Recovery of meiofauna communities following mudflat disturbance by trampling associated with crab-tiling

The provision of artificial shelters for the collection of crabs, known as crab-tiling, and the subsequent harvesting of the soft "peeler" crabs for angling bait, are associated with trampling disturbance of intertidal mudflats in the United Kingdom. Recovery of meiofauna communities following crab-tiling activity was investigated on an intertidal mudflat in SW England. Harvesting of experimental plots was reproduced six times over a 2-week period. Meiofauna was collected at low tides 12h, 36 h and 144 h after treatment. Meiofaunal and nematode abundance, and nematode species number, was significantly greater in controls compared to crab-tile stations at 12h. At 36 h and 144 h there were no significant differences between treatments, indicating recovery had occurred in 12-36 h. Multivariate analysis showed nematode assemblage composition from control plots to be significantly different from crab-tile plots at 12h. No significant differences were observed between sediment physical parameters with treatment. Results suggest that the predominant effect of disturbance may be vibration-induced burial, which causes nematodes to bury deeper into the sediment, beyond the depth sampled, and explains the rapid recovery.     

Potential impact of climate change and reindeer density on tundra indicator species in the Barents Sea region

Climate change is expected to alter the distribution of habitats and thus the distribution of species connected with these habitats in the terrestrial Barents Sea region. It was hypothesised that wild species connected with the tundra and open-land biome may be particularly at risk as forest area expands. Fourteen species of birds were identified as useful indicators for the biodiversity dependent upon this biome. By bringing together species distribution information with the LPJ-GUESS vegetation model, and with estimates of future wild and domestic reindeer density, potential impacts on these species between the present time and 2080 were assessed. Over this period there was a net loss of open land within the current breeding range of most bird species. Grazing reindeer were modelled as increasing the amount of open land retained for nine of the tundra bird species.     

A large collection of Presbyornis (Aves,Anseriformes, Presbyornithidae) from the late Paleocene and early Eocene of Mongolia

We describe a large collection of fossil ‘waterfowl’ bones that are referable to the extinct clade Presbyornithidae (Anseriformes). All of these fossils were collected between 1971 and 1994 from Upper Paleocene and Lower Eocene sediments at the Tsagaan Khushuu site in the Gobi Desert of southern Mongolia. The collection includes specimens referred to a new small species within the genus Presbyornis Wetmore, 1926 as well as large numbers of bones that we place in the genus Presbyornis. On this basis of the Tsagaan Khushuu collection we suggest that several species of Presbyornis likely coexisted in this region; indeed, the presence of large numbers of middle‐sized, morphologically consistent but probably ecologically disparate species at the Tsagaan Khushuu site is consistent with the range of variation seen, for example, in taxa of extant dabbling ducks (Anatini). Although the anatomy and phylogenetic position of Presbyornithidae (in particular Presbyornis) are well known, this material from Mongolia further demonstrates the prevalence of these birds in aquatic and semi‐aquatic habitats by the earliest Paleogene. Because presbyornithids are also well documented from the late Cretaceous, their palaeoecology and morphological diversity provides a clue to selective avian survivorship across the Cretaceous‐Paleogene (K‐Pg) boundary. Copyright © 2009 John Wiley & Sons, Ltd.     

A review of Late Cretaceous fossil birds from Hungary

We review the previously described Late Cretaceous (Santonian) bird remains from the Csehbánya Formation in the Bakony Mountains of Hungary, augmenting initial work by Ősi ( 2008 ), and add a number of newly collected fossils. All together, the eight fossil specimens so far collected from this site are important to our understanding of avian evolution because they document a large range of taxon body sizes from at least one major lineage (Enantiornithes) and come from a critically undersampled time period in the Cretaceous. Globally, very little fossil bird material has been collected from the middle stages of the Late Cretaceous, the Coniacian and Santonian; most known taxa are either Early Cretaceous (ca. 120 Ma) in age or are from the terminal Campanian and Maastrichtian (ca. 70–65 Ma). Indeed, one of the Csehbánya Formation fossil birds is recognized as a new taxon of large enantiornithine, an avisaurid apparently similar in its largely unfused foot morphology to the Argentine Soroavisaurus and to the North American Avisaurus. The Central European records reviewed in this paper highlight the wide distribution of some Late Cretaceous fossil birds, particularly avisaurid enantiornithines, and lead us to a brief discussion of avian biogeography at the end of the Mesozoic. Copyright © 2010 John Wiley & Sons, Ltd.     

Numerical and analogue modelling of induction effects in laterally non-uniform conductors

Modelling of electromagnetic fields in laterally non-uniform geoelectric structures is briefly reviewed. Attention is paid to progress achieved specifically during the last three years in numerical and analogue techniques of solving two- and three-dimensional problems. Some new important results are also mentioned.     

A contribution to the asymptotic expression of the electromagnetic field of an electric dipole

Studia Geophysica et Geodaetica - Были выведены...     

Partial derivatives of dispersion curves of love waves in a layered medium

Zusammenfassung Es werden Formeln abgeleitet, die die Gruppengeschwindigkeit und partielle Ableitungen der Phasen- und Gruppengeschwindigkeit der Love-Wellen im geschichteten Medium zu berechnen erm?glichen, und zwar ohne Verwendung der numerischen Ableitungen. Die Berechnungen mit Hilfe dieser Formeln sind vielfach schneller als bei Verwendung der numerischen Methoden; sie sind sogar genauer, besonders bei der Berechnung der partiellen Ableitungen der Gruppengeschwindigkeit. Ausführlich werden die partiellen Ableitungen der Dispersionskurven der Love-Wellen für das Model des Kanadischen-Schilds studiert.

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Address: Ke Karlovu 3, Praha 2.     

Anomalous induction zones in the Czech Republic in relation to large scale european anomalies

Summary Induction response has been investigated at 57 field stations covering the Bohemian Massif (BM) and the Bruno-Vistulicum (BV), and at 93 temporary observing sites across the West Carpathians (WCP). Induction response data at 958 localities covering mainly the Central European area were also collected and analysed. Components of transfer functions (TF), moduli and arguments of corresponding induction vectors are analyzed for individual profiles. Pseudo-sections of induction parameters at profiles are used to visualize the period dependence of induction response and computer generated contour maps of TF components define zones of anomalous induction and their relation to large scale anomalies. Depths of anomalous field source are estimated by separating variations into internal and external parts. Correlations among induction response characteristics and the results of other geophysical investigations are discussed.