ALBERT

Description: The underlying basis for Mg/Ca paleothermometry is that the amount of magnesium in calcite precipitated from seawater is dependent on temperature. Here we review the state of the art of the Mg/Ca seawater paleotemperature proxy, summarized by the following: 1) Calcite, whether formed abiotically or biologically as foraminifera and ostracode shells, incörporates variable amounts of magnesium into the crystal structure. 2) Uptake of Mg varies positively with temperature. 3) The relationship between temperature and the amount of Mg in calcite has been quantified by experiments on synthetic calcite growth and by culture, core top, and sediment trap experiments using living organisms. 4) The most careful calibrations of the Mg/Ca paleothermometer have been done for planktic foraminifera, then benthic foraminifera; there are species-specific variations in the amount of Mg incorporated into foraminifera shells. 5) The Mg/Ca ratio of calcite from planktic foraminifera in deep-sea cores has been widely used to interpret sea surface temperatures. 6) Measurement of both Mg/Ca and δ18O in planktic foraminifera have been used to calculate δ18O in seawater, and after correction for global ice volume, salinity could be inferred. 7) Mg/Ca from benthic foraminifera have been used to reconstruct deep-sea temperatures and cooling of ~12°C over the last 50 million years. 8) One problem with the Mg/Ca seawater temperature proxy is partial dissolution of. foraminifer shells, which lowers the Mg/Ca, and leads to an underestimation of ocean temperature. Benthic foraminifers appear to be more resistant to partial dissolution. 9) Past changes in the Mg/Ca ratio of seawater are an important factor in determining the amount of Mg in fossil skeletal calcite, and thus add another variable to the Mg/Ca temperature proxy. All Mg/Ca paleotemperature studies on fossil calcite older than Pleistocene should take into account the Mg/Ca of the seawater from which it precipitated.

Description: The scleractinian coral Lophelia pertusa (Caryophylliidae) is the most common frameworkforming cold-water coral with a global distribution. L. pertusa bioherms are hot-spots of biodiversity because their three-dimensional framework provides niches and nursery grounds for a variety of species, including commercially important fish species. In contrast to shallowwater corals from the tropics, very little is known about the ecophysiology of cold-water corals such as L. pertusa and their sensitivity towards climate change. The present study intends to start filling this knowledge gap by examining a variety of L. pertusa’s ecophysiological responses (e.g. food uptake, respiration, growth, fitness, behaviour) under present-day (in the following referred as “ambient”) and experimentally manipulated environmental conditions. Living specimens of L. pertusa from two Norwegian cold-water coral locations (Oslofjord and Sula Reef Complex) were collected during two research cruises with the aid of the manned submersible JAGO and transferred into a newly established closed recirculating system at IFM-GEOMAR. Long-term analyses (〉3 years) of dissolved inorganic nutrients revealed the high tolerance of L. pertusa to rising concentrations of nitrate and phosphate. However, for the main toxic compound - ammonium - it could be demonstrated that the corals’ polyp behaviour alters if concentrations are increased to 〉 17 μmol L-1. Food availability is thought to be one of the most important factors determining cold-water coral distribution and growth. This study provides feeding rates for three live food organisms encompassing different sizes and qualities. It also describes the food uptake mechanism for mesozooplankton based on the first video documentation of the whole feeding process. The effect of rising temperatures (ocean warming) on the oxygen consumption, fitness, and behaviour was investigated through a combination of short-term and long-term aquarium experiments. This study shows that at ambient conditions of 7.5 °C L. pertusa exhibits low respiration rates of ~ 0.3 μmol O2 g-1 h-1 which may increase up to 58 % after a relatively small temperature change (+ 3.5 °C). High Q10 values of 3.7 ± 0.7 in these corals and significantly depressed RNA/DNA ratios in coral polyps maintained for 2 weeks under elevated temperatures (11°C) revealed that L. pertusa is sensitive to small temperature changes even though analyses of their behaviour may suggest some acclimatisation. L. pertusa exhibits relatively low bulk calcification rates that vary over time and applied measurement methods. On average calcification amounts to 8.7 x 10-3 % d-1 which is intermediate in the broad range of reported L. pertusa growth rates. Interestingly, corals fed under nearby ad libitum conditions showed no relationship between food quality/quantity and growth. This indicates a degree of regulation in the feeding mechanism and may suggest that calcification is rather dependent on a basic metabolic rate than on specific food supply. The impact of increasing concentrations of CO2 (ocean acidification) on L. pertusa growth rates and fitness was examined in a short-term (one week) and a long-term (8 months) experiment. This study shows for the first time that - when kept under long-term exposure to elevated CO2 levels - L. pertusa is capable to compensate for adverse effects as experienced during short-term incubations. Net growth is sustained even in waters undersaturated with respect to aragonite (ΩAr 〈 1). These results suggest that cold-water coral reefs, the majority of which will be exposed to undersaturated waters before the end of this century, may not suffer immediate wide-spread extinction as previously projected. However, the fact that even a temperature increase of about 3 °C seems to be of higher relevance in respect to fitness than a doubling of the pCO2 emphasises the problem of synergistic impacts between ocean warming and ocean acidification and the need for further long-term incubation experiments.

Description: In der vorliegenden Arbeit wird - basierend auf externmorphologischen Kriterien von Brachiopodengehäusen aus dem spongiolithischen süddeutschen Oberjura - eine ökologische Interpretation von Brachiopodenassoziationen vorgestellt und diese mit nicht verschwammten Vorkommen unter Verwendung verschiedener methodischer Ansätze verglichen. Aus insgesamt elf brachiopodenführenden Lokalitäten unterschiedlicher stratigraphischer und fazieller Niveaus wurden die generell bevorzugt auftretenden Wuchsformen ermittelt, zu Standardmorphotypen zusammengefaßt und mit digitalisierten Abbildungen aus vorhergehenden Bearbeitungen ökologisch verglichen. [ …] [ … Tabelle 1. Stratigraphie, Fazies und dominierende Externmorphologie der Brachiopodengehäuse (Standardmorphotyp) in den untersuchten Lokalitäten.] Die Analysen ergaben, daß mit Hilfe des Verlaufs der dorsalen Umrißlinie, dem Verlauf der Frontalkommissur und untergeordnet der Foramengröße eine hinreichende Interpretation des Environments hinsichtlich Substratbeschaffenheit, Hydrodynamik und Bathymetrie erfolgen kann. Die wichtigsten Ergebnisse sind: a) Die Brachiopoden der süddeutschen Spongiolithfazies zeigen im Vergleich mit je einer Fauna aus einer schwach verschwammten Schichtfazies, einer Korallenfazies und einer oolithischen Mergelkalkfazies grundlegende Unterschiede in der äußeren Morphologie ihrer Gehäuse, b) In mergeldominierten Lokalitäten sind die Sphärizitätsindizes der Gehäuse deutlich höher als in der Korallenfazies, c) Reduzierte Werte des Dicken / Breiten - Verhältnisses scheinen ein Indiz für weichere Substrate zu sein, d) Im zeitlichen Verlauf (Oxfordium bis Unter-Tithonium) nehmen die Werte der Sphärizitätsindizes der Brachiopodengehäuse ab. e) Die Amplituden der Frontalkommissuren von Brachiopoden aus dem Moundbereich sind höher als diejenigen aus der Korallenfazies, f) Das Mengenverhältnis von terebratuliden zu rhynchonelliden Brachiopoden läßt Rückschlüsse auf das dominierende Substrat in den Moundbereichen zu. Ein quantitatives Übergewicht rhynchonellider Brachiopoden geht mit einem mergelreichen, stillen Tieferwasserenvironment einher, während die kalkdominierten Flachwasserbereiche mit erhöhter Hydrodynamik bevorzugt von Terebratuliden besiedelt werden, g) Untergeordnet wird ein Substratwechsel durch die Foramengröße und -position angezeigt. Große mesothyridide Foramina kennzeichnen meist Festsubstrate. Kleine hypothyridide Foramina sind eher für allomikritische Bereiche charakteristisch, h) Brachiopoden der koralligenen Fauna zeichnen sich durch Asymmetrien der Frontalkommissur (Rhynchonellida) und Asymmetrien in der dorsalen Umrißlinie aus (Terebratulida). Die artikulaten Brachiopoden aus den untersuchten „Riff-Ablagerungen scheinen hinsichtlich ihrer Morphologie und faunistischen Komposition von den kontrollierenden Bildungsfaktoren (besonders Sedimentationsrate, Substratbeschaffenheit und Hydrodynamik) der Schwamm- und Korallenassoziationen, beeinflußt worden zu sein. Die in den jeweiligen Aufschlüssen dominierenden Brachiopoden-Morphotypen reflektieren wenigstens statistisch die Bildungsbedingungen.

Description: Data on brachiopods in spongolites from the Upper Jurassic of southern Germany were collected in order to establish associations based on paleoenvironmental parameters and compare these results to similar fauna across a range of depositional paleoenvironments. Fossils were sampled and their dominant growth morphotypes identified from 11 localities representing different ages and facies of the Upper Jurassic in the Franconian and Swabian Alb. These growth morphotypes were compared to standard morphotypes and to biometric data of modern brachiopods gleaned from the literature. Through statistical analysis, it was found that the mode of commissure line and in part the diameter of the foraminae correlate well with substrate types and hydrodynamic to bathymetric paleoconditions. General results include: a) the external morphology of brachiopods from spongolites is significantly different from that of brachiopods from well-bedded limestone containing few to no sponges but corals and oolites, b) within a mostly marl substrate, the sphericity index of brachiopod shells is much larger than for shells in coral-bearing rocks, c) width to length ratios of shells are less for softer substrates indicating possible use as an index for substrate consistency, d) from the Lower Oxfordian to the Tithonian, the sphericity index of shells in general decreases, e) amplitudes of the frontal commissure line of brachiopods found within spongolite build-ups are much larger than those from coral-bearing rocks, f) Terebratulidae to Rhynchonellida biometric relations may be used as an index for judging the “quality” of the paleoenvironment; rhynchonellid brachiopods were dominantly found in marly, deeper paleoenvironments, whereas carbonate sediments deposited under shallow, high energy, water paleoconditions were colonized by terebratulid brachiopods, g) the size and position of foraminae are linked to the substrate type; brachiopods with larger mesothyrid foraminae are found associated with hard substrates while smaller hypothyrid foraminae in soft carbonate sediment areas, h) brachiopods from coral rocks are characterized by their asymmetric growth in form (Terebratulida) and of their frontal commissure (Rhychonellida). In general, brachiopods from reefal deposits appeared to have been directly influenced morphologically by paleoecologic factors, such as sedimentation rate, substrate type, and water energy levels. The dominant standard morphotype of brachiopods appears to correlate in a statistically significant way with the interpreted depositional circumstances at each locality. Due to here presented morphological data of brachiopodes from the Upper Jurassic of Southern Germany, associations of brachiopodes in spongiolites are interpreted palecologically and compared to similar faunae from other depositional environments. From 11 localities of different stratigraphical age and facies in the Franconian and Swabian Alb the dominant growth morphotypes are presented and abstracted to so-called „standard morphotypes“. The latter are compared to biometrical data of modern brachiopodes, mainly extracted from literature data. Interpreting the mathematical analyses it can be concluded that the dorsal outline, the mode of commissur line and partially the diameter of the foraminae can be used as indicator of substrates, hydrodynamical and paleobathymetrical conditions. The main results are: a) External morphology of brachiopodes from spongiolites exhibits strong differences in contrast to brachiopodes from well-bedded limestones with few or no sponges, to coral-bearing strata and to oolithic limestones, b) In localities, where marls have been predominantly deposited, the sphericity index is much larger than in the coral-bearing rocks, c) Reduced relations of width and length can be tentatively used as index for soft substrates, d) From the Lower Oxfordian to the Tithonian the sphericity index becomes smaller, e) Amplitudes of the frontal commissur line from brachiopodes of spongiolitic buildups are much higher than from brachiopodes in coral-bearing rocks, f) Quantitative relations from Terebratulidae to Rhynchonellida can be used as index for quality of substrates. Rhynchonellid brachiopodes are dominating marly, deeper environments, whereas carbona-tic sediments deposited under shallow water conditions with higher water energy are dominated by terebratulid brachiopodes. g) Changes of substrates are indicated by the size and position of foraminae. Larger mesothyrid foraminae characterize hard substrates, smaller hypothyrid foraminae are typically developed in allomicritic areas, h) Brachiopodes from coralligene rocks are characterized by their asymmetrical growth of form (Terebratulida) and of their frontal commissure (Rhynchonellida). Generally, brachiopodes from reefal deposits have been influenced morphologically by ecologically controlling factors such as the sedimentation rate, the substrate, and the water energy levels. The dominating standard morphotypes of brachiopodes in each locality reflect at least statistically the former depositional environments. (Translation: Dr. Elizabeth H. Gierlowski-Kordesch, Department of Geological Sciences, Ohio University)

Description: thesis

Description: DFG, SUB Göttingen

Description: research

Description: research

Description: research

Description: Scientists have long attempted to explain why closely similar age patterns of death are characteristic of highly diverse human and nonhuman populations. Historical efforts to identify a general "law of mortality" from these patterns that applied across species ended in 1935 when it was declared that such a law did not exist. These early efforts were conducted using mortality curves based on all causes of death. The authors predict that if comparisons of mortality are based instead on "intrinsic" causes of death (i.e., deaths that reflect the basic biology of the organism), then age patterns of mortality consistent with the historical concept of a law might be revealed. Using data on laboratory animals and humans, they demonstrate that age patterns of intrinsic mortality overlap when graphed on a biologically comparable time scale. These results are consistent with the existence of a law of mortality following sexual maturity, as originally asserted by Benjamin Gompertz and Raymond Pearl. The societal, medical, and research implications of such a law are discussed.

Description: We present a detailed field and petrological study of charnockites and ultra-high temperature (UHT) granulites from the Gruf Complex, eastern Central Alps. Charnockites occur as up to 0.5 km wide and 8 km long, internally boudinaged, opx-bearing sheet-like bodies within the regionally dominant migmatitic biotite-orthogneisses. Granulites occur as garnet–orthopyroxene–biotite–alkali feldspar-bearing schlieren (± sapphirine, sillimanite, cordierite, corundum, spinel, plagioclase, and quartz) within charnockites and as residual enclaves both in the charnockites and the migmatitic orthogneisses. Thermobarometric calculations, P–T pseudosections and orthopyroxene Al content, show that both charnockites and granulites equilibrated at metamorphic peak conditions of T = 920–940 °C and P = 8.5–9.5 kbar. Peak assemblages were subsequently overprinted by intergrowth, symplectite and corona textures involving orthopyroxene, sapphirine, cordierite and spinel at T = 720–740 °C and P = 7–7.5 kbar. We suggest that granulites and charnockites are lower crustal relicts preserved in the migmatitic orthogneisses. Garnet diffusion modelling shows that metamorphic garnet–opx ± sapphirine ± sillimanite peak assemblages and post-peak reaction textures always involving cordierite developed during two separate metamorphic cycles. Peak assemblages reflect UHT metamorphism related to post-Varican Permian extension, but post-peak coronae and symplectites formed during the mid-Tertiary, upper amphibolite facies, Alpine regional metamorphism. Fluid-absent partial melting of pelitic and psammitic sediments during the Permian UHT event lead to the formation of charnockitic magmas and granulitic residues. Intense melt loss and thorough dehydration of the granulites (although retaining biotite) favoured the partial preservation of peak mineral assemblages during Alpine metamorphism.

Description: The ‘law of the wall’ for the inner part of a turbulent shear flow over a solid surface is one of the cornerstones of fluid dynamics, and one of the very few pieces of turbulence theory whose results include a simple analytic function for the mean velocity distribution, the logarithmic law. Various aspects of the law have recently been questioned, and this paper is a summary of the present position. Although the law of the wall for velocity has apparently been confirmed by experiment well outside its original range, the law of the wall for temperature seems to apply only to very simple flows. Since the two laws are derived by closely analogous arguments this throws suspicion on the law of the wall for velocity. Analysis of simulation data, for all the Reynolds stresses including the shear stress, shows that law-of-the-wall scaling fails spectacularly in the viscous wall region, even when the logarithmic law is relatively well behaved. Virtually all turbulence models are calibrated to reproduce the law of the wall in simple flows, and we discuss whether, in practice or in principle, their range of validity is larger than that of the law of the wall itself: the present answer is that it is not; so that when the law of the wall (or the mixing-length formula) fails, current Reynolds-averaged turbulence models are likely to fail too.

Description: This paper describes a Bayesian inversion of acoustic reflection loss versus angle measurements to estimate the compressional and shear wave velocities in young uppermost oceanic crust, Layer 2A. The data were obtained in an experiment on the thinly sedimented western flank of the Endeavor segment of the Juan de Fuca Ridge, using a towed horizontal hydrophone array and small explosive charges as sound sources. Measurements were made at three sites at increasing distance from the ridge spreading center to determine the effect of age of the crust on seismic velocities. The inversion used reflection loss data in a 1/3-octave band centered at 16 Hz. The compressional and shear wave velocities of the basalt were highly sensitive parameters in the inversion. The compressional wave velocity increased from 2547±30 to 2710±18 m/s over an age span of 1.4 million years (Ma) from the spreading center, an increase of 4.5±1.0%/Ma. The basalt shear wave velocity increased by nearly a factor of 2, from ∼725 to 1320 m/s over the same age span. These results show a decreasing trend of Poisson’s ratio with age, from a value of 0.46 at the youngest site closest to the ridge axis.