Physical properties and neutron texture measuerments of deep-sea carbonates of DSDP Holes 62-463 and 62-465A

In weakly indurated, nannofossil-rich, deep-sea carbonates compressional wave velocity is up to twice as fast parallel to bedding than normal to it. It has been suggested that this anisotropy is due to alignment of calcite c-axes perpendicular to the shields of coccoliths and shield deposition parallel to bedding. This hypothesis was tested by measuring the preferred orientation (fabric) of calcite c-axes in acoustic anisotropic, calcareous DSDP sediment samples by X-ray goniometry, and it was found that the maximum c-axis concentrations are by far too low to explain the anisotropies. The X-ray method is subject to a number of uncertainties due to preparatory and technical shortcomings in weakly indurated rocks. The most serious weaknesses are: sample preparation, volume of measured sample (fraction of a mm3), beam defocusing and background intensity corrections, combination of incomplete pole figures, and necessity of recalculation of the c-axis orientations from other crystallographic directions. Goniometry using thermal neutrons overcomes most of these difficulties, but it is time consuming. We test the interferences made about velocity anisotropy by X-ray studies about the concentration of c-axes in deep-sea carbonates by employing neutron texture goniometry to eight DSDP samples comprising mostly nannofossil material. Fabric and sonic velocity were determined directly on the core specimens, thus from the same rock volume and requiring no preparation. The c-axis orientation is obtained directly from the [0006] calcite diffraction peak without corrections. The fabrics are clearly defined, but weak (1.1 to 1.86 times uniform) with the maximum about normal to bedding. They have crudely orthorhombic symmetry, but are not axisymmetric around the bedding normal. The observed c-axis intensities, although higher than determined by the X-ray method on other samples, are by far too low to explain the observed acoustic anisotropies.

Impact of thermal stress on evolutionary trajectories of pathogen resistance in three-spined stickleback (Gasterosteus aculeatus), supplementary material

Background: Pathogens are a major regulatory force for host populations, especially under stressful conditions. Elevated temperatures may enhance the development of pathogens, increase the number of transmission stages, and can negatively influence host susceptibility depending on host thermal tolerance. As a net result, this can lead to a higher prevalence of epidemics during summer months. These conditions also apply to marine ecosystems, where possible ecological impacts and the population-specific potential for evolutionary responses to changing environments and increasing disease prevalence are, however, less known. Therefore, we investigated the influence of thermal stress on the evolutionary trajectories of disease resistance in three marine populations of three-spined sticklebacks Gasterosteus aculeatus by combining the effects of elevated temperature and infection with a bacterial strain of Vibrio sp. using a common garden experiment. Results: We found that thermal stress had an impact on fish weight and especially on survival after infection after only short periods of thermal acclimation. Environmental stress reduced genetic differentiation (QST) between populations by releasing cryptic within-population variation. While life history traits displayed positive genetic correlations across environments with relatively weak genotype by environment interactions (GxE), environmental stress led to negative genetic correlations across environments in pathogen resistance. This reversal of genetic effects governing resistance is probably attributable to changing environment-dependent virulence mechanisms of the pathogen interacting differently with host genotypes, i.e. GPathogenxGHostxE or (GPathogenxE)x(GHostxE) interactions, rather than to pure host genetic effects, i.e. GHostxE interactions. Conclusion: To cope with climatic changes and the associated increase in pathogen virulence, host species require wide thermal tolerances and pathogen-resistant genotypes. The higher resistance we found for some families at elevated temperatures showed that there is evolutionary potential for resistance to Vibrio sp. in both thermal environments. The negative genetic correlation of pathogen resistance between thermal environments, on the other hand, indicates that adaptation to current conditions can be a weak predictor for performance in changing environments. The observed feedback on selective gradients exerted on life history traits may exacerbate this effect, as it can also modify the response to selection for other vital components of fitness.

Regional geoid model for the area of the subglacial Lake Vostok

We present a regional geoid model for the area of Lake Vostok, Antarctica, from a combination of local airborne gravity, ice-surface and ice-thickness data and a lake bathymetry model. The topography data are used for residual terrain modelling (RTM) in a remove-compute-restore approach together with the GOCE satellite model GOCO03S. The disturbing potential at the Earth's surface, i.e. the quasigeoid, is predicted by least-squares collocation (LSC) and subsequently converted to geoid heights. Compared to GOCO03S our regional solution provides an additional short-wavelength signal of up to 1.48 m, or 0.56 m standard deviation, respectively. More details can be found in Schwabe et. al (2014).

AMS and EBSD maps of rock salt - lamprophyre dyke contact zone, Loule diapir, Algarve basin, Portugal

A rock salt-lamprophyre dyke contact zone (sub-vertical, NE-SW strike) was investigated for its petrographic, mechanic and physical properties by means of anisotropy of magnetic susceptibility (AMS) and rock magnetic properties, coupled with quantitative microstructural analysis and thermal mathematical modelling. The quantitative microstructural analysis of halite texture and solid inclusions revealed good spatial correlation with AMS and halite fabrics. The fabrics of both lamprophyre and rock salt record the magmatic intrusion, "plastic" flow and regional deformation (characterized by a NW-SE trending steep foliation). AMS and microstructural analysis revealed two deformation fabrics in the rock salt: (1) the deformation fabrics in rock salt on the NW side of the dyke are associated with high temperature and high fluid activity attributed to the dyke emplacement; (2) On the opposite side of the dyke, the emplacement-related fabric is reworked by localized tectonic deformation. The paleomagnetic results suggest significant rotation of the whole dyke, probably during the diapir ascent and/or the regional Tertiary to Quaternary deformation.

Tough as a rock-boring urchin: adult Echinometra sp. EE from the Red Sea show high resistance to ocean acidification over long-term exposures

Ocean acidification, a process caused by the continuous rise of atmospheric CO2 levels, is expected to have a profound impact on marine invertebrates. Findings of the numerous studies conducted in this field indicate high variability in species responses to future ocean conditions. This study aimed at understanding the effects of long-term exposure to elevated pCO2 conditions on the performance of adult Echinometra sp. EE from the Gulf of Aqaba (Red Sea). During an 11-month incubation under high pCO2 (1,433 µatm, pHNBS 7.7) and control (435 µatm, pHNBS 8.1) conditions, we examined the urchins' somatic and gonadal growth, gametogenesis and skeletal microstructure. Somatic and gonadal growths were exhibited with no significant differences between the treatments. In addition, all urchins in the experiment completed a full reproductive cycle, typical of natural populations, with no detectable impact of increased pCO2 on the timing, duration or progression of the cycle. Furthermore, scanning electron microscopy imaging of urchin tests and spines revealed no signs of the usual observed effects of acidosis, such as skeletal dissolution, widened stereom pores or non-smoothed structures. Our results, which yielded no significant impact of the high pCO2 treatment on any of the examined processes in the urchins studied, suggest high resistance of adult Echinometra sp. EE to near future ocean acidification conditions. With respect to other findings in this area, the outcome of this study provides an example of the complicated and diverse responses of echinoids to the predicted environmental changes.

Table 2: Firn temperature, ram resistance, mass balance and submergence velo city measurements on Colle Gnifetti

Distributional patterns of glaciological parameters at the Colle Gnifetti core drilling site are described and their interrelationships are brietly discussed. Observations within a stake network established in 1980 furnish information about snow accumulation (short term balance), submergence velocity of ice tlow (long term balance), ram hardness (melt layer stratigraphy), and firn temperature. In addition, a numerical model was used to estimate local variations of available radiant energy. Melt layer formation is considerably more intensive on the south facing parts of the firn saddie where incoming radiation is high. These melt layers seem to effectively protect some of the fallen snow from wind erosion. As a result, balance ist up to one order of magnitude larger on south facing slopes. Heat applied to the surface is therefore positively correlated with balance, whereas the relation between solar radiation and firn temperature is less dear. Distributional patterns of submergence velocity confirm that the observed spatial variability of surface balance is representative for longer time periods and greatly intluences the time scale and the stratigraphy of firn and ice cores from Colle Gnifetti.