Palaeobiology, ecology, and distribution of stromatoporoid faunas in biostromes of the mid-Ludlow of Gotland

Six well exposed mid−Ludlow stromatoporoid−dominated reef biostromes in four localities from the Hemse Group in southeastern Gotland, Sweden comprise a stromatoporoid assemblage dominated by four species; Clathrodictyon mohicanum, “Stromatopora” bekkeri, Plectostroma scaniense, and Lophiostroma schmidtii. All biostromes investigated in this area (of approximately 30 km2) are interpreted to belong to a single faunal assemblage forming a dense accumulation of fossils that is probably the best exposed stromatoporoid−rich deposit of the Silurian. The results from this comprehensive study strengthen earlier interpretations of a combination of genetic and environmental control on growth−forms of the stromatoporoids. Growth styles are similar for stromatoporoids in all six biostromes. Differences in biostrome fabric are due to variations in the degree of disturbance by storms. The uniformity of facies and the widespread low−diversity fauna support the view that palaeoenvironmental conditions were similar across the area where these biostromes crop out, and promoted the extraordinary growth of stromatoporoids in this shallow shelf area

Beef and cone-in-cone calcite fibrous cements associated with the end-Permian and end-Triassic mass extinctions: Reassessment of processes of formation

This paper is a contribution to IGCP630.This paper reassesses published interpretation that beef and cone-in-cone (B-CIC) fibrous calcite cement were precipitated contemporaneously just below the sea floor in unconsolidated sediment, in limestones associated with the end-Permian (P/T) and end-Triassic (T/J) mass extinctions. That interpretation introduced the concept of a sub-seafloor carbonate factory associated with ocean acidification by raised carbon dioxide driven by volcanic eruption, coinciding with mass extinction. However, our new fieldwork and petrographic analysis, with literature comparison, reveals several problems with this concept. Two key points based on evidence in the T/J transition of UK are: A) that B-CIC calcite deposits form thin scattered layers and lenses at several horizons, not a distinct deposit associated with volcanic activity; B) B-CIC calcite is more common in Early Jurassic sediments after the extinction and after the end of the Central Atlantic Magmatic Province volcanism proposd to have supplied the carbon dioxide required. Our samples from Late Triassic, Early Jurassic and Early Cretaceous limestones in southern UK show that B-CIC calcite occurs in both marine and non-marine sediments, therefore ocean processes are not mandatory for its formation. There is no proof that fibrous calcite was formed before lithification, but our Early Jurassic samples do prove fibrous calcite formed after compaction, thus interpretation of crystal growth in unconsolidated sediment is problematic. Furthermore, B-CIC crystals mostly grew both upwards and downwards equally, contradicting the interpretation of the novel carbonate factory that they grew preferentially upwards in soft sediment. Finally, Early Jurassic and Early Cretaceous examples are not associated with mass extinction. Three further key points derived from literature include: A) B-CIC calcite is widespread geographically and stratigraphically, not clustered around mass extinctions or the PETM event; B) isotope signatures suggest BCIC calcite formed under high pressure in burial at 70-120 oC, incompatible with interpretation of formation of B-CIC calcite at the redox boundary below the ocean floor; and C) B-CIC calcite reported in P/T boundary microbialites in one site in Iran is the only occurrence known despite extensive published studies of similar shallow marine settings, demonstrating its formation is localised to the Iran site. Based on the above evidence, our opinion is that B-CIC calcite is best explained as a later diagenetic feature unrelated to rapid Earth-surface environmental change associated with mass extinctions; thus a novel carbonate factory is highly unlikely

Quantitative chemical analysis of perovskite deposition using spin coating

Lead and halide ion compositions of spin coated organo-lead halide perovskite films have been quantified using ion chromatography (IC) and atomic absorption spectroscopy (AAS) using perovskite films manufactured by 5 different researchers (3 replicates per treatment) to monitor variability between researchers and individual researcher reproducibility. Planar and mesoporous TiO2-coated glass substrates have been studied along with tribromide (CH3NH3PbBr3), triiodide (CH3NH3PbI3) and mixed halide (CH3NH3PbI3�xClx) perovskite films. The data show low yields of spin coated perovskite material (ca. 1%) and preferential deposition of I� over Cl� in mixed halide films

Seasonal variation in harbour seal (Phoca vitulina) blubber cortisol - A novel indicator of physiological state?

The authors would also like to thank DRG International Inc. for their financial support that enabled the attendance of The European Cetacean Society Conference in 2012 where part of this work was presented. This work was partly supported by the National Capability Funding from the Natural Environment Research Council and by a School of Biology Class Grant.Cortisol is one of the main glucocorticoid hormones involved in both the mammalian stress response, and in fat metabolism and energy regulation, making it of increasing interest as a biomarker for stress, health and overall physiological state. However, transient stress responses to animal handling and sampling may be important sources of measurement artefact when investigating circulating concentrations of this hormone in wildlife. Here, cortisol concentrations were measured in the plasma and, for the first time, in the blubber of live captured adult harbour seals (Phoca vitulina). Plasma cortisol concentrations were positively correlated with capture time, suggesting that they were largely driven by a stress response to the capture event. In contrast, blubber cortisol concentrations were shown not to be significantly affected by capture time and varied significantly by sex and by season, with higher concentrations during natural fasting periods of their life cycle, particularly during the moult. These results suggest that cortisol may play a key role in increased fat metabolism during highly energetically demanding periods, and that blubber concentrations have the potential to be used as physiological state indicators in phocid seals.Publisher PDFPeer reviewe