ALBERT

Description: The marine sedimentary record in Kejser Franz Joseph Fjord and on the East Greenland continental margin contains a history of Late Quaternary glaciation and sedimentation. Evidence suggests that a middle-shelf moraine represents the maximum shelfward extent of the Greenland Ice Sheet during the last glacial maximum. On the upper slope, coarse-grained sediments are derived from the release of significant quantities of iceberg-rafted debris (IRD) and subsequent remobilization by subaqueous mass-flows. The middle-lower slope is characterized by hemipelagic sedimentation with lower quantities of IRD (dropstone mud and sandy mud), punctuated episodically by deposition of diamicton and graded sand/gravel facies by subaqueous debris flows and turbidity currents derived from the mass failure of upper slope sediments. The downslope decrease of IRD reflects either the action of the East Greenland Current (EGC) confining icebergs to the upper slope, or to the more ice-proximal setting of the upper slope relative to the LGM ice margin. Sediment gravity flows on the slope are likely to have fed into the East Greenland channel system, contributing to its formation in conjunction with the cascade of dense brines down the slope following sea-ice formation across the shelf. Deglaciation commenced after 15,300 14C years, as indicated by meltwater-derived light oxygen isotope ratios. An abrupt decrease in both IRD deposition and delivery of coarse-grained debris to the slope at this time supports ice recession, with icebergs confined to the shelf by the EGC. Glacier ice had abandoned the middle shelf before 13,000 14C years with ice loss through iceberg calving and deposition of diamicton. Continued retreat of glacier-ice from the inner shelf and through the fjord is marked by a transition from subglacial till/bedrock in acoustic records, to ice-proximal meltwater-derived laminated mud to ice-distal bioturbated mud. Ice abandoned the inner shelf before 9100 14C years and probably stabilized in Fosters Bugt at 10,000 14C years. Distinct oxygen isotope minima on the inner shelf indicate meltwater production during ice retreat. The outer fjord was free of ice before 7440 14C years. Glacier retreat through the mid-outer fjord was punctuated by topographically-controlled stillstands where ice-proximal sediment was fed into fjord basins. The dominance of fine-grained, commonly laminated facies during deglaciation supports ablation-controlled, ice-mass loss. Glacimarine sedimentation within the Holocene middle-outer fjord system is dominated by sediment gravity flow and suspension settling from meltwater plumes. Suspension sediments comprise mainly mud facies indicating significant meltwater-deposition that overwhelms debris release from icebergs in this East Greenland fjord system. The relatively widespread occurrence of fine-grained lithofacies in East Greenland fjords suggests that meltwater sedimentation can be significant in polar glacimarine environments. The ice-distal continental margin is characterized by meltwater sedimentation in the inner shelf deep, iceberg scouring over shallow shelf regions, winnowing and erosion by the East Greenland Current on the middle-outer shelf, and hemipelagic sedimentation on the continental slope.

Description: Continental flood basalt (CFB) volcanism is hypothesized to have played a causative role in global climate change and mass extinctions. Uncertainties associated with radiometric dating preclude a clear chronological assessment of the environmental consequences of CFB volcanism. Our results document a 25% decline in the marine 187Os/188Os record that predates the Cretaceous-Tertiary boundary (KTB) and coincides with late Maastrichtian warming. We argue that this decline provides a chemostratigraphic marker of Deccan volcanism and thus constitutes compelling evidence that the main environmental consequence of Deccan volcanism was a transient global warming event of 3° to 5°C that is fully resolved from the KTB mass extinction.

Description: Predation pressure was examined for the epibenthic fauna of a intertidal seagrass bed of the Sylt-Rømø bight. Starting from the question for the dominant epibenthic prey and the intensity of predation pressure in seagrass habitats, we investigated a seegrasbed in the Sylt- Rømø bight. in sommer 2003. A predator enclosure experiment has been carried out in artificial tide pools of similar size, and a bait experiment were carried out in the surrounding seagrass bed. The most frequent epibenthic organisms within the intertidal seagrass beds consist of four dominant species: The brown shirmp (Crangon crangon, Linnaeus), the sand goby (Pomatoschitus microps, Krøyer), the isopode (Idotea balthica, Pallas) and the shore crab (Carcinus maenas, Linnaeus.). C. crangon showed an average annual abundance during high water of approximately 80 animals per m-2 (P.POL TE pers. Com.). Pomatoschistus microps and Carcinus maenas showed an average annual abundance of 7 animals m 2 and of 195 animals m-2. An abundance of 26 individuals m-2 was found for I. balthica (P.POLTE pers. Com.). As shown for the seagrass bed, C.crangon, P.microps and C.maenas were also the dominant forms in the tide pools. I. balthica could be found with 26 individuals m-2. The abundance of C. crangon were measured with an Annual average of 157 animals m-2 and therefore showed different results for the seagrassbeds. P. microps and C. maenas showed an average annual abundance of 15 animals m-2 and of 22 animals m-2 respectively. Mobile fauna migrates with the ebb tide into deeper waters (e.g. Pomatoschistus microps.) The substantially lower results of C. maenas within tide pools compared to adjacent seagrass beds can be partly explained by sampling time. In the seagrasbed sampling started earlier in the year (of May), and included the larval and juvenile stages of C. maenas. This led to a substantially higher abundance. Low abundance of I. balthica can be explained by its requirement for a structured habitat. I. balthica needs branched algal structures as a firm substrat. Such structures were hardly available in the tide pools...

Description: In Europe, increased attempts to intensify crayfish aquaculture have been carried out in recent years. Some of the major problems arising from the intensification are related to dietary supply of the animals in culture ponds and tanks. This study therefore focussed on some of the key objectives supporting the development of suitable diets for signal crayfish Pacifastacus leniusculus aquaculture. A large-scale response surface experiment was carried out to study the influences of different macronutrients (protein, lipid, carbohydrate) on crayfish growth and body composition. The results from this experiment led to the development of an improved experimental diet containing high levels of protein and carbohydrates, while increased lipid concentrations seemed to be influencing growth adversely. Further experiments were carried out to improve diet quality. For this purpose, diet types and the suitability of different binding agents were investigated. A small experiment was carried out to monitor the effects of attractants on growth of juvenile signal crayfish. A second objective of this study was the establishment of a new method to measure physiological responses of crayfish to different treatments. Running mid-term or long term experiments require high amounts of resources and slow down the process of dietary development. The measurement of RNA/DNA ratio has proven to be a suitable instrument to examine short-term metabolic responses to different key factors such as feeding regime, diet quality and digestibility and bioavailability of essential nutrients. The study has stressed the importance of proper diet preparation and composition for successful astaciculture. Binding agents were found to have major influence on diet digestibility and bioavailability of macronutrients. As another result of this study, further experiments are regarded to be necessary to examine the response of signal crayfish to different levels of lipid and protein in their diet. Some of the results obtained suggest a lack of regulatory capacity regarding the animals’ protein/lipid ratio. Further experiments however will have to be carried out to proof this hypothesis.

Description: In this study the mean tropospherical total zonal energy fluxes based on the NCEPNCAR reanalyses data are calculated for the time period 1948-2003. The interannual wintertime variability and the vertical structure of the fluxes are analysed. Since the dominant mode of atmospheric variability, the North Atlantic Oscillation, modulates the mean zonal current over the northern Atlantic region on monthly timescales, the NAO is expected to be the main cause for the interannual variability of energy fluxes. This study aims to analyse the linkage between this variabilty of zonal energy fluxes and the NAO. If the interannual variability of zonal energy transport directed to the european continent is associated with the NAO, the interannual energy flux variability can be referred to the variability of atmospheric circulation. In the first section, a climatology shows the three-dimensional structure of the mean zonal energy fluxes and its interannual seasonal standard deviations. In the second section, the dominant patterns of variability in various cross-sections parallel to the circles of longitude are obtained by EOF-analysis. The two leading EOF-patterns show barotropic structures, which in general agree in all sections. The 1.EOF explains more than 50% of the variance, the 2.EOF 25%. There exists however a significant correlation between the principle components only of the first EOFs of the western and eastern cross sections. The connection between zonal fl ux anomalies and the NAO yields a di polar correlationstructure, which is comparable to the correlation-pattern between the NAO and the zonal wind. The barotropic feature is predominant in each cross-section, moreover the regression-patterns show an eastward increasing tilt of the vertical axis towards north with a clear downward propagation of the northern center of activity from the middle troposphere to the lowest levels over Europe. It is shown that the NAO explains more than 30% of the total variance of interannual variability of the seasonal zonal energy fluxes, over the central Atlantic region even more than 40%, whereby anomalies reach up to 30% of the seasonal mean fluxes during extreme NAO-phases. Subsequently, flux anomalies associated with the Niño3-SST are analysed to clarify the dependence upon ENSO. In western parts of the Atlantic region, the Niño3-SST explains less than 5% of the variability of the zonal energy fluxes. Correlations between them are widely non significant in the analysed area. Nevertheless, strong El Niño events tend to cause stronger flux anomalies. In the last section, vertically integrated energy fluxes through the western and eastern boundary of the Atlantic region (represented as 60°W and 0°W longitudes) are computed. Fluctuations of the total energy flux through these sections are proved to be highly correlated with the NAO. The zonal convergence of flux anomalies between the boundaries show weak linkages to NAO, so that meridional atmospheric energy transport anomalies associated with NAO in the Atlantic region are assumed.

Description: The aim of this study is to examine the influence of both thermohaline and wind driven circulation changes on oceanic and atmospheric CO2-concentrations. For this the biopump three- and seven-box models of Toggweiler [1999] are integrated from an interglacial into a glacial steady state and vice versa. In contrast to previous studies which concentrated on steady state situations, here the focus is on transient CO2-concentrations after a sudden change in thermohaline and wind driven circulations. In addition timescales and amplitudes of atmospheric pC02-concentrations during the transition are compared to measurements of ice core datasets.

Description: Studies of animal populations are important and, in the case of harbour seals, have been considered particularly valuable as part of an assessment of the distemper epidemic that has plagued the northern Atlantic population over the last years. Head counts of seals by plane- or ship-based observers are biassed because these animals spent a large percentage of their time underwater. This study seeks to quantify the time that seals can be seen so that head counts can be appropriately corrected. Over the last two years 19 harbour seals were equipped with multiple channel loggers which recorded dive depth every 3-15 seconds for periods lasting up to two month. In this work the diving behaviour of 11 seals, from which the devices could be recovered, was analysed to examine how much time the animals spent at the water surface and on land where they can be counted and the extent to which this varied according to behaviour and water depth. Dives executed conformed broadly to either U- or V-shaped dives according to their profile of depth over time. During U-shaped dives, which comprised about 80% of all dives, the seals always apparently dived to the seabed. Both dive duration and surface duration changed systematically with maximum depth reached during the dive, both increasing: surface time as a cubed function of water depth and dive duration as a squared function of water depth. The percentage time that seals spent at the water surface where they can be seen could described by the equation: % time at surface = (21,55+0,00016( depth)3) / (21,55+0,00016(depth)3)+(156, 7+6,07(1n(depth)2) X 100 Implementation of this formula on seal-counting transects should help in calculations of seal density at sea and thus be useful in population assessments.

Description: Obwohl im terrestrischen Bereich die induzierte Verteidigung durch Herbivore weit verbreitet ist, sind nur wenige Beispiele für marine Makrophyten bekannt. In dieser Studie wurden in zwei Laborexperimenten die Effekte von 1. direktem Fraß durch Amphipoden und 2. wassergetragenen Signalen von Fraß an benachbarten Algen und 3. der Effekt eines benachbarten Konsumenten auf die Antifraßverteidigung von sieben bzw. vier Makroalgen der portugiesischen Südküste untersucht. Die Braunalge Fucus vesiculosus und die Rotalge Sphaerococcus coronopifolius wiesen nach einer Behandlungsphase von 14 Tagen mit drei Amphipodenarten als Konsumenten eine induzierte Verteidigung in intakten Algenstücken auf. Diese Verteidigung wurde innerhalb von zwei Wochen wieder herabgesetzt, nachdem der Fraßdruck reduziert wurde. Für F. vesicu/osus konnte weiter nachgewiesen werden, dass die Verteidigung teilweise auf den lipophilen Bestandteilen der Pflanze beruht. Außerdem konnte für beide Algenarten eine saisonale Variation in der Intensität des Auftretens der Verteidigungsinduktion beobachtet werden. Weiterhin konnte festgestellt werden, dass wassergetragene Signale von 1. benachbartem Fraß sowie 2. von einem benachbarten Konsumenten, der nicht fraß, eine Antifraßverteidigung auslösen. Diese Studie zeigt, dass nicht nur Braunalgen dazu in der Lage sind, auf die Signale von Herbivoren in kürzester Zeit - also innerhalb von 14 Tagen - zu reagieren, sondern dass dies auch bei Rotalgen der Fall sein kann. Nach unserem Wissen ist dies die erste Studie, die zeigt, dass bei Rotalgen eine Verteidigung durch direkten Fraß induziert werden kann und dass wassergetragene Signale von einem nicht fressenden Konsumenten ebenfalls eine Verteidigung auslösen. Hieran ist zu erkennen, dass induzierte Verteidigung durch direkten Fraß wie auch durch wassergetragene Signale in marinen Makrophyten eine größere ökologische Relevanz spielt, als bisher angenommen wurde.