Can Rock Composition Affect Sublittoral Epibenthic Communities?     

Riccardo Cattaneo-Vietti  Giancarlo Albertelli  Giorgio Bavestrello  Carlo Nike Bianchi  Carlo Cerrano  Mariachiara Chiantore  Laura Gaggero  Carla Morri  Stefano Schiaparelli 《Marine Ecology》2002,23(S1):65-77

Abstract. Biomineralogy, as the complex of interactions at different levels (cell, organism, species, and community) between organisms and minerals, may play a significant role in the spatial distribution and structure of marine communities. For instance, a negative influence of quartz has been underlined on the Mediterranean benthic communities, which show a species-poorer structure in quartz-rich environments. Excluding the role of quartz, the aim of this work is to verify whether the composition of various mineralogical substrata can affect a hard-bottom benthic community. In the Ligurian Sea, the Levanto area shows an astonishing complex of substrata with different petrographic characters: in a few kilometres, sandstones, serpentinites, gabbros, and basalts occur in geometric association. Consequently, this area represents a suitable frame for this type of study. Herein, algal photophilic assemblages growing on the four mineralogical substrata show significant differences in number of species and percentage cover or abundance. This suggests a significant influence of rock mineral composition on the hard bottom community. Therefore, rock composition must be taken into account for a better understanding of the processes at the basis of hard-bottom community development and diversity.  相似文献   

Spatial characterisation of the Benguela ecosystem for ecosystem-based management     

SP Kirkman  L Blamey  T Lamont  G Bianchi  JA Huggett 《African Journal of Marine Science》2016,38(1):7-22

The three countries of the Benguela Current Large Marine Ecosystem (BCLME), namely Angola, Namibia and South Africa, have committed to implementing ecosystem-based management (EBM) including an ecosystem approach to fisheries (EAF) in the region, to put in practice the principles of sustainable development in ocean-related matters. There is also recognition of the need for marine spatial planning (MSP) as a process for informing EBM with regard to the allocation and siting of ocean uses so that ecosystem health is ensured and trade-offs between ecosystem services are appropriately dealt with. Marine spatial planning is both an integrated and an area-based process, and this paper produces a spatial characterisation of the BCLME for achieving a common basis for MSP in the region, focusing on the oceanography, biology and fisheries. Recognising spatial variation in physical driving forces, primary and secondary production, trophic structures and species richness, four different subsystems are characterised: (1) north of the Angola–Benguela Front, (2) from the Angola–Benguela Front to Lüderitz, (3) from Lüderitz to Cape Agulhas, and (4) from Cape Agulhas to Port Alfred on the south-east coast of South Africa. Research and monitoring requirements of relevance for MSP and EBM in the region are identified, focusing on understanding variability and change, including with regard to the boundary areas identified for the system. To this end, 14 cross-shelf monitoring transects are proposed (including seven that are already being monitored) to estimate fluxes of biota, energy and materials within and between the subsystems. The usefulness of models for understanding ecosystem variability and changes is recognised and the need for fine-scale resolution of both sampling and modelling for adequate MSP as input to EBM for the often-conflicting interests of conserving biodiversity, and managing fisheries, recreation, offshore oil and gas exploration and exploitation, offshore mining and shipping routes, is emphasised.  相似文献   

Search for narrow energy‐shifted lines in AGN spectra in the XMMNewton archive     

A. L. Longinotti  S. Bianchi  M. Guainazzi  J. Roa  M. Santos‐Lleo 《Astronomische Nachrichten》2006,327(10):1020-1023

Thanks to the large effective area and the spectral resolution of current X‐ray satellites, the detection of X‐ray narrow spectral features in the 5–7 keV band is becoming commonplace in many AGN observations. Such lines, both in emission and in absorption, are mostly interpreted as arising from Iron atoms. When observed with some displacement from their rest frame position, these lines carry the potential to study the motion of circumnuclear gas in AGN, providing a diagnostic of the effects of the gravitational field of the central black hole. These narrow features have been often found with marginal statistical significance. A systematic search for narrow features in type1 AGN is being performed on all spectra available in the XMM‐Newton archive with the aim to estimate the significance of the features with Monte Carlo simulations of synthetic spectra. The project and preliminary results are presented. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Variable sequence of events during the past seven terminations in two deep-sea cores from the Southern Ocean     

Aya Schneider Mor  Ruth Yam  Cristina Bianchi  Martina Kunz-Pirrung  Rainer Gersonde  Aldo Shemesh 《Quaternary Research》2012,77(2):317-325

The relationships among internally consistent records of summer sea-surface temperature (SSST), winter sea ice (WSI), and diatomaceous stable isotopes were studied across seven terminations over the last 660 ka in sedimentary cores from ODP sites 1093 and 1094. The sequence of events at both sites indicates that SSST and WSI changes led the carbon and nitrogen isotopic changes in three Terminations (TI, TII and TVI) and followed them in the other four Terminations (TIII, TIV, TV and TVII). In both TIII and TIV, the leads and lags between the proxies were related to weak glacial mode, while in TV and TVII they were due to the influence of the mid-Pleistocene transition. We show that the sequence of events is not unique and does not follow the same pattern across terminations, implying that the processes that initiated climate change in the Southern Ocean has varied through time.  相似文献   

The GALEX public archive at MAST     

A. Conti  L. Bianchi  B. Shiao 《Astrophysics and Space Science》2011,335(1):329-331

The Galaxy Evolution Explorer (GALEX) was successfully launched on April 28, 2003. Over the last 7 years, the GALEX mission has expanded our understanding of the process of star formation and galaxy evolution. GALEX data, consisting of far-UV (1344-1786A) and near-UV (1771-2831A) imaging over most of the sky, and grism spectroscopy, are available to the entire astronomical community and to the general public via the Multi-mission Archive at Space Telescope (MAST). The main characteristics and access tools to the large data archive (16TB) are presented. Groups within the GALEX Science Team, and the MAST archive teams, have undertaken complementary projects to conduct all-sky searches for time-variable and transient sources within GALEX data (e.g. Welsh et al. in Astron. J. 130:823, 2005; Wheatley et al. in Astron. J. 136:259, 2008). Results and tools for variability searches developed by MAST during this process, will be made available to the general community.  相似文献   

http://www.sciencedirect.com/science/article/pii/S1674987114000887     

Gerald Grellet-Tinner  Michael B.Thompson  Lucas E.Fiorelli  Eloísa Argaaraz  Laura Codorniú  E.Martín Hechenleitner 《地学前缘(英文版)》2014,5(6):759-765

The increasing number of fossil pterosaur eggs sheds light on nesting environments and breeding be- haviors of these extinct flying reptiles. Here we report the first partial three-dimensional egg of the pterosaur, Pteroduustro guinazui, from central Argentina. The specimen was discovered from the same Albian deposits as the exceptional R guinazui embryo described in 2004. Microscopic characterizations indicate a pristine preservation of the 50 Bm thick calcium carbonate, which differs significantly from the soft shell of Chinese pterosaur eggs. Estimate of the eggshell conductance implies that the nest had a minimum moisture content of 75%. This moisture estimate, combined with geological and taphonomical data, suggests that P. guinazui may have adopted a nesting strategy similar to those of grebes and flamingos rather than being buried on land, as previously hypothesized. Moreover, our results demon- strate that the nesting paleoenvironment of this pterosaur species was closely linked to a mesohaline lacustrine ecosystem in a basin governed by regional tectonic subsidence, a setting characteristic for the feeding and reproduction of modern flamingos.  相似文献   

Carbonate Chemistry Dynamics of Surface Waters in the Northern Gulf of Mexico     

Nina Keul  John W. Morse  Rik Wanninkhof  Dwight K. Gledhill  Thomas S. Bianchi 《Aquatic Geochemistry》2010,16(3):337-351

This paper presents the results of two cruises in the Northern Gulf of Mexico in 2008 that investigated local and short-term factors influencing the carbonate chemistry dynamics and saturation state with respect to aragonite (Ω_aragonite) of surface seawater in this region. One cruise covered much of the northern half of the Gulf, and the other focused on the coastal zone west of the Atchafalaya Bay outlet of the Mississippi River—the region where the hypoxic “dead zone” occurs on the Louisiana shelf. Offshore waters (>100 m depth) exhibited only small variations in CO₂ fugacity (fCO₂), total alkalinity (TA) and Ω_aragonite. Values were close to those typically observed in subtropical Atlantic Ocean and Caribbean Sea waters of similar salinity. However, inner shelf waters (<50 m depth) exhibited large variations in fCO₂, TA, and Ω_aragonite that were not directly related to salinity or distance from the Mississippi River plume. Changes in TA values were not the result of simple mixing of end-member freshwater and seawater TA concentrations but exhibited a minimum in values near salinity of 25. This minimum could be the result of microbial recycling across salinity gradients, biological removal of alkalinity by formation of calcium carbonate or mixing of a third end-member with a low alkalinity such as Terrebonne Bay. All waters were supersaturated with respect to aragonite. Offshore waters had an average Ω_aragonite of 3.86 with a standard deviation of only ±0.06 and inner shelf waters had a range in Ω_aragonite values from 3.9 to 9.7 with a median of 4.3. Shelf water Ω_aragonite values were elevated relative to the offshore as a consequence of both high TA input from Mississippi River and biological drawdown of CO₂. A dominant factor controlling Ω_aragonite distribution in offshore waters with relatively constant temperatures was fCO₂, with higher supersaturation occurring in areas with low fCO₂.  相似文献   

Much damage for little advantage: Field studies and morphodynamic modelling highlight the environmental impact of an apparently minor coastal mismanagement     

Roberta LasagnaMonica Montefalcone  Giancarlo AlbertelliNicola Corradi  Marco FerrariCarla Morri  Carlo Nike Bianchi 《Estuarine, Coastal and Shelf Science》2011,94(3):255-262

While coastal management activities have long been known to exert a strong influence on the health of marine ecosystems, neither scientists nor administrators have realized that small interventions may lead to disproportionately larger impacts. This study investigated the broad and long-lasting environmental consequences of the construction of an ill-planned, although small (only 12 m long) jetty for pleasure crafts on the hydrodynamic conditions and on the meadow of the seagrass Posidonia oceanica of an embayed cove in the Ligurian Sea (NW Mediterranean). There, P. oceanica used to develop on a high (>1.5 m) matte (a lignified terrace causing seafloor elevation) in which the leaves reach the surface and form a compact natural barrier to waves in front of the beach. Such a so-called ‘fringing reef’ of P. oceanica is today recognized of high ecological value and specific conservation efforts are required. The construction of the jetty implied the cutting of the matte, which directly destroyed part of the fringing reef. In addition, meadow mapping and sedimentological analyses coupled with morphodynamic modelling showed that the ecosystem of the whole cove had been greatly altered by the jetty. We used the geometric planform approach, a proper tool in the study of headland-controlled embayment, both to characterise the present situation of Prelo cove and to simulate the original one, before the jetty was built. In the long term, such a small jetty completely altered the configuration and the hydrodynamic conditions of the whole cove, splitting the original pocket beach into two smaller ones and creating strong rip-currents flowing seaward along the jetty. These rip-currents enhanced erosion of residual shallow portions of the meadow and further modified the sedimentary fluxes in shallow waters. A century after the construction of the jetty, an irreversible environmental damage has occurred, as the slow growing rate of P. oceanica implies that the high matte terrace and the fringing reef will hardly form again, even after the removal of the jetty. The lesson learnt from this study is that even such small, and therefore reputed intrinsically ‘innocent’, interventions on the coastal zone require accurate planning based on interdisciplinary studies to understand and respect the delicate interplay among morphological, hydrodynamic and ecological components.  相似文献   

Fe xxv and Fe xxvi lines from low-velocity, photoionized gas in the X-ray spectra of active galactic nuclei     

Stefano Bianchi  Giorgio Matt  Fabrizio Nicastro  Delphine Porquet  Jacques Dubau 《Monthly notices of the Royal Astronomical Society》2005,357(2):599-607

We have calculated the equivalent widths of the absorption lines produced by Fe  xxv and Fe  xxvi in a Compton-thin, low-velocity photoionized material illuminated by the nuclear continuum in active galactic nuclei. The results, plotted against the ionization parameter and the column density of the gas, are a complement to those presented by Bianchi & Matt for the emission lines from the same ionic species. As an extension to the work by Bianchi & Matt, we also present a qualitative discussion on the different contributions to the He-like iron emission line complex in the regimes where recombination or resonant scattering dominates, providing a useful diagnostic tool to measure the column density of the gas. Future high-resolution missions (e.g. Astro-E2 ) will allow us to fully take advantage of these plasma diagnostics. In the meantime, we compare our results with an up-to-date list of Compton-thick and unobscured (at least at the iron line energy) Seyfert galaxies with emission and/or absorption lines from H- and He-like iron observed with Chandra and XMM–Newton .  相似文献   

A multiwavelength map of the nuclear region of NGC 7582     

Stefano Bianchi  Marco Chiaberge  Enrico Piconcelli  Matteo Guainazzi 《Monthly notices of the Royal Astronomical Society》2007,374(2):697-702

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