ALBERT

Description: Horizontal starch gel electrophoresis was employed to investigate levels of genetic differentiation between 13 samples of the neritic squid species Loligo forbesi Steenstrup obtained from throughout the majority of its known geographical range. Six enzyme loci identified in a preliminary study as being polymorphic were screened for variation between samples. No significant differences in allele distribution were detected between any of the samples obtained from the Faroe Bank in the north to Lisbon in the south, suggesting that squid throughout this range in the vicinity of the continental shelf are able to maintain panmixia, and effectively belong to a single population sharing a common gene pool. No clinal variation in allele distribution was detected throughout this range, a result which complements the findings of a detailed morphological companion study of the same individuals. Comparison of this homogenous European continental shelf population with squid from the Azores revealed highly significant (P〈0.01) differences in allele distribution at five of the six polymorphic enzyme loci studied. A genetic identity value (I) equivalent to 0.93 over 33 loci was obtained. Analysis of F-statistics suggested migration rates between sites to be as low as one individual per five generations, a rate deemed insufficient under most models to prevent divergence by random genetic drift. The large distance and oceanic depths separating the Azores from continental Europe seem to present an effective barrier to gene flow to L. forbesi, a squid belonging to a family considered to be confined in distribution to relatively shallow, near coastal waters. The two populations of squid in the Azores and along the European continental shelf currently both ascribed to L. forbesi should therefore probably best be regarded as relative subspecies.

Description: Beak lengths (lower rostral length and upper rostral length) were taken for a sample of Moroteuthis ingens which were captured on the Chatham Rise, New Zealand. Beak lengths were plotted against both mantle length and wet weight to determine the relationship between these parameters for future use in biomass estimates in predator analysis. Although M. ingens is markedly sexually dimorphic, with females reaching 5 times the weight of males, there was no obvious sexual dimorphism in either lower or upper rostral length. This resulted in sex-specific relationships between both LRL and mantle length, LRL and weight; and URL and mantle length, and URL and weight. Males appeared to have a curvilinear relationship between beak length and mantle length and beak length and weight (even for log-transformed data). There was also considerable spread in the data in the plot between beak length and weight for females of similar weight. These characteristics of the data makes biomass estimates based on rostral length measurements for this species difficult. Other beak parameters may prove more useful for estimating biomass of M. ingens.

Description: Body size at sexual maturity, egg-size distributions, and potential reproductive output have been estimated for female and male squid, Loligo forbesi Steenstrup, off the west coast of Scotland. Two size modes at maturity were found in both sexes, but separation into size cohorts was more pronounced in males (180 and 350 mm mantle length, ML). Preliminary ageing studies based on statolith ring-counts suggest that these size modes are not due to different age groups at breeding. Females have a single size mode of mature eggs in the proximal oviduct, but may have at least two size modes of eggs within the ovary. This finding is interpreted as evidence of batch-spawning in this squid. There was a weak relationship between total egg numbers (range 1000 to 16000) and body size (range 196 to 318 mm ML) and between mature egg size and body size. Males showed a strong positive relationship between spermatophore length and body length but a weak relationship between total number of spermatophores and body size. The results are discussed in the context of flexibility of breeding strategies in the loliginids and variety of life-cycle patterns.

Description: This study assesses the potential of the tropical loliginid squid Photololigo sp. to lay multiple batches of eggs and examines changes in somatic growth during reproduction. Histological analysis of the ovary and the relative size of the oviduct to mantle weight and ovary weight were used to determine the potential for multiple spawning. Ovaries of mature females always had immature and mature oocytes present, suggesting that not all the oocytes were maturing simultaneously and that multiple batches of eggs were being produced. Furthermore, poor correlations of oviduct weight with body size and ovary weight indicated that mature oocytes were not accumulating in the oviduct for a single spawning event. Both these observations supported the hypothesis that Photololigo sp. has the potential to lay multiple batches of eggs throughout its life. Specific growth rates, length-weight relationships, relative growth of somatic and reproductive tissue and microscopic assessment of muscle tissue were compared between immature and mature females. Growth rates of immature females were almost twice as fast as those of mature females. Mature females also had no large muscle fibres present, suggesting that energy for reproduction was mobilised from the muscle tissue.

Description: Alkaline volcanic rocks including nephelinites, basanites and trachybasalts dredged from the volcanic pedestal of Rakahanga Atoll and from a volcanic edifice with 100 satellite volcanoes at the eastern edge of the Manihiki Plateau, ca. 40 km southwest of the atoll, fall well within the category of EM-type ocean island basalts. They indicate a hotspot involvement during the formation of the plateau basement. The rocks are thought to be products of explosive eruptions which took place subaerially or in shallow water in the Aptian. The volcanoes, together with other volcanic eruption centers, most likely were responsible for the formation of the 230 m thick volcaniclastite layer which rests on the basement for at least 5000 km2 of the eastern part of the Manihiki Plateau. Erosion has prevented any substantial sediment cover on the volcanic cone field and most of the slope of Rakahanga and thin pelagic limestones were deposited instead at least since the Maastrichtian.

Description: The natural feeding of 485 Octopus mimus (164 to 3088 g) was studied in relation to the species' life cycle and environmental seasonal variations off the north of Chile from autumn 1991 to summer 1992. Analysis of digestive-tract contents revealed that O. mimus preyed upon 25 different prey items belonging to five zoological groups (Teleostei, Mollusca, Crustacea, Echinodermata and Polychaeta). Cannibalism was only occasional. The results indicate that the diet and food intake of this species are significantly affected by sex and maturation. Senescent individuals ingest a small amount of food, and their diet is mainly based on small, not very motile prey. The food intake, expressed as body weight, of non-senescent individuals is higher in females than in males. Seasonal changes in sea-water temperature seem to be followed by adjustments in food intake. Like other Octopus species, O. mimus appears to be an opportunistic predator.

Description: The relationship between reproduction and condition was studied in a 15 mo sample of 919 maturing, mature and post-spawning female Octopus mimus (388 to 3714 g) caught in Iquique (North Chile). O. mimus is a semelparous species, with reproduction taking place all year round. Investment in reproductive tissues was, on average, 9.9% of mature female body weight, independent of season. However, somatic growth during maturation was dependent on season and varied between 26 and 63% of the whole-body growth in weight. The condition of females did not vary markedly until spawning, although seasonal variations were apparent, winter being the most unfavourable. Condition deteriorated dramatically after spawning, during parental care of the eggs. During this period, somatic-tissue depletion, mainly from the muscles, was 〉25% of the total body weight of mature females. The fecundity of O. mimus was probably limited by the costs associated with parental care of the eggs.

Description: This chapter discusses the rates of protein synthesis in fish. Protein synthesis can be viewed at a number of levels. Whole-animal values can be integrated into the descriptions of assimilation/growth or assimilation/metabolism patterns in different fish species and is the focus of the chapter. The measurement of protein synthesis rates in body organs and tissues can provide information on the extent to which differences exist among various tissues and offer a challenge in understanding the integration of organ metabolism into whole animal physiology. The majority of methods for estimating protein synthesis measure the flux of an amino acid or nitrogen. This involves the use of tracer substances—that is, amino acids labeled with an isotope, which are given in a single dose or by continuous infusion. The measurements, parameters, and formulae that are commonly employed in the studies of protein growth, synthesis, and degradation are described in the chapter. It discusses the mechanism of nutrition and protein synthesis in the fish and explains the impact that protein synthesis has upon the rates of oxygen consumption.

Description: In the Neil Brown Instruments' MKIIIB-CTD (conductivity-temperature-depth profiler), the system's digital outputs for the three basic measurements of temperature, conductivity and pressure typically show some small amplitude deviations from smooth calibrations which should be corrected for to achieve high accuracies, as required, e.g. within the Hydrographic Program (WHP) of the current World Ocean Circulation Experiment (WOCE). These deviations show up as (i) a strong nonlinearity or even discontinuity of several mK close to 0°C in temperature output leading to too high subzero temperatures; (ii) a jump of order 0.002 mS cm−1 in conductivity output when passing the half-range value 32.768 mS cm−1, which causes jumps in the relation of potential temperature and salinity; and (iii) errors in pressure measurements of up to 4 dbar due to mechanical hysteresis and both static and dynamic responses to temperature changes. The existence of these effects is demonstrated, and methods to reduce the associated errors are suggested.

Description: Based on various lines of evidence such as the widespread occurrence of basalts, pumice, volcanic glass shards and their transformational products (zeolites, palagonites, and smectite-rich sediments), we suggest the presence of a volcanic province in the Central Indian Basin (CIB). In addition to the rocks studied, the occurrence of many morpho-tectonic features such as seamounts, abyssal hills and major fracture zones at 73 degrees E, 75 degrees 45'E and 79 degrees E, have helped in correlating and in deciphering the source of the rock types. Further, the large manganese nodule fields in the CIB are seen to occur in conjunction with the volcanic materials, since the latter forms nuclei and substrates for ferromanganese deposits. It is concluded that a spatial relation exists between the occurrence of the volcanic materials and the ferromanganese deposit in the CIB

Description: The diet of emperor penguins Aptenodytes forsteri was studied during late austral summer at Drescher Inlet, eastern Weddell Sea, Antarctica. Antarctic krill Euphausia superba was a major component of the food, accounting for 75% of all prey items. Emperor penguins appear to feed on krill during shallow dives under the fast sea ice. Fish, mainly nototheniids, accounted for less than 20% by number of all prey. An evaluation of the main prey types in terms of mass indicated, however, that fish represented up to 75% approximately of prey mass. Feeding experiments were performed on captive penguins and showed that squid beaks can accumulate for up to 3 weeks within the stomach without any clear signs of erosion. The lack of cephalopod soft parts in the samples makes it likely that all squid beaks were derived from animals captured some time previously. Squid seems to be a very minor dietary component of emperor penguins at the Drescher Inlet.

Description: Dinoflagellate cysts and other organic-walled microfossils have been studied in recent surface sediments from the entire Norwegian-Greenland Sea. More than 30 taxa have been recognized, of which only few show a distinct distribution pattern, and allow description of four assemblages. The occurrence of most taxa is related to the relatively warmer waters of the Norwegian Sea. Algidaspaeridium? minutum s.1., Brigantedinium simplex and Impagidinium? pallidum are the only species showing a preference for colder water masses. Two species, I.? pallidum and Nematosphaeropsis labyrinthus are mainly restricted to the oceanic environment, whereas the other species have also been reported from neritic environments in previous studies. Due to the limited knowledge of the ecological and sedimentological factors influencing the occurrence of dinoflagellate cysts in oceanic environments, their distribution in recent sediments can be only related to surface water masses in a broad sense. Although the distribution of assemblages correlates with specific surface water masses, comparison with assemblages recovered from sediment traps deployed basinwide in the Norwegian-Greenland Sea (Dale and Dale, 1992) revealed some major discrepancies in species composition and percentage abundances. The differences cannot be explained with certainty at the moment, although there is some evidence that transport of dinoflagellate cysts and other fossilizable microplankton in water masses by currents, in sea-ice and sediments may modify the assemblages found in recent oceanic surface sediments from the Norwegian-Greenland Sea.

Description: The flow field in the area of what was thought to be the source region of the North Brazil Current (NBC) off the northeast coast of Brazil between 5 degrees 30'S and 10 degrees S was investigated in austral spring during November 1992 and compared with observations in October 1990. The data were taken with several different instruments, including vessel-mounted ADCP, lowered-ADCP, Pegasus, CTD and XBTs. The flow was found off the coast at 5 degrees 30'S as well as at 10 degrees S as an undercurrent, the North Brazil Undercurrent (NBUC). The NBUC shows a subsurface core at about 200 m depth with velocities of up to 90.0 cm s(-1), resulting in large northward transports of more than 22 Sv in the upper 1000 m. The transport is about the same at 5 degrees 30'S and 10 degrees S, hence no net inflow from the east is required to feed the NBUC. The climatological Ekman transport is to the south between 5 degrees 30'S and 10 degrees S, and in consequence the northward flow near the surface was reduced and might be one reason for the existence of the undercurrent. The flow near the coast was to the north at 10 degrees S, therefore the Brazil Current had to start as a coastal current south of 10 degrees S. For the zonal sections at 5 degrees 30'S and 10 degrees S the geostrophic computations relative to the density surface sigma(1) = 32.15 kg m(-3) (about 1150 m depth) resulted in transports comparable to those obtained from direct measurements. The results further show that the choice of a correct level of no motion can be supported by the direct observations. A shallower reference based on water mass boundaries alone would reduce the NBUC transport to almost zero. Computations with data from the historical data base for austral fall resulted in a weaker NBUC of less than 20 Sv near 10 degrees S, indicating a possible seasonal signal in the NBUC with a stronger NBUC in austral spring.

Description: While the aggregation and mass settlement of diatoms at the termination of blooms results in significant export of carbon from the surface ocean, the mechanisms of bloom aggregation have been poorly understood. The aggregation of a multispecies diatom bloom was investigated under controlled conditions in a 1200 liter, nutrient-enriched, laboratory mesocosm in order to elucidate the parameters sufficient to accurately predict bloom aggregation. A diverse bloom of diatoms dominated by several species of Chaetoceros and Thalassiosira progressed through a classic pattern of exponential, stationary, and senescent phases in the mesocosm. Aggregates larger than 0.5 mm became detectable on the eighth day after inoculation, and aggregates 〉1 mm increased exponentially from Day 10 onward producing the appearance of a mass aggregation event late on Day 10. The bloom aggregated sequentially with Thalassiosira dominating early aggregates and Chaetoceros dominating later ones. Chaetoceros resting spores formed only in aggregates. Aggregation was not linked to nutrient depletion or to the physiological state of the cells since the onset of aggregation and the mass aggregation event occurred 1 to 3 days prior to nutrient depletion and while carbon:nitrogen ratios of cells were still very low and growth rates high. Moreover, visible aggregates did not form in the mesocosm until cell abundances were considerably higher than abundances observed to aggregate in nature, suggesting that aggregation was not strongly linked to phytoplankton cell concentration. Complementary studies in this volume clarify the role of non-phytoplankton particles in aggregation of the mesocosm bloom. The mesocosm approach proved highly effective in producing an aggregating diatom bloom under controlled conditions.

Description: This note describes a method for the determination of the age of individual water mass contributions in a mixture of water masses. The method is based on a combination of Optimum Multi parameter analysis and CFC analysis. Synthetic data designed to mirror the situation in the permanent thermocline of the eastern Indian Ocean are used to demonstrate the method. The feasibility of applications to oceanic data is discussed.

Description: The pelagic nekton community was sampled with the RMT 25 opening/closing net and a neuston net at two stations in the Scotia Sea south of the Antarctic Polar Front in the open ocean (Station 1) and on the South Georgia northwestern slope (Station 2). Downward oblique tows were made with the RMT 25 through discrete 200 m layers to 1000 m in daylight and darkness. A total of 119 cephalopods representing nine species were removed from the samples, and mantle and arm lengths were measured to the nearest 0.1 mm. The most abundant species at each station was an undescribed Brachioteuthis sp. (B. ?picta). Galiteuthis glacialis and Alluroteuthis antarcticus were caught at both stations. Histioteuthis eltaninae, Bathyteuthis abyssicola and Psychroteuthis glacialis were caught at Station 1. Mastigoteuthis psychrophila and a Chiroteuthis sp. were caught at Station 2. B. ?picta was present throughout the water column to 1000 m at both stations, with little evidence of ontogenetic descent. There was evidence for ontogenetic descent in G. glacialis. This species was absent from the Antarctic Surface Water (ASW) at Station 1, where it was concentrated in the Circumpolar Deep Water (CDW). At Station 2 it was present throughout the water column to 1000 m. The other species were all caught in the core of the CDW (〉400 m). In juvenile B. ?picta, G. glacialis and A. antarcticus, growth of the brachial crown is positively allometric with respect to mantle length. Recent data on biomass spectra in high-latitude pelagic systems show that they are characterised by the presence of peaks of biomass separated by biomass minima. Positive allometric growth in the brachial crown of these antarctic oceanic squid is suggested to have evolved as an adaptation to the peaked, or domed, structure of the pelagic biomass spectrum which must be spanned by these predators as their optimum prey size increases with growth. Interspecific differences in the allometry of tentacle growth are probably related to differences in strategies for stalking and capture of prey.

Description: The history of the Late Weichselian northwestern Barents Shelf, including western Svalbard, has been investigated by provenance/sedimentologist studies of five cores from the continental shelf and slope west of Svalbard. The chronostratigraphy of the cores is based on AMS 14C dates and oxygen isotope analyses. Interpretations of the cores suggest that the ice sheets of western Svalbard and northwestern Barents Sea experienced advances and retreats in two steps. The first significant ice advance beyond the present coastline occurred ca. 22,000 14C yr B.P. and was followed by an ice advance to the shelf edge ca. 18,000 14C yr B.P. Ice recession from the outer shelf and the southwestern Barents Sea began 14,800 14C yr B.P. and was followed by a second ice recession between 13,000 and 12,000 14 C yr B.P. during which ice withdrew from the inner shelf. A minor readvance of the ice sheet on the shelf west of Svalbard occurred close to 12,400 14C yr B.P. The first deglaciation event was associated with release of icebergs containing ice-rafted detritus, while the later episode also included significant amounts of meltwater and fine-grained sediment.

Description: Past hydrothermal activity has been exarpined from the compositions of the bottom sediments adjoining the rift zone at 21 °S in the EPR. The dating studies have been performed using radiocarbon and nonequilibrium 230Th. Some 644 bottom-sediment samples were analyzed for 24 elements. About 40% of the variability is due to factors that reflect the hydrothermal activity. In the surface layer, the detailed distribution of fluxes of the main ore-forming elements Fe and Mn, Cu (an element of hydrogene-hydrothermal origin), and Ti (an element entering the sediments from bedrock weathering) were studied. The maximal fluxes for elements of hydrothermal origin occur at a considerable distance from the ridge axis, since hydrothermal elements entered the sediments only after the plume had broken up. Elevated concentrations of elements of edaphogene origin on the other hand adjoin the ridge axis. Using seven columns of bottom sediments with ages in the range from 24 to 340 thousand years, we analyzed the change with time in the. content of hydrothermal material and the fluxes of hydrothermal material and of Fe/Mn and 1 Ni. It is shown that the most effective indicator of change in hydrothermal activity on the moving floor is provided not by the flux of hydrothermal material but by its concentration and the Fe/Mn ratio. The cyclic nature of the hydrothermal process is most reliably indicated by the changes in concentration of the ore material, but only in columns near the source.

Description: Single crystal ages of sanidine phenocrysts from pumice lapilli of the Late Glacial phonolitic Laacher See Tephra (East Eifel Volcanic Field, FRG) are determined by laser probe 40Ar/ 39Ar analysis. Sanidine megacrysts from the East and West Eifel (SAN6001, 410.4 ± 0.9 kyr; SAN6165, 469.8 ± 1.1 kyr) are applied as irradiation monitors, and their potential as Quaternary interlaboratory single crystal standards assessed. The apparent ages of Laacher See sanidine phenocrysts range from 6.4 ± 3.8 kyr to 127 ± 2 kyr (1σ), comprising up to four distinct subpopulations of crystals with individual ages, weighted mean apparent ages or isochron ages of 127 kyr, 55 kyr, 25 kyr and 12.9 kyr. The Laacher See Tephra 40Ar/ 39Ar eruption age is estimated as 12,900 ± 560 yr BP. Older crystals are interpreted as remnants of three earlier magma emplacement and crystallization events in the Laacher See magma system. These recycled, older crystals make up ca. 20% of the apparent juvenile sanidine phenocryst population in the essential phonolite clasts studied.

Description: An undisturbed 16 m late Pliocene-Pleistocene sediment core spanning 2.6 Myr of deposition was recovered from the Manihiki Plateau by the German research vessel Sonne in 1990. This core 34KL complements the heavily disturbed late Pliocene-Pleistocene core sections of DSDP Site 317, and is well suited for stratigraphic correlation. The sediments consist of calcareous microfossils (93–97% CaCO3), minor portions of siliceous microfossils and detrital minerals. All important calcareous microfossil zones could be identified and correlated with the magnetostratigraphic and isotope stratigraphic events, stages and periods. Due to the high degree of silica dissolution, the late Quaternary radiolarian Buccinosphaera invaginata Zone is the only siliceous fossil zone which could be identified. An interval with Globigerinoides gomitulus/pink was found within the middle Pleistocene which is clearly distinguished from the Globigerinoides ruber/pink interval of the late Pleistocene. The magnetostratigraphic Gauss-Matuyama and Matuyama-Brunhes boundaries as well as the Olduvai and Jaramillo events were clearly identified. The δ180 curve displays the 100 kyr (Milankovitch) and the 41 kyr (Laplace) cyclicity periods. The beginning of the Laplace Period and the last occurrence of the calcareous nannofossil Discoaster brouweri, which marks the end of the Pliocene, fall within the base of the Olduvai Event. There is also a marked drop in sedimentation rates around this time, which seems to be a regional phenomenon. Prominent 3.5 kHz subbottom reflectors at 8 ms and 15 ms reflection time are related to lithologic changes near the Mid-Pleistocene Revolution (MPR) and the beginning of the Laplace Period or the Pleistocene, respectively. It is possible to trace these reflectors laterally to the eroded eastern edge of the Manihiki Plateau where they can be tied to older strata.

Description: Four spicule-bearing chaetetid sponges are described from Upper Triassic (Norian) reef carbonates of the WesternTaurids (Antalya-Region, SW Turkey): Atrochaetetes alakirensisCuif & Fischer, Blastochaetetes dolomiticusBizzarini & Braga, Ptychochaetetes sp. and ?Bauneia sp.. Spicules are preserved as calcitic pseudomorphs. They are either short and thick or long and slender, corresponding to typical styles; oxes are rarely present in Atrochaetetes alakirensis. The styles are mainly embedded in the secondary rigid skeleton, but their rounded ends appear to be attached to the primary wall. In Blastochaetetes dolomiticus and ?Bauneia sp. styles are also embedded in the primary wall. A comparison of these spicule-skeletons with those of other chaetetids, especially Paleozoic species, confirms the polyphyletic origin of the Taxon Chaetetida.

Description: Rubrik "Neues aus dem Geologenarchiv (1994)": Da die Jahresversammlung 1995 in Bremen vor allem der Meeresgeologie gewidmet war, soll durch die Veröffentlichung eines im Archiv verwahrten Briefs zur Planung der ersten "Meteor"-Expedition an den Wiederbeginn der deutschen Hochseeforschung nach dem ersten Weltkrieg erinnert werden. Scon im Sommer 1919 wurden in der Admiralität der damaligen Reichsmarine Pläne erörtert, wie man wieder an die Tradition der Forschungsfahrten der Kaiserlichen Marine mit S.M.S.S. "Gazelle", "Planet" und "Möwe" anknüpfen könne. Ein 1915 vom Stapel gelaufenes Kanonenboot "Meteor" bot sich zum Ausbau als Forschungsschiff an (F. Spiess, 1928). Vorschläge für Forschungsfahrten wurnden von der Deutschen Seewarte und vom Berliner Institut für Meereskunde eingeholt. Dessen damaliger Direktor, der vor allem durch seine Eiszeitforschungen bekannt gewordene Geograph Geheimrat Professor Albrecht Penck (Leipzig 1858 - Prag 1945), legte daraufhin der Marineleitung eine Denkschrift seines Abteilungsvorstands Alfred Merz (Wien 1880 - Buenos Aires 1925) für eine dreijährige Expedition in den Pazifik vor. (Auszug)

Description: Viable counts of aerobic and anaerobic chemotrophic sulphur-oxidizers as well as phototrophic sulphur bacteria were determined in sediment samples taken from two different areas along the Baltic Sea shore which were known to regularly develop sulphidic conditions. Depth profiles of bacterial cell counts were correlated with concentration profiles of chloride, sulphate, sulphide, nitrate and phosphate in the pore water of these sediments and with potential activities of nitrate reduction, thiosulphate transformation and sulphate formation. The data revealed a complex multilayered structure within the sediments. Sulphide was released into the water from sediments of both sampling areas, but it was found that light and the availability of oxygen significantly reduced this amount. In the highly reduced sediment at Hiddensee, the highest numbers of phototrophic and chemotrophic sulphur-oxidizers were found near the sediment surface. Therefore, it was concluded that the combined action of both groups of bacteria most efficiently oxidizes reduced sulphur compounds in the top layers of the sediments. Nitrate may replace oxygen as final electron acceptor and will support oxidation of sulphide, in particular when oxygen and light are limiting

Description: The record of glacier fluctuations in western Scandinavia, as reconstructed from continental data, has been correlated with records of ice-rafted detritus (IRD) from well-dated sediment cores from the Norwegian Sea covering the past 150,000 yr B.P. The input of IRD into the ocean is used as a proxy for ice sheet advances onto the shelf and, thus, for the calibration of a glaciation curve. The marine results generally support land-based reconstructions of glacier fluctuations and improve the time-control on glacial advances. The Saalian ice sheet decayed very rapidly approximately 125,000 yr B.P. In the Early Weichselian, a minor but significant IRD maximum indicates the presence of icebergs in isotope substage 5b (especially between 95,000 and 83,000 yr B.P.). Reduced amounts of calcareous nannofossils indicate that surface waters were influenced by meltwater discharges during isotope substages 5d and 5b. An extensive build-up of inland ice began again during isotope stage 4, but maximum glaciation was reached only in early stage 3 (58,000-53,000 yr B.P.). Marine sediments have minimum carbonate content, indicating strong dilution by lithogenic ice-rafted material. Generally, the IRD accumulation rate was considerably higher in stages 4-2 than in stage 5. A marked peak in IRD accumulation rates from 47,000 to 43,000 yr B.P. correlates well with a second Middle Weichselian ice sheet advance dated by the Laschamp/Olby paleomagnetic event. Minimum ice extent during the Ålesund interstade (38,500-32,500 yr B.P.) and several glacial oscillations during the Late Weichselian are also seen in the IRD record. Of several late Weichselian glacial oscillations on the shelf, at least four correspond to the North Atlantic Heinrich events. Ice sheet behavior was either coupled or linked by external forcing during these events, whereas internal ice sheet mechanisms may account for the noncoherent fluctuations.

Description: Data from sections across the Eurasian Basin of the Arctic Ocean occupied in 1987 and 1991 are used to derive information on the freshwater balance of the Arctic Ocean and on sources of the deep waters of the Nansen, Amundsen and Makarov basins. Using salinity, H218O, and mass balances we estimate the river-runoff and the sea-ice melt water fractions contained in the upper waters of the Arctic Ocean and infer pathways of the river-runoff signal from the shelf seas across the central Arctic Ocean to Fram Strait. The average mean residence time of the river-runoff fraction contained in the Arctic Ocean halocline is determined to be about 11 to 14 years. Pacific water entering through Bering Strait is traced using silicate and its influence on the halocline waters of the Canadian Basin is estimated. Water column inventories of river-runoff and sea-ice melt water are calculated for a section just north of Fram Strait and implications of these inventories for sea-ice export through Fram Strait are discussed. Comparison of the ratios of shelf water, Atlantic water and the deep waters of the Arctic Ocean indicate that the sources of the deep and bottom waters of the Eurasian Basin are located in the Barents and Kara seas.

Description: Catalytic cathodic stripping voltammetry (CSV) preceded by adsorptive collection of complexes of 1-nitroso-2-napthol (NN) can be used to determine iron in seawater. It is shown here that iron(II) is effectively masked in the presence of 2,2-dipyridyl (Dp) so that iron(III) is measured selectively. The concentration of iron(II) is then calculated as the difference between the concentrations of reactive iron (Fe-R) in the absence and presence of 2 mu M Dp, Fe-R being defined as that which was complexed by 20 mu M NN at pH 6.9 in the presence of 1.8 mM H2O2 and 5 ppm sodium dodecyl sulphate. A 30 min reaction time was allowed for Dp to react with iron(II) in seawater prior to the determination of reactive iron(III) using the same conditions as used for Fe-R. Detection limits of 0.08 nM, 0.077 nM and 0.12 nM were obtained for Fe-R, iron(III) and iron(II), respectively, using a 60 s deposition time. The method was utilised to determine the redox speciation of iron in the northern North Sea. Concentrations of Fe-R ranged between 0.8 and 3.5 nM with nutrient-like depth profiles. Iron(II) was found to be present at concentrations up to 1.2 nM, the highest concentrations occurring in the upper 20 m of the water column.

Description: Detailed investigations have been made of two amphibole samples where 40Ar/39Ar age spectra have been interpreted to show argon diffusive loss. Both samples display complex compositional zoning that reflects partial major and minor element chemical re-equilibration during later thermal events that is associated with the loss of radiogenic 40Ar. The apparent diffusive loss age spectra in these samples are an artefact of this chemical re-equilibration process. One sample additionally shows the effect of potassium gain and contamination with a potassium-rich phase (biotite). The resulting ages in this sample are geologically meaningless and the apparent fit to a theoretical diffusive loss curve is coincidental. This study shows that volume diffusive loss of argon appears to operate at slower rates than argon loss by chemical re-equilibration in amphiboles.

Description: The photoactive yellow protein of Ectothiodospira halophila (PYP) was purified to homogeneity by an advanced method and applied as an affinity ligand for the isolation of an anti-PYP IgG fraction which was used for immunoscreening. The distribution of proteins immunologically related to PYP was investigated in protein fractions of 51 strains from 38 species of non-halophilic and halophilic phototrophic and chemotrophic eubacteria and archaeobacteria. Strong immunoreactive bands indicating the presence of authentic PYP on Western blots (apparent mass 17.8 kDa) was only found in the strains of E. halophila. Additionally, two soluble proteins of Chromatium salexigens and Rhodospirillum salexigens (apparent molecular masses 16.4 and 19 kDa, respectively) cross-reacted to approx. 6% and 4%. Analyses of cell fractions of E. halophila revealed that PYP is a cytoplasmic protein.

Description: The concept of sequence-stratigraphy uses the stratal geometries at the margins of carbonate platforms to define depositional sequences and systems tracts. The aim of this study was to research if prograding, purely aggrading and retrograding phases of a Cretaceous carbonate platform showed differences in the composition and facies type of the slope sediments. The Vercors Plateau in SE France provides excellent outcrops to study this relationship. Continuous exposure of the platform-to-basin transition allowed direct examination of the margin geometries. Five successions were measured and sampled in great detail. Samples were thin-sectioned and point-counted, using point-count groups characterizing palaeoenvironments along the platform-to-basin transect. The composition logs as well as the numerical analysis of the point-count data, both show a clear relationship between grain composition and stratal geometry. The prograding and purely aggrading intervals are similar in composition, as they are both relatively coarse grained, and enriched in platform biota and limeclasts. Retreating units are relatively fine grained and rich in basinal grains (small benthic foraminifers, sponge spicules), non-carbonate grains and embedding material. These observations suggest that the retreating intervals represent incipient drownings of the platform. However, rather than distinctly separated groups the different phases of platform development form a continuous range of variation between high platform input and high basinal input. Compared to the prograding units the purely aggrading intervals are relatively rich in peloids, which may be suggestive of relatively low-energy conditions on the platform during aggradation. The compositional analysis also revealed significant variation in the frequency of ooids, but these variations showed no relationship with the progradation, aggradation or retreat of the platform.

Description: A synchrotron microprobe has been used to characterize ion implantations of nickel and cobalt in silicon (100) or (111) wafers. The synchrotron radiation is collimated by means of a rigid cylindrical glass capillary of 110 mm length, 5 mm outer and 30 μm or 10 μm inner diameter. The beam is pointed at the wafer sample and the emitted radiation of X-rays is detected by an energy dispersive spectrometer. Line scans are recorded step by step over the implantation areas and across their borders. The sharpness of the borders is characterized at a lateral resolution of 13 μm and the edge lengths ranging from 0.6 to 8 mm are determined with an accuracy better than ± 20 μm. The signal intensity and implantation dose of cobalt ranging from 1 × 1015 to 1 × 1017 ions cm−2 show a linear relationship as is to be expected for the micrometre thin implanted layers.

Description: Dispersal characteristics of the T, We, Wn, Pu, Ps, Ye, Yn and Yb plinian fall deposits of Mount St. Helens have been measured at 80 sites downwind of the volcano in order to model eruption dynamics and atmospheric transport. Isopleth contours for the sizes of maximum pumice and lithic clasts are used to calculate peak eruption column heights and intensities (magma discharge) based on a theoretical model of tephra dispersal. New proximal thickness measurements are combined with an empirical distal extrapolation, based on studies of 53 plinian deposits, to calculate the magnitude (erupted mass) of each eruption. Layer Yn (3510 y r B.P.) represents the highest intensity and largest magnitude eruption at Mount St. Helens in post-glacial times. Modeling suggests column height grew to about 31 km before gradually declining at the end of the plinian phase (~ 26 hours). Several intraplinian surge deposits are present in the upper part of the fall layer close to the volcano and up to 15 km to the northeast of Mount St. Helens. Peak intensity of the plinian phase was 108 kg/s and the total erupted volume was 4 km3 (DRE of magma). Small plinian-style eruptions are represented by layers such as Ps and Pu of the Pine Creek eruptive period (3000-2500 yr B.P.) and have intensities of only ~ 106 kg/s. When compared with plinian eruptions from other volcanoes, the Holocene eruptions of Mount St. Helens span from the lower to the middle part of the known range in intensity and magnitude and are typical of events derived from intermediate-sized stratovolcanoes. There is also a general correlation between the intensity of plinian eruptions within eruptive cycles and the repose period prior to each cycle. This relationship may be related to a time-dependent process for the accumulation of differentiated and volatile-rich magma within the chamber beneath Mount St. Helens.

Description: Metabolism of chlorobiphenyls (CBs) was studied in harbour porpoise by comparing patterns of CB-X/CB-153 ratios in blood, brain, liver and blubber with the patterns in herring, the main food source. The CBs were classified in five groups, based on the presence/absence of vicinal H-atoms (vic. Hs) in meta,para (m,p) and/or ortho,meta (o,m) positions and the number of ortho-Cl-atoms (ortho-Cls). Plots of CB-X/CB-153 ratios in porpoise tissue vs the ratios in herring appeared to be linear for each CB group in all tissues. Slopes of these plots (metabolic slopes) were used as quantitative indicators of metabolic activity. In this way, activity of PB-type isozymes of the P450 monooxygenase system was apparent: in contrast to existing literature data, harbour porpoise appears to be able to metabolize congeners with m,p vic. Hs, even in the presence of more than 2 ortho-Cls. The presence of 3-MC-type (MC-type) isozymes was also detected. The metabolic slopes were also used as basis for risk assessment. Due to their metabolism the most toxic non-ortho CBs were not present in the tissues at detectable levels. We suggest a risk assessment approach which takes this into account. It is considered to be an alternative and more reliable basis for risk assessment than the use of toxic equivalent factors. The results support the model of equilibrium distribution of CBs in harbour porpoise and the role of blood as central transport medium. The model has been developed for persistent compounds; it appears to hold for metabolizable CB congeners as well.

Description: Both living (stained) and dead (unstained) foraminiferal assemblages from surface sediments (0–2 cm) in the northwestern part of the Skagerrak have been studied in order to (1) define and characterize the distribution of various modern benthic environments and (2) by comparing these findings with surface samples collected 40–60 years ago, to document possible faunal changes that might have occurred. The investigated area is physiographically divided into the Norwegian slope, the Skagerrak Basin, and the Danish slope. The latter is under the influence of the Jutland Current, while the basin and the investigated parts of the Norwegian slope are bathed in Atlantic water. All areas have bottom waters with a high oxygen concentration. Three living (stained) and three dead (unstained) assemblages occupy the three physiographic areas. Only one assemblage (on the Norwegian slope) is common to both the living and dead assemblages but the boundaries between them lie at comparable depths. The higher standing crops are found on the fertile Danish slope while the lower ones are in the deep basin where the diversity is at a maximum. In the dead assemblages, the relative abundance of agglutinated tests increases with depth. Comparison with data collected 40 to 60 years ago shows increases in absolute numbers of tests, especially in the deep basin. There are changes in assemblage compositions in all areas. The dominant species found in 1937 are different from those of 1992/1993. There is a major change in the basin where one agglutinated species has changed its depth distribution downslope and two present day abundant species are new arrivals. These faunal events are probably linked to environmental changes.

Description: Investigations of living (stained) benthic foraminifera in the surface (0–1 cm) sediments along a depth transect in Drammensfjord, southern Norway, have been carried out on samples collected in 1984 and during all four seasons in 1988. The transect runs through strongly variable environments from a well oxygenated, brackish surface layer to anoxic waters of slightly less than normal marine salinity. The objectives were to study foraminiferal recolonization patterns after a prolonged period (〉 5 years) of nearly permanent anoxic bottom water conditions in the lower parts of the transect, the seasonal stability of the assemblages after recolonization, and interspecific tolerances to various environmental parameters (i.e., temperature, salinity, dissolved oxygen concentration, water depth). When the redox-boundary was at its shallowest position in the water column (30–35 m water depth; salinity 29–30 ‰), Ammodiscus? gullmarensis was dominant adjacent to the anoxic areas. This represents the first record of agglutinated dominated assemblages bordering anoxic environments. It took more than one year after reaeration before the areas, where anoxic conditions had prevailed for more than five years, became suitable for colonization. By 1988, the foraminiferal standing crop had more than doubled in areas influenced by the transitional water masses and living (stained) individuals were present down to the redox-boundary. Additionally, four species, which were not found along the transect in 1984, had been introduced. These immigrants had probably been transported into the area in suspension from the south. Stainforthia fusiformis was the first and most successful species to recolonize the formerly anoxic areas and it showed exceptionally high densities in samples collected a few meters above the redox-boundary. After recolonization, all species showed a distinct depth succession which, for most of them, prevailed throughout the year. Possible lack of seasonal population fluctuations in several species is thought to be due to a permanently plentiful food supply. The nine abundant species have been ranked in accordance with their interspecific tolerance to increasing euryhaline and eurythermal environmental conditions.

Description: The role of TEP (Transparent Exopolymer Particles) in the flocculation of a diatom bloom was studied under controlled conditions in a mesocosm. The concentration of TEP increased exponentially during growth, flocculation and senescence of the bloom. Aggregation began dominating the particle dynamics of TEP during the early growth phase of the bloom, several days prior to the appearance of large flocs and nutrient depletion. TEP aggregated with themselves and with phytoplankton due to the high stickiness of TEP, but phytoplankton was not observed to aggregrate with itself. The production of TEP, estimated from changes in concentration, did not increase after nutrients were depleted. The concentration of TEP was a linear function of chl a and particulate organic carbon (POC), indicating that production of TEP was linked to growth rather than standing stocks of phytoplankton. The ratio between TEP and phytoplankton appeared to be one of the factors determining the onset of the flocculation of the bloom. The concentration of TEP may have been decreased by bacterial degradation. Bacterial degradation of TEP may explain the low TEP to chl a values, the decrease in stickiness of particles as the bloom progressed, and the retarded onset of flocculation.

Description: Stratigraphy, lithology and depositional structures of Liassic red limestone-breccias of the Adnet Formation, including the ‘Adnet Scheck’, were studied at several outcrops of the Northern Calcareous Alps (NCA) south-east of Salzburg. A four-fold lithostratigraphic division is proposed for the Adnet Formation of the Osterhorn Mountains: the hemipelagic Schmiedwirt (Sinemurian) and Kehlbach (Carixian) members are separated from the pelagic Saubach Member (Toarcian) by a layer of amalgamated breccias (Scheck Member, probably Domerian to early Toarcian). Several other breccia beds occur locally from the base of the Kehlbach Member up to the lower Saubach Member. Although the sediments overlying the Scheck Member breccias are of coeval age, the ages of the underlying strata are very different. This can be explained by submarine Liassic erosion during a period of resedimentation from the middle Carixian until the early Toarcian. At least 10–15 m of partly lithified sediments were eroded by gravity flows. The entire Kehlbach Member and up to two-thirds of the Schmiedwirt Member were removed at Adnet. The breccias originated from submarine debris flows. Repeated flows over a long period and the depositional setting exclude a triggering by sea-level fluctuations. Most probably they arose from tectonically triggered slumps and slides of superficial sediments. The ‘Scheck’ was initiated on the steep upper slope of the drowned Triassic Adnet reef and flowed to the north-east. The Pliensbachian to early Toarcian period of tectonic activity indicated by the breccias was the most important during the Liassic in the Osterhorn Mountains and other parts of the NCA. From the large-scale regional distribution of the breccias and in accord with published data, a roughly northeast trending strike-slip fault zone is proposed, crossing the NCA south of the Osterhorn block, with a peaking activity during the Pliensbachian to early Toarcian as the cause of the tectonic movements.

Description: A mega-submarine slide was evidenced along the Peruvian margin during a Seabeam survey of the R/V Charcot (Bourgois et al., 1986). The debris-slide was initially interpreted as the result of the slope failure occurring along a seaward curved scarp, and extending from east to west, along the line of maximum slope. Complementary bathymetrie data obtained from the R/V Sonne survey conducted to the north and to the south of the previous surveyed area has resulted in the identification of large-scale polyphase submarine slides involving a total surface of about 1000 km2, between latitudes 5 °15′S and 6 °05′S. Using Seabeam and Hydrosweep multibeam echosounder data in combination with deep-sea submersible observations, three distinct slope-failure types related to three main stages have been revealed. The three sliding phases occurred roughly along the same trend, orientated N230 °, and are therefore mainly controlled by the N80 ° orientation of the subducting Nazca plate. (1) The first phase of slope failure is documented by a debris-avalanche deposit, which extends from the lower slope down to 5 km within the trench floor. The deposit originates from the northern wall of a wide valley located along the upper slope. (2) The second phase of slope failure is characterized by a debris-avalanche, with a crescent-shaped scar, located along the middle slope and a hummocky deposit covering the lower slope and extending up to 10 km across the trench. The volume of rock involved in this event is estimated to some 250 km3. The slope failure is assumed to be related to an oversteepening of the middle slope induced by a rollover deformation. (3) The third phase of slope failure corresponds to a translational sliding block and a toppling block with volumes of 6 km3 and 13 km3, respectively. The seismic energy produced during the seismic cycle has greatly increased facturation and fluids buildup along the area previously weakened by a rollover fold. A restricted N-S folding is observed in the vicinity of the trench, to the north of the two debris-avalanche deposits. It may have formed in relation to the local compression limited to the subduction of the Nazca plate. Sliding and folding thus document the paradox between the compressive regime in the lower plate and the extensional regime in the upper part of the upper plate.

Description: We review and evaluate the design and operation of twenty-seven known autonomous benthic chamber and profiling lander instruments. We have made a detailed comparison of the different existing lander designs and discuss the relative strengths and weaknesses of each. Every aspect of a lander deployment, from preparation and launch to recovery and sample treatment is presented and compared. It is our intention that this publication will make it easier for future lander builders to choose a design suitable for their needs and to avoid unnecessary mistakes.

Description: The 14.1 Ma old composite ignimbrite cooling unit P1 (45 km3) on Gran Canaria comprises a lower mixed rhyolite-trachyte tuff, a central rhyolite-basalt mixed tuff, and a slightly rhyolite-contaminated basaltic tuff at the top. The basaltic tuff is compositionally zoned with (a) an upward change in basalt composition to higher MgO content (4.3–5.2 wt.%), (b) variably admixed rhyolite or trachyte (commonly 〈5 wt.%), and (c) an upward increasing abundance of basaltic and plutonic lithic fragments and cognate cumulate fragments. The basaltic tuff is divided into three structural units: (I) the welded basaltic ignimbrite, which forms the thickest part (c. 95 vol.%) and is the main subject of the present paper; (II) poorly consolidated massive, bomb- and block-rich beds interpreted as phreatomagmatic pyroclastic flow deposits; and (III) various facies of reworked basaltic tuff. Tuff unit I is a basaltic ignimbrite rather than a lava flow because of the absence of top and bottom breccias, radial sheet-like distribution around the central Tejeda caldera, thickening in valleys but also covering higher ground, and local erosion of the underlying P1 ash. A gradual transition from dense rock in the interior to ash at the top of the basaltic ignimbrite reflects a decrease in welding; the shape of the welding profile is typical for emplacement temperatures well above the minimum welding temperature. A similar transition occurs at the base where the ignimbrite was emplaced on cold ground in distal sections. In proximal sections the base is dense where it was emplaced on hot felsic P1 tuff. The intensity of welding, especially at the base, and the presence of spherical particles and of mantled and composite particles formed by accretion and coalescence in a viscous state imply that the flow was a suspension of hot magma droplets. The flow most likely had to be density stratified and highly turbulent to prevent massive coalescence and collapse. Model calculations suggest eruption through low pyroclastic fountains (〈1000 m high) with limited cooling during eruption and turbulent flow from an initial temperature of 1160°C. The large volume of 26 km3 of erupted basalt compared with only 16 km3 of the evolved P1 magmas, and the extremely high discharge rates inferred from model calculations are unusual for a basaltic eruption. It is suggested that the basaltic magma was erupted and emplaced in a fashion commonly only attributed to felsic magmas because it utilized the felsic P1 magma chamber and its ring-fissure conduits. Evolution of the entire P1 eruption was controlled by withdrawal dynamics involving magmas differing in viscosity by more than four orders of magnitude. The basaltic eruption phase was initially driven by buoyancy of the basaltic magma at chamber depth and continued degassing of felsic magma, but most of the large volume of basalt magma was driven out of the reservoir by subsidence of a c. 10 km diameter roof block, which followed a decrease in magma chamber pressure during low viscosity basaltic outflow.

Description: High resolution 230Thex and 10Be and biogenic barium profiles were measured at three sediment gravity cores (length 605–850 cm) from the Weddell Sea continental margin. Applying the 230Thex dating method, average sedimentation rates of 3 cm/kyr for the two cores from the South Orkney Slope and of 2.4 cm/kyr for the core from the eastern Weddell Sea were determined and compared to δ18O and lithostratigraphic results. Strong variations in the radionuclide concentrations in the sediments resembling the glacial/interglacial pattern of the δ18O stratigraphy and the 10Be stratigraphy of high northern latitudes were used for establishing a chronostratigraphy. Biogenic Ba shows a pattern similar to the radionuclide profiles, suggesting that both records were influenced by increased paleoproductivity at the beginning of the interglacials. However, 230Thex0 fluxes (0 stands for initial) exceeding production by up to a factor of 4 suggest that sediment redistribution processes, linked to variations in bottom water current velocity, played the major role in controlling the radionuclide and biogenic barium deposition during isotope stages 5e and 1. The correction for sediment focusing makes the ‘true’ vertical paleoproductivity rates, deduced from the fluxes of proxy tracers like biogenic barium, much lower than previously estimated. Very low 230Thex0 concentrations and fluxes during isotope stage 6 were probably caused by rapid deposition of older, resedimented material, delivered to the Weddell Sea continental slopes by the grounded ice shelves and contemporaneous erosion of particles originating from the water column.

Description: Recent measurements indicate the transatlantic extent of the Namib Col Current at depths of 1300-3000 m near Lat. 22 degrees S in the South Atlantic Ocean. This current forms a continuous circulation structure from the Namib Col on the Walvis Ridge to the western trough, though its characteristic change as deepwater with varying properties enters and leaves the current owing to a meridional flow component. Transport estimates from hydrographic sections on the Walvis Ridge and at 15 degrees W near the crest of the Mid-Atlantic Ridge indicate a strength of about 3 x 10(6) m(3) s(-1) The current is part of a larger-scale eastward Row at Lon. 25 degrees W; transport estimates across the salinity maximum core there show a similar strength. Associated with this high-salinity high-oxygen current is a basin-wide front in these properties of varying intensity (weaker in the east) marking the transition to deep water whose North Atlantic characteristics have been partly erased by mixing with Circumpolar Deep Water in the southwest South Atlantic. The water which finally crosses the Walvis Ridge is supplied both by the eastward flow of this (diluted) North Atlantic Deep Water and by a general southeastward interior flow from the northern Angola Basin. Evidence suggests that this deep water continues south in the eastern Cape Basin, leaving the South Atlantic near the African continent.

Description: A data assimilation system has been developed which has been used in conjunction with a primitive equation model of the tropical Pacific. The assimilation system is based on a time weighted successive correction method. The data are inserted continuously by updating the model solution every time step. The inserted data are taken from a time window, centered on the present model time step. Three experiments were performed. In the first assimilation run, SST observations were assimilated. In the second experiment, island based sea level observations were assimilated, while in the third run subsurface temperature data were assimilated. An intercomparison between the three assimilation runs was made and we discuss two questions. First, to which extent can the model fields be improved, and second, how long is the assimilated information retained by the ocean model.

Description: Various models of surface and deep-water circulation in the Norwegian-Greenland Sea (NGS) have been proposed for the last two glacial to interglacial transitions. Although much progress has been made in understanding the sedimentary response to climatic and oceanographic changes, conflicting interpretations have been developed. To clarify some of these discrepancies and to test or modify the existing circulation concepts, a multiparameter approach is applied, combining sedimentological, micropaleontological, organic-geochemical and isotopic methods. On the basis of indicative properties a combined litho- and organofacies concept is developed and calibrated with modern depositional settings beneath different surface water masses. Sedimentary regimes are then derived for glacial and deglacial settings. Atlantic water intrusions in the NGS reveal complex and highly dynamic patterns for the last two glacial and interglacial periods, with repetitive inflows during Isotope Stage 6 and a high variability in Isotope Stage 5. Specific facies patterns show maximum extensions of Atlantic Water intrusions during the climatic highstands 5.5.1, 5.3 and 5.1 and narrowest intrusions in the cool phases 5.4 and most pronounced in 5.2. In contrast, different glacio-marine depositional regimes depict variable sea ice coverage and supply of ice-rafted debris. Most conspicuous are short-term depositional events marked by diamictons, which are related to the high instabilities of continental ice sheets. Some of the diamictons seem to occur contemporaneously with Heinrich layers H1 and H2. The probable temporal and obvious phenomenological concidence of Heinrich layers and NGS diamictons suggests a common trigger mechanism which caused an almost simultaneous disintegration of huge continental ice masses along the shelves of North America and the eastern margin of the NGS. A previous estuarine circulation model claims regional upwelling along the eastern margin of the NGS for specific periods of the last deglaciation. The organic character of sediments covering the same time intervals show a clear predominance of reworked fossil organic matter and thus does not support the estuarine model.

Description: The accumulation rates (AR) of coarse (〉 63 μm) terrigenous material in the Norwegian-Greenland Sea (NGS) were investigated for the last ca. 200 kyr. Comparisons of accumulation rates in the northern, western and eastern NGS show different histories. The highest AR peak in the eastern NGS occurs near the beginning of Stage 6 (183 ka); this peak may signal the rapid growth and deterioration of the Scandinavian Ice Sheet. An AR peak in the northern NGS at the Stage 6/5 transition (Termination II; 128 ka) may signal the decay of the Barents Sea Ice Sheet. The highest peak in the western NGS occurs during the Stage 2/1 transition (Termination I; 13.6 ka); due to its location near the East Greenland Current, correlation with ice sheets is difficult. Comparisons of the AR data from the eastern NGS with terrestrial data from Scandinavia demonstrate a clear link between glacial advances/retreats and accumulation rates of coarse-grained material in the deep ocean: the retreat of tidewater ice fronts correlates with high ARs. Thus marine data can be used to determine the movement history of continental ice sheets.

Description: Pelagic processes and their relation to vertical flux have been studied in the Norwegian and Greenland Seas since 1986. Results of long-term sediment trap deployments and adjoining process studies are presented, and the underlying methodological and conceptional background is discussed. Recent extension of these investigations at the Barents Sea continental slope are also presented. With similar conditions of input irradiation and nutrient conditions, the Norwegian and Greenland Seas exhibit comparable mean annual rates of new and total production. Major differences can be found between these regions, however, in the hydrographic conditions constraining primary production and in the composition and seasonal development of the plankton. This is reflected in differences in the temporal patterns of vertical particle flux in relation to new production in the euphotic zone, the composition of particles exported and in different processes leading to their modification in the mid-water layers. In the Norwegian Sea heavy grazing pressure during early spring retards the accumulation of phytoplankton stocks and thus a mass sedimentation of diatoms that is often associated with spring blooms. This, in conjunction with the further seasonal development of zooplankton populations, serves to delay the annual peak in sedimentation to summer or autumn. Carbonate sedimentation in the Norwegian Sea, however, is significantly higher than in the Greenland Sea, where physical factors exert a greater control on phytoplankton development and the sedimentation of opal is of greater importance. In addition to these comparative long-term studies a case study has been carried out at the continental slope of the Barents Sea, where an emphasis was laid on the influence of resuspension and across-slope lateral transport with an analysis of suspended and sedimented material.

Description: Interactions between epibiotic bacteria and organisms possibly play a central role in marine ecology. Despite its potential significance, this held has long time been neglected. For most aquatic taxa nothing is known about presence/absence of bacteria on their. surface, much less about specific associations or potential interactions between epibiotically associated micro- and macroorganisms. Bahamian and Pacific ascidians, most of them colonial, were screened for the presence, abundance and diversity of epibiotic bacteria and macroepibionts. Only one species, Polyclinum planum, occasionally carried macroepibionts. All ascidian species exhibited varying densities of epibiotic bacteria on their surfaces. Average epibacterial abundance as assessed by plate counts on the 29 species ranged from 60 to 1.2X10(7)/cm(2). Significant differences in bacterial abundances were observed between species, families and geographical regions. On the family level, Polyclinidae were the most densely colonized. Bahamian species exhibited less dense epibacterial communities than Pacific species, a difference that may partly be caused by the absence of the heavily fouled Polyclinidae from the Bahamian collection. Diversity of culturable strains, evaluated for the Bahamian species only, was uniformly high on most species. I did not find any evidence for specific associations (as reflected by dominance of single strains) between culturable bacteria and ascidian species. Contrarily, direct observation by epifluorescence revealed the presence of an apparently dominant photosynthetic symbiont on several didemnid species. The presence of this symbiont correlated negatively with abundance and diversity of culturable epibionts. This negative correlation could reflect properties of the host's surface which selectively favor proliferation of the symbiont or antagonistic interactions between the symbionts and other potential bacterial colonizers.

Description: This interim report deals with investigations on key factors controlling reef growth by zoophysiologists, ecologists, paleontologists and geologists. The different levels of emphasis are the coral animal and the reef community. The main study area is the Red Sea which reaches over 20°C latitude up to the northernmost margin of the global coral reef belt. Supplementary results on microborer ecology are provided from the Bahamas. The desert enclosed Red Sea, not influenced by land runoff and only minimally by anthropogenic (urban and touristic) nutrient inputs, is predestined for a study on the principal influence of light on calcification within bathymetrical and latitudinal gradients. Hence, on the level of the zooxanthellate scleractinian animal phototrophic and heterotrophic energy supply and its bearing on calcification are being measured in different coral species—in particular inPorites sp., one of the most important reef builders. The growth of 15 zooxanthellate scleractinians in the Gulf of Aqaba correlates with the annual light cycle. This correlation is observable down to 40 m depth. Other growth promoting factors seem to have less influence on coral extension. The availability of organically enriched sediments in shallow water probably yields nutritional value, in particular for filter feeding species, thus restricting their distribution to those areas. Zooxanthellae, when isolated fromMycedium elephantotus, are different in their dependence on depth in maximum rates of photosynthesis and photosynthetic efficiency (-slope). Increasing concentrations of pigments as a function of depth could be determined. Maximum rates of photosynthesis of zooxanthellae in vivo, collected at corresponding depth, have been 4 times higher. Structural and physiological adaptations improving heterotrophic and phototrophic energy intake are highlighted. Porites sp. was the subject of annual growth studies at locations extending from Aqaba in the North over the northern and southern Egyptian coast and islands, Sanganeb Atoll and Wingate reef offshore Sudan to the Gulf of Tadjoura in the Gulf of Aden (Djibouti). Mean growth rates in the shallow water zone increase with decreasing latitude and are highest at the southernmost studied reefs in the Gulf of Tadjoura. However, the observed latitutdinal growth reduction is restricted to the upper ca. 15 m of the water column. The upper limit of growth potential decreases with depth parallel to the decrease of light availability. Highest growth rates are recorded in shallow depth (10–2.9 mm yr−1). This zone reaches at Aqaba (29°30′N) to a depth of ca. 10 m. At the southern Egyptian reefs (24°30′N) this zone extends to ca. 15 m water depth. This effect is probably a result of the stronger reduction of winter light levels and water temperature in the northern regions. Compared to other oceans the decrease of growth with increasing latitude of Red SeaPorites corals is far less, and growth rates at Aqaba are the highest observed at these latttudes. On the level of the community of reef inhabitants four principal topics are addressed: The first one is the dynamics of the proportions of hermatypic and ahermatypic organisms and open space. The occurrence of stony and soft corals and the sharing of empty space in different reef sections at Aqaba and on Sanganeb Atoll were quantified. Soft corals, mainlySinularia- and xeniid species, occupy decreasing shares with depth. Among theXenia species a bathymetrical zonation pattern was detected. The next issue is the growth impeding role of soft corals and gastropod parasites and predators on scleractinians. Experimental and field observations showed xeniid soft corals to be opportunistic i.e. occupying rapidly open space rather than to attacking and outcompeting stony corals. An increasingly specialized behaviour was detected among corallivorous gastropods of the family Coralliophilidae to exploit their coral hosts. Whereas these snails are more or less sessile and depend for a long time on the surrounding host polyps the mobileDrupella cornus (Thaididae) forms feeding aggregations which denude mainly branching corals on shallow reef parts. Furthermore, the role counteracting reef growth of macro- and microbioeroders is investigated.Diadema setosum is a major destructive agent on reefs at Aqaba (not in the central Red Sea). The grazing sea urchins do not only keep potential colonization area free but also erode carbonate material (e. g. 1468 g/m2/year, 10 m depth). Demographic and bathymetric patterns in the sea urchin population are analyzed including their bearing on bioerosion of the reef. Investigations on microboring organisms in carbonate material have started in the Red Sea; initial results, however, are only available from similar studies near Lee Stocking Island, Bahamas. Three major environments have been identified based on the distribution of the different microborers. These are the intertidal environment dominated by boring cyanobacteria., reef sites from 2 to 30 m water depth dominated by a diverse assemblage of boring cyanobacteria and chlorophytes, and the deep reef slope from 100 to 300 m dominated by boring green algae and heterotrophs. The boring chlorophyte genusPhaeophila appears rapidly and dominates at sites from 2 to 30 m, but it leaves vacated borings and is replaced byOstreobium quekettii after 1 year. Different substrate types show very different rates of colonization by microborers. The greatest excavation rates (100 g/m2/3 months) occur in fine-grained limestone, while the slowest rates (0.5 g/m2/3 months) occur in calcite crystals. Molluscan shell material shows intermediate rates of excavation. Light conditions appear very important in determining the growth rate and distribution of different microborers between the sites, however, the interaction of light with other factors, such as substrate, time period of exposure, and water quality conditions may be involved.

Description: Polymetallic massive sulfides on the modern seafloor have been found in diverse volcanic and tectonic settings at water depths ranging from about 3700 to 1500 m. These deposits are located at fast-, intermediate-and slow-spreading mid-ocean ridges, on axial and off-axis volcanoes and seamounts, in sedimented rifts adjacent to continental margins and in subduction-related back-arc environments. High-temperature hydrothermal activity and large accumulations of polymetallic sulfides, however, are known at fewer than 25 different sites. Several individual deposits contain between 1 and 5 million tonnes of massive sulfide (e.g., Southern Explorer Ridge, East Pacific Rise 13°N, TAG Hydrothermal Field) and only two deposits (Middle Valley and Atlantis II Deep, Red Sea) are known to contain considerably higher amounts of sulfides ranging between 50 and 100 million tonnes. This range (1–100 million tonnes) is similar to the size of many volcanic-associated massive sulfide deposits found on land. However, the vast majority of known sulfide occurrences on the modern seafloor amount to less than a few thousand tonnes and consist largely of scattered hydrothermal vents, mounds and individual chimney structures.Recovered samples from about 25 deposits world-wide represent no more than a few hundred tonnes of material. The mineralogy of these samples includes both high (〉 300°–350°C) and lower-temperature (〈 300°C) assemblages consisting of varying proportions of pyrrhotite, pyrite/marcasite, sphalerite/wurtzite, chalcopyrite, bornite, isocubanite, barite, anhydrite and amorphous silica. Massive sulfide deposits in back-arc environments additionally may contain abundant galena, PbAsSb sulfosalts (including jordanite, tennatite and tetrahedrite), realgar, orpiment and locally native gold. Close to 1300 chemical analyses of these samples indicate that the seafloor deposits contain important concentrations of Cu and Zn comparable to those of massive sulfide deposits on land. The sediment-hosted deposits, while being somewhat larger than deposits on the sediment-starved mid-ocean ridges, appear to have lower concentrations and different proportions of the base metals due to fluid-sediment interaction. Initial sampling of sulfides in the back-arc spreading centers of the West and Southwest Pacific suggests that these deposits have higher average concentrations of Zn, Pb, As, Sb and Ba than deposits at the sediment-starved mid-ocean ridges. Gold and silver concentrations are locally high in samples from a number of mid-ocean ridge deposits (up to 6.7 ppm Au and 1000 ppm Ag) and may reach concentrations of more than 50 ppm Au and 1.1 wt% Ag in massive sulfides from immature back-arc rifts, that are dominated by felsic volcanic rocks. Precious metal contents of seafloor sulfides thus are well within the range of those found in land-based deposits.Although massive sulfide deposits have been found at water depths as shallow as 1500 m, boiling of the hydrothermal fluids may prevent the formation of typical polymetallic massive sulfides at shallower depths (i.e., less than a few hundred meters), where the hydrostatic pressure is too low to prevent phase separation. In this case, mineralization with distinct epithermal characteristics and significant amounts of precious metals can be expected.

Description: An electrochemical model for a microbial fuel cell process is proposed here. The model was set up on the basis of the experimental results and analysis of biochemical and electrochemical processes. Simulation of the process shows that the model describes the process reasonably well. The analysis of model simulation illustrates how the current output depends on the substrate concentration, mediator concentration and other main variables. The relationship between the current output and over-voltage is revealed from the modelling study.

Description: Methylcyclohexane dissolved in and forming a thin film on purified seawater with traces of anthraquinone added as triplet sensitizer was exposed to natural sunlight in a quartz flask. The water was circulated through a glass cartridge filled with Amberlite XAD-2 for the concentration of reaction products which were identified by GC/MS after elution and silica gel chromatography. They included isomeric methylcyclohexanols as the principal components, primary hydroperoxides, a tentatively identified secondary peroxide, methylcyclohexanones, and acyclic ketones. Mass spectra and mechanisms are discussed as well as possible biological consequences of the formation of these compounds.

Description: The resolution of the conflict between eggcare and foraging was studied in male and female wandering albatrosses. The foraging zone and range, duration of incubation shifts and foraging trips, and associated changes in body mass were studied. Costs during incubation, expressed as the time spent incubating and the proportional loss of body mass, were similar for both sexes. The mass gained at sea was related to the duration of foraging trips, but the relationship was much less significant in males, where foraging ranges, though similar on average to those of females, were very variable. Males foraged in more southerly waters than females, and gained mass more rapidly. Only females appeared to regulate the duration of foraging trips, and this compensated for the mass lost during the incubation fast. Previous breeding experience had no influence on foraging efficiency. Egg desertion because of depletion of body reserves was very rare because birds have a wide “safety margin”, i.e. the difference between the average body mass when relieved and that at nest desertion. This safety margin enables the birds to compensate for the high variability in the duration of foraging trips, and is probably a reason for the high breeding success of wandering albatrosses. Decisions to return from the sea to the nest or to desert the nest are probably related to the status of body reserves, and have been selected in the large wandering albatross so that both present and future reproductive success are maximised.

Description: We have determined the content of free l-amino acids and d-aspartate in the nervous tissue of three representative cephalopods: Sepia officinalis, Octopus vulgaris, and Loligo vulgaris, and the optic lobes of adult and embryo Sepia officinalis. Taurine is the most abundant amino acid in the cephalopod nervous tissue. Its content amounts to more than 50% of the total free amino acids. The other most concentrated amino acids are Glu, Ala, Asp, and GABA. High concentrations of d-aspartate were found in the nervous tissue of all cephalopods examined (7–12 μmol/g wet tissue) which represents 50–80% of the total aspartate (d + l), depending on the animal. Among the various regions of the brain of Octopus vulgaris, d-aspartate was found to be evenly distributed in the various regions of the brain. In nerve tissue of Sepia officinalis, there is no significant difference in the pattern of free l-amino acids, in particular of the d-aspartate concentration, between adults and embryos, except for GABA, Gly, His and Thr. This suggests that d-aspartate in nerve tissue of the Cephalopoda is of endogenous origin and not a product of accumulation from exogenous sources. From a comparative study of the content of d-aspartate in the nervous tissue of different animals, we found that protostomia contain a significantly higher amount than deuterostomia. Thus, d-aspartate could be a criterion to distinguish the protostomia phyla from the deuterostomia phyla.

Description: A structural model encompassing the southern North Sea basin west of the Central Graben has been developed. This model consists of a rift system affecting the post-salt section around the basin margin and a large area of detached compressional buckle folds within the basin. This pattern is initially a response to gravity sliding of the post-salt section on the salt within the basin during the late Triassic to late Jurassic. A close relationship between the location and trend of the peripheral graben system and basement structures in the pre-salt is noted. Pre-Jurassic extension across the peripheral graben systems was balanced by the sum of fault heaves at the pre-salt (Rotliegend) level and shortening across salt-cored buckle folds in the post-salt section. Salt pillows and swells passively infilled the cores of these gravity-induced buckle folds. Cretaceous and Tertiary inversion involved basin tilt and renewed movement on basin-bounding basement faults; notably, reverse movements did not propagate from basement structures up into the peripheral graben systems. The post-salt sedimentary section experienced gravity spreading in response to inversion-related uplift, resulting in syn-inversion extensional faulting in the Sole Pit High, where the Mesozoic section was thickest. This extension, combined with a loss of fault heave in the pre-salt section, was balanced by amplification of salt-cored buckle folds in the centre of the basin. In the context of the model described here, salt pillows represent passive infill of thin-skinned, compressional buckle folds which later amplified during thick-skinned basement shortening. Crestal collapse of such folds occurs via normal faulting, accompanied by reactive diapirism. Such reactive diapirs establish conduits through which salt may leak, leading to pillow deflation and ultimately conduit preservation as a salt wall (flanked by rim synclines in areas where the buckle folds were emergent). The salt structures described here are related to cover folds and faults, which in turn reflect episodes of basin extension, tilting and inversion. Hence individual salt structures can be said to be only remotely connected with regional, intraplate stresses.

Description: Normal faulting and halokinesis have been important controls on the deposition and subsequent deformation of Mesozoic and Tertiary strata in the North Sea. In addition to the previously documented mechanisms of salt withdrawal, dissolution and differential sedimentary loading, it is recognized that gravity-driven thin-skinned extension above inclined salt layers has played an important part in North Sea basin development. Commercial section restoration software has been used to facilitate depth conversion, restoration and decompaction of seismic sections selected from an interpreted regional database in the western central North Sea, allowing validation of the interpretations, and a graphical and highly quantitative description of salt-assisted extension. Results of this work show that Zechstein Group evaporites were deposited in shallow sag basins during the Permian. Triassic sedimentary pods were generated by localized deposition in synclinal basins and grabens above the evaporites. Bedded salt became folded, while mobile salt flowed to fill anticline cores. Since the early Jurassic, regional tectonic tilting related to post-rift subsidence and increasing sedimentary overburden have caused allochthonous Mesozoic and Tertiary strata to extend by gravity spreading above the mobile salt layer, which detaches the allochthon from the underlying autochthonous Late Palaeozoic rocks. Concave-up listric normal faults sole out in the salt layer, propagate into the overlying cover sewuence, and have been active at different geological times causing stratal thickening and folding within the allochthon. Antithetic and synthetic normal faults have developed, producing complex upward branching fault systems. In map view, the listric faults form curvilinear en echelon arrays, the faults linked by relay ramps. Fault blocks are typically 3–7 km wide, 2–3 km thick and 7–10 km long. Salt movement during the Jurassic-Tertiary has been driven by active extension of the cover, causing salt to fill potential voids created by fault block rotation. Thus salt highs occur beneath sites of extension. The listric faults generally dip in the same direction as the sub-salt surface, although there are also some major counter-regional faults. During extension, regional dips have increased up to about 5, which is sufficient for gravity-driven extension above a salt layer. A total extension of about 6% has occurred. The gravity-driven thin-skinned extension documented in the western central North Sea is a phenomenon which can be recognized elsewhere in the North Sea basin, and can be readily compared with similar phenomena already documented in offshore Angola, Brazil, Nova Scotia and the Gulf of Mexico.

Description: The alternation of two major climatic types, the glacial and nonglacial, in the Phanerozoic history of the Earth is well-documented at present. These climates affected the state of the biosphere to such an extent that cool (glacial) and warm (nonglacial) biospheres can be distinguished. The main features of the cool biosphere can be determined from its state at present and during the Pleistocene. The cool biosphere is characterized by features such as the following: permanent glacial or ice polar caps, occasional glacial covers or permafrost occurrences in the temperate labtudes, an oceanic psychrosphere, low temperature and intense circulation in the atmosphere and hydrosphere, low oceanic level, high rates of erosion and sedimentation, a low concentration of atmospheric carbon doxide, contrasting climate and landscape zonation, clearly pronounced biogeographic and ecological differentiation, rapid fluctuations of the above features, frequent biotic crises, and so on. Evidently, the warm biosphere exhibited different characteristics, perhaps even opposite to those of the cold biosphere. However, our understanding of the properties of the warm biosphere is far from being clear and complete, even though this type of biosphere has sharply prevailed in geological history. Defining these properties is a principal goal of historical geological and ecological studies . When solved, this problem will be of prognostic and general methodic importance for the earth sciences, allowing the applicability of the actualistic method to be specified.

Description: It is well known that spatial scales of oceanic eddies are smaller than scales of atmospheric eddies. Since the spectral distribution of kinetic energy of atmospheric eddies may influence the properties of wind driven oceanic eddies, an excellent resolution of small scale variability of wind fields used as input fields of coupled models of atmosphere and ocean is necessary. Analysis of spatial scales of atmospheric fields is done in terms of spectral energy densities. These are determined in two different ways: directly from objectively analysed fields or by using spatial correlation functions of direct observations averaged for 20 km × 20 km boxes. In the spectral range of wavelengths of less than 1000 km spectral energy densities of analysed fields have lost about 15 to 50% of the variance compared to direct observations. A considerable part of this loss of the variance depends on smoothing done by interpolation schemes themselves. Concerning problems of air-sea interaction care should be taken also to avoid that systematic errors of analysed wind fields lead to systematic errors in turbulent exchange. It is shown that high observed wind speeds are considerably underestimated in analysed fields of numerical models of weather prediction.

Description: The Lau Basin comprises oceanic crust that separates the remnant Lau Ridge volcanic arc from the active Tofua arc. The basin is situated above mantle exhibiting strong seismic wave attenuation; it overlies the west dipping seismic zone of the Tonga Trench subduction system and is presently opening at rates as high as 1.6 cm/yr. Seaward rollback of the trench axis, coupled with upwelling high temperature mantle diapirs, is proposed as the main driving force to cause crustal extension in this region of oceanic plate convergence. The trapezoidal shape of the basin suggests that it has opened progressively from north to south; the trace of the Louisville seamount chain may help constrain the southern apex of the basin. The basin has opened in two tectonic styles. Initially, beginning at about 6 Ma, attenuation and rifting of the forearc or outer part of the Lau Ridge formed a series of half-grabens that were partly sedimented and received basaltic flows. This extension and magmatism overlapped with Lau Ridge arc volcanism. The second stage of opening (about 5.5-5 Ma) was promoted by a southward-propagating rift system that formed new crust by seafloor spreading. A second propagator (about 1.5 Ma) has overtaken the first and forms an overlapping ridge system. A small three-limbed spreading system in the northeastern basin forms a triple junction. A fourth spreading system is recognized in the northwestern part of the basin.

Description: High resolution 230Thex and 10Be and biogenic barium profiles were measured at three sediment gravity cores (length 605–850 cm) from the Weddell Sea continental margin. Applying the 230Thex dating method, average sedimentation rates of 3 cm/kyr for the two cores from the South Orkney Slope and of 2.4 cm/kyr for the core from the eastern Weddell Sea were determined and compared to δ18O and lithostratigraphic results. Strong variations in the radionuclide concentrations in the sediments resembling the glacial/interglacial pattern of the δ18O stratigraphy and the 10Be stratigraphy of high northern latitudes were used for establishing a chronostratigraphy. Biogenic Ba shows a pattern similar to the radionuclide profiles, suggesting that both records were influenced by increased paleoproductivity at the beginning of the interglacials. However, 230Thex0 fluxes (0 stands for initial) exceeding production by up to a factor of 4 suggest that sediment redistribution processes, linked to variations in bottom water current velocity, played the major role in controlling the radionuclide and biogenic barium deposition during isotope stages 5e and 1. The correction for sediment focusing makes the ‘true’ vertical paleoproductivity rates, deduced from the fluxes of proxy tracers like biogenic barium, much lower than previously estimated. Very low 230Thex0 concentrations and fluxes during isotope stage 6 were probably caused by rapid deposition of older, resedimented material, delivered to the Weddell Sea continental slopes by the grounded ice shelves and contemporaneous erosion of particles originating from the water column.

Description: Single and multidimensional GC-ECD techniques were applied to determine individual chlorobiphenyls (CBs) in solution and in suspended particles in the Baltic Sea (some data were also obtained for the adjacent German Bight in the North Sea). Large volumes (up to 1100 dm3) were analysed in transects in November 1988 and 1989 and in spring 1991. Salinity and temperature were measured continuously along the sampling tracks in all three cruises; nutrients and pH only in the latter two cruises. Concentrations of individual CBs in solution were in the sub- and low pg dm−3 range (detection limit being 0.05 pg dm−3), and of their sum between 2 and 237 pg dm−3. These concentrations are considerably lower than previously reported data. This is mainly the result of the elimination of contamination and interference problems in the sampling, clean-up and GC-ECD procedures. It may also partly reflect the reduction in the production and use of PCBs in the last decade. The highest concentrations in solution originated from local sources in the Belt Sea and the Gulf of Finland. Regional differences were found for the compositions of the CB mixtures in solution. The lowest concentrations of CBs in solution were found in areas and periods of plankton production (spring 1991), with ΣCB concentrations between 2 and 14 pg dm−3. The compositions of the CB mixtures showed regional differences in each cruise. These could be interpreted in terms of mixing between different water bodies. The classification of transects on the basis of these CB patterns agreed well with the distinction of water bodies on the basis of T-S diagrams and hydrochemical data. Concentrations of individual CBs in suspension were generally 0.1–0.5 pg dm−3, those of their sum (ΣCB) between 4 and 6 pg dm−3 during the autumn cruises. Extremely high values were found in the Belt Sea-Kattegat area in spring 1991 (up to 589 pg dm−3 for individual CBs and up to 2859 pg dm−3 for ΣCB). This probably reflects the uptake of CBs into particulates during a plankton bloom. Primary production may effectively remove CBs from the water column into the sediments. The amounts of chlorobiphenyls presently stored in the sediments of the Baltic Sea exceed the amounts in the water column by several orders of magnitude. The compositions of the CB mixtures differed considerably between solution and suspension. The relations between log K′d (apparent particle/water partition coefficient) and log Kow (octanol-water distribution coefficient) suggest the existence of (quasi-)equilibrium conditions in autumn. Deviations from this behaviour arise from biological activity in spring. The contribution of toxic congeners to the CB mixtures was dominated by the mono- and di-ortho-Cl substituted derivatives of the most toxic non-ortho-Cl CBs. The toxicity of the CB mixtures in solution was between 0.01 and 12fg dm−3 TEQs (TCDD toxic equivalents). CBs-77, -118, -105 and -156 had the largest contributions to TEQs.

Description: The Easter microplate-Crough Seamount region located between 25° S–116° W and 25° S–122° W consists of a chain of seamounts forming isolated volcanoes and elongated (100–200 km in length) en echelon volcanic ridges oriented obliquely NE (N 065°), to the present day general spreading direction (N 100°) of the Pacific-Nazca plates. The extension of this seamount chain into the southwestern edge of the Easter microplate near 26°30′ S–115° W was surveyed and sampled. The southern boundary including the Orongo fracture zone and other shallow ridges (〈 2000 m high) bounding the Southwest Rift of the microplate consists of fault scarps where pillow lava, dolerite, and metabasalts are exposed. The degree of rock alternation inferred from palagonitization of glassy margins suggests that the volcanic ridges are as old as the shallow ridges bounding the Southwest Rift of the microplate. The volcanics found on the various structures west of the microplate consist of depleted (K/Ti 〈 0.1), transitional (K/Ti = 0.11−0.25) and enriched (K/Ti 〉 0.25) MORBs which are similar in composition to other more recent basalts from the Southwest and East Rifts spreading axes of the Easter microplate. Incompatible element ratios normalized to chondrite values [(Ce/Yb)N = 1−2.5}, {(La/Sm)N = 0.4−1.2} and {(Zr/Y)N = 0.7−2.5} of the basalts are also similar to present day volcanism found in the Easter microplate. The volcanics from the Easter microplate-Crough region are unrelated to other known South Pacific intraplate magmatism (i.e. Society, Pitcairn, and Salas y Gomez Islands). Instead their range in incompatible element ratios is comparable to the submarine basalts from the recently investigated Ahu and Umu volcanic field (Easter hotspot) (Scientific Party SO80, 1993) and centered at about 80 km west of Easter Island. The oblique ridges and their associated seamounts are likely to represent ancient leaky transform faults created during the initial stage of the Easter microplate formation (≈ 5 Ma). It appears that volcanic activity on seamounts overlying the oblique volcanic ridges has continued during their westward drift from the microplate as shown by the presence of relatively fresh lava observed on one of these structures, namely the first Oblique Volcanic Ridge near 25° S–118° W at about 160 km west of the Easter microplate West Rift. Based on a reconstruction of the Easter microplate, it is suggested that the Crough seamount (〈 800 m depth) was formed by earlier (7–10 Ma) hotspot magmatic activity which also created Easter Island.

Description: Surface samples from the eastern Barents and south-western Kara seas have been analysed for clay mineralogy. Transport paths, the role of regional sources and local bedrock outcrops and the influence of hydrodynamic and glacigenous processes for clay distribution on the shelves are discussed in relation to central Arctic Ocean deep sea and sea ice sediments. Franz Josef Land and Novaya Zemlya show significantly different clay mineral associations. Although smectite concentrations are fairly high, Franz Josef Land can be excluded as a source for central Arctic sea ice sediments, which are relatively rich in smectite. In the Kara Sea, smectite concentrations in coastal sediments surpass even the Franz Josef Land concentrations. The large cyclonic gyre in the eastern Barents Sea between Novaya Zemlya and Franz Josef Land, which serves as a mixing zone between Arctic and North Atlantic water, is apparently reflected within the smectite distribution pattern. With the exception of Franz Josef Land, the area of investigation is typically low in kaolinite. In particular, coastal areas and areas north of Novaya Zemlya, influenced by the inflow of Arctic waters, show the lowest kaolinite concentrations. A high kaolinite occurrence within the Nansen Basin is most probably related to Franz Josef Land and emphasizes the importance of long-range downslope transport of sediments across the continental slope. The surface water circulation pattern in close interaction with local outcrops onshore Novaya Zemlya and locally restricted occurrences within the eastern Barents Sea significantly alter the illite dispersal pattern. Illite concentrations are lowest around Franz Josef Land. Chlorite is generally low in the area of investigation. Submarine outcrops and important chlorite occurrences onshore Novaya Zemlya bias its distribution pattern.

Description: Drifting sea ice in the Arctic may transport contaminants from coastal areas across the pole and release them during melting far from the source areas. Arctic sea ice often contains sediments entrained on the Siberian shelves and receives atmospheric deposition from Arctic haze. Elevated levels of some heavy metals (e.g. lead, iron, copper and cadmium) and organochlorines (e.g. PCBs and DDTs) have been observed in ice sampled in the Siberian seas, north of Svalbard, and in Baffin Bay. In order to determine the relative importance of sea ice transport in comparison with air/sea and oceanic processes, more data is required on pollutant entrainment and distribution in the Arctic ice pack.

Description: During its formation on the vast Siberian shelves, Arctic surface water is strongly enriched in 228Ra. When 228Ra of surface samples from the Arctic interior is plotted against the river water component fr, derived from salinity, δ180 and silicate as tracers, a shelfwater end-member can be calculated by extrapolation. Highest values occur in the core of the Transpolar Drift, indicating rapid transport of surface water, comparable to the known ice-drift pattern. Low values at Ice Island T3 are explained by radioactive decay (5.8 year half-life) during the long residence time of fresh and shelf-influenced water in the Beaufort Gyre. Some evidence of decay and, consequently, prolonged transit times is also observed in the southern Nansen Basin. Future research is required to establish the seasonal, interannual and spatial variability of 228Ra on the shelves in order to determine the full potential of 228Ra as a tracer for the origin and transport rates of shelfwater in the Arctic Basin. Apart from the usual 228Ra signature of bottom waters, the tracer is also observed in intermediate layers where it gives evidence of recent contact with slope or shelf sediments. The Atlantic Inflow along the Barents slope is enriched down to 2000 m. The return flow over the Amundsen Basin and Lomonosov Ridge carries a shelf signature of 228Ra and 228Th down to more than 1200 m depth, in agreement with the enrichment observed in 137Cs. Deeper maxima around 1900–2500 m in the Nansen Basin are interpreted as inflow of bottom water from the Norwegian Sea through Fram Strait.

Description: As the result of intensive studies conducted by U.S., French, and Japanese scientific teams, the North Fiji Basin ridge, poorly known 10 years ago, is one of the most exhaustively investigated ridge axes of the world’s oceans. Today, a ridge segment more than 800 km long and 100 km wide has been fully mapped with the Sea Beam and Furono echo sounders. This ridge axis shows four main segments characterized by the same morphostructural aspect and limits that characterize mid-oceanic ridges. Along the whole length of the axis, a water-column sample has been taken every 20 km and rock samples every 10 km. Different types of hydrothermal activity have been discovered and explored either during the Nautile cruise in 1989 or during the Shinkai 6500 cruise in 1992. The most famous site is the “White Lady,” located around 17°S; it is characterized by 285°C shimmering hot water, which is very poor in metallic elements, expelled through an anhydrite chimney. This water probably represents the low salinity end-member resulting from phase separation in the deep levels of the oceanic crust. Other active sites have been observed all along the axis showing different characteristics such as low-temperature diffusion zones. Even though some parts of the North Fiji Basin remain poorly investigated, the newly acquired data from the ridge axis and from the eastern and northwestern parts allow us to develop a new tectonic model of basin evolution since its creation 12 m.y. ago.

Description: O2-flux into sediments attributed to the pumping behaviour of two macrofauna species, Callianassa subterranea (Decapoda) and Lanice conchilega (Polychaeta) was investigated. Samples were obtained from the North Sea near Helgoland in 1989 and 1990. The two species were found to transport roughly similar amounts (3 mmolm-2d-1) of oxygen into the sediment although they displayed markedly different pumping behaviours. Irrigation by C. subterranea was intermittent and characterized by regularly recurring breathing currents which lasted 2.6 min and were separated by 40-min pauses. In addition to this regular intermittent irrigation, an irregular mode was observed. C. subterranea constructed a complex burrow system. At least half of the burrow wall was not in contact with oxygenated water, however, and thus not effective as additional interface for O2-exchange. Sediment expelled from the burrow increased the total oxygen uptake (TOU) relative to the surrounding sediment surface. L. conchilega moved water much more frequently (every 4 min) than C. subterranea. We suggest that L. conchilega acted as a piston when moving in its tube, exchanging burrow water with the overlying water. This mechanism, termed ‘piston-pumping’, is also potentially important in other smaller tube dwelling organisms. At a shallow water station in the southern North Sea 21 ind of C. subterranea constructed 1.6 m2 burrow surface per m2. L. conchilega (300 ind m-2) created only 0.37 m2m-2 tube surface. On the basis of the abundance and oxygen transport associated with pumping activity, it is calculated that the two species increase TOU by 85% compared to O2-flux across the sediment-water interface.

Description: The sedimentation pattern of organic material in the Greenland-Norwegian Sea is reflected in the surface sediments, although less than 0.5% of the organic matter is buried in the sediment. Maximum fluxes and benthic responses are observed during June and/or August/September, following the pattern of export production in the pelagial zone. The annual remineralization rate on the Vøring Plateau is 3.0 g C m−2 a −1 Freshly settled phytodetritus, as detected by chlorophyll measurements, is rapidly mixed into the sediment and decomposed. It stimulates the activity of benthic organisms, especially foraminifera. The mixing coefficient for this material is D b=0.2 cm2 d−1, which is two to three orders of magnitude higher than that estimated from radiotracer methods. The effect on the geological record, however, is likely to be small. Chlorophyll-containing particles are at first very evenly distributed on the seafloor. After partial decomposition and resuspension, a secondary redistribution of particles occurs which can result in the formation of a high accumulation area, with an up to 80-fold increase in the sedimentation rate by lateral advection. This is mainly due to physical processes, because biodeposition mediated by benthic animals increases sedimentation by only a factor of two or three.