ALBERT

Description: Foraging rate was highly variable among shore crabs of the same size category and for individual crabs from day to day. Possible physiological reasons for this variability are discussed. Shore crab foraging rate, both in terms of mussels eaten per day and energy intake per day, was estimated to be higher at 17°C than at 10°C. The shape of diet curves and their mode for male shore crabs at 17°C closely resembled those for 10°C, indicating that the temperature increase had no effect on their previously demonstrated optimal foraging strategy. Female and certain male shore crabs showed a preference for prey smaller than for other equivalent sized males. These suboptimally feeding male and female crabs attained a relatively higher prédation rate (mussels day‐1), although their energy intake (KJ day‐1) remained lower than that of optimally feeding males. Preferred mussel size, number of mussels eaten per day and energy intake were strongly related to master chela height. The diet curves for female and suboptimally feeding male shore crabs could be explained by these crabs’ proportionately smaller master chelae.

Description: The rate of reaction of OH with CS2 to form OCS by reaction (1) has been measured through observation of O14CS following 254 nm equation image photolysis of mixtures of H2O2 with 14CS2. The OH concentrations have been monitored through simultaneous measurement in the same cell of either (a) the oxidation of CO to CO2, or (b) the removal of a hydrocarbon such as C3H8 or iso-C4H10. The upper limit for the formation of OCS based on (a) corresponds to a rate constant k1 〈 0.3 × 10−14 cm³ molecule−1 sec−1. Other chemical reactions in the system have led to the formation of both 14CO and 14CO2, indicating the existence of a complex combination of reactions such that the observed O14CS need not have been formed by (1). The rate of reaction (1) is sufficiently slow that it is neither an important atmospheric sink for CS2 nor an important source for atmospheric OCS. The reaction of OH with OCS has not been measured in these experiments, but by analogy with k1 it is probably not an important atmospheric sink for OCS nor an important source of SO2.

Description: Meiobenthos densities and higher taxon composition were studied in an active gas seepage area at depths from 182 to 252 m in the submarine Dnieper Canyon located in the northwestern part of the Black Sea. The meiobenthos was represented by Ciliata, Foraminifera, Nematoda, Polychaeta, Bivalvia, Gastropoda, Amphipoda, and Acarina. Also present in the sediment samples were juvenile stages of Copepoda and Cladocera which may be of planktonic origin. Nematoda and Foraminifera were the dominant groups. The abundance of the meiobenthos varied between 2397 and 52,593 ind.·m−2. Maximum densities of Nematoda and Foraminifera were recorded in the upper sediment layer of a permanent H2S zone at depths from 220 to 250 m. This dense concentration of meiobenthos was found in an area where intense methane seeps were covered by methane-oxidizing microbial mats. Results suggest that methane and its microbial oxidation products are the factors responsible for the presence of a highly sulfidic and biologically productive zone characterized by specially adapted benthic groups. At the same time, an inverse correlation was found between meiofauna densities and methane concentrations in the uppermost sediment layers. The hypothesis is that the concentration of Nematoda and Foraminifera within the areas enriched with methane is an ecological compromise between the food requirements of these organisms and their adaptations to the toxic H2S.

Description: Force chain buckling, leading to unjamming and shear banding, is examined quantitatively via a discrete element analysis of a two-dimensional, densely-packed, cohesionless granular assembly subject to quasistatic, boundary-driven biaxial compression. A range of properties associated with the confined buckling of force chains has been established, including: degree of buckling, buckling modes, spatial and strain evolution distributions, and relative contributions to non-affine deformation, dilatation and decrease in macroscopic shear strength and potential energy. Consecutive cycles of unjamming–jamming events, akin to slip–stick events arising in other granular systems, characterize the strain-softening regime and the shear band evolution. Peaks in the dissipation rate, kinetic energy and local non-affine strain are strongly correlated: the largest peaks coincide with each unjamming event that is evident in the concurrent drops in the macroscopic shear stress and potential energy. Unjamming nucleates from the buckling of a few force chains within a small region inside the band. A specific mode of force chain buckling, prevalent in and confined to the shear band, leads to above-average levels of local non-affine strain and release of potential energy during unjamming. Ongoing studies of this and other buckling modes from a structural stability standpoint serve as the basis for the formulation of internal variables and associated evolution laws, central to the development of thermomicromechanical constitutive theory for granular materials.

Description: A simple unified critical state constitutive model for bonded geomaterials is presented in this paper. The model, which is called CASM-n, is an enhancement of an existing unified critical state model for reconstituted geomaterials (CASM). Characteristic behaviours of a bonded geomaterial such as the pre-yield higher strength and stiffness and the cohesive–frictional shearing mode in the post-yield region are taken into account and included in the reference model. The salient feature of the proposed model is the incorporation of cohesive component into the stress–dilatancy relationship. Consideration of the contribution of cohesion to plastic flow allows the modelling of delayed dilatancy and softening–contraction behaviour, which are two interesting phenomena observed in bonded geomaterials.

Description: Diosmetin, 5,7,3′-trihydroxy-4′-methoxyflavone shows chemopreventive, antimutagenic, and antiallergic effects. On the other hand, chrysoeriol, 5,7,4′-trihydroxy-3′-methoxyflavone induced nodABC-lacZ in Rhizobium meliloti. Both of them belong to hydroxymethoxy- flavones. One major difference between diosmetin and chrysoeriol is the substituted position of hydroxyl and methoxyl groups. In order to elucidate the relationships between their structures and activity, one of the first things to be done is the determination of their structures. However, most flavones occur widely in nature, and thus it is difficult to obtain in sufficient amounts from natural sources to identify their structures. Assignments of NMR data of several hydroxymethoxyflavones may help us to identify novel flavonoid compounds isolated from natural sources based on their NMR experiments. Therefore, we report here the complete assignments of 1H and 13C NMR data of 13 hydroxymethoxyflavones.

Description: Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is a high spatial resolution analytical method which has been applied to the analysis of silicic tephras. With current instrumentation, around 30 trace elements can be determined from single glass shards as small as ∼ 40 µm, separated from tephra deposits. As a result of element fractionation during the ablation process using a 266 nm laser, a relatively complex calibration strategy is required. Nonetheless, such a strategy gives analyses which are accurate (typically within ±5%) and have an analytical precision which varies from ∼ ±2% at 100 ppm, to ∼ ±15% at 1 ppm. Detection limits for elements used in correlation and discrimination studies are well below 1 ppm. Examples of the application of trace element analysis by LA-ICP-MS in tephra studies are presented from the USA, New Zealand and the Mediterranean. Improvements in instrumental sensitivity in recent years have the potential to lower detection limits and improve analytical precision, thus allowing the analysis of smaller glass shards from more distal tephras. Laser systems operating at shorter wavelengths (e.g. 193 nm) are now more widely available, and produce a much more controllable ablation in glasses than 266 nm lasers. Crater sizes of 〈10 µm are easily achieved, and at 193 nm many of the elemental fractionation issues which mar longer wavelengths are overcome. By coupling a short wavelength laser to a modern ICP-MS it should be possible to determine the trace element composition of glass shards as small as 20 µm and, providing sample preparation issues can be overcome, the determination of the more abundant trace elements in glass shards as small as 10 µm is within instrumental capabilities. This will make it possible to chemically fingerprint tephra deposits which are far from their sources, and will greatly extend the range over which geochemical correlation of tephras can be undertaken.

Description: 18.2.80 - 23.2.80 - Auf diesen Fahrten sollten geologisch-geophysikalische Untersuchungen in der Mecklenburger Bucht und in der Kieler Bucht (Vejsnäs Flak), im Zuge einer Zusammenarbeit zwischen den Geologischen und Geophysikalischen Instituten durchgeführt werden. Ziel der Arbeiten ist die Vertiefung unserer Kenntnisse über die Oberflächensedimentverteilung und deren Zusammenhang mit der Struktur des glazialen, flachgrundigen Untergrundes. Dabei wurden auf die akustischen Eigenschaften der Oberflächensedimente besonders Wert gelegt. In Erweiterung des kombinierten Meßsystems, das auf früheren Fahrten ("Poseidon 40" Planet 5/79) erprobt worden ist, wurden auf dieser Fahrt zusätzliche geophysikalische Geräte eingesetzt.

Description: Tropical cyclones (TC) under different climate conditions in the Northern Hemisphere have been investigated with the Max Planck Institute (MPI) coupled (ECHAM5/MPI-OM) and atmosphere (ECHAM5) climate models. The intensity and size of the TC depend crucially on resolution with higher wind speed and smaller scales at the higher resolutions. The typical size of the TC is reduced by a factor of 2.3 from T63 to T319 using the distance of the maximum wind speed from the centre of the storm as a measure. The full three-dimensional structure of the storms becomes increasingly more realistic as the resolution is increased. For the T63 resolution, three ensemble runs are explored for the period 1860 until 2100 using the IPCC SRES scenario A1B and evaluated for three 30 yr periods at the end of the 19th, 20th and 21st century, respectively. While there is no significant change between the 19th and the 20th century, there is a considerable reduction in the number of the TC by some 20% in the 21st century, but no change in the number of the more intense storms. Reduction in the number of storms occurs in all regions. A single additional experiment at T213 resolution was run for the two latter 30-yr periods. The T213 is an atmospheric only experiment using the transient sea surface temperatures (SST) of the T63 resolution experiment. Also in this case, there is a reduction by some 10% in the number of simulated TC in the 21st century compared to the 20th century but a marked increase in the number of intense storms. The number of storms with maximum wind speeds greater than 50 m s−1 increases by a third. Most of the intensification takes place in the Eastern Pacific and in the Atlantic where also the number of storms more or less stays the same. We identify two competing processes effecting TC in a warmer climate. First, the increase in the static stability and the reduced vertical circulation is suggested to contribute to the reduction in the number of storms. Second, the increase in temperature and water vapour provide more energy for the storms so that when favourable conditions occur, the higher SST and higher specific humidity will contribute to more intense storms. As the maximum intensity depends crucially on resolution, this will require higher resolution to have its full effect. The distribution of storms between different regions does not, at first approximation, depend on the temperature itself but on the distribution of the SST anomalies and their influence on the atmospheric circulation. Two additional transient experiments at T319 resolution where run for 20 yr at the end of the 20th and 21st century, respectively, using the same conditions as in the T213 experiments. The results are consistent with the T213 study. The total number of TC were similar to the T213 experiment but were generally more intense. The change from the 20th to the 21st century was also similar with fewer TC in total but with more intense cyclones.

Description: The distribution of benthic foraminifera in Miocene deposits of the continental margin of southeastern South America is compared with that in the Recent. The comparison indicates that Miocene zoogeographic boundaries were located in higher latitudes than at present, suggesting that the climate at that time was warmer than now. In the Pliocene, temperatures were lower than at present. This signifies that a considerable decrease in water temperature took place in the latest Miocene or at the Miocene/Pliocene boundary in the southwestern Atlantic. The main reason for this drop in temperature was the opening of the Drake Passage and the establishment of the Circumpolar Antarctic Current and a branch — the Malvin Current. The opening resulted from strong orogenic movements, in the latest Miocene, which created the main part of the Andes. Prior to the opening of the passage, the anticyclonic (counterclockwise) gyre of surface currents in the South Atlantic was much larger and warm Brazilian waters reached higher latitudes. The Austral Strait, connecting the Pacific and Atlantic Oceans, may have existed from the Cretaceous in the southern part of South America, but its location and character did not permit the establishment of the true Circumpolar Antarctic Current. The Austral Strait was closed simultaneously with the opening of the Drake Passage.

Description: Natural communities are constantly changing due to a variety of interacting external processes and the temporal occurrence and intensity of these processes can have important implications for the diversity and structure of marine sessile assemblages. In this study, we investigated the effects of temporal variation in a disturbance regime, as well as the specific timing of events within different regimes, on the composition and diversity of marine subtidal fouling assemblages. We did this in a multi-factorial experiment using artificial settlement tiles deployed at two sites on the North East coast of England. We found that although there were significant effects of disturbances on the composition of assemblages, there were no effects of either the variation in the disturbance regime or the specific timing of events on the diversity or assemblage composition at either site. In contrast to recent implications we conclude that in marine fouling assemblages, the variability in disturbance regimes (as a driving force) is unimportant, while disturbance itself is an important force for structuring robust ecosystems.

Description: The measurements of dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) in seawater are key in global change and coastal eutrophication studies. Nowadays, the high-temperature combustion (HTC) technique is a widely used method for DOC and TDN analysis. However, uncertainties exist about the operation of the catalyst in the conversion process of DOC and TDN in the HTC method. In this study, five different 'catalyst' materials were tested for their blanks, calibration slopes, and conversion efficiency of DOC and TDN using the Shimadzu TOC 5000A total organic carbon analyser coupled to a Sievers NCD 255 nitrogen chemiluminescence detector. The materials included four metallic catalysts (Shimadzu and Johnson 0.5 Pt-alumina, 13 Cu(II)O-alumina, 0.5 Pd-alumina) and quartz beads. The results indicated that DOC blank signals for the HTC approach using metallic catalysts with an alumina support are higher compared with quartz beads, as a result of the amphoteric nature of the alumina. However, the slopes of the standard calibration graphs were lowest for DOC and TDN determinations on the quartz beads. The DOC recoveries for the metallic catalysts were close to 100 for all compounds tested, with the exception of ammonium pyrrolidine dithiocarbamate. Using quartz beads, poor recoveries were obtained for a range of organic compounds, including the commonly used calibration compounds potassium hydrogen phthalate and glycine. The TDN recoveries for all compounds were typically >90, with the exception of NaNO2. Furthermore, analysis using the CuO-alumina and Pd-alumina catalysts and quartz beads showed low recoveries for NH4Cl. This study showed that catalyst performance should be verified on a regular basis using model compounds and blank checks made during every run, and that the Shimadzu 0.5 Pt-alumina material was an efficient catalyst for DOC and TDN analyses using the coupled total organic carbon-nitrogen chemiluminescence detector (TOC-NCD) analyser. © 2007 Taylor & Francis.

Description: The annual cycle of sedimentation in Kiel Bight is described from data collected over 3 years with multisample sediment traps. Settling matter was collected from 2 depths (15 and 18 m) in a 20 m water column at 2-4 day intervals. The pattern of sedimentation was alike each year, although considerable differences in the quantity collected were present. Resuspended sediment and primary settling matter originating from the pelagic system (phytoplankton cells, detritus) were the main contributors to the particulate material collected by the traps. High sedimentation rates from November to March were due to resuspended sediment. The composition of this material differed from that of bulk surface sediment due to the selective effect of water movement during resuspension. Peaks in sedimentation of primary material were observed in spring and autumn when the pelagic food web is poorly developed. From May to August sedimentation rates were low although this is the period of high primary production with large standing stocks of plankton. Apparently, organic substance produced here is consumed within the pelagic food web, as herbivore and carnivore populations are well developed and turnover time of particles is short. Sedimentation rates of primary material are estimated to be in the range of 50-65 g C · m-2 · yr-', but in reality year to year differences are probably greater than indicated by this range.

Description: Data from two cross-shelf sediment sampling cruises were used to explain reasons for the sediment biogeochemical variability in respect of carbon, nitrogen and sulphur, and how the cycling of these elements governs the biogeochemistry of the overlying water through their control of the redox conditions. The spatial extent of this benthic–pelagic flux link is limited to the innershelf mud belt system on the Namibian shelf. The inshore mud belt is the primary deposition area of the carbon and nitrogen new production export flux. The offshore organic-rich zones are thought to be relict particulate organic matter originating from the inshore mud belt rather than from an overlying pelagic source. These data were used to set up a multi-layer sediment model that was used through sensitivity analyses to elucidate the input characteristics that result in the most significant feedbacks on hypoxia in the overlying water. The analyses showed that, although the new production flux is a requirement to drive an oxygen demand in the sediments, the onset and persistence of anoxia may depend critically on a low-oxygen boundary condition threshold. This is thought to be a key differentiating factor between systems that, despite comparable carbon export fluxes, are characterised by a persistent hypoxia/anoxia signal and those that are characterised by episodic hypoxia events. It was concluded that sediment oxygen demand and methane and 'sulphide' emissions from the central Benguela sediments are responses to external hypoxia boundary conditions rather than the local drivers of oxygen variability.

Description: The functional response of Sepia officinalis early stages, preying on mysids of the species Mesopodopsis slabberi was investigated. The effects of five prey densities (12.5, 25, 37.5, 50 and 125 mysids l−1) and two hatchling ages (1-day-old and 7-day-old) on consumption rate and the frequency of non-feeding animals were tested. Older animals were approximately 50% heavier than newly hatched ones. Hatchlings were individually assayed under 0.25 W m−2 natural light, 37.8 psu in salinity and 19°C. The effect of prey density on consumption rate was highly significant and no effect of age was detected within the age range tested. Maximal values recorded for consumption rate were about 0.45 mysids h−1. The frequency of non-feeding individuals was strongly reduced at saturating prey densities. The functional response curve showed an interval of prey densities for which density-dependent prey mortality is probable.

Description: We report data on the stomach contents of the long‐finned pilot whale, Globicephala melas, recovered from a group of whales stranded on Ruakaka Beach, northeastern New Zealand, in November 2006. In nine whales for which identifiable stomach contents were recovered (three that stranded on 10 November and six that stranded on 11 November) prey remains comprised exclusively cephalopod beaks attributed to five squid species. The stomachs of a further two whales contained unidentifiable upper beaks only, while the stomachs of five whales were completely empty. No whale appeared to have been satiated immediately before stranding, given that the maximum biomass of prey recently consumed by any one whale was calculated to be 〈5 kg. All squids ingested represented oceanic species, found from 50 to 1000 m but more common towards the deeper end of this range. These data both complement and contrast with the only other dietary information available for this species in New Zealand waters, reported from stomach contents of whales stranded on Farewell Spit, South Island in December 2005.

Description: Stomach contents of the long‐finned pilot whale, Globicephala melas, are reported for the first time from New Zealand waters. Analyses based on two male and three female whales (2.5–5.3 m in length) that stranded on Farewell Spit, Golden Bay, South Island in December 2005 revealed a diet comprised exclusively of cephalopods (2-33 lower cephalopod beaks per stomach). Two genera of cephalopod from two orders; arrow squid, Nototodarus spp. (Teuthoidea: Ommastrephidae), and common octopus, Pinnoctopus cordiformis (Octopoda: Octopodidae) were represented. A further five pilot whale stomachs were examined and found to be empty.