhibitor in this class of compounds, N-acetyl-β-d-glucopyranosylamine (NAG) (Ki = 32 μM), has been previously characterized by biochemical, biological and crystallographic experiments at 2.3 Å resolution. Bioisosteric replacement of the acetyl group by trifluoroacetyl group resulted in an inhibitor, N-trifluoroacetyl-β-d-glucopyranosylamine (NFAG), with a Ki = 75 μM. To elucidate the structural basis of its reduced potency, we determined the ligand structure in complex with GPb at 1.8 Å resolution. To compare the binding mode of N-trifluoroacetyl derivative with that of the lead molecule, we also determined the structure of GPb–NAG complex at a higher resolution (1.9 Å). NFAG can be accommodated in the catalytic site of T-state GPb at approximately the same position as that of NAG and stabilize the T-state conformation of the 280s loop by making several favourable contacts to Asn284 of this loop. The difference observed in the Ki values of the two analogues can be interpreted in terms of subtle conformational changes of protein residues and shifts of water molecules in the vicinity of the catalytic site, variations in van der Waals interaction, and desolvation effects.

Description: We employ a combined interpretation of Hydrosweep swath bathymetry and high resolution multi-channel seismic reflection data to investigate the development of Cap Timiris Canyon, a newly discovered submarine canyon offshore Mauritania. The dominantly V-shaped and deeply entrenched canyon exhibits many fluvial features including dendritic and meander patterns, cut-off loops and terraces, and is presently incising. Distal meander patterns, confined within a narrow fault-controlled corridor, show several stages of evolution, the latest of which is dominated by a down-system meander-loop migration. Terraces exhibit a variety of internal structures suggesting they originated through different processes including sliding/slumping, uplift-induced incision and lateral accretion. We ascribe canyon origin to an ancient river system in the adjacent presently arid Sahara Desert that breached the shelf during a Plio/Pleistocene sea level lowstand and delivered sediment directly into the slope area. Our data suggest that the initial invading unchannelised sheet of sand-rich turbidity flows initiated canyon formation by gradually mobilising along linear seafloor depressions and fault-controlled zones of weakness. We propose that the development of canyon morphology and structure was influenced by the stages of active flow of the coupling river system, and hence could act as a proxy for understanding the paleo-climatic evolution of a ‘green’ Sahara since Plio/Pleistocene times.

Description: Numerous methane-emitting bottom features, such as seeps, methane clathrate hydrates (clathrates), and mud volcanoes, have been identified recently in the Black Sea. The fluxes of methane from these sources averaged over large spatial scales are unknown. Here we take advantage of the fact that the Black Sea is a semi-enclosed basin with restricted deep water circulation to establish first-order estimates of basin-wide fluxes of methane from these sources to the water column and atmosphere. First, we measured the natural radiocarbon content of methane (14C–CH4) dissolved in the water column and emitted from seeps. The 14C–CH4 results showed that the dominant source of methane to the water column is emitted from seeps and a smaller source is diagenetically produced in relatively modern sediments. The 14C–CH4 results were then used to partition a basin-wide total methane budget; this analysis estimated the basin-wide flux of methane from seeps and clathrates to the water column to be 3.60 to 4.28 Tg yr− 1. Second, a geochemical box model was used to calculate possible distributions of methane inputs from seeps and clathrates as well as provide additional estimates of the basin-wide flux of methane from seeps and clathrates to the water column (4.95 to 5.65 Tg yr− 1).

Description: The behavioural and physical mechanisms involved in the tactics used by predators to catch their prey have been explored for a wide variety of vertebrate taxa but most studies have considered the viewpoints of predator and prey independently. We tackled this issue using an ecologically relevant predator–prey model: wolf spiders (Pardosa spp.) and wood crickets, Nemobius sylvestris. Crickets are particularly challenging prey to catch because their air-sensing systems enable them to detect small air movements caused by approaching predators. Using a high-speed video camera, we found that freely behaving spiders adopted either a fast or a slow velocity tactic to approach crickets. We then developed a device using a piston to simulate, as faithfully as possible, the spider's attack. The air flow generated by the piston was quantified by particle image velocimetry and then used to test the escape success of crickets at different attack velocities. Cricket escape success was lower for low and high piston velocities, matching the two tactics adopted by the spiders. Based on our results, we propose that the escape probability of prey after a given predator signal can be explained by the distance between the prey and the predator, the velocity of the predator and the strength of the signal. Both methodological and conceptual approaches presented in this study could provide useful methods to understand the biological and physical basis of predatory tactics in other animals.

Description: This study was performed to investigate gas formation and gas saturation conditions related to acoustic turbidity in shallow (∼40 m deep) marine basins. The Arkona Basin, Baltic Sea, with its organic-rich fine-grained surface sediment provides an ideal “Natural Laboratory” to characterise free gas using seismic, geoacoustic, and geochemical methods. The area of acoustic turbidity covers about 1500 km2 of the central Arkona Basin, corresponding to areas where organic-rich post-glacial sediments exceed 4–6 m in thickness. The highest concentration of pore water methane (7660 μmol L−1), found in areas of high acoustic turbidity, was near the calculated lower limit of methane solubility for the measured in situ temperature, salinity, and pressure. Pore water methane concentration decreased to near 4 μmol L−1 in areas outside of the zone of high acoustic turbidity. Stable carbon (−70.7‰ to −92.3‰ PDB) and hydrogen (−124‰ to −185‰ SMOW) isotope values of methane indicate that methane is predominantly formed by microbial CO2 reduction in Arkona Basin surface sediments and rules out significant contributions of other sources.

Description: The study of interfacial properties in the marine environment is important for the understanding of air-sea gas exchange processes, especially with respect to the behaviour of entrained air bubbles. Seawater contains surfactant material, much of which is thought to origin from the exudation of dissolved organic material (DOM) by phytoplankton. This study aims at investigating the influence of different phytoplankton species on the surface shear viscosity of an air-water interface. Measurements of surface shear viscosity were carried out with the ISR1 interfacial shear rheometer. Surface shear viscosities of stock cultures of Phaeocystis sp., Thalassiosira rotula, Thalassiosira punctigera and Nitzschia closterium as well as of F/2 nutrient medium and seawater were measured. The surface shear viscosity of N. closterium was investigated during different stages of its growth as well as for an unfiltered stock culture sample and its filtrate. Results reveal that the influence of phytoplankton on the surface shear viscosity is species specific. An increase in surface shear viscosity occurred for the N. closterium stock culture only. The remaining cultures showed similar behaviour to F/2 nutrient medium. The increase of surface shear viscosity during the growth of N. closterium occurred mainly during the exponential growth phase. The increases in surface shear viscosity depend on the presence of phytoplankton cells in the sample. The formation of compact mechanical structures at the air-water interface originating from the aggregation of DOM released by N. closterium as a cause for the observed increases in surface shear viscosity is discussed.

Description: During the MARGASCH cruise M52/1 in 2001 with RV Meteor we sampled surface sediments from three stations in the crater of the Dvurechenskii mud volcano (DMV, located in the Sorokin Trough of the Black Sea) and one reference station situated 15 km to the northeast of the DMV. We analysed the pore water for sulphide, methane, alkalinity, sulphate, and chloride concentrations and determined the concentrations of particulate organic carbon, carbonate and sulphur in surface sediments. Rates of anaerobic oxidation of methane (AOM) were determined using a radiotracer (14CH4) incubation method. Numerical transport-reaction models were applied to derive the velocity of upward fluid flow through the quiescently dewatering DMV, to calculate rates of AOM in surface sediments, and to determine methane fluxes into the overlying water column. According to the model, AOM consumes 79% of the average methane flux from depth (8.9 · 10+ 6 mol a− 1), such that the resulting dissolved methane emission from the volcano into the overlying bottom water can be determined as 1.9 · 10+ 6 mol a− 1. If it is assumed that all submarine mud volcanoes (SMVs) in the Black Sea are at an activity level like the DMV, the resulting seepage represents less than 0.1% of the total methane flux into this anoxic marginal sea. The new data from the DMV and previously published studies indicate that an average SMV emits about 2.0 · 10+ 6 mol a− 1 into the ocean via quiescent dewatering. The global flux of dissolved methane from SMVs into the ocean is estimated to fall into the order of 10+ 10 mol a− 1. Additional methane fluxes arise during periods of active mud expulsion and gas bubbling occurring episodically at the DMV and other SMVs

Description: Phagotrophy and competitive ability of the mixotrophic Ochromonas minima were investigated in a three-factorial experiment where light intensity (low: 1.0 μmol m−2 s−1 and high: 60 μmol m−2 s−1 PPFD), nutrient concentration (ambient: 7.0 μmol N l−1, 0.11 μmol P l−1 and enriched: 88 μmol N l−1, 6.3 μmol P l−1) and DOC supply (without and with enrichment, 250 μmol C l−1) were manipulated. Ochromonas minima and bacterial abundance were monitored for 12 days. We found significant and interacting effects of light and nutrients on Ochromonas minima growth rate and abundance. At high light intensity, nutrient enrichment resulted in increased growth rates and population sizes. In contrast, reduced growth rates and population sizes were observed for nutrient enrichment when light intensity was low. Although, Ochromonas minima was able to ingest bacteria under both high and low light conditions, it grew only when light intensity was high. At high light intensity, Ochromonas minima grew exponentially under nutrient conditions that would have been limiting for photoautotrophic microalgae. In non-enriched low light treatments, Ochromonas minima populations survived, probably by using background DOC as an energy source, indicating that this ability can be of relevance for natural systems even when DOC concentrations are relatively low. When competing with photoautotrophic microalgae, the ability to grow under severe nutrient limitation and to survive under light limitation should be advantageous for Ochromonas minima.

Description: La Palma (Canary Islands) represents an oceanic island volcano with an active rift zone, inferred to have formed during the last 800 ka following southward growth of the former radial–symmetrical stratovolcano Taburiente. We carried out clinopyroxene–melt thermobarometry and microthermometry of fluid inclusions to reconstruct the evolution of the magma plumbing systems over time and to understand the genetic relationship between Taburiente and the presently active Cumbre Vieja rift zone. Clinopyroxene–melt equilibria of phenocryst rims and glassy groundmass indicate pressures of 0.60–1.04 GPa (∼19–34 km depth) for Taburiente, 0.47–1.17 GPa (16–40 km) for the former Cumbre Nueva rift arm of Taburiente, and 0.50–0.78 GPa (16–26 km) for Bejenado volcano that formed after collapse of the Cumbre Nueva rift. These pressures are interpreted to reflect depths of magma storage and major crystal fractionation. CO2-dominated fluid inclusions hosted by clinopyroxenes and olivines indicate pressures of formation or re-equilibration within an overall range of 0.25–0.61 GPa (∼8–19 km depth). Respective frequency maxima are at 0.41–0.50 GPa for Taburiente dunite xenoliths, 0.26–0.43 GPa for Cumbre Nueva ankaramites, and 0.26–0.32 GPa for Bejenado cumulate xenoliths. These pressures are interpreted to reflect levels of temporary magma stagnation during ascent. Our data show that the magma pathways during all volcanic phases including the presently active Cumbre Vieja rift [Klügel, A., Hansteen, T.H., Galipp, K., 2005. Magma storage and underplating beneath Cumbre Vieja volcano, La Palma (Canary Islands). Earth and Planetary Science Letters 236, 211–226] are characterized by two distinct storage levels: a system of prolonged storage within the upper mantle, and a system of short-term stagnation within the lower crust or near to the Moho. Both the mantle and crustal storage systems show a migration to shallower levels from 1.0 Ma to present, probably as a result of changing thermomechanical properties of the mantle and crust and possibly stoping. Our combined barometric data and field observations suggest that the extinct Taburiente/Cumbre Nueva and the active Cumbre Vieja represent two distinct volcanoes with separate magma plumbing systems. In this case, the present rift configuration does not reflect continuous growth of the Taburiente shield volcano during the last 800 ka. None of the La Palma volcanoes shows any indicators of a long-lived shallow magma reservoir where magmas fractionate and from which rift zones emanate, which is an important difference to Hawaiian shield volcanoes characterized by shallow subcaldera magma chambers.

Description: A recurrent interpretation of ancient climate based on the oxygen isotopic composition of marine carbonates and cherts suggests that Earth's climate was substantially warmer in the distant past and remained so until as recently as 400 Myr ago. This interpretation is difficult to reconcile with the long-term glacial record, with evidence for modest weathering rates during most of Earth's history, with biomarker and fossil evidence for eukaryotes and even vertebrates at times of anomalously low δ18O values, and with the predicted faintness of the young Sun. We argue here, following earlier suggestions, that the low δ18O values in ancient rocks are a consequence of the low δ18O of ancient seawater. A modest increase in ocean depth with time, together with progressive increases in pelagic sedimentation on midocean ridge flanks since about 550 Ma, could account for the variation in seawater isotopic composition. The required change in ocean depth, coupled with thinning of the oceanic crust, is a natural consequence of the decline in heat flow over time. Contrary to previous assertions, such a model is not inconsistent with data from ophiolites. It seems likely that Earth's climate remained largely within Phanerozoic norms throughout the past 3.5 Ga

Description: In late summer 2002 and 2003, exceptionally warm inflow events of saline water were observed in the Baltic. These warm saline waters were embedded in the halocline of the Bornholm Basin and caused a strong anomaly of the seasonal temperature cycle. The temperature in October 2002 was the highest ever observed in the halocline of the Bornholm Basin. Although the oxygen content of the inflowing water was only about 1.5 ml l− 1 at the Darss Sill, it caused a moderate ventilation of the halocline in the Bornholm Basin. On the way through the Arkona Basin, the entrainment of ambient water increased the oxygen content of the inflowing saline water masses. Warm summer inflows were rare events in the last 50 years, but their frequency has increased since 1990. This is likely caused by climate change. The analysis of a 50-year time series of hydrographic parameters reveals significant changes of the thermal regime around the year 1988. The winter surface and intermediate water temperatures of the Bornholm Basin increased by about 1 °C. Also, the duration of warm water in the surface layer was prolonged after 1988. A high correlation between the minimum intermediate winter water temperatures and the NAO winter index was found. Since temperature is a key parameter for many biological processes various responses of the ecosystem to the change in hydrographic conditions could be expected. Possible biological implications of the warm inflow events for the ecosystem are discussed.

Description: A detailed, high-resolution stratigraphic analysis of the Mediterranean Outflow contourite system at the continental slope of the Gulf of Cadiz has been carried out through the correlation between a dense network of seismic reflection profiles (sparker, airgun, 3.75 kHz and parametric echosounder — TOPAS), Calypso giant piston and standard gravity cores. From such correlation we determine a stacking pattern constituted by four main seismic units (a–d) that are internally structured into ten subunits. Each subunit shows a single sequence formed by transparent seismic facies at the base to smooth, parallel reflectors of moderate to high amplitude facies at the top, being well correlated in the cores with a coarsening-upward sequence. The latest Pleistocene–Holocene deposits form glacial/interglacial depositional sequences related to cycles with a frequency range below the Milankovitch band that corresponds to millennial timescale climatic changes such as Dansgaard–Oeschger (1.5 ka) and Bond Cycles (10–15 ka). Oxygen isotope records of planktonic foraminifera and the occurrence of ice-rafted debris (IRD) in the most recent contourite subunits show clear evidence of the influence of the North Atlantic climatic conditions, especially the climatic Heinrich events (H) in the slope sedimentation of the Gulf of Cadiz and then in the circulation of the Mediterranean Outflow Water (MOW). The coarser contourite deposits are mostly associated with the Last Glacial Maximum, Younger Dryas and Heinrich events on the central area of the middle slope. During globally cooler conditions, the MOW was denser so that it was more active in deeper areas than today. On the other hand, during warm periods the MOW became less dense favoring an increased intensity of the MOWon the distal area of the upper slope. Therefore, spatial and vertical fluctuations of the MOW contourite system are strongly affected by global climate and oceanographic changes, being clearly influenced by iceberg discharges and probably also, by the resumption of thermohaline circulation in the North Atlantic Ocean during ice melting periods.

Description: New time series of Nd and Pb isotopes were generated from two hydrogenous ferromanganese crusts from the eastern Indian Ocean, which were dated by 10Be / 9Be profiles and Co chronometry. The goal was to gain information on the nature and timing of variations of the deep water radiogenic isotope composition as a function of the evolution of the Indonesian Island Arcs since the Early Miocene, changes in ocean circulation related to the different stages of the closing of the Indonesian seaway for deep and intermediate water mass exchange since the Mid-Miocene, and enhanced Himalayan weathering since the Late Oligocene. A crust from 4119 m water depth in the Wharton Basin adjacent to Sumatra and the Java Trench (DODO 232D) has recorded a small variability in Nd isotope, but pronounced variations in Pb isotope composition over the past 17 Myr. Patterns and absolute values of the Nd and Pb isotope time series closely resemble the record of previously published crust SS663 from the central Indian Ocean, located some 2500 km SW of crust DODO 232D in the northern central Indian Ocean. In accordance with the interpretation derived from crust SS663, the Pb isotope composition of deep water in the Wharton Basin has apparently been mainly controlled by products of Himalayan erosion and weathering and to a lesser extent by the evolution of the Indonesian Island Arcs. The location of a second crust (VA16 13KD-1) from 2100 m water depth on the Scott Plateau off NW Australia is beneath the present day outflow of Pacific-derived surface and thermocline water masses into the eastern Indian Ocean. The pattern of the Pb isotope time series of this crust and the observed changes in Pb isotope mixing relationships, which occurred at ∼ 11.5 and ∼ 3.5 Ma, reflect the combined influence of advection and mixing of water masses through the Indonesian Seaway and weathering of volcanic source rocks within the emerging Indonesian Island Arcs over the past 33 Myr. The Nd isotope time series shows a pattern similar to central and southwest Pacific crusts and is best explained by a mixture between Nd from water masses advected from the Indian and Southern Ocean and Nd released by weathering from the emerging Indonesian Island Arcs.

Description: Four mud extrusions were investigated along the erosive subduction zone off Costa Rica. Active fluid seepage from these structures is indicated by chemosynthetic communities, authigenic carbonates and methane plumes in the water column. We estimate the methane output from the individual mud extrusions using two independent approaches. The first is based on the amount of CH4 that becomes anaerobically oxidized in the sediment beneath areas covered by chemosynthetic communities, which ranges from 104 to 105 mol yr− 1. The remaining portion of CH4, which is released into the ocean, has been estimated to be 102–104 mol yr− 1 per mud extrusion. The second approach estimates the amount of CH4 discharging into the water column based on measurements of the near-bottom methane distribution and current velocities. This approach yields estimates between 104–105 mol yr−1. The discrepancy of the amount of CH4 emitted into the bottom water derived from the two approaches hints to methane seepage that cannot be accounted for by faunal growth, e.g. focused fluid emission through channels in sediments and fractures in carbonates. Extrapolated over the 48 mud extrusions discovered off Costa Rica, we estimate a CH4 output of 20·106 mol yr− 1 from mud extrusions along this 350 km long section of the continental margin. These estimates of methane emissions at an erosional continental margin are considerably lower than those reported from mud extrusion at accretionary and passive margins. Almost half of the continental margins are described as non-accretionary. Assuming that the moderate emission of methane at the mud extrusions off Costa Rica are typical for this kind of setting, then global estimates of methane emissions from submarine mud extrusions, which are based on data of mud extrusions located at accretionary and passive continental margins, appear to be significantly too high.

Description: The composition of fossil insect faunas from northeastern Siberia changed significantly during the Pleistocene–Holocene transition. The Late Pleistocene insect fauna reflects tundra-steppe environments, and was dominated by xerophilic species. This fauna persisted regionally until ca 12,000 yr BP. A radical transformation of the environment occurred between 12,000 and 10,000 yr BP, marked by the permafrost degradation and invasion of tall shrubs and later trees into the higher latitudes. The early Holocene insect assemblages are dominated by mesophilic tundra species, but also include small number of more thermophilic species, which are currently restricted to the taiga zone. Tree-dependent species, however, were virtually absent. This early Holocene fauna has no modern analogue. The faunal assemblages indicate that the early Holocene climate was more humid than that of the Late Pleistocene, and warmer than today. Post-glacial sea level rise was in progress at that time, but the shoreline was still much further north, and the New Siberian Islands were still a part of the mainland. During the second-half of the Holocene, sea level continued to rise, and trees and tall shrubs retreated to the south. Regional ecosystems, including insect faunas, approached their modern compositions and boundaries.

Description: An accumulation terrace close to the El'gygytgyn Impact Crater in northeastern Siberia contains stratigraphic and periglacial evidence of the paleoenvironmental and paleoclimatic history and permafrost dynamics during late Quaternary time. A succession of paleo active-layer deposits that mirror environmental changes records periods favorable for the establishment and growth of ice-wedge polygonal networks and sediment variations. These two elements of the periglacial landscape serve as complementary paleoenvironmental archives that can be traced back to ∼ 14,000 cal yr BP. The slope sediments and the ground ice contained therein have prominent relative maxima and minima in properties (grain size, total organic content, oxygen isotopes). They document a regional early Holocene thermal maximum at about 9000 cal yr BP, followed by a transition to slightly cooler conditions, and a subsequent transition to slightly warmer conditions after about 4000 cal yr BP. Results from sedimentary analysis resemble morphological and geochemical (oxygen and hydrogen isotopes) results from ice wedge studies, in which successive generations of ice-wedge polygonal networks record warmer winters in late Holocene time. Moreover, peaks of light soluble cation contents and quartz-grain surface textures reveal distinct traces of cryogenic weathering. We propose a conclusive sedimentation model illustrating terrace formation in a permafrost terrain.

Description: As part of Ocean Drilling Program Leg 204 at southern Hydrate Ridge off Oregon we have monitored changes in sediment electrical resistivity during controlled gas hydrate dissociation experiments. Two cores were used, each filled with gas hydrate bearing sediments (predominantly mud/silty mud). One core was from Site 1249 (1249F-9H3), 42.1 m below seafloor (mbsf) and the other from Site 1248 (1248C-4X1), 28.8 mbsf. At Site 1247, a third experiment was conducted on a core without gas hydrate (1247B-2H1, 3.6 mbsf). First, the cores were imaged using an infra-red (IR) camera upon recovery to map the gas hydrate occurrence through dissociation cooling. Over a period of several hours, successive runs on the multi-sensor track (includes sensors for P-wave velocity, resistivity, magnetic susceptibility and gamma-ray density) were carried out complemented by X-ray imaging on core 1249F-9H3. After complete equilibration to room temperature (17–18 °C) and complete gas hydrate dissociation, the final measurement of electrical resistivity was used to calculate pore-water resistivity and salinities. The calculated pore-water freshening after dissociation is equivalent to a gas hydrate concentration in situ of 35–70% along core 1249F-9H3 and 20–35% for core 1248C-4X1 assuming seawater salinity of in situ pore fluid. Detailed analysis of the IR scan, X-ray images and split-core photographs showed the hydrate mainly occurred disseminated throughout the core. Additionally, in core 1249F-9H3, a single hydrate filled vein, approximately 10 cm long and dipping at about 65°, was identified. Analyses of the logging-while-drilling (LWD) resistivity data revealed a structural dip of 40–80° in the interval between 40 and 44 mbsf. We further analyzed all resistivity data measured on the recovered core during Leg 204. Generally poor data quality due to gas cracks allowed analyses to be carried out only at selected intervals at Sites 1244, 1245, 1246, 1247, 1248, 1249, and 1252. With a few exceptions, data from these intervals yield low to no gas hydrate concentration, which corresponds to estimates from downhole resistivity logs. However, since the gas cracking may be the result of gas hydrate dissociation, this is a biased sampling. Cores that had contained some gas hydrate may have been excluded.

Description: Two pennate microphytobenthic diatoms, Amphora coffeaeformis (Agardh) Kutzing and Navicula transitans var. derasa f. delicatula Heimdal, were cryopreserved and monitored on thawing to track the mechanical injuries and their post-preservation recovery. Cells were subjected to (1) direct freezing in liquid nitrogen and (2) two-step cooling with and without the cryoprotectant, dimethyl sulfoxide (Me(2)SO). Mechanical injury due to exposure to low temperature differed between the two species. While A. coffeaeformis cells were intact and could survive even direct freezing without a cryoprotectant, N. delicatula cell chloroplasts were damaged. However, the two-step cooling along with a cryoprotectant minimized the mechanical injury to cells of both species thereby enhancing the post-thaw viability.

Description: he ability to routinely cryopreserve micro-algal species reduces costs associated with maintaining large culture collections and reduces the risks of losing particular strains or species through contamination and genetic drift. Cryopreservation is also a useful adjunct in aquaculture hatcheries for strains of micro-algae where the nutritional status may change as a result of continuous sub-culture. In this study, cryopreservation of isolates from seven micro-algal classes was investigated. Successful candidates included the marine dinoflagellates Amphidinium carterae, Amphidinium trulla, and Gymnodinium simplex, and the haptophytes Chrysochromulina simplex, Prymnesium parvum, Prymnesium parvum f. patelliferum, Isochrysis galbana, and Pavlova lutheri. Also successfully cryopreserved were the planktonic diatoms Chaetoceros calcitrans, Chaetoceros muelleri, Chaetoceros sp., and the benthic Nitzschia ovalis, the chlorophyte Chlamydomonas coccoides, the rhodophyte Porphyridium purpureum, the prasinophytes Tetraselmis chuii, and Tetraselmis suecica, and the cyanophytes Raphidiopsis sp., and Aphanizomenon flos-aquae. All species were successfully cryopreserved using 15% Me2SO.

Description: Interannual variability in the spring bloom in the Irminger Basin, northern North Atlantic, is investigated using SeaWiFS-derived chlorophyll-a (chl-a) concentration and satellite or model-derived meteorological data. Variability in the timing and magnitude of the spring bloom in the basin is evaluated. A method for estimating a time series of Sverdrup's critical depth from satellite-derived data is introduced. Comparison with modelled mixed layer depth and chlorophyll concentration demonstrates that Sverdrup's critical depth model is valid for the Irminger Basin spring bloom. The dependence of the timing and magnitude of the spring bloom on winter pre-conditioning is investigated. We find that in the Irminger Basin the start of the spring bloom can be estimated from the preceding winter's mean wind speed and net heat flux. We also find that the maximum chl-a concentration during the bloom can be estimated from the frequency of winter storms. Increased storm activity results in a reduced bloom chlorophyll maximum by delaying the development of spring stratification, resulting in the bloom missing the ‘window of opportunity’ for optimum phytoplankton growth.

Description: Hydrographic surveys in three consecutive seasons in the Irminger Sea in 2001/2002 have revealed six physical regimes (zones) in which different surface mixing and spring re-stratification processes dominate. They are the South Irminger Current, the North Irminger Current, the Central Irminger Sea, the Polar-origin East Greenland Current, the Atlantic-origin East Greenland Current and the Reykjanes Ridge. The variations in restratification processes in particular have significant implications for the timing of shallow spring mixed layer development and therefore the timing and strength of the spring bloom. The relative roles of heat and freshwater in controlling re-stratification are examined for each hydrographic zone, and it is shown that the simplest concept of solar warming generating spring stratification is appropriate for the Irminger Current and the central Irminger Sea. However in the East Greenland Current and the Reykjanes Ridge zones, the springtime arrival of fresh or saline water at the surface dominates re-stratification and generates the earliest and strongest spring blooms of the region. In the cool fresh centre of the Irminger Sea the relatively low chlorophyll-a throughout the year cannot be wholly explained by stratification or nutrient concentrations. Details of the annual cycle in temperature, salinity, chlorophyll-a and nutrients are presented for each hydrographic zone

Description: The upper water column in the Irminger Sea is characterized by cold fresh arctic and subarctic waters and warm saline North Atlantic waters. In this study the local physical and meteorological preconditioning of the phytoplankton development over an annual cycle in the upper water column in four physical zones of the Irminger Sea is investigated. Data from four cruises of the UK's Marine Productivity programme are combined with results from a coupled biological–physical nitrogen–phytoplankton–zooplankton–detritus model run using realistic forcing. The observations and model predictions are compared and analyzed to identify the key parameters and processes which determine the observed heterogeneity in biological production in the Irminger Sea. The simulations show differences in the onset of the bloom, in the time of the occurrence of the maximum phytoplankton biomass and in the length of the bloom between the zones. The longest phytoplankton bloom of 90 days duration was predicted for the East Greenland Current of Atlantic origin zone. In contrast, for the Central Irminger Sea zone a phytoplankton bloom with a start at the beginning of May and the shortest duration of only 70 days was simulated. The latest onset of the phytoplankton bloom in mid May and the latest occurrence of the maximum biomass (end of July) were predicted for the Northern Irminger Current zone. Here the bloom lasted for 80 days. In contrast the phytoplankton bloom in the Southern Irminger Current zone started at the same time as in Central Irminger Sea, but peaked end of June and lasted for 80 days. For all four zones relatively low daily (0.3–0.5 g C m− 2d− 1) and annual primary production was simulated, ranging between 35.6 g C m− 2y− 1 in the East Greenland Current of Atlantic origin zone and 45.6 g C m− 2y− 1 in the Northern Irminger Current zone. The model successfully simulated the observed regional and spatial differences in terms of the maximum depth of winter mixing, the onset of stratification and the development of the seasonal thermocline, and the differences in biological characteristics between the zones. The initial properties of the water column and the seasonal cycle of physical and meteorological forcing in each of the zones are responsible for the observed differences during the Marine Productivity cruises. The timing of the transition from mixing to stratification regime, and the different prevailing light levels in each zone are identified as the crucial processes/parameters for the understanding of the dynamics of the pelagic ecosystem in the Irminger Sea.

Description: The Benguela Current Large Marine Ecosystem (BCLME) is situated along the coast of south-westem Africa, stretching from east of the Cape of Good Hope in the south equatorwards to the Angola (Cabinda) Front, near the northern border of Angola. It encompasses one of the four major coastal upwelling ecosystems of the world, which lie at the eastern boundaries of the oceans. The BCLME's distinctive bathymetry, hydrography, chemistry and trophodynamics combine to make it one of the most productive ocean areas in the world. This high level of primary productivity of the BCLME supports an important global reservoir of biodiversity and biomass of zooplankton, fish, sea birds and marine mammals. Near-shore and off-shore sediments hold rich deposits of precious minerals (particularly diamonds), as well as oil and gas reserves. The natural beauties of the coastal regions, many of which are still pristine by global standards, have also enabled the development of significant tourism along parts of the coast. Pollution, poorly planned coastal developments, population pressure and near-shore activities such as mining are, however, resulting in rapid degradation of some vulnerable coastal habitats. International thinking is very much in keeping with the strategy and workplan of the BCLME Program, where a key policy action is the assessment of environmental variability, ecosystem impacts and the improvement of predictability.

Description: As a component of the meridional overturning variability experiment in the tropical North Atlantic, a four-year-long time series of meridional transport of North Atlantic deep water has been obtained from moored end point measurements of density and bottom pressure. This study presents a quality assessment of the measurement elements. Rigorous pre- and post- deployment in situ calibration of the density sensors and subsequent data processing establish an accuracy of O(1.5 Sv) in internal transport in the 1200–5000 dbar range at subinertial time scales. A similar accuracy is reached in the bottom pressure-derived external transport fluctuations. However, for pressure, variability with periods longer than a deployment's duration (presently about one year) is not measurable. This effect is demonstrated using numerical simulations and a possible solution for detecting long-term external transport changes is presented.

Description: Temporal variations in Fe isotope compositions at three locations in the Pacific Ocean over the last 10 Ma are inferred from high-resolution analyses of three hydrogenetic ferromanganese crusts. Iron pathways to the central deep Pacific Ocean appear to have remained constant over the past 10 Ma, reflected by a remarkably constant Fe isotope composition, despite large changes in the Fe delivery rates to the surface ocean via dust. These results suggest that the Fe cycle in the deep ocean is decoupled from that in surface waters. By contrast, one ferromanganese crust from the Izu-Bonin (IB) back-arc/marginal basin of the W. Pacific exhibits large δ56Fe variations. In that crust, decreases in δ56Fe values correlate with increases in Mn, Mg, Ni, Cu, Zn, Mo, and V contents, and consistent with periods of intense hydrothermal input and increased growth rates. A second crust located within 100 km of the first IB sample does not record any of these periods of enhanced hydrothermal input. This probably reflects the isolated pathways by which hydrothermally sourced Fe may have migrated in the back arc, highlighting the high degree of provinciality that Fe isotopes may have in the modern (oxic) oceans. Our results demonstrate that despite efficient removal at the source, hydrothermal Fe injected into the deep ocean could account for a significant fraction of the dissolved Fe pool in the deep ocean, and that hydrothermally sourced Fe fluxes to the open ocean may have lower δ56Fe values than those measured so far in situ at hydrothermal vents. Correlation between δ56Fe values and elements enriched in hydrothermal fluids may provide a means for distinguishing hydrothermal Fe from other low-δ56Fe sources to the oceans such as dissolved riverine Fe or porewaters in continental shelf sediments.

Description: “Non-volcanic” rifted margins exhibit very little evidence of synrift magmatism, even where the continental crust has been thinned to such an extent that the mantle has been exhumed across a transitional zone (up to ∼100 km wide), called the continent–ocean transition (COT). Using dynamical models of rifting, we explore how extension velocity, mantle composition and potential temperature influence the nature and extent of the COT and compare our results to observations at the West Iberia margin (WIM) and the ancient margins of the Liguria-Piemonte Ocean (LP) now exposed in the Alps. We find a first order relationship between extension velocity and the amagmatic exposure of mantle at the COT. For very slow half extension velocities, (〈 6 mm/yr), mantle exhumation begins before melting. At these velocities, by the time melting starts at the rift centre, the area of exhumed mantle has moved sideways creating a COT, the width of which increases with decreasing velocities. However, at 10 mm/yr, a velocity probably appropriate for the exhumation of mantle at the WIM and LP, melting starts prior to mantle exhumation. In this case, our models show that by the time mantle exhumation starts, a ∼4.5 km column of melt has been produced, much more than the ∼2 km maximum mean melt thickness inferred at the COT of these margins. Even considering that 25% of the produced melt may be trapped in the mantle, as in slow-spreading mid-ocean ridges, still more melt is produced in the models than inferred from observations. Thus, extension velocity alone cannot explain the practical absence of synrift magmatism at the COT of the WIM and LP. We find that the formation of a wide, amagmatic COT requires that either the mantle was depleted in basaltic constituents by 〉 10% prior to rifting or that its potential temperature was ∼50 °C lower than normal (≤ 1250 °C).

Description: Diatoms are important primary producers not only in the oceans but also in the freshwater environment. The efficiency of biomass formation strongly depends on the metabolic regulation of carbon and nutrient assimilation. Recent studies have given evidence that many metabolic regulations are quite different from green algae and higher plants. The major known differences concern the following processes: (1) pigment biosynthesis, (2) lightharvesting organisation, (3) mechanism of photoprotection, (4) regulation of photosynthetic electron flow, (5) regulation of the enzyme activity in the Calvin-Benson cycle, (6) photorespiration, (7) carbon aquisition and CO2-concentrating mechanisms, (8) synthesis and breakdown of storage products under starvation, (8) nutrient uptake (9) adaptation to extreme environments. This review summarises these differences phenomenologically and presents the actual knowledge of the underlying mechanisms. The availability of whole genome sequence data is an important basis to learn in more detail how photosynthesis in these tremendously successful primary producers is regulated.

Description: Data from Late Cretaceous paleoclimate simulations and their linkage to a geological model derived from long-term high-resolution proxy-data indicate and support strong relationships between African climate and tropical Atlantic sedimentation. Here, we present results from an interdisciplinary study. By varying only one parameter in the set of orbital boundary conditions of the numeric model, we focus on the climatic impact of precessional forcing on the global and regional climate system. As a result, new insights to the internal dynamics of climate, the different compartments and fluxes of the hydrological cycle, and finally the sedimentary response within the oceanic realm during greenhouse conditions have been approached. The climate models suggest that insolation changes at 25–55°S are the trigger for cyclic variations of the tropical hydrological cycle of northern Africa. Between the various models, a maximum difference in insolation at the top of the atmosphere of 14 W/m2 is needed to produce the documented changes in the hydrological cycle. First of all, the simulations do not suggest any substantial latitudinal movement of the ITCZ over the course of one precessional cycle. The models rather indicate cross-latitudinal variation of pressure systems and variation in the magnitude and direction of surface winds, linking tropical Africa to the mid-southern latitudes. This cross-latitudinal atmospheric teleconnection denotes a reduced role of the tropics as driver of Cretaceous climate system. Therefore, the linkage of proxy-based geological and numeric models rather supports the idea that tropical Atlantic black shale formation in the Late Cretaceous was ultimately triggered by climate change in mid-southern latitudes, with precipitation and river discharge being the transport mechanisms. As a hypothesis that will be tested in the near future, we speculate that the mid-latitudes represent the “ultimate” region of climate signal formation during times of extreme global warmth.

Description: The dacite to andesite zoned Mateare Tephra is the fallout of a predominantly plinian eruption from Chiltepe peninsula at the western shore of Lake Managua that occurred 3000–6000 years ago. It comprises four units: Unit A of high-silica dacite is stratified, ash-rich lapilli fallout generated by unsteady subplinian eruption pulses affected by minor water access to the conduit and conduit blocking by degassed magma. Unit B of less silicic dacite is well sorted, massive pumice lapilli fallout from the main, steady plinian phase of the eruption. Unit C is andesitic fallout that is continuous from unit B except for the rapid change in chemical composition, which had little influence on the ongoing eruption except for a minor transient reduction of the discharge rate and access of water to the conduit. After this, discharge rate re-established to a strong plinian eruption that emplaced the main part of unit C. This was again followed by water access to the conduit which increased through upper unit C. The lithic-rich lapilli to wet ash fallout of unit D is the product of the fully phreatomagmatic terminal phase of the eruption. A massive well-sorted sand layer, the Mateare Sand, replaces laterally variable parts of unit A and lowermost part of unit B in outcrops up to 32 m above present lake level. The corresponding interval missing in the primary fallout can be identified by comparing the composition of pumice entrained in the sand, and pumice from the local base of unit B on top of the sand, with the compositional gradient in undisturbed fallout. The amount of fallout entrained in the sand decreases with distance to the lake. The Mateare Sand occurs at elevations well above beach levels and its widespread continuous distribution defies a fluviatile origin. Instead, it was produced by lake tsunamis triggered by eruption pulses during the initial unsteady phase of activity. Such tsunamis could threaten areas not affected by fallout, and represent a hazard of particular importance in Nicaragua where two large lakes host several explosive volcanoes.

Description: Coastal areas such as continental shelves, estuaries, deltas, fjords and lagoons can release high amounts of nitrous oxide (N2O) and methane (CH4) to the atmosphere. However, estimates of trace gas emissions are often biased by incomplete spatial and temporal coverages. Based on a compilation of literature data, the distributions of N2O and CH4 in European coastal areas (i.e. Arctic Ocean, Baltic Sea, North Sea, northeastern Atlantic Ocean, Mediterranean Sea, Black Sea) were reviewed and their emissions to the atmosphere reassessed. Maximum N2O saturations were found in estuarine systems, whereas the shelf waters, which are not influenced by freshwater plumes, are close to equilibrium with the atmosphere. This implies that N2O is mainly formed in estuarine systems. European coastal waters are a net source of N2O to the atmosphere (0.33–0.67 Tg N year−1) with the major contribution coming from estuarine/river systems and not from open shelf areas. European shelf areas contribute significantly (up to 26%) to the global oceanic N2O emissions. CH4 saturations show a high temporal and spatial variability with maximum values in estuarine/fjord systems. European coastal areas are a source of atmospheric CH4 (0.35–0.75 Tg C year−1) and contribute significantly to the overall global CH4 oceanic emissions. However, this estimate still seems to be a severe underestimation since CH4 fluxes from estuaries and shallow seeps are not adequately represented. Future N2O and CH4 emissions from coastal areas strongly depend on the degree of eutrophication of coastal waters and might increase in the future.

Description: The distribution of silicon in the North Pacific is controlled by the utilization of silicic acid by diatoms, a process that fractionates silicon (Si) isotopic compositions. Silicon isotope variations are presented for six water column profiles from the surface mixed layer down to the deep waters of the North Pacific Ocean. Although the observed Si isotopic variations display an apparently simple inverse relationship with dissolved nutrient concentrations, in fact they reflect mixing of surface waters undergoing active Si isotope fractionation and deep-waters with more uniform concentrations and isotope compositions. Samples from the surface of the subtropical gyre have the lowest dissolved Si concentrations and heaviest Si isotope compositions of marine waters measured thus far. Fractionation in the surface waters follows a typical Rayleigh-type distillation curve for a ‘closed’ surface water reservoir resulting from stratification of the surface layer in the subarctic region. In contrast, an ‘open’ system prevails within the subtropical gyre where there is significant recycling of silicic acid in the upper water column and lateral transport of silicon within surface currents. For deep waters, the Si isotope composition distinguishes between the northern North Pacific Deep Water (NPDW) and the southerly-derived bottom water. The relatively light Si isotope compositions measured from waters within the subarctic gyre provides evidence for isolation of the nutrient pool in the North Pacific.

Description: Taken together, evidence from east Greenland's mountain moraines and results from atmospheric models appear to provide the answer to a question which has long dogged abrupt climate change research: namely, how were impacts of the Younger Dryas (YD), Dansgaard–Oeschger (D–O) and Heinrich (H) events transmitted so quickly and efficiently throughout the northern hemisphere and tropics? The answer appears to lie in extensive winter sea ice formation which created Siberian-like conditions in the regions surrounding the northern Atlantic. Not only would this account for the ultra cold conditions in the north, but, as suggested by models, it would have pushed the tropical rain belt southward and weakened the monsoons. The requisite abrupt changes in the extent of sea ice cover are of course best explained by the turning on and turning off of the Atlantic's conveyor circulation.

Description: The Gulf of Cadiz is a tectonically active area of the European continental margin and characterised by a high abundance of mud volcanoes, diapirs, pockmarks and carbonate chimneys. During the R/V SONNE expedition ‘‘GAP–Gibraltar Arc Processes (SO-175)’’ in December 2003, several mud volcanoes were surveyed for gas seepage and associated microbial methane turnover. Pore water analyses and methane oxidation measurements on sediment cores recovered from the centres of the mud volcanoes Captain Arutyunov, Bonjardim, Ginsburg, Gemini and a newly discovered, mud volcano-like structure called ‘‘No Name’’ show that thermogenic methane and associated higher hydrocarbons rising from deeper sediment strata are completely consumed within the seabed. The presence of a distinct sulphate–methane transition zone (SMT) overlapping with high sulphide concentrations suggests that methane oxidation is mediated under anaerobic conditions with sulphate as the electron acceptor. Anaerobic oxidation of methane (AOM) and sulphate reduction (SR) rates show maxima at the SMT, which was found between 20 and 200 cm below seafloor at the different mud volcanoes. In comparison to other methane seeps, AOM activity (〈383 mmol m�2 year�1) and diffusive methane fluxes (〈321 mmol m�2 year�1) in mud volcano sediments of the Gulf of Cadiz are low to mid range. Corresponding lipid biomarker and 16S rDNA clone library analysis give evidence that AOM is mediated by a mixed community of anaerobic methanotrophic archaea and associated sulphate reducing bacteria (SRB) in the studied mud volcanoes. Little is known about the variability of methane fluxes in this environment. Carbonate crusts littering the seafloor of mud volcanoes in the northern part of the Gulf of Cadiz had strongly 13C-depleted lipid signatures indicative of higher seepage activities in the past. However, actual seafloor video observations showed only scarce traces of methane seepage and associated biological processes at the seafloor. No active fluid or free gas escape to the hydrosphere was observed visually at any of the surveyed mud volcanoes, and biogeochemical measurements indicate a complete methane consumption in the seafloor. Our observations suggest that the emission of methane to the hydrosphere from the mud volcano structures studied here may be insignificant at present.

Description: Long-term macrobenthos data from Kiel Bight in the Western Baltic collected between 1968 and 2000 have been correlated with the winter NAO index (North Atlantic Oscillation Index) and other environmental data such as temperature, salinity and oxygen content in the bottom water in order to detect systematic patterns related to so far unexplained abiotic signals in the dynamics of zoobenthic species assemblages. The benthos data come from a cluster of five stations (Süderfahrt/ Millionenviertel) in Kiel Bay. Our investigations concentrated on the macrobenthic dynamics with a focus on the number of species m− 2 (species richness). Using logarithms and the time series analysis approach of Box/Jenkins (ARIMA modelling, transfer function modelling) it was shown that species richness was strongly influenced by the winter NAO (adjusted for a linear time trend within the 1968-2000 period) and salinity (with a shift/lag of four years). Bootstrapping experiments (i.e. sampling from the error process) and analysis of prediction power (by means of the one- or more-years leaving-out method) showed that the parameter estimates behaved in a stable way, leading to a relatively robust model.

Description: This study determined the effects of two test diets — a dry-phytoplankton and a trout-fry feed — and a control diet (Artemia nauplii) on tryptic activity, growth and survival rates during early life stages of Nile tilapia (Oreochromis niloticus) larvae. In addition, during a second experimental series, the interaction between trypsin and CCK (cholecystokinin) secretion was monitored in larvae fed with a PHA (phytohemagglutinin, a protein extract from the red kidney bean) enriched commercial trout-diet and compared with the data resulting from the use of the same but non-enriched feed. Subgroups were taken from the experimental units and kept under starvation. Oreochromis niloticus was chosen as a model species, since the larvae are able to intake artificial diets by the time of first feeding, and thus featuring the experiments with a manipulated micro-diet. The results demonstrated that larval mortality and growth are affected by the diet given and this was mostly observed in the group fed on dry-phytoplankton (12.2% mortality, 1.45 mg/d; control group: 2.9% mortality, 3.19 mg/d). The same larval group showed also a higher tryptic activity compared with all the other groups, which in combination with the bad survival and poor growth performance gives evidence for inadequate nutritional quality of the dry-phytoplankton feed for larvae aged more than two weeks after hatching. Every other feeding group showed good growth rates (trout-fry feed: 3.04–3.19 mg/d, with PHA enriched trout-fry feed: 2.85 mg/d), similar to the larvae fed with live prey (3.19–3.35 mg/d). A reduction of tryptic activity characterised the starvation process. These results confirm the usefulness of monitoring the individual tryptic activity as an indicator for evaluating the quality of a diet and the nutritional condition of fish larvae, but also the necessity of combining data of tryptic activity with growth and survival data for a correct interpretation. An interaction between trypsin and CCK secretion was also confirmed with this experimental approach, since induction and reduction of tryptic activity followed a reverse pattern compared with the concentration of CCK.

Description: Past changes in the Arctic Ocean and its marginal seas have been profound, even during the last 10,000 years. Understanding these changes, such as those occurring during the transition from glacial to interglacial climates, are important for research on modern processes, because this knowledge provides a framework and unique perspective in which to view the modern physical and biological processes. This paper discusses our current understanding of past environmental change and processes relative to those currently in progress. Special emphasis is placed on the most recent transition from a glacial state to the modern interglacial conditions.

Description: A significant part of the variation in the early life history traits of fish can be ascribed to the parental origin of the individual larvae. The primary source of this parental contribution has been attributed to maternal effects and evidence for paternal effects is equivocal. Maternal effects are a non-genetic contribution of a female to its offspring but most reported maternal effects are products of both genetic and non-genetic contributions, i.e. female effects. In this study, parental effects on traits of larvae of Atlantic herring (Clupea harengus L.) at hatch were investigated at one temperature using a 5 × 3 factorial mating design (North Carolina Design II). This allowed estimation of the true maternal effect and the additive genetic variation (heritability). Furthermore, relationships between individual traits were examined and for the first time nucleic acid content and otolith size at hatch were examined together. A significant correlation between the two was found and it is argued to support the notion that otolith growth is more related to metabolic rate than to somatic growth. Maternal effects were detected in larval weight and yolk-sac volume, while paternal and, hence, genetic effects appeared in larval length, yolk-sac volume, RNA : DNA ratio, and lapillar area. The findings suggest that an increased emphasis should be placed upon the importance of male influence on success of early larval fishes.

Description: The Northern Calcareous Alps (NCA) are the site of very large top-to-north convergent movements during Cretaceous–Tertiary Alpine mountain building. To determine the amount of shortening, the depth of detachment and the style of deformation, we retro-deformed an approximately 40 × 40 km area comprising the Lechtal and Allgäu Nappes. On the basis of all available geological data and processed sections of the TRANSALP reflection seismic experiment, coherent 3D models were constructed by splining lines from N–S cross-sections. Integration of 3D kinematic modeling and field data shows the following. The structure of the Lechtal Nappe is controlled by the Triassic Hauptdolomit. Four main thrusts link to a detachment at 2–6 km depth below sea level. Shortening estimates vary, from 25% (east) to 42% (west). Additional contraction is accommodated by folding. In the east the subjacent Allgäu Nappe can be traced about 10 km down-plunge, and is shortened by about one third. In the western part the downplunge width is at least 15–20 km, with restorable shortening of one third. The triple (Inntal, Lechtal, Allgäu Nappes) NCA nappe system was moved uniformly N–S to produce laterally heterogeneus shortening of 40–90 km or 50–67%. We suggest that the NCA are underlain by substantial amounts of buried Molasse sediments and/or overthrust units of Helvetic and Rheno-Danubian Flysch, indicating post-Eocene N–S shortening of at least 55 km. Restored to an initial configuration, the basin topography of the NCA reveals strong E–W thickness variations of the Triassic Wettersteinkalk and Hauptdolomit platform carbonates. Such variations may pertain to N–S trending growth faults, which were important precursors to later Jurassic extension of the Austroalpine passive margin. Such structures are unlikely to be seen in the conventional N–S cross-sections, but form an essential geometrical and mechanical element in later, convergent mountain building.

Description: Young (≤3Ma) lavas from volcanic centers along a 75-km N–S transect from northern Madeira Island to a submarine volcanic field 55km south of Madeira exhibit distinct spatial geochemical variations. From south to north along this transect, there is a general decrease in Fe(8) (total Fe as FeO normalized to MgO=8wt.%), K(8), Pb isotope ratios and Zr/Hf and an increase in Al(8) and Nd isotope ratios, reflecting an increasing contribution of depleted source components to the north. The south to north spatial variations mimic the ca. 6million year temporal geochemical evolution on Madeira with the isotopic composition of the volcanic rocks becoming progressively more depleted through time. The temporal and spatial variation in chemical composition of lavas is consistent with melt extraction from a heterogeneous blob of upwelling mantle consisting of enriched garnet pyroxenite/eclogite material (recycled hydrothermally altered oceanic crust) in a depleted ultramafic/peridotitic matrix (recycled lower oceanic crust and/or lithospheric mantle). The geochemical transect provides new insights into the spatial heterogeneity of the Madeira plume pulse and confirms models for the temporal evolution of ocean island volcanoes.

Description: Active hydrothermal vent sites were sampled during 1997 in a series of submersible dives at the active Grimsey (GHF) and Kolbeinsey (KHF) hydrothermal fields off the north coast of Iceland. This study focuses on secondary clay minerals which were formed in two different settings. The GHF is characterized by the presence of clay minerals precipitated within active chimneys. By contrast, the KHF is characterized by the presence of secondary clay minerals, which are the products of hydrothermal alteration of lava fragments. Based on XRD, electron microprobe and ICP-MS analyses, the dominant clay mineral in both hydrothermal fields is saponite (Mg-rich smectite). Chlorite and chlorite–smectite mixed-layer minerals also occur at the KHF. The Mg-rich nature of saponite from the GHF chimneys suggests intense Mg metasomatism in the mixing zone where hydrothermal fluids interact with seawater at temperatures of 250 °C. Saponite formation resulted in the additional uptake of Cu, Zn, and Pb. Enrichment in Ba is evident in the almost pure saponite from the KHF. Based on oxygen isotope data, the saponite formation at the KHF occurred at 148 °C, which is close to the maximum measured fluid temperature of 131 °C in this field.

Description: The eastern Sunda margin off Indonesia (from central Java to Sumba Island) remains a little investigated subduction zone, contrary to its well-studied northwestern segment. Whereas large portions of the Sunda margin are considered a classical accretionary zone, subduction characteristics along the central Java sector indicate erosive processes as the dominant mode of mass transfer. The tectonic framework of the central Java margin, with a convergence rate of 6.7 cm/yr, insignificant sediment input and a pronounced seafloor roughness where the oceanic Roo Rise is subducting underneath Java, facilitates subduction erosion. Evidence for erosion comes from newly acquired geophysical data off central Java: local erosive processes in the wake of seamount subduction are documented by a high-resolution bathymetric survey and result in an irregular trend of the deformation front sculpted by seamount collision scars. Subduction of oceanic basement relief leads to large-scale uplift of the forearc, as recorded on a reflection seismic profile, and to a dismemberment of the previous outer forearc high, giving way to isolated topographic elevations. The broad retreat of the Java Trench and deformation front above the leading edge of the Roo Rise has exposed an area of approximately 25,000 km2 of deeper seafloor formerly covered by the previous frontal prism. Frontal erosion coincides with a steepening of the lower slope angle in the central Java sector compared to the neighbouring segments. In global compilations, the key geological parameters of the central Java margin lie in the erosive regime, reflecting the interplay of basement relief subduction, negligible sediment supply and a high convergence rate on the evolution of the margin.

Description: Abiogenic methane may be produced in submarine hydrothermal systems by degassing of basalts or serpentinization of ultramafic outcrops. The latter process presumably releases little primordial helium and is therefore implicated by high CH4/3He ratios in vent fluids from the ultramafic-hosted Rainbow field and in methane plumes near ultramafic outcrops. In two segments of the Mid-Atlantic Ridge, at 5.4°N and 51°N, we have observed depth-separated CH4 and 3He plumes. In both cases, the helium plume was deeper, near the valley floor. It may be that the plumes issue from separate vents, where the helium is discharged near the volcanic axis and the methane is generated by serpentinization on the valley wall. However, at the present time the locations of the vents that produce these plumes are not known. Using a one-pass model, we investigated whether separate venting could arise from heat conduction from a primary, helium-carrying, hydrothermal circulation to a second, shallower fracture loop intersecting ultramafic rock. The model results indicate that the flow rate through the secondary loop would have to be relatively low in order for it to stay warm enough for serpentinization to proceed. In this case, some of the exothermic heat production is lost by conduction, and the temperature increase in the circulating fluid is only a fraction of that expected from a water/rock ratio of 1:1.

Description: Seven sediment cores were taken in the Sea of Okhotsk in a south-north transect along the slope of Sakhalin Island. The retrieved anoxic sediments and pore fluids were analyzed for particulate organic carbon (POC), total nitrogen, total sulfur, dissolved sulfate, sulfide, methane, ammonium, iodide, bromide, calcium, and total alkalinity. A novel method was developed to derive sedimentation rates from a steady-state nitrogen mass balance. Rates of organic matter degradation, sulfate reduction, methane turnover, and carbonate precipitation were derived from the data applying a steady-state transport-reaction model. A good fit to the data set was obtained using the following new rate law for organic matter degradation in anoxic sediments: View the MathML sourceRPOC=KCC(DIC)+C(CH4)+KC·kx·POC Turn MathJax on The rate of particulate organic carbon degradation (RPOC) was found to depend on the POC concentration, an age-dependent kinetic constant (kx) and the concentration of dissolved metabolites. Rates are inhibited at high dissolved inorganic carbon (DIC) and dissolved methane (CH4) concentrations. The best fit to the data was obtained applying an inhibition constant KC of 35 ± 5 mM. The modeling further showed that bromide and iodide are preferentially released during organic matter degradation in anoxic sediments. Carbonate precipitation is driven by the anaerobic oxidation of methane (AOM) and removes one third of the carbonate alkalinity generated via AOM. The new model of organic matter degradation was further tested and extended to simulate the accumulation of gas hydrates at Blake Ridge. A good fit to the available POC, total nitrogen, dissolved ammonium, bromide, iodide and sulfate data was obtained confirming that the new model can be used to simulate organic matter degradation and methane production over the entire hydrate stability zone (HSZ). The modeling revealed that most of the gas hydrates accumulating in Blake Ridge sediments are neither formed by organic matter degradation within the HSZ nor by dissolved methane transported to the surface by upward fluid flow but rather through the ascent of gas bubbles from deeper sediment layers. The model was further applied to predict rates of hydrate accumulation in Sakhalin slope sediments. It showed that only up to 0.3% of the pore space is occupied by gas hydrates formed via organic matter degradation within the HSZ. Gas bubble ascent may, however, significantly increase the total amount of hydrate in these deposits.

Description: Assemblage structures and distribution patterns of larval fishes and paralarval cephalopods were examined in September 1998 at Great Meteor Seamount, an isolated seamount located in the subtropical eastern North Atlantic. Early life stages of fish (n=18555) and cephalopods (n=1200) were collected at 23 stations with a multiple opening–closing net, in seven discrete depth strata from 290 m depth (close to the seamount plateau) to the surface. Oceanic species dominated in both taxonomic groups. A peak in diversity was observed at an intermediate depth, in the 100–150 m water layer. Direct and indirect gradient analyses showed distinct species assemblages in the upper and lower part of the water column, separated by approximately 150 m. The division was statistically significant, although a considerable overlap between species was also observed. Above the summit, vertical gaps were found in the distributions of the deeper assemblages, likely caused by increased predation pressure by benthopelagic fish. Horizontal distribution patterns of fish and cephalopods were similar and corresponded to the structure of closed circulation cells detected above the flanks and the flat plateau area. Fish assemblages were significantly different between the inner and outer seamount regime, which was approximately separated by the 1500 m depth contour. Differences in the taxonomic composition of cephalopods were less pronounced; for only one cephalopod species could a direct association with the seamount be assumed. The study indicates a significant retention potential at the seamount that facilitates local recruitment of resident stocks and generates self-sustainable populations isolated from the continental shelf and oceanic islands.

Description: The Dnepr paleo-delta area in the NW Black Sea is characterized by an abundant presence of methane seeps. During the expeditions of May–June 2003 and 2004 within the EU-funded CRIMEA project, detailed multibeam, seismic and hydro-acoustic water-column investigations were carried out to study the relation between the spatial distribution of methane seeps, sea-floor morphology and sub-surface structures. 2778 new methane seeps were detected on echosounding records in an area of 1540 km2. All seeps are located in the transition zone between the continental shelf and slope, in water depths of 66 to 825 m. The integration of the different geophysical datasets clearly indicates that methane seeps are not randomly distributed in this area, but are concentrated in specific locations. The depth limit for the majority of the detected seeps is 725 m water depth, which corresponds more or less with the stability limit for pure methane hydrate at the ambient bottom temperature (8.9 °C) in this part of the Black Sea. This suggests that, where gas hydrates are stable, they play the role of buffer for the upward migration of methane gas and thus prevent seepage of methane bubbles into the water column. Higher up on the margin, gas seeps are widespread, but accurate mapping illustrates that seeps occur preferentially in association with particular morphological and sub-surface features. On the shelf, the highest concentration of seeps is found in elongated depressions (pockmarks) above the margins of filled channels. On the continental slope where no pockmarks have been observed, seepage occurs along crests of sedimentary ridges. There, seepage is focussed by a parallel-stratified sediment cover that thins out towards the ridge crests. On the slope, seepage also appears in the vicinity of canyons (bottom, flanks and margins) or near the scarps of submarine landslides where mass-wasting breaches the fine-grained sediment cover that acts as a stratigraphic seal. The seismic data show the presence of a distinct “gas front,” which has been used to map the depth of the free gas within the sea-floor sediments. The depth of this gas front is variable and locally domes up to the sea floor. Where the gas front approaches the seafloor, gas bubbles were detected in the water column. A regional map of the sub-surface depth of the gas front emphasises this “gas front-versus-seep” relationship. The integration of all data sets indicates that the spatial distribution of methane seeps in the Dnepr paleo-delta is mainly controlled by the gas-hydrate stability zone as well as by stratigraphic and sedimentary factors.

Description: Exploring the potentials of new methods in palaeothermometry is essential to improve our understanding of past climate change. Here, we present a refinement of the published δ44/40Ca-temperature calibration investigating modern specimens of planktonic foraminifera Globigerinoides sacculifer and apply this to sea surface temperature (SST) reconstructions over the last two glacial–interglacial cycles. Reproduced measurements of modern G. sacculifer collected from surface waters describe a linear relationship for the investigated temperature range (19.0–28.5 °C): δ44/40Ca [‰] = 0.22 (±0.05)∗SST [°C] −4.88. Thus a change of δ44/40Ca[‰] of 0.22 (±0.05) corresponds to a relative change of 1 °C. The refined δ44/40Camodern-calibration allows the determination of both relative temperature changes and absolute temperatures in the past. This δ44/40Camodern-calibration for G. sacculifer has been applied to the tropical East Atlantic sediment core GeoB1112 for which other SST proxy data are available. Comparison of the different data sets gives no indication for significant secondary overprinting of the δ44/40Ca signal. Long-term trends in reconstructed SST correlate strongly with temperature records derived from oxygen isotopes and Mg/Ca ratios supporting the methods validity. The observed change of SST of approximately 3 °C at the Holocene-last glacial maximum transition reveals additional evidence for the important role of the tropical Atlantic in triggering global climate change, based on a new independent palaeothermometer.

Description: 10.1016/j.epsl.2005.10.027

Description: Many marine radiogenic isotope records show both spatial and temporal variations, reflecting both the degree of mixing of distinct sources in the oceans and changes in the distribution of chemical weathering on the continents. However, changes in weathering and transport processes may themselves affect the composition of radiogenic isotopes released into seawater. The provenance of physically weathered material in the Labrador Sea, constrained through the use of Ar–Ar ages of individual detrital minerals, has been used to estimate the relative contributions of chemically weathered terranes releasing radiogenic isotopes into the Labrador Sea. A simple box-model approach for balancing observed Nd-isotope variations has been used to constrain the relative importance of localised input in the Labrador Sea, and the subsequent mixing of Labrador Sea Water into North Atlantic Deep-Water. The long-term pattern of erosion and deep-water formation around the North Atlantic seems to have been a relatively stable feature since 1.5 Ma, although there has been a dramatic shift in the nature of physical and chemical weathering affecting the release of Hf and Pb isotopes. The modelled Nd isotopes imply a relative decrease in water mass advection into the Labrador Sea between 2.4 and 1.5 Ma, accompanied by a decrease in the rate of overturning, possibly caused by an increased freshwater input into the Labrador Sea.

Description: In situ microbialites occurring in reef rocks dredged between 80 and 130 m water depth on the modern fore-reef slopes of Tahiti and the Marquesas islands yield ages ranging from 17,100 ± 2900 to 4410 ± 2250 years BP, suggesting that they played a prominent role during the last deglacial sea level rise. Microbialites developed in both shallow and deep water depositional environments where they characterize various zones of the reef tracts (reef crests, upper reef slopes, deep fore-reef slopes), reflecting contrasting scenarios of microbialite development involving «reefal microbialites» in shallow-water settings and «slope microbialites» that formed in environments deeper than 10–20 m and extending down to more than 100 m. Reefal microbialites correspond to a late stage of encrustation of the dead parts of coral colonies, or more commonly, of related encrusting organisms (red algae and foraminifers), thus forming surface crusts. Slope microbialites generally form the ultimate stage of a biological succession indicating a deepening sequence, whereby shallow water corals and associated encrusting organisms are replaced by deeper water assemblages of red algae and foraminifers before microbialite growth. The precipitation of phosphatic–iron–manganese crusts and the deposition of planktonic micritic limestones on the microbialites characterize a deepening-upward sequence. The widespread development of microbialites in reef sequences from the Last Deglaciation characterizes a period of environmental degradation consequential on the rapid sea-level rise and abrupt climatic changes of that time. The reported biological succession reflects changes in water quality, and especially an increase in nutrients. In shallow-water settings, increased alkalinity and nutrient availability in interstitial waters were related to surface fluxes and terrestrial groundwater seepage while slope environments were exposed to continuous upwelling of nutrient-rich deeper waters during the last deglacial sea level rise. The age differences between corals and overlying slope microbialites range from 1600 to 8400 years, based on high-precision U-series age measurements of both corals and microbialites, and indicates that a significant time (several thousand years) elapsed between the development of the coralgal frameworks and the growth of slope microbialite crusts. Microbialites cannot be considered as part of the drowning event some 14,000 years ago that resulted in the demise of reef frameworks in the 90–110 m present depth range, but are substantially younger.

Description: A representative suite of deformed, metamorphic rocks from the TRANSALP reflection seismic traverse in the Eastern Alps was studied in the laboratory with respect to elastic properties and whole-rock texture. Compressional wave (P-wave) velocities and their anisotropies were measured at various experimental conditions (dry, wet, confining pressure), and compared to the texture-related component of anisotropy. Here ‘texture’ refers to crystallographic preferred orientations (CPOs), which were determined by neutron texture goniometry. In gneisses and schists P-wave anisotropies are mainly controlled by the microcrack fabric. In marbles and amphibolites CPO contributes very significantly to anisotropy. At 200 MPa confining pressure the degree of anisotropy is between 5% and 15%, depending on rock composition and/or CPO intensity. Special emphasis was also put on discussing possible effects of fluids on seismic velocity and anisotropy. Distributions of water-filled microcracks and pores are distinctly anisotropic, with maximum contribution to bulk rock velocity mostly parallel to the foliation pole. Decreasing P-wave velocity and increasing anisotropy of immersed samples may be explained by crack-induced changes of the elastic moduli of bulk rock. The main conclusion regarding interpretation of TRANSALP data is that strong reflections in the deep Alpine crust are probably due to marble–gneiss and metabasite–gneiss contacts, although P-wave anisotropy and boundaries between zones of ‘dry’ or ‘wet’ series may contribute to reflectivity to some extent.

Description: A mud volcano area in the deep waters (〉 2000 m) of the Black Sea was studied by hydroacoustic measurements during several cruises between January 2002 and June 2004. Gas bubbles in the water column give strong backscatter signals and thus can be detected even in great water depths by echosounders as the 38 kHz EK500 scientific split-beam system that was used during the surveys. Because of their shape in echograms and to differentiate against geochemical plumes and real upwelling bubble-water plumes, we call these hydroacoustic manifestations of bubbles in the water column ‘flares’. Digital recording and processing of the data allows a 3D visualization and data comparison over the entire observation period, without artefacts caused by changing system settings. During our surveys, we discovered bubble release from three separate mud volcanoes, Dvurechenskiy (DMV), Vodianitskiy (VMV) and the Nameless Seep Site (NSS), in about 2080 m water depth simultaneously. Bubble release was observed between 9 June 2003 and 5 June 2004. The most frequently surveyed, DMV, was found to be inactive during very intensive studies in January 2002. The first activity was observed on 27 June 2002, which finally ceased between 5 and 15 June 2004 after a period of continuously decreasing activity. This observed 2-yr bubble-release period at a mud volcano may give an indication for the duration of active periods. The absence of short-term variations (within days or hours) may indicate that the bubble release from the observed mud volcanoes does not undergo rapid changes. The recorded echograms show that bubbles rise about 1300 m high through the water column, to a final water depth of about 770 m, which is ∼75 m below the phase boundary of pure methane hydrate in the Black Sea. With a release depth from 2068 m and a detected rise height of 1300 m, the flare at VMV is among the deepest and highest reported so far, and gives evidence of highly extended bubble life times (up to 108 min) in deep marine environments. To better understand how a methane bubble (gas analyses of the pore water and gas hydrate gave 99.4% methane) can rise so high without dissolving, we applied a recently developed bubble dissolution model that takes into account a decreased mass transfer due to an immediately formed gas-hydrate rim. Using the hydroacoustically determined bubble rising speeds (19–22 cm/s at the bottom; 12–14 cm/s at the flare top) and the relation between the rising speed of ‘dirty’/gas hydrate rimmed bubbles and the bubble size, we could validate that a gas-hydrate-rimmed bubble with a diameter of 9 mm could survive the 1300-m-rise through the water column, before it is finally dissolved. A diameter of about 9 mm is reasonable for bubbles released at seep sites and the coincidence between the observed bubble rising speed and the model approach of a 9-mm bubble supports the assumption of gas-hydrate-rimmed bubbles

Description: It has been proposed that silicon (Si) isotopes are fractionated during weathering and biological activity leading to heavy dissolved riverine compositions. In this study, the first seasonal variations of stable isotope compositions of dissolved riverine Si are reported and compared with concomitant changes in water chemistry. Four different rivers in Switzerland were sampled between March 2004 and July 2005. The unique high-resolution multi-collector ICP-MS Nu1700, has been used to provide simultaneous interference-free measurements of 28Si, 29Si and 30Si abundances with an average limiting precision of ± 0.04‰ on δ30Si. This precision facilitates the clarification of small temporal variations in isotope composition. The average of all the data for the 40 samples is δ30Si = + 0.84 ± 0.19‰ (± 1σSD). Despite significant differences in catchment lithologies, biomass, climate, total dissolved solids and weathering fluxes the averaged isotopic composition of dissolved Si in each river is strikingly similar with means of + 0.70 ± 0.12‰ for the Birs,+ 0.95 ± 0.22‰ for the Saane,+ 0.93 ± 0.12‰ for the Ticino and + 0.79 ± 0.19‰ for the Verzasca. However, the δ30Si undergoes seasonal variations of up to 0.6‰. Comparisons between δ30Si and physico–chemical parameters, such as the concentration of dissolved Si and other cations, the discharge of the rivers, and the resulting weathering fluxes, permits an understanding of the processes that control the Si budget and the fate of dissolved Si within these rivers. The main mechanism controlling the Si isotope composition of the mountainous Verzasca River appears to be a two component mixing between the seepage of soil/ground waters, with heavier Si produced by clay formation and superficial runoff associated with lighter Si during high discharge events. A biologically-mediated fractionation can be excluded in this particular river system. The other rivers display increasing complexity with increases in the proportion of forested and cultivated landscapes as well as carbonate rocks in the catchment. In these instances it is impossible to resolve the extent of the isotopic fractionation and contributed flux of Si contributed by biological processes as opposed to abiotic weathering. The presence of seasonal variations in Si isotope composition in mountainous rivers provides evidence that extreme changes in climate affect the overall composition of dissolved Si delivered to the oceans. The oceanic Si isotope composition is very sensitive to even small changes in the riverine Si isotope composition and this parameter appears to be more critical than plausible changes in the Si flux. Therefore, concurrent changes in weathering style may need to be considered when using the Si isotopic compositions of diatoms, sponges and radiolaria as paleoproductivity proxies.

Description: The late Holocene mud wedge on the Adriatic shelf offshore Ortona, Italy, shows undulating sub-parallel seismic reflector sequences which extend several kilometres along strike and 100–200 m down-dip in water depth between 20 and 80 m. The amplitude of such undulations is up to 5 m and the undulations continue as stacked sediment packages downwards throughout the 35 m thick mud wedge. The undulations are separated by 4° to 5° dipping boundary zones and at first glance these sediment undulations resemble the seafloor sedimentary structures visible in the Humboldt Feature offshore California. There is an ongoing debate whether seafloor undulations are the result of deformation processes or sediment deposition and/or reworking due to submarine shelf currents. A dense net of recently reprocessed and digitally interpreted high-resolution Chirp seismic data on the Adriatic shelf favours an interpretation that these undulations developed, in the upper part of the stratigraphic section through sediment reworking rather than through deformation. There are three lines of evidence for this: (1) the spatial extent of the undulations coincides with higher seabed reflector amplitudes than found both on the shelf and in the distal part of the shelf. If the features were solely caused by slope failure there should be no change of amplitudes, (2) the seabed reflector amplitude is generally higher on the gently dipping or flat upslope limbs than on the steeper downslope limbs, supporting a current origin that causes preferred deposition of sediments with higher acoustic impedance on the top, (3) the boundaries between the undulations are dipping at angles that are much lower than the angle of internal friction of these sediments excluding that a simple model like the Mohr–Coulomb under gravitational loading could describe the undulations as sediment deformation and failures.

Description: We have developed a new, bimonthly resolved coral δ18O time series from the Seychelles (55°E, 4°S). Our coral time series covers the period of 1840–1994 AD and shows stable correlations with regional sea surface temperatures over the past 50 years. The strength of the proxy-climate relationship depends on the annual cycle of the Asian monsoon. Seasonal correlation patterns suggest that the coral primarily records the boreal summer cooling in the western Indian Ocean and Arabian Sea, which results from wind-induced mixing and evaporation during the SW monsoon season. We have combined our coral time series with an existing 150-year long coral record from the Seychelles to strengthen the climatic signals recorded in the two cores. This new coral index shows a strong correlation with historical surface temperatures from the Arabian Sea and India, suggesting that the corals can be used to reconstruct regional temperature trends in pre-instrumental times. The coral index also shows a significant correlation with the Niño 3.4 index, which captures the ENSO phenomenon centred in the tropical Pacific. Cross-spectral analysis confirms that the coral index and Niño 3.4 are coherent at decadal periods, supporting the notion that decadal El Niño-like variability influences the Indian Ocean.

Description: Mafic blueschists of the Tianshan (NW China) display an interconnected network of eclogite-facies veins derived by prograde blueschist dehydration. The eclogite-facies vein-network in the Tianshan blueschist was found to be the product of hydrofracturing induced by fluids released by the breakdown of glaucophane, paragonite and epidote minerals during blueschist–eclogite transition and, thus represent former fluid pathways within a Paleozoic subduction zone. The veins are predominantly composed of omphacite fibers with minor quartz, calcite, and apatite. The transition from blueschist- to eclogite-facies parageneses occurs as “dehydration” halos along some of these veins. The fluids are interpreted to have been derived from the host blueschist as a result of dehydration reactions at peak metamorphic conditions of 480–600 °C and 18–21 kbar (Gao and Klemd, 2001 and John et al., 2006). The low in trace element fluid caused a strong mobilization of LILE, REE, and high field strength elements (HFSE) in those parts of the host rock with which the passing fluid reacted (John et al., 2006). Hence indicating that so-called immobile elements can be mobilized by reactive flow. Furthermore, field evidence shows that rutile occurs in the form of needle-like segregations in an eclogite boudin and as prismatic crystals in an omphacite-bearing vein cross-cutting foliated host eclogites. Textural and geochemical studies indicate that titanium, niobium and tantalum can be mobilized and transported by fluids which were liberated by means of dehydration of the subduction oceanic crust. Vein-rutile precipitation occurred at sites where evidence for an increasing oxygen fugacity in the acting fluid is found, causing a sudden depletion of the HFSE concentration in the fluid. Such a fluid may act as agent for the subduction component seen in the distinct chemistry of normal island-arc magmas.

Description: A new high resolution sea-level curve for the Late Cenomanian M. geslinianum Zone has been generated using sequence stratigraphic analysis on transects through the margins of the Anglo-Paris Basin in the UK and Saxony Basin in Germany. Transgressive sediments that bury a rocky shoreline in the Dresden area have proved particularly useful in determining both the absolute amount of sea-level change and the rate of rise. After a brief fall at the base of the M. geslinianum Zone, sea level rose rapidly through the higher part of the zone, resulting in an overall short term eustatic rise of 22–28 m. Biostratigraphy and carbon isotope stratigraphy have enabled detailed correlations to be made between marginal locations and thick, relatively complete, basinal successions. The basinal successions at Eastbourne, UK, and Gröbern, Germany, provide both geochemical proxies for palaeoenvironmental change, including oxygen and carbon isotope records, and an orbital timescale graduated in precession and eccentricity cycles. Integration of the sea-level history with palaeoclimate evolution, palaeoceanography and changes in carbon cycling allows a detailed reconstruction of events during the Late Cenomanian. Orbital forcing on long eccentricity maxima provides the underlying drive for these changes, but amplification by tectonic events and feedback mechanisms augmented the orbital effects and made the Cenomanian/Turonian Boundary Event distinctive. In particular, variations in atmospheric CO2 caused by oceanic drawdown and a brief period of intense volcanic outgassing resulted respectively in short term cooling and warming events. The magnitude and high rates (up to 1 m/1 kyr) of sea-level rise are diagnostic of glacioeustasy, however improbable this may appear at the height of the Cretaceous greenhouse.

Description: Osbourn Trough is a key piece in an outstanding problem: do the Ontong Java, Manihiki and Hikurangi large igneous provinces represent a single ~100 million km3 magmatic pulse? Bathymetric mapping of a 145-km-wide swath across the ∼900-km-long Osbourn Trough revealed three segments offset by 23–35-km-long basins that strike perpendicular to the trough axis. Each segment comprises a 10–15-km-wide axial valley bounded by 300–500-m-high ridge mountains, has inside corner highs at its NW and SE margins that rise 1000–1200 m above the axial valley, and has a flanking set of subparallel abyssal hills. Dredging on steep escarpments successfully penetrated thick sediments and recovered Fe–Mn oxyhydroxide-encrusted volcaniclastic breccias. Lava clasts within the breccias have undergone variable degrees of marine weathering, leading to strong enrichment in most alkali elements and the light REE (except Ce). Nevertheless, their immobile element concentrations are consistently MORB-like and they plot within the MORB fields of tectonic discrimination diagrams. Isotope analyses indicate an affinity with Pacific MORB-source mantle. Both the morphology of Osbourn Trough and geochemistry of its lavas establish that it represents an extinct spreading ridge system. The trough is nearly equidistant (1750 km vs. 1550 km) from the Manihiki and Hikurangi Plateaus, which we interpret as remnants of a formerly contiguous Ontong Java–Manihiki–Hikurangi large igneous province. Inception of the Osbourn spreading ridge was coincident with reorganization of the former Pacific–Phoenix–Farallon spreading system and mega-plateau fragmentation at ∼118 Ma. Spreading across Osbourn Trough ceased when the Hikurangi Plateau collided with and blocked a southward-dipping subduction system developed along the Chatham Rise (eastern New Zealand) sector of the Gondwana margin at ∼86 Ma.

Description: Settling rates of faecal material from three size categories of cultured gilthead sea bream, Sparus aurata, and sea bass, Dicentrarchus labrax, were determined. Faecal material was collected from underneath commercial cages and subsequently transferred to a settling column. Particle settling velocity was determined using particle tracking software. Image analysis software was used to determine dimensions of selected faecal particles from which particle volume was then estimated. Faecal particles (all fish sizes) had a mean settling velocity of 0.48 cm/s (range 0.05–3.94 cm/s, n = 1021) for sea bream and 0.70 cm/s (range 0.10–6.27 cm/s, n = 1042) for sea bass. The faecal material largely consisted of very small particles and mean particle size was 0.71 mm (n = 151) and 1.12 mm (n = 150) for S. aurata and D. labrax, respectively. More than 50% of the total particle volume had a settling velocity less than 2.0 cm/s in all S. aurata size categories. In D. labrax, more than 75% of the total particle volume had settling velocities greater than 2.0 cm/s. The particle tracking DEPOMOD model was highly sensitive to different representations of these data. The predicted seabed flux of waste faecal material (g/m2/year) for D. labrax using the mean settling velocity at 0 m and 50 m from the cage was 3196 g/m2/year and 248 g/m2/year, respectively. However, when using particle settling velocity and volume distribution data, the predicted flux was over three times greater at 0 m but five times less at 50 m. For S. aurata, the predicted flux using the mean settling velocity was 3018 g/m2/year and 464 g/m2/year at 0 and 50 m, respectively. However, where distribution data were used, the values were over twice as high at 0 m and but were halved at 50 m. These results indicate that use of a single mean settling velocity value in this type of modelling does not accurately predict the extent of benthic flux. In addition, species-specific faecal settling rates should be used when modelling polyculture operations.

Description: The 44Ca/40Ca ratios of cultured (Acropora sp.) and open ocean (Pavona clavus, Porites sp.) tropical reef corals are positively correlated with growth temperature. The slope of the temperature–fractionation relation is similar to inorganic aragonite precipitates. However, δ44/40Ca of the coral aragonite is offset from inorganic and sclerosponge aragonite by about +0.5‰. This offset can neither be explained by the very fast, biologically controlled calcification of scleractinian corals, nor as a consequence of calcification from a partly closed volume of fluid. As corals actively transport calcium through several cell layers to the site of calcification, the most likely explanation for the offset is a biologically induced fractionation. Our results indicate a limited use of Ca isotopes in scleractinian corals as temperature proxy.

Description: A compilation of data on volumes and masses of evaporite deposits is used as the basis for reconstruction of the salinity of the ocean in the past. Chloride is tracked as the only ion essentially restricted to the ocean, and past salinities are calculated from reconstructed chlorine content of the ocean. Models for ocean salinity through the Phanerozoic are developed using maximal and minimal estimates of the volumes of existing evaporite deposits, and using constant and declining volumes of ocean water through the Phanerozoic. We conclude that there have been significant changes in the mean salinity of the ocean accompanying a general decline throughout the Phanerozoic. The greatest changes are related to major extractions of salt into the young ocean basins which developed during the Mesozoic as Pangaea broke apart. Unfortunately, the sizes of these salt deposits are also the least well known. The last major extractions of salt from the ocean occurred during the Miocene, shortly after the large scale extraction of water from the ocean to form the ice cap of Antarctica. However, these two modifications of the masses of H2O and salt in the ocean followed in sequence and did not cancel each other out. Accordingly, salinities during the Early Miocene were between 37‰ and 39‰. The Mesozoic was a time of generally declining salinity associated with the deep sea salt extractions of the North Atlantic and Gulf of Mexico (Middle to Late Jurassic) and South Atlantic (Early Cretaceous). The earliest of the major extractions of the Phanerozoic occurred during the Permian. There were few large extractions of salt during the earlier Palaeozoic. The models suggest that this was a time of relatively stable but slowly increasing salinities ranging through the upper 40‰'s into the lower 50‰'s. Higher salinities for the world ocean have profound consequences for the thermohaline circulation of the ocean in the past. In the modern ocean, with an average salinity of about 34.7‰, the density of water is only very slightly affected by cooling as it approaches the freezing point. Consequently, salinization through sea-ice formation or evaporation is usually required to make water dense enough to sink into the ocean interior. At salinities above about 40‰ water continues to become more dense as it approaches the freezing point, and salinization is not required. The energy-consuming phase changes involved in sea-ice formation and evaporation would not be required for vertical circulation in the ocean. The hypothesized major declines in salinity correspond closely to the evolution of both planktonic foraminifera and calcareous nannoplankton. Both groups were restricted to shelf regions in the Jurassic and early Cretaceous, but spread into the open ocean in the mid-Cretaceous. Their availability to inhabit the open ocean may be directly related to the decline in salinity. The Permian extraction may have created stress for marine organisms and may have been a factor contributing to the end-Permian extinction. The modeling also suggests that there was a major salinity decline from the Late Precambrian to the Cambrian, and it is tempting to speculate that this may have been a factor in the Cambrian explosion of life.

Description: The warmest millennia of at least the past 250,000 years occurred during the Last Interglaciation, when global ice volumes were similar to or smaller than today and systematic variations in Earth's orbital parameters aligned to produce a strong positive summer insolation anomaly throughout the Northern Hemisphere. The average insolation during the key summer months (M, J, J) was ca 11% above present across the Northern Hemisphere between 130,000 and 127,000 years ago, with a slightly greater anomaly, 13%, over the Arctic. Greater summer insolation, early penultimate deglaciation, and intensification of the North Atlantic Drift, combined to reduce Arctic Ocean sea ice, allow expansion of boreal forest to the Arctic Ocean shore across vast regions, reduce permafrost, and melt almost all glaciers in the Northern Hemisphere. Insolation, amplified by key boundary condition feedbacks, collectively produced Last Interglacial summer temperature anomalies 4–5 °C above present over most Arctic lands, significantly above the average Northern Hemisphere anomaly. The Last Interglaciation demonstrates the strength of positive feedbacks on Arctic warming and provides a potentially conservative analogue for anticipated future greenhouse warming.

Description: A novel technique was applied to estimate differences in core shortening in three gravity cores taken at the same core location on the Portuguese continental slope using different coring devices. No obvious deformational features are visible in the fresh core sediments; the isotope stratigraphy and abundance maxima of ice-rafted debris, representing North Atlantic Heinrich-events, indicate identical stratigraphic range in all three cores. However, one of the cores is significantly shorter than the others. X-ray radiographs of the cores reveal that the shorter core shows typical deformation structures, whereas the two other cores are lacking signs of deformation. This serious disturbance had likely gone unnoticed had it not been for the X-ray radiographs. As an approach to semi-quantitatively estimate the core shortening, we used the fragmentation and displacement of the pyritized trace fossil Trichichnus that is easily recognizable in X-ray radiographs through its high contrast. The Trichichnus data indicate that a shortening of 50–60% occurred in the lower part of the shorter core. This estimate is in good agreement with variations in apparent sedimentation rates for the interval considered. Accurate flux rates are essential for our understanding marine biogeochemical cycles in general and the marine budgets of nutrients such as carbon and phosphorus in particular. X-ray radiographs are very useful in assessing the intactness of the sedimentary records and the presented method has potential to become a valuable tool in correcting sedimentation rates in disturbed gravity cores.

Description: Thirteen lipophilic extracts prepared with n-hexane from various parts of Pistacia vera L. tree (Anacardiaceae) growing in Turkey were screened for their in vitro activity against four parasitic protozoa, Trypanosoma brucei rhodesiense, Trypanosoma cruzi, Leishmania donovani and Plasmodium falciparum. Melarsoprol, benznidazole, miltefosine, artemisinin and chloroquine were used as reference drugs. The cytotoxic potentials of the extracts on rat skeletal myoblast (L6) cells were also assessed and compared to that of podophyllotoxin. The screening method employed was medium-throughput, where the extracts were tested at two concentrations, at 0.8 and 4.8 μg/ml (T. brucei rhodesiense, L. donovani and Plasmodium falciparum), or at 1.6 and 9.7 μg/ml (T. cruzi and L6 cells). At 4.8 μg/ml concentration, the branch extract of Pistacia vera (PV-BR) significantly inhibited (77.3%) the growth of L. donovani, whereas the dry leaf extract (PV-DL) was active against Plasmodium falciparum (60.6% inhibition). The IC50 values of these extracts were determined as 2.3 μg/ml (PV-BR, L. donovani) and 3.65 μg/ml (PV-DL, Plasmodium falciparum). None of the extracts possessed cytotoxicity on mammalian cells.

Description: The ethanolic extracts of a number of Turkish freshwater macrophytes (Potamogeton perfoliatus, Ranunculus tricophyllus and Cladophora glomerata) and marine macroalgae (Dictyota dichotoma, Halopteris scoparia, Posidonia oceanica, Scinaia furcellata, Sargassum natans and Ulva lactuca) were assayed for their in vitro antiprotozoal activity. Trypanosoma brucei rhodesiense, Trypanosoma cruzi, Leishmania donovani and Plasmodium falciparum were used as test organisms. The cytotoxicity of the extracts was also assessed against primary rat skeletal myoblasts (L6 cells). Whereas none of the extracts were active against T. cruzi, all crude extracts displayed appreciable trypanocidal activity against T. brucei rhodesiense, with S. natans being the most active one (IC50 7.4 μg/ml). Except for the marine alga H. scoparia, all extracts also possessed leishmanicidal potential. The best antileishmanial activity was exerted by U. lactuca and P. oceanica (IC50's 5.9 and 8.0 μg/ml, respectively). Five extracts that demonstrated inhibitory activity towards P. falciparum (IC50's 18.1–48.8 μg/ml) were simultaneously assayed against FabI, a crucial enzyme of the fatty acid system of P. falciparum, to find out whether FabI was their target. The extracts of C. glomerata and U. lactuca efficiently inhibited the FabI enzyme with IC50 values of 1.0 and 4.0 μg/ml, respectively. None of the extracts were cytotoxic towards mammalian L6 cells. This work reports for the first time antiprotozoal activity of some Turkish marine and freshwater algae, as well as a target-based antiplasmodial screening for the identification of P. falciparum FabI inhibitors from aquatic and marine macrophytes.

Description: The first large-scale international intercomparison of analytical methods for the determination of dissolved iron in seawater was carried out between October 2000 and December 2002. The exercise was conducted as a rigorously "blind" comparison of 7 analytical techniques by 24 international laboratories. The comparison was based on a large volume (700 L), filtered surface seawater sample collected from the South Atlantic Ocean (the "IRONAGES" sample), which was acidified, mixed and bottled at sea. Two 1-L sample bottles were sent to each participant. Integrity and blindness were achieved by having the experiment designed and carried out by a small team, and overseen by an independent data manager. Storage, homogeneity and time-series stability experiments conducted over 2.5 years showed that inter-bottle variability of the IRONAGES sample was good (〈 7), although there was a decrease in iron concentration in the bottles over time (0.8-0.5 nM) before a stable value was observed. This raises questions over the suitability of sample acidification and storage. For the complete dataset of 45 results (after excluding 3 outliers not passing the screening criteria), the mean concentration of dissolved iron in the IRONAGES sample was 0.59 ± 0.21 nM, representing a coefficient of variation (CV) for analytical comparability ("community precision") of 36 (1s), a significant improvement over earlier exercises. Within-run precision (5-10), inter-run precision (15) and inter-bottle homogeneity (〈 7) were much better than overall analytical comparability, implying the presence of: (1) random variability (inherent to all intercomparison exercises); (2) errors in quantification of the analytical blank; and (3) systematic inter-method variability, perhaps related to secondary sample treatment (e.g. measurement of different physicochemical fractions of iron present in seawater) in the community dataset. By grouping all results for the same method, analyses performed using flow injection-luminol chemiluminescence (with FeII detection after sample reduction) Bowie, A.R., Achterberg, E.P., Mantoura, R.F.C., Worsfold, P.J., 1998. Determination of sub-nanomolar levels of iron in seawater using flow injection with chemiluminescence detection. Anal. Chim. Acta 361, 189-200 and flow injection-catalytic spectrophotometry (using the reagent DPD) Measures, C.I., Yuan, J., Resing, J.A., 1995. Determination of iron in seawater by flow injection analysis using in-line preconcentration and spectrophotometric detection. Mar. Chem. 50, 3-12 gave significantly (P = 0.05) higher dissolved iron concentrations than analyses performed using isotope dilution ICPMS Wu, J.F., Boyle, E.A., 1998. Determination of iron in seawater by high-resolution isotope dilution inductively coupled plasma mass spectrometry after Mg(OH) 2 co-precipitation. Anal. Chim. Acta 367, 183-191. There was, however, evidence of scatter within each method group (CV up to 59%), implying that better uniformity in procedures may be required. This paper does not identify individual data and should not be viewed as an evaluation of single laboratories. Rather it summarises the status of dissolved iron analysis in seawater by the international community at the start of the 21st century, and can be used to inform future exercises including the SAFE iron intercomparison study in the North Pacific in October 2004. © 2005 Elsevier B.V. All rights reserved.

Description: Phytochelatins (PCs) and glutathione (GSH) are -SH-containing compounds produced by a range of organisms for intracellular functions, such as protection against oxidative stress, metal detoxification and regulation of intracellular metal concentrations. These compounds, particularly PCs, have a potential use as metal-stress indicators for phytoplankton in natural waters. Despite their important roles, there is a paucity of data on intracellular GSH and PCs produced by natural phytoplankton assemblages. Current analytical methods for the determination of these compounds in phytoplankton from natural waters are based on high-performance liquid chromatography (HPLC) with detection of fluorescent derivatives, and comprise multi-step protocols. In this article, we discuss the analytical methods for HPLC determination of PCs and GSH, as there are limitations and practical challenges when they are applied to environmental studies. © 2005 Elsevier Ltd. All rights reserved.

Description: Massive scleractinian corals secrete an aragonitic skeleton which incorporates a large array of chemical tracers. Corals present several advantages for palaeoclimate research: they grow continuously, and can live up to 1000 years; they are easy to date; and they can be sampled at high resolution (weekly to monthly resolution). Both live and fossil corals can be collected in the field. In the past two decades, significant efforts have been made to identify robust tracers of sea surface temperature (SST) and salinity (SSS) in corals. To date, Sr/Ca and δ18O are considered to be the most reliable SST tracers, although changes in seawater δ18O can significantly alter SST reconstructed from coralline δ18O. Because these variations in seawater δ18O can be linked to SSS changes, this initial problem can in fact be turned into an advantage and provide us with an SSS tracer. The SST component in the coral δ18O signal can either be evaluated through Sr/Ca measurements, or in some case simply filtered out. However, there is still much uncertainty concerning the exact mode of incorporation of trace elements and stable isotopes into the coral skeleton. The effects of growth rate, light intensity, feeding habits, pH and water chemistry are still poorly documented. A review of the strength and weaknesses of Sr/Ca and δ18O is presented, together with some examples of SST and SSS reconstructions. Other potential SST tracers are also reviewed. It is expected that the ability to grow corals in aquarium under controlled conditions, and that the development of sophisticated analytical techniques at the micrometric level should help us understand better the robustness of each tracers and the factors controlling their incorporation in coral aragonite.

Description: We report on the structural properties of natural gas hydrate crystals from the Sea of Okhotsk. Using powder X-ray diffraction (PXRD), it was determined that sediments from four locations contained type I gas hydrate, which encage mostly methane (96–98%) and a small amount of carbon dioxide. For all hydrates, the lattice constant was estimated to be at 113 K, which approximately equals that of pure methane hydrate. The result is in good agreement with the structure of artificially synthesized methane carbon dioxide mixed-gas hydrates. These results suggest that the lattice constant of the natural gas hydrate does not change due to a change of gas content. In addition, the thermal expansion of the sampled hydrate was measured for the temperature range of 83–173 K, and the resulting density of the hydrate crystal at 273 K was estimated to be . These results are essential for applying natural gas hydrates as an alternative natural fuel resources.

Description: This chapter discusses the structure and composition of the clay minerals and their physical and chemical properties. The atomic structure of the clay minerals consists of two basic units, an octahedral sheet and a tetrahedral sheet. The octahedral sheet is comprised of closely packed oxygen's and hydroxyls in which aluminum, iron, and magnesium atoms are arranged in octahedral coordination. When aluminum with a positive valence of three is the caution present in the octahedral sheet, only two-thirds of the possible positions are filled in order to balance the charges. When only two-thirds of the positions are filled, the mineral is termed dioctahedral. When magnesium with a positive charge of two is present, all three positions are filled to balance the structure and the mineral is termed trioctahedral.

Description: The distribution of pyroclasts from 79 A.D. eruption of Vesuvius is analysed to assess the ejection velocities of ballistic particles pertaining to the white and gray eruption phases. This distribution is related to the energy of the eruptive mixture and conditions of the atmosphere during the eruption. Ballistic debris is common in the deposits, and within the sampled area (3–14 km S-SE from the vent) the ejected blocks are scattered throughout the fine-grained pumice fall. We measured about 300 ballistic blocks with diameters between 0.07 and 1 m. Some fragments as large as 0.3 m are located at 9 km from the vent, which probably represents the ballistic limit of such fragments. By using a ballistic model for large blocks permitted an assessment of their initial velocities which range from 170 to 2300m/s, and since some of these velocities exceed the maximum observed velocities of plinian eruptions we conclude that the ballistic model is deficient. The trajectories of smaller blocks (0.1〈d〈0.3m) are not truly ballistic, because these can be sustained in the eruptive column and dispersed by means of the finger-like projections from the jet thrust region of the column from where they fall or produce gravity currents on the slopes of the volcano. The gas expansion in the column reduces the drag force on particulates and aids in their vertical and lateral transport. In modeling an explosive scenario at Vesuvius it is thus necessary to account for a wide variety of particulate sizes in the presence of local and stratospheric wind conditions and changing characteristics of magma as it is being evacuated from the volcanic system.

Description: Extreme global warmth and an abrupt negative carbon isotope excursion during the Paleocene–Eocene Thermal Maximum (PETM) have been attributed to a massive release of methane hydrate from sediments on the continental slope [1]. However, the magnitude of the warming (5 to 6 °C [2],[3]) and rise in the depth of the CCD (〉 2 km; [4]) indicate that the size of the carbon addition was larger than can be accounted for by the methane hydrate hypothesis. Additional carbon sources associated with methane hydrate release (e.g. pore-water venting and turbidite oxidation) are also insufficient. We find that the oxidation of at least 5000 Gt C of organic carbon is the most likely explanation for the observed geochemical and climatic changes during the PETM, for which there are several potential mechanisms. Production of thermogenic CH4 and CO2 during contact metamorphism associated with the intrusion of a large igneous province into organic rich sediments [5] is capable of supplying large amounts of carbon, but is inconsistent with the lack of extensive carbon loss in metamorphosed sediments, as well as the abrupt onset and termination of carbon release during the PETM. A global conflagration of Paleocene peatlands [6] highlights a large terrestrial carbon source, but massive carbon release by fire seems unlikely as it would require that all peatlands burn at once and then for only 10 to 30 ky. In addition, this hypothesis requires an order of magnitude increase in the amount of carbon stored in peat. The isolation of a large epicontinental seaway by tectonic uplift associated with volcanism or continental collision, followed by desiccation and bacterial respiration of the aerated organic matter is another potential mechanism for the rapid release of large amounts of CO2. In addition to the oxidation of the underlying marine sediments, the desiccation of a major epicontinental seaway would remove a large source of moisture for the continental interior, resulting in the desiccation and bacterial oxidation of adjacent terrestrial wetlands.

Description: A phase-field theory is applied to model the growth of carbon dioxide hydrate and methane hydrate from a supersaturated solution in water. Temperature- and pressure-dependent thermodynamics for the two systems are accounted for. Simulations of the growth of a planar hydrate film and a circular hydrate nucleus are presented and the interface velocity has been extrapolated from the results to experimental time scales. We discuss how pressure and temperature affects the growth rate and argue that the governing process for the dynamics is the chemical diffusion of the guest molecule in the aqueous solution. We also present results from anisotropic simulations and outline how this will affect the growth.

Description: A two-stage method is presented to separate Lu and Hf from silicate rock and mineral samples digested by either flux melting or HF–HNO3 dissolution using TODGA resin from Eichrom Industries. A first-stage chemistry employs a 2-ml cation exchange column that separates the high-field-strength elements (HFSE) and rare-earth elements (REE) from the matrix. Hf–Zr and Yb–Lu are subsequently separated from the HFSE-REE concentrates on a second-stage 0.2-ml TODGA column. This method returns sufficiently pure cuts to overcome all atomic and molecular interferences as well as the detrimental effects of Ti on Hf fractionation associated with MC-ICP-MS. Boric acid serves two roles in this method: (1) it effectively breaks down fluorides formed in the dry-down step after HF–HNO3 digestions, thereby avoiding use of perchloric acid and/or multiple dry-down and re-dissolution steps, and (2) it is added to the loading solution of the second-stage chemistry to prevent formation of Hf-fluorides that would not be retained by TODGA resin. Using these methods, international rock standards BHVO-1 (processed by both flux melting and HF–HNO3 dissolution) and BCR-2 (processed by HF–HNO3 dissolution) yield 176Hf/177Hf and 176Lu/177Hf ratios that overlap with published values. Permutations of the basic method are presented for samples with significantly elevated LREE contents and for the separation of Lu and Hf from zircon.

Description: During the present study, we aimed at providing a first look at the elemental composition of the early stages of cephalopods as an approach to their elemental requirements in culture. Essential and non-essential elemental profiles of the European cuttlefish Sepia officinalis, the European squid Loligo vulgaris and the common octopus Octopus vulgaris laboratory hatchlings and wild juveniles were analysed. In addition, for O. vulgaris we determined elemental profiles of mature ovary, eggs in different stages of development and followed possible effects of four dietary treatments during paralarval rearing, also analyzing elemental content of the live preys Artemia nauplii and Maja brachydactyla hatchling zoeae. Content was determined for essential (As, Ca, Cr, Co, Cu, Fe, K, Mg, Mn, Na, Ni, P, Rb, S, Sr, Zn) and non-essential (Ag, Al, Ba, Cd, Hg, Pb) elements. The content in non-essential elements found in hatchlings and juveniles of the three species analyzed here seems to be far lower in comparison with subadult and adult stages of coastal cephalopods. In the octopus eggs, the non-essential element concentrations remained globally low compared to hatchlings and juveniles indicating the absorption of these elements along the ontogenetic development. The elemental composition of the octopus ovary and of the eggs, hatchlings and juveniles of the three cephalopod species analyzed here showed a high content in S. As expected, the calcified internal shell of the cuttlefish, rich in Ca and Sr, originates the main difference between species. It is remarkable the richness in Cu of hatchling octopus, that may indicate a particular nutritional requirement for this element during the planktonic life. The reared octopus paralarvae feed on Artemia nauplii, a prey with relatively low Cu content, showed nearly half Cu content that the “natural” profile of octopus hatchlings or wild juveniles. This suggests a dietary effect and/or an indication of the poor physiological stage of the Artemia-fed paralarvae. At the present, the percentage of essential element absorption by food or seawater is unknown for cephalopods and should be determined in the future to understand their feeding requirements in culture.

Description: Total (T–Hg) and organic (O–Hg) mercury concentrations and tissue distribution were examined in 20 species of cephalopods (n = 278) from the north eastern Atlantic waters, i.e. from the Bay of Biscay to the Faroe Islands. Concentrations of T–Hg in whole cephalopods showed elevated variations among species, i.e. from 40 to 3560 ng g− 1 dwt, but a low variability within each species (mean CV% = 39%). With the exception of oceanic squids, the digestive gland globally displayed higher T–Hg concentrations than the remaining tissues. In contrast, O–Hg concentrations determined in selected species were generally higher in the remaining tissues. Despite higher T–Hg concentrations, the digestive gland weakly contributed to the total body burden of both T–Hg and O–Hg (〈 25% and 〈 15%, respectively). In fact, from 75% to 95% of the T–Hg and O–Hg were contained in the muscular remaining tissues. Therefore, O–Hg may have a strong affinity to proteins in cephalopods. Sex and size only significantly influenced the bioaccumulation of Hg for the Loliginidae family. T–Hg and O–Hg concentrations were also influenced by geographical origin: Celtic Sea 〉 Bay of Biscay 〉 Faroe Islands, corresponding to the seawater Hg concentrations in these areas. In the Faroe Islands and the Celtic Sea, benthic cephalopods contained significant higher Hg concentrations compared to pelagic ones. This suggests that diet is not the main pathway of Hg uptake in cephalopods as pelagic species were expected to be more exposed to O–Hg through fish consumption than benthic ones.

Description: Biological information for Eledone cirrhosa has been reassessed through two series of trawls in the framework of the Research Projects MEDITS (summer) and GRUND (autumn) over a 10-year period of surveys in the Ligurian Sea. This information covers aspects such as life span and growth and mortality rates. The sum of samples obtained in the two different seasons allowed the analysis of consistent length frequency distributions and resulted in distinguishing recruits/juveniles from adults of two different ages, i.e. E. cirrhosa is a relatively long living cephalopod, whose reproduction occurs in the second or third year of life. By sampling in different bathymetric strata, different densities on shelf and slope fishing grounds were measured and their displacements with changing season were monitored. The most important stratum in terms of summer densities was in the range 100–200 m depth, which includes the shelf edge, at 150 m. In a relatively narrow strip of seabed, covered by the shelf-edge detritic assemblage and adjacent muddy bottom assemblage VTC (80–150 m), the recruitment of E. cirrhosa occurs from January onwards, while till recent times a specific trawling targeting juveniles used to be carried out in late spring and summer months. In autumn E. cirrhosa is mainly concentrated in shallower waters where trawling activity does not specifically target this species. Trends in numbers and biomass derived by the two series of surveys, and in particular those during autumn series have revealed a significant decrease over the studied time interval. Therefore, the possible relationship between large-scale environmental factors and/or exploitation, was investigated and a positive relationship between summer biomass and winter NAO index was found, even if the cause of such relationship remains unexplained. However, trends of E. cirrhosa landings reported in other studies of the north-western Mediterranean resulted in a similar relationship, thus reinforcing the hypothesis of climatic factors influencing the success of the fishery of this biological resource. A tentative stock assessment, based on relative yield-per-recruit functions, taking into account the two different lengths at first capture and corresponding to mesh sizes of 20 or 40 mm (juveniles and adults nets), showed overexploitation and underexploitation, respectively. A preliminary study of density indices by vital phase also demonstrated a correlation between summer spawners and autumn juveniles of the following year, thus providing evidence of a stock–recruitment relationship.

Description: A microcosm experiment was conducted to test the short-term effects of nitrogen (as TKN, total Kjeldahl nitrogen) and sulphide (as AVS, acid volatile sulphide) on macrobenthic infauna over a period of 8 weeks. The experiment consisted of four treatments using sediment cores (D: 8 cm, H: 20 cm) with addition of: I, nitrogen (N) to an in situ mean level of 0.48 mg N g−1 dw; II, sulphidic solution (S) to an in situ mean level of 318.8 μM S g−1 dw; III, nitrogen and sulphidic solution (NS) to in situ mean levels of 0.45 mg N g−1 dw and 329.0 μM S g−1 dw, respectively, and IV, control with no addition of N and S. Sediment cores were retrieved for analysis of infaunal composition after weeks 2, 4 and 8. A total of 646 specimens of macrobenthic infauna belonging to 27 species were recorded from the cores, in which polychaetes were the most abundant with respect to species and individual numbers. Mean species number and diversity H′ of the control and N treatment was statistically higher than S and NS treatments, mean individual number of the S treatment was larger than the NS treatment, and mean evenness J of the S treatment was lower than the N and NS treatments as well as the control. Individual numbers also showed a significant increase from weeks 2 to 8, whereas evenness J decreased in weeks 4 and 8. Multivariate analyses of the faunal data suggested that benthic composition of the N treatment and control did not differ during the experimental period, but changes in benthic structure in S and NS treatments were evident. The present findings demonstrated the dose–response relationship of benthic species changes under controlled addition of N and S. The response to N and S additions in the sediment microcosms was in agreement with the general effects of organic enrichment on macrobenthic communities along a spatial gradient of organic pollution as described by Pearson and Rosenberg [Pearson, T.H., Rosenberg, R., 1978. Macrobenthic succession in relation to organic enrichment and pollution of the marine environment. Oceanography and Marine Biology Annual Review 16, 229–311]. However, in the present experiment, community changes in the treatments were observable in a short, temporal scale.

Description: In the present study, cuttlefish (Sepia officinalis) aged 60-day-old (age-group I) and 120-day-old (age-group II) were fed with live shrimp and live fish fry for 60 days, in order to study the diet influence on growth, mantle lipid composition, and astaxanthin content in the skin. The most noteworthy difference was the higher growth observed in shrimp-fed cuttlefish with respect to fish-fed cuttlefish in both age groups. Total lipids (TL), lipid classes (LC) and their associated fatty acids (FA) from both diets and mantle of cuttlefish were analysed. The lipid profiles of both diets were clearly different in their LC distribution, with higher levels of Polar Lipids (PL) in shrimp with respect to fish fry. However, both diets did not show outstanding differences in the FA composition of TL except for 20:5n-3 (EPA), which was higher in shrimp than in fish fry. With respect to lipid composition of cuttlefish mantle, the TL content and cholesterol (CHO) percentage increased with age, while phosphatidylinositol (PI) and phosphatidylcholine (PC) percentage decreased. On the other hand, phosphatidylserine (PS), phosphatidylethanolamine (PE) and PC percentages in both cuttlefish age groups were also affected by the different diets, although this difference was higher in age-group I. The general pattern of fatty acid composition of TL in the mantle of cuttlefish was similar in all groups studied. It is remarkable the low levels of monoene FAs in both age-group cuttlefish mantle, despite of the high level of this FA group in both diets, which suggests that these FAs are not stored in the mantle. An opposite tendency was observed regarding the n-3 HUFA, especially 22:6n-3 (DHA) which remained constant despite the different age or diet. High levels of astaxanthin were found in shrimp with respect to fish, but this was only reflected on skin accumulation in age-group I, showing no differences in age-group II. This suggests differences in the astaxanthin metabolism according to the age. The results suggest that the growth differences observed in shrimp-fed cuttlefish with respect to fish-fed cuttlefish were not reflected in outstanding differences in mantle composition.

Description: The stable isotope ratios (δ18O, δ13C) of the aragonite of cuttlebones of Sepia officinalis were measured on a high resolution scale where every septum was measured. Our studies aim at understanding whether variations of the isotope signature are controlled by ontogenetic and/or ecological factors. Five specimens were reared from eggs under known water temperatures, a sixth specimen was caught in the German part of the North Sea. The data suggest that the oxygen isotope composition is in isotopic equilibrium with the surrounding seawater and reflects ambient temperature. Migration and seasonal temperature changes are visible in the acquired data set. The carbon isotope signature shows signs of biofractionation and no direct correlation to the oxygen signature as far as ontogeny and ecology are concerned.

Description: Population substructure of the cuttlefish Sepia officinalis (Mollusca: Cephalopoda), as investigated by genetic variation of microsatellite loci, has been reported to be significantly extensive around the Iberian Peninsula with FST = 0.061 [Pérez-Losada, M., Guerra, A., Carvalho, G.R., Sanjuan, A., Shaw, P.W., 2002. Extensive population subdivision of the cuttlefish Sepia officinalis (Mollusca: Cephalopoda) around the Iberian Peninsula indicated by microsatellite DNA variation. Heredity 89, 417–424] and panmictic in the semi-enclosed Adriatic Sea with FST = 0.011 [Garoia, F., Guarniero, I., Ramsak, A., Ungaro, N., Landi, M., Piccinetti, C., Mannini, P., Tinti, F., 2004. Microsatellite DNA variation reveals high gene flow and panmictic populations in the Adriatic shared stocks of the European squid and cuttlefish (Cephalopoda). Heredity 93, 166–174]. Yet, no verified genetic information on population substructure existed for the northern distribution range of this species in the English Channel and the Bay of Biscay. So far, reproductive and migration behaviour and in vitro oxygen binding properties of haemocyanin have suggested the existence of separate populations in the English Channel and the Bay of Biscay. Examination of genetic variation at seven microsatellite loci within samples from the Bay of Biscay, the English Channel and the southern North Sea indicated low levels of genetic differentiation in this area but also a breakdown of free gene flow at highly significant average FST = 0.018. Although there is a considerable genetic exchange between populations of S. officinalis in the English Channel and the Bay of Biscay, they cannot be regarded as a single, freely interbreeding population. Earlier reported biological differences might thus be due to genetic variability between the populations.

Description: Fatty acid and stable isotope analyses have previously been used to investigate foraging patterns of fish, birds, marine mammals and most recently cephalopod species. To evaluate the application of these methods for dietary studies in squid, it is important to understand the degree to which fatty acid and stable isotope signatures of prey species are reflected in the squids' tissue. Four groups of Lolliguncula brevis were fed on prey species with distinctly different fatty acid and stable isotope profiles over 30 consecutive days. One group of squid were fed fish for fifteen days, followed by crustaceans for a further fifteen days. A second and third group were fed exclusively on fish or crustaceans for thirty days. And a fourth group was fed on a mixture of fish and crustaceans for thirty days. Analysis of squid tissue showed that, after 10 days of feeding, fatty acid profiles of squid tended to reflect those of their prey. Squid that fed on a single prey type, i.e. fish or crustacean, showed only minor modifications in fatty acid proportions after the initial change and fatty acid profiles were clearly distinguishable between the two feeding groups. Shifts in fatty acid proportions towards respective prey profiles could clearly be observed in squid the diet of which was swapped after 15 days. Clear differences could also be seen in fatty acid profiles of squid feeding on a mixed diet with trends towards either fish or crustacean fatty acid signatures. Stable isotope signatures of squid tissues clearly distinguished between animals feeding on different diets and supported findings from fatty acid analysis, thus indicating both methods to be viable tools in feeding studies on squid species.

Description: The developmental changes in the concentration of 8 essential and non-essential heavy metals (Ag, Cd, Cu, Co, Fe, Pb, V, Zn) in the tissues (digestive gland, cuttlebone and whole animal) of the common cuttlefish Sepia officinalis collected in the bay of the river Seine were monitored from the end of the embryogenesis until the adult reproductive stage. Compared to embryos, juveniles after hatching displayed much higher concentrations of Ag, Cu, Fe and Zn, suggesting an efficient incorporation from seawater. Conversely, the amounts of Cd, Pb and V in hatchlings remained constant suggesting that these metals are barely bioavailable for juveniles. Once the juveniles start to feed, the digestive gland appears to play a major role in the storage of all metals. After only one month of benthic life, the digestive gland already contains up to 90% of the total metal body burden, indicating that it plays a major role in the storage and presumed detoxification of the selected metals. Metal concentrations in the digestive gland increase in a logarithmic fashion with age during the entire life of cuttlefish, except for Ag, which decreases as soon as cuttlefish migrate to open sea. This strongly suggests that (1) Ag is excreted from the digestive gland in relation to presumably lower exposure in less contaminated environments compared to coastal waters and (2) the digestive gland of cephalopods could be a very good indicator of Ag contamination in the marine environment.

Description: This study examines factors affecting the rate and extent of biomass build-up among commercially important groupers, snappers, grunts, parrotfish and surgeonfish in a network of four marine reserves in southwest St. Lucia, Caribbean. Reserves constituted 35% of the total reef area originally available for fishing. Protection was instigated in 1995 after a baseline survey with annual or biennial censuses performed until 2002. Each survey consisted of 114 fifteen minute fish counts in reserves and 83 in fishing grounds, at depths of 5 m and 15 m in a 10 m diameter counting area. Estimates of number and size (cm) of target species were used to calculate fish family biomass. Data were analysed using three-way ANOVA in a before-after-control-impact pairs (BACIP) design. All families increased significantly in biomass over time at nearly all sites. Increases were greater in reserves than fishing grounds, except for grunts, and responses were strongest in parrotfish and surgeonfish. The combined biomass of families more than quadrupled in reserves and tripled in fishing grounds between 1995 and 2002. During this period coral cover declined by 46% in reserves and 35% in fishing grounds. Multiple regression showed that neither habitat characteristics nor habitat deterioration significantly affected rates of biomass build-up. The key factor was protection from fishing, which explained 44% of the variance in biomass growth. A further 28% of the variance was explained by sedimentation, a process known to stress reef invertebrates, significantly reducing the rate of biomass build-up. St. Lucia’s reserves succeeded in producing significant gains to fish stocks despite coral cover and structural complexity falling steeply over the period of the study.

Description: Seismic profiling in the equatorial Atlantic reveals deep-water (〉 4500 m) sediment bodies formed by current-controlled deposition near the intersection of large-offset fracture zones with the African margin. A 600 km-long drift accumulation, the Ivory Coast Rise, lies north of the St Paul Transform near 3° N. A smaller drift deposit has been identified along the northern side of the Guinea Transform at 10° N. Antarctic Bottom Water (AABW), which presently enters the eastern Atlantic basins through the Romanche and Vema Fracture Zones, probably played an important role in the development of these features. Proto-AABW may have reached the equatorial region as early as mid-Eocene time, before the establishment of permanent ice sheets in Antarctica. The Ivory Coast Rise existed as a distinct sedimentary drift by the mid-Eocene as a result of deposition from bottom water moving southwards along the African margin and westwards parallel to the St Paul Fracture Zone. This early flow pattern is in the opposite sense to the present movement of deep water in the Sierra Leone Basin. A reversal in abyssal circulation may have been caused by the northward passage of the region across the paleoequator during the Cenozoic.

Description: The eruptive history of Santorini was dominated by twelve major Plinian eruptions. Six of these (Middle Pumice, Vourvoulos, Upper Scoriae 1, Upper Scoriae 2, Cape Riva and Minoan) occurred during the past ∼150 ky. This study focuses on the stratigraphy and geochemistry of the interplinian pyroclastic deposits between 145 ka (Middle Pumice) and 3.6 ka (Minoan). Five interplinian eruptive intervals were identified between these major eruptions and are numbered M8-M12. The Upper Scoriae 1/Upper Scoriae 2 (M10) and Upper Scoriae 2/Cape Riva (M11) intervals are divided into sub-intervals by voluminous interplinian lava formations, the Skaros and Andesites of Oia and Therasia lavas, respectively. Each interval lasted between ∼17 and ∼45 ky and contains pyroclastic deposits of numerous eruptions indicating considerable volcanic activity between the major Plinian events. Most of these interplinian eruptions produced scoria-fall and ash-fall deposits predominantly from subplinian-type eruptions. Surge deposits, resulting from phreatomagmatic activity, are predominant in the Upper Scoriae 1/Skaros sub-interval (M10a). The Andesites of Oia/Cape Riva sub-interval (M11b) is entirely composed of subplinian pumice-fall and ash deposits. Other subplinian pumice-fall deposits occur in the intervals Vourvoulos/Upper Scoriae 1 (M9) and Upper Scoriae 1/Upper Scoriae 2 (M10). The Upper Scoriae 1/Skaros sub-interval (M10a) belongs to one of the longest interplinian intervals (M10) that is characterized by the thickest eruptive units and the largest number of eruptions. A further prominent interplinian pyroclastic formation in northern Thera is the Megalo Vouno cinder cone deposit, which occurred in a time span between the Vourvoulos eruption and the formation of the Skaros lava shield. The interplinian deposits vary from 50 to 70 wt.% SiO2 and are classified as basalt, basaltic andesite, andesite and dacite with a typical calc-alkaline affinity in accordance with the general characteristics of Santorini. They are dominated by a mafic magma component, exemplified by extensive scoria-fall deposits, which is generally absent or only a minor constituent of the silicic Plinian eruptions. Major and trace element compositional trends indicate a significant role of fractional crystallization in the evolution of the interplinian Santorini magmas, where repeated replenishment of primitive magma appears to have prevented magmatic differentiation towards highly silicic compositions that dominate the Plinian eruptions. Pauses in igneous activity, immediately prior to the Plinian and often caldera-forming eruptions, are inferred to be crucial for the generation of more evolved magma compositions erupted during Plinian events

Description: Laboratory experiments have demonstrated that supercritical water has extremely low solubility for normal sea salts. This fact opens up the possibility for the precipitation of salt from seawater that circulates in faults and fractures close to a heat source in tectonically active basins (typically extensional pre-rifts and rift settings). Seawater attains supercritical conditions at depths exceeding 2800 m (corresponding to a pressure of 300 bars) and temperatures above 405 °C. Salts may also precipitate by the boiling of seawater in sub-surface or submarine settings. This is demonstrated by a simple laboratory experiment. The theoretical basis for the precipitation of salts from seawater attaining supercritical condition has been examined by molecular modelling. These processes of salt precipitation constitute a new approach to the geological understanding of salt deposits, and two regions are selected to examine whether salt may have deposited under such hydrothermal conditions today: the Atlantis II Deep in the Red Sea (marine setting), and Lake Asale, Dallol, Ethiopia (continental setting).

Description: Using high quality 3D seismic data within the Lower Congo Basin (LCB), we have identified pockmarks that are aligned above the sinuous belt of a buried turbiditic palaeo-channel, 1000 m beneath the seafloor. Geochemical analyses on cores (GC traces), taken in the centre of four of these pockmarks along this channel, show no clear evidence for migrated oil. But, some features of the GC traces, including elevated baselines (UCM〉34 μg/g) and a broad molecular weight range of n-alkanes with little odd–even preference, may be interpreted as indicating the presence of thermogenic hydrocarbons in the cores. Seismic profiles show that these pockmarks developed above two main features representative of pore fluid escape during early compaction: (1) closely spaced normal faults affecting the upper 0–800 ms TWT of the sedimentary column. This highly faulted interval (HFI) appears as a hexagonal network in plane view, which is characteristic of a volumetrical contraction of sediments in response to pore fluid escape. (2) Buried palaeo-pockmarks and their underlying chimneys seem to be rooted at the channel–levee interface. The chimneys developed during early stages of burial and are now connected to the HFI. This study shows that the buried turbiditic channel now concentrates thermogenic fluids that can migrate through early chimneys and polygonal faults to reach the seafloor within some pockmarks. Using a multidisciplinary approach within the Lower Congo Basin, combining 3D seismic data and geochemical analyses on cores, we trace the fluid history from early compaction expelling pore fluids to later migration of thermogenic hydrocarbons.

Description: Based on high-resolution 3D seismic data sets, we document the subsurface reservoir architecture and organization of a portion of the Oligocene–Miocene stratigraphy within the Congo Basin, offshore southwestern Africa. Within the 3D seismic volume, we have identified four levels of turbiditic palaeochannels, which are separated by low-amplitude continuous reflectors interpreted as hemipelagic sediments. Geochemical analyses on sediment samples taken within overlying seafloor pockmarks reveal the presence of thermogenic gases and oils, suggesting that deep-seated fluids have migrated through both the channel deposits and the impermeable layers between them, forming a conduit to the surface. Deep thermogenic fluids produced within Cretaceous source rocks are preferentially entrapped within coarse-grained turbiditic Oligocene–Miocene palaeochannels. We show in this study that the vertical stacking pattern of turbiditic palaeochannels allows the best pathway for fluids migration. Once the fluids migrate to the upper layer (i.e., Upper Miocene) of palaeochannels, they can reach the seafloor via migration along a highly faulted interval composed of polygonal faults. They are temporarily inhibited below an interpreted 300-m-thick gas hydrate layer marked by a strong BSR on seismic profiles. Fluids accumulate under the hydrate stability zone to form a thick layer of free gas. The generation of excess pore fluid pressure in the free gas accumulation leads to the release of fluids along faults of the highly faulted interval forming pockmarks on the seafloor. Ultimately, we show in this study that fluids are progressively concentrated in the sedimentary column and aligned pockmarks on the seafloor may represent a focused fluid flow from stacked turbiditic palaeochannels.

Description: Species of Fucus are among the dominant seaweeds along Northern Hemisphere shores, but taxonomic designations often are confounded by significant intraspecific morphological variability. We analyzed intra- and inter-specific phylogenetic relationships within the genus (275 individuals representing 16 taxa) using two regions of the mitochondrion: a variable intergenic spacer and a conserved portion of the 23S subunit. Bayesian ML and MP analyses verified a shallow phylogeny with two major lineages (previously reported) and resolved some intra-lineage relationships. Significant species-level paraphyly/polyphyly was observed within lineages 1A and 2. Despite higher species richness in the North Atlantic, a North Pacific origin of the genus is supported by a gradient of decreasing haplotype and nucleotide diversities in F. distichus from the North Pacific to the East Atlantic.

Description: We determined the complete mitochondrial genomes of five cephalopods of the Subclass Coleoidea (Suborder Oegopsida: Watasenia scintillans, Todarodes pacificus, Suborder Myopsida: Sepioteuthis lessoniana, Order Sepiida: Sepia officinalis, and Order Octopoda: Octopus ocellatus) and used them to infer phylogenetic relationships. In our Maximum Likelihood (ML) tree, sepiids (cuttlefish) are at the most basal position of all decapodiformes, and oegopsids and myopsids form a monophyletic clade, thus supporting the traditional classification of the Order Teuthida. We detected extensive gene rearrangements in the mitochondrial genomes of broad cephalopod groups. It is likely that the arrangements of mitochondrial genes in Oegopsida and Sepiida were derived from those of Octopoda, which is thought to be the ancestral order, by entire gene duplication and random gene loss. Oegopsida in particular has undergone long-range gene duplications. We also found that the mitochondrial gene arrangement of Sepioteuthis lessoniana differs from that of Loligo bleekeri, although they belong to the same family. Analysis of both the phylogenetic tree and mitochondrial gene rearrangements of coleoid Cephalopoda suggests that each mitochondrial gene arrangement was acquired after the divergence of each lineage.

Description: This is a study about the spreading of newly formed deep waters following open ocean deep convection in the Northwestern Mediterranean Sea. The main results are from the SOFARGOS large scale float experiment initiated in 1994–1995. During the SOFARGOS project, CTD stations and Lagrangian observations of ocean currents were carried out in the Gulf of Lion from December 1994 to July 1995. Hydrological observations confirmed that deep water formation occurred very early during winter 1994–1995 (late December, early January) in conjunction with atmospheric cooling, deep convection penetrating down to 2000 m in the so-called Medoc area. Numerous eddies (both anticyclonic and cyclonic) drifted away from the convection area and advected newly formed deep waters far away from the source region. In particular, compact anticyclones appeared to be the most coherent (long-lived) eddies and capable of transporting newly formed Western Mediterranean Deep Waters several hundreds of kilometers away from the convection area. Characterized by an inner core of about 5 km in radius, these eddies are submesoscale features in the outer domain and appear as key elements of the open ocean convection processes. During their long journeys, these eddies interacted with larger scale features such as the Northern Boundary Current, the North Balearic Front, topographic Rossby waves, and Sardinian eddies. These interactions influenced the long-term behavior of the eddies (mean drift, composition) and represented an important part of (1) the spreading phase following deep convection and (2) the large scale thermohaline circulation

Description: The pore water chemistry of mud volcanoes from the Olimpi Mud Volcano Field and the Anaximander Mountains in the eastern Mediterranean Sea have been studied for three major purposes: (1) modes and velocities of fluid transport were derived to assess the role of (upward) advection, and bioirrigation for benthic fluxes. (2) Differences in the fluid chemistry at sites of Milano mud volcano (Olimpi area) were compiled in a map to illustrate the spatial heterogeneity reflecting differences in fluid origin and transport in discrete conduits in near proximity. (3) Formation water temperatures of seeping fluids were calculated from theoretical geothermometers to predict the depth of fluid origin and geochemical reactions in the deeper subsurface. No indications for downward advection as required for convection cells have been found. Instead, measured pore water profiles have been simulated successfully by accounting for upward advection and bioirrigation. Advective flow velocities are found to be generally moderate (3–50 cm y− 1) compared to other cold seep areas. Depth-integrated rates of bioirrigation are 1–2 orders of magnitude higher than advective flow velocities documenting the importance of bioirrigation for flux considerations in surface sediments. Calculated formation water temperatures from the Anaximander Mountains are in the range of 80 to 145 °C suggesting a fluid origin from a depth zone associated with the seismic decollement. It is proposed that at that depth clay mineral dehydration leads to the formation and advection of fluids reduced in salinity relative to sea water. This explains the ubiquitous pore water freshening observed in surface sediments of the Anaximander Mountain area. Multiple fluid sources and formation water temperatures of 55 to 80 °C were derived for expelled fluids of the Olimpi area.

Description: In this study, we investigated the effect of mono-species and multi-species biofilms on larval attachment of the bryozoan Bugula neritina. The effect of biofilms was examined through a double-dish choice bioassay in which larvae were given the choice of attaching either to a clean surface of a container or to surfaces covered with biofilms. Larvae attached in response to mono-species biofilms of 5 out of 7 bacterial isolates from a subtidal region, but they avoided surfaces covered by biofilms of 7 out of 8 isolates obtained from an intertidal region. In the follow-up choice experiments with multi-species biofilms developed for 2 days, 7 days, 14 days, 28 days and 30 days, larvae preferentially attached to filmed surfaces over the unfilmed surfaces. When biofilms from 2 different tidal regions (intertidal and subtidal) were offered as choices in the double-dish bioassay, larvae in all cases attached on the subtidal biofilms. Two-day-old subtidal biofilms with low densities of bacteria induced significantly higher (p 〈 0.05) attachment than did 30- day-old intertidal biofilms, which had high bacterial density. Terminal Restriction Fragment Polymorphism (T-RFLP) analysis revealed that the bacterial communities were substantially different in the subtidal and intertidal regions during all periods of the experiment. Attachment of B. neritina on subtidal biofilms did not depend on the bacterial density but rather was negatively correlated with diatom density, thickness of the exopolysaccharide layer and biofilm age. Our results suggest that the larvae of B. neritina can discriminate between biofilmed and clean surfaces and between biofilms developed under different tidal zones.

Description: We report a total evaporation negative ion thermal mass spectrometry (TE-NTIMS) technique that enables precise and accurate (± 0.7‰; 2 s.d.) measurements of boron isotope ratios. The fundamental advantage of TE-NTIMS is that the effect of instrumental mass fractionation is minimised and sample signal maximised by analysing samples to exhaustion. We can analyse as little as 300 pg of B, which enables repeat analyses of dissolutions of small numbers of foraminifera (as little as 0.1 mg or ∼10 individual foraminfera). This represents a several fold reduction in the number of tests required compared to previous NTIMS studies and brings the amount of sample into line with other commonly used paleo-proxies. Standard addition experiments indicate that the 11B / 10B ratio of the NIST SRM 951 standard is not biased by differing amounts of seawater or carbonate matrix and yield an 11B / 10B within error of the certified value. We also show that our sample preparation induces no additional variations (e.g. blank contribution) beyond our analytical uncertainty. We obtain 11B / 10B ratios for seawater within error of values obtained using plasma ionisation, positive and negative thermal ionisation mass-spectrometry. Our measurements of core-top G. sacculifer from three ocean basins yield δ11B within analytical error (23.3–24.3‰) and fall within the range of published values. This study, however, further highlights significant interlaboratory biases in isotopic compositions of core-top foraminifera. Significantly, we show that our approach is not influenced by processing blank nor systematic differences in mass bias between measurements of sample and standard, which has yet to be documented for some other laboratories.