The influence of the geomorphological and sedimentological settings on the distribution of epibenthic assemblages on a flat topped hill on the over-deepened shelf of the western Weddell Sea (Southern Ocean)

Epibenthos communities play an important role in the marine ecosystems of the Weddell Sea. Information on the factors controlling their structure and distribution are, however, still rare. In particular, the interactions between environmental factors and biotic assemblages are not fully understood. Nachtigaller Hill, a newly discovered seabed structure on the over-deepened shelf of the northwest Weddell Sea (Southern Ocean), offers a unique site to study these interactions in a high-latitude Antarctic setting. Based on high-resolution bathymetry and georeferenced biological data, the effect of the terrain and related environmental parameters on the epibenthos was assessed. At Nachtigaller Hill, both geomorphological and biological data showed complex distribution patterns, reflecting local processes such as iceberg scouring and locally amplified bottom currents. This variability was also generally reflected in the variable epibenthos distribution patterns although statistical analyses did not show strong correlations between the selected environmental parameters and species abundances. By analysing the interactions between environmental and biological patterns, this study provides crucial information towards a better understanding of the factors and processes that drive epibenthos communities on the shelves of the Weddell Sea and probably also on other Antarctic shelves

Traces for star products on the dual of a Lie algebra

In this paper, we describe all traces for the BCH star-product on the dual of a Lie algebra. First we show by an elementary argument that the BCH as well as the Kontsevich star-product are strongly closed if and only if the Lie algebra is unimodular. In a next step we show that the traces of the BCH star-product are given by the \ad-invariant functionals. Particular examples are the integration over coadjoint orbits. We show that for a compact Lie group and a regular orbit one can even achieve that this integration becomes a positive trace functional. In this case we explicitly describe the corresponding GNS representation. Finally we discuss how invariant deformations on a group can be used to induce deformations of spaces where the group acts on.Comment: 18 pages, LaTeX2e. Updated reference

SOUTH AMERICAN AND ANTARCTIC INTERACTIONS IN THE MARINE ENVIRONMENT - BIOLOGICAL RELATIONSHIPS, GENERAL RELEVANCE AND RESEARCH PERSPECTIVE

The  relevance  of  faunistic  intercontinental  comparisons  is  discussed  here  in  the  context  of  the  past and  current  projects  related  to Antarctic  biodiversity  research.  Some  of  these  have  focussed  on  questions regarding Antarctic isolation and evolutionary pathways between South America and that continent, such as the  ‘Investigación  Biológica  Marina  en  Magellanes  relacionada  con  la Antártida'(IBMANT),  ‘Ecology  of the Antarctic  Sea  Ice  Zone'  (EASIZ),  and  more  recently  the  ‘Evolution  and  Biodiversity  in  the Antarctic' (EBA) as well as the ‘Census of Antarctic Marine Life' (CAML) and the ‘Scientific Committee on Antarctic Research Marine Biodiversity Information Network' (SCARMarBIN). The Latin American subproject of the ‘Census of Antarctic Marine Life' (LA-CAML) provided a landmark to collect data on the biodiversity and life history for all groups of organisms ranging from microbes to endotherms. In addition to such fundamental knowledge the application of molecular techniques and highly sophisticated methods to study macroecological processes are necessary to better understand ecosystem functioning and large-scale comparisons in the southern hemisphere, especially between South America and Antarctica. More cooperation between scientists and more interdisciplinary approaches are required to develop reliable projections for the future of our biosphere under anthropogenic stress and its ecosystem services.INTERACCIONES ENTRE AMÉRICA DEL SUR y ANTÁRTICA EN EL AMBIENTE MARINO -- RELACIONES BIOLÓGICAS, RELEVANCIAS GENERALES y PERSPECTIVAS DE ESTUDIO.  En este trabajo se discute la importancia de las comparaciones intercontinentales relacionadas con la fauna, en el contexto de los proyectos científicos pasados y actuales relacionados con la investigación de la diversidad biológica  Antártica.  Algunos  de  dichos  estudios  están  enfocados  en  aspectos  referidos  al  aislamiento  del continente Antártico  y  en  los  procesos  evolutivos  entre  Sudamérica  y Antártica,  tales  como  ‘Investigación Biológica Marina en Magallanes relacionada con la Antártica' (IBMANT), ‘Ecology of the Antarctic Sea Ice Zone'(EASIZ), y más recientemente ‘Evolution and Biodiversity in the Antarctic' (EBA) así como ‘Census of  Antarctic  Marine  Life'  (CAML)  y  ‘Scientific  Committee  on  Antarctic  Research  Marine  Biodiversity Information Network' (SCARMarBIN). El subproyecto latinoamericano de ‘Census of Antarctic Marine Life' (LA-CAML)  inició  la  recolección  y  recopilación  de  información  referidas  a  la  biodiversidad  e  historia  de vida  de  todos  los  grupos  de  organismos,  desde  microbios  hasta  animales  endotérmicos. Además  de  dicho conocimiento  básico,  es  necesario  la  aplicación  de  técnicas  moleculares  y  sofisticados  métodos  de  estudio de  procesos  macroecológicos,  para  un  mejor  entendimiento  del  funcionamiento  del  ecosistema  y  de  las comparaciones a gran escala en el hemisferio sur, especialmente entre Sudamérica y Antártica. Una mayor cooperación entre científicos y la realización de estudios interdisciplinarios son necesarios para el desarrollo de  proyecciones confiables para el futuro de nuestra biosfera bajo estrés antropogénico y sus servicios ecológicos. Palabras claves: Biodiversidad; estudios interdisciplinarios; funcionamento de los ecosistemas; predicciones.INTERAÇÕES  ENTRE  AMÉRICA  DO  SUL  E  ANTÁRTICA  NO  AMBIENTE  MARINHO  -- RELAÇÕES  BIOLÓGICAS,  RELEVÂNCIA  E  PERSPECTIVAS  DE  ESTUDO.  A  relevância  de comparações intercontinentais relacionadas à fauna é discutida aqui no contexto de projetos científicos passados e atuais relacionados às pesquisas sobre biodiversidade na Antártica. Alguns destes estudos são focados em questões relacionadas ao isolamento do continente Antártico e nos processos de evolução entre América do Sul e Antártica, como por exemplo, os projetos ‘Investigación Biológica Marina en Magellanes relacionada con la Antártida'( IBMANT), ‘Ecology of the Antarctic Sea Ice Zone' (EASIZ), e mais recentemente o projeto ‘Evolution and Biodiversity in the Antarctic' (EBA), bem como o ‘Census of Antarctic Marine Life' (CAML) e o ‘Scientific Committee on Antarctic Research Marine Biodiversity Information Network' (SCARMarBIN). O subprojeto Latino Americano do ‘Census of Antarctic Marine Life' (LA-CAML) iniciou a coleta e reunião de informações referentes á biodiversidade e história de vida de todos os grupos de organismos desde micróbios a animais endotérmicos. Adicionalmente a estes conhecimentos básicos, a aplicação de técnicas moleculares e sofisticados métodos de estudos de processos macroecológicos são necessários para o melhor entendimento do ecossistema como um todos e de comparações de larga escala no hemisfério sul, especialmente entre América do Sul e Antártica. Uma maior cooperação entre cientistas e a realização de estudos interdisciplinares são necessários para o desenvolvimento de projeções confiáveis para o futuro da nossa biosfera sob stress antropogênico e seus serviços ecológicos. Palavras chave: Biodiversidade; estudos interdisciplinares; funcionamento de ecossistemas; previsões

Infinitesimal deformations of a formal symplectic groupoid

Given a formal symplectic groupoid $G$ over a Poisson manifold $(M, \pi_0)$, we define a new object, an infinitesimal deformation of $G$, which can be thought of as a formal symplectic groupoid over the manifold $M$ equipped with an infinitesimal deformation $\pi_0 + \epsilon \pi_1$ of the Poisson bivector field $\pi_0$. The source and target mappings of a deformation of $G$ are deformations of the source and target mappings of $G$. To any pair of natural star products $(\ast, \tilde\ast)$ having the same formal symplectic groupoid $G$ we relate an infinitesimal deformation of $G$. We call it the deformation groupoid of the pair $(\ast, \tilde\ast)$. We give explicit formulas for the source and target mappings of the deformation groupoid of a pair of star products with separation of variables on a Kaehler- Poisson manifold. Finally, we give an algorithm for calculating the principal symbols of the components of the logarithm of a formal Berezin transform of a star product with separation of variables. This algorithm is based upon some deformation groupoid.Comment: 22 pages, the paper is reworked, new proofs are adde

Weddell Sea iceberg drift: Five years of observations

Since 1999, 52 icebergs have been tagged with GPS buoys in the Weddell Seato enable monitoring of their position. The chosen icebergs were of small tomedium size, with a few icebergs larger than 10 km associatedwith the calving of icebergs A38 and A43 from the Ronne Ice Shelf.The majority of icebergs were tagged off Neumayer Station (8E, 70S).It was found that smaller bergs with edges shorter than 200 m had the shortestlife cycle (< 0.5 yr). Iceberg and thus freshwater export out of theWeddell Sea was found to be highly variable. In one year the majority of buoysdeployed remained in the Weddell Sea, constituting about 40 % of the NCEP P-Efreshwater input, whereas in other years all of the tagged icebergs were exported.The observed drifts of icebergs and sea-ice showed a remarkably coherent motion.The analysis of an iceberg - sea-ice buoy array in the western Weddell Seaand an iceberg array in the eastern Weddell Sea showed a coherent sea-iceiceberg drift in sea-ice concentrations above 86 %. Dynamic kinematic parameter(DKP) during the course of coherent movement were low and deviations from the meancourse associated with the passage of low-pressure system. The length scale ofcoherent movement was estimated to be less than 250km; about half the value found forthe Arctic Ocean

The Stability of Bredigite and Other Ca-Mg Silicates

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65844/1/j.1151-2916.1980.tb10213.x.pd

Antarctic Climate Change and the Environment

The Antarctic climate system varies on timescales from orbital, through millennial to sub-annual, and is closely coupled to other parts of the global climate system. We review these variations from the perspective of the geological and glaciological records and the recent historical period from which we have instrumental data (the last 50 years). We consider their consequences for the biosphere, and show how the latest numerical models project changes into the future, taking into account human actions in the form of the release of greenhouse gases and chlorofluorocarbons into the atmosphere. In doing so, we provide an essential Southern Hemisphere companion to the Arctic Climate Impact Assessment