Community structure of macrobenthos in two tropical sandy beaches with different morphodynamic features, Rio de Janeiro, Brazil     

Renata Soares Ramalho Fernandes  & Abilio Soares-Gomes 《Marine Ecology》2006,27(2):160-169

The macrobenthos of two exposed tropical sandy beaches in Rio de Janeiro (Brazil) were compared in relation to density, species richness, and vertical zonation. Biological and sediment samplings were carried out in the austral winter of 2002 and the austral summer of 2003. The sampling design consisted of 10 transects perpendicular to the water line, evenly divided into strata. A sampling unit was taken in each stratum with a 0.04 m² quadrat sampler. Beaches were also compared according to physical features, such as slope, wave period, wave height, and grain size. According to Dean's Ω morphodynamic index the Pontal is a dissipative beach while the Costa Azul is a reflective one. The mean grain size ranged from median to coarse sand in Costa Azul, whereas in Pontal it ranged from median to very fine sand. Eleven species were collected in the two beaches. Crustaceans were the dominant in the Costa Azul Beach, while the polychaete Scolelepis squamata dominated the Pontal beach. A negative correlation was found between the density of the macrobenthos and mean grain size, and beach slope. On the other hand, the Dean's parameter correlated positively with faunal density. Based on the results of ANOSIM, in both beaches, two groups of stations were identified, defining an upper and a lower beach zone along the vertical distribution of the macrobenthos.  相似文献   

Survey of Geomagnetic Observations Made in the Northern Sector of Russia and New Methods for Analysing Them     

Alexei Gvishiani  Renata Lukianova  Anatoly Soloviev  Andrei Khokhlov 《Surveys in Geophysics》2014,35(5):1123-1154

An overview of the geomagnetic observations made in the northern part of Russia is presented from a historical perspective. Several stations were deployed on the territory of the former Soviet Union during the International Geophysical Year, 1957–1958, with the active participation and guidance of the Interagency Geophysical Committee which is inherited by the Geophysical Center of the Russian Academy of Sciences (GC RAS). In the 1990s, the majority of these stations, especially those in the remoter regions, were closed. Nowadays, the geomagnetic network, including the observatories of the INTERMAGNET program, has been restored. Examples of high-latitude geomagnetic variations in the Russian longitudinal sector are shown, and maps and trends of the secular variation over the territory of Russia presented. Particular attention is paid to the automated processing of data and to the analysis methods used. To process the growing amount of high-resolution geomagnetic data, sophisticated mathematical methods based on the fuzzy logic approach and new discrete mathematical analysis algorithms have been developed. The formal methods and algorithms for recognizing both artificial and natural disturbances in the magnetograms are described.  相似文献   

Hydrology needed to manage droughts: the 2015 European case   总被引：1，自引：0，他引：1       下载免费PDF全文

Henny A.J. Van Lanen  Gregor Laaha  Daniel G. Kingston  Tobias Gauster  Monica Ionita  Jean‐Philippe Vidal  Radek Vlnas  Lena M. Tallaksen  Kerstin Stahl  Jamie Hannaford  Claire Delus  Miriam Fendekova  Luis Mediero  Christel Prudhomme  Ekaterina Rets  Renata J. Romanowicz  Sébastien Gailliez  Wai Kwok Wong  Mary‐Jeanne Adler  Veit Blauhut  Laurie Caillouet  Silvia Chelcea  Natalia Frolova  Lukas Gudmundsson  Martin Hanel  Klaus Haslinger  Maria Kireeva  Marzena Osuch  Eric Sauquet  James H. Stagge  Anne F. Van Loon 《水文研究》2016,30(17):3097-3104

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Probabilistic modelling of macroseismic attenuation and forecast of damage scenarios     

Renata Rotondi  Elisa Varini  Carla Brambilla 《Bulletin of Earthquake Engineering》2016,14(7):1777-1796

According to the idea now widespread that macroseismic intensity should be expressed in probabilistic terms, a beta-binomial model has been proposed in the literature to estimate the probability of the intensity at site in the Bayesian framework and a clustering procedure has been adopted to define learning sets of macroseismic fields required to assign prior distributions of the model parameters. This article presents the results concerning the learning sets obtained by exploiting the large Italian macroseismic database DBM1I11 (Locati et al. in DBMI11, the 2011 version of the Italian Macroseismic Database, 2011. http://emidius.mi.ingv.it/DBMI11/) and discusses the problems related to their use in probabilistic modelling of the attenuation in seismic regions of the European countries partners of the UPStrat-MAFA project (2012), namely South Iceland, Portugal, SE Spain and Mt Etna volcano area (Italy). Anisotropy and the presence of offshore earthquakes are some of the problems faced. All the work has been carried out in the framework of the Task B of the project.  相似文献   

Asymmetric structures of field-aligned currents and convection of ionospheric plasma controlled by the IMF azimuthal component and season of year     

R. Yu. Lukianova  A. Kozlovsky  F. Christiansen 《Geomagnetism and Aeronomy》2010,50(5):667-678

We present the results of using the statistical model of field-aligned currents (FACs) based on satellite data and the numerical model of the electric potential distribution in order to detect the asymmetric part in FAC structures and ionospheric plasma convection controlled by the IMF azimuthal (B _y ) component at different seasons of the year. These structures can be identified by plotting diagrams, which represent differences in corresponding maps for opposite signs of IMF B _y . Circular near-pole current symmetric about the noon meridian and corresponding convection vortices around the pole have been obtained for the summer and equinox periods. It is difficult to detect distinct structures under winter conditions, and the current is most intense on the morning side. A two-cell convection system with the foci in the afternoon and postmid-night sectors is created in the electric potential difference diagrams. Thus, qualitatively different FAC and convection patterns exist during the solstice in opposite hemispheres. The value of the electric potential originating in the near-pole region under the action of the B _y component and a change in the potential under the action of additional factors have been estimated.  相似文献   

Ice-margin retreat and grounding-zone dynamics during initial deglaciation of the Storfjordrenna Ice Stream,western Barents Sea     

Calvin S. Shackleton  Monica C. M. Winsborrow  Karin Andreassen  Renata G. Lucchi  Lilja R. Bjarnadóttir 《Boreas: An International Journal of Quaternary Research》2020,49(1):38-51

Processes occurring at the grounding zone of marine terminating ice streams are crucial to marginal stability, influencing ice discharge over the grounding-line, and thereby regulating ice-sheet mass balance. We present new marine geophysical data sets over a ~30×40 km area from a former ice-stream grounding zone in Storfjordrenna, a large cross-shelf trough in the western Barents Sea, south of Svalbard. Mapped ice-marginal landforms on the outer shelf include a large accumulation of grounding-zone deposits and a diverse population of iceberg ploughmarks. Published minimum ages of deglaciation in this region indicate that the deposits relate to the deglaciation of the Late Weichselian Storfjordrenna Ice Stream, a major outlet of the Barents Sea–Svalbard Ice Sheet. Sea-floor geomorphology records initial ice-stream retreat from the continental shelf break, and subsequent stabilization of the ice margin in outer-Storfjordrenna. Clustering of distinct iceberg ploughmark sets suggests locally diverse controls on iceberg calving, producing multi-keeled, tabular icebergs at the southern sector of the former ice margin, and deep-drafted, single-keeled icebergs in the northern sector. Retreat of the palaeo-ice stream from the continental shelf break was characterized by ice-margin break-up via large calving events, evidenced by intensive iceberg scouring on the outer shelf. The retreating ice margin stabilized in outer-Storfjordrenna, where the southern tip of Spitsbergen and underlying bedrock ridges provide lateral and basal pinning points. Ice-proximal fans on the western flank of the grounding-zone deposits document subglacial meltwater conduit and meltwater plume activity at the ice margin during deglaciation. Along the length of the former ice margin, key environmental parameters probably impacted ice-margin stability and grounding-zone deposition, and should be taken into consideration when reconstructing recent changes or predicting future changes to the margins of modern ice streams.  相似文献   

Projected changes in flood indices in selected catchments in Poland in the 21st century     

Marzena?OsuchEmail author  Deborah?Lawrence  Hadush?K.?Meresa  Jaroslaw?J.?Napiorkowski  Renata?J.?Romanowicz 《Stochastic Environmental Research and Risk Assessment (SERRA)》2017,31(9):2435-2457

The aim of this study is to estimate likely changes in flood indices under a future climate and to assess the uncertainty in these estimates for selected catchments in Poland. Precipitation and temperature time series from climate simulations from the EURO-CORDEX initiative for the periods 1971–2000, 2021–2050 and 2071–2100 following the RCP4.5 and RCP8.5 emission scenarios have been used to produce hydrological simulations based on the HBV hydrological model. As the climate model outputs for Poland are highly biased, post processing in the form of bias correction was first performed so that the climate time series could be applied in hydrological simulations at a catchment-scale. The results indicate that bias correction significantly improves flow simulations and estimated flood indices based on comparisons with simulations from observed climate data for the control period. The estimated changes in the mean annual flood and in flood quantiles under a future climate indicate a large spread in the estimates both within and between the catchments. An ANOVA analysis was used to assess the relative contributions of the 2 emission scenarios, the 7 climate models and the 4 bias correction methods to the total spread in the projected changes in extreme river flow indices for each catchment. The analysis indicates that the differences between climate models generally make the largest contribution to the spread in the ensemble of the three factors considered. The results for bias corrected data show small differences between the four bias correction methods considered, and, in contrast with the results for uncorrected simulations, project increases in flood indices for most catchments under a future climate.  相似文献   

Integrated monitoring of the hydro-morphodynamics of a beach protected by low crested detached breakwaters     

Renata Archetti  Barbara Zanuttigh 《Coastal Engineering》2010

The aim of this paper is to propose an integrated low cost system for monitoring the performance of beach defence works during storms. For this purpose, the site of Igea Marina, Northern Adriatic Sea, Italy, which is protected by low crested detached breakwaters, is selected. The monitoring system is composed by a video installation, for the identification of the shoreline position and of the intertidal bathymetry at high space and time resolution, and a 2DH numerical model, to reconstruct the hydrodynamics induced by coastal defenses. The accuracy of the monitoring system is verified against available measurements of waves and currents performed during a field campaign with acoustic Doppler profilers. Assimilation of data on the shoreline position in 2DH model operatively working is challenging in the improvement of the production of risk maps. These show the current intensities and flooded areas during forecasted storms. First promising results suggest the possibility of setting up an early warning tool.  相似文献   

Mediterranean commercial sponges: over 5000 years of natural history and cultural heritage     

Roberto Pronzato  & Renata Manconi 《Marine Ecology》2008,29(2):146-166

This paper deals with the history of the exploitation of a natural resource made up of various types of Mediterranean horny sponges. It also provides an update on trends in the trade of these sponges. The distribution and taxonomic status of Mediterranean species of commercial interest belonging to the genera Spongia and Hippospongia are reported upon and partly emended by (i) the selection of neotypes for Spongia mollissima , Hippospongia communis , and Spongia agaricina from the Indo-Pacific Ocean versus the Mediterranean Spongia lamella , and (ii) the discussion regarding the problematic status of Spongia zimocca . Attention is also focused upon species that have been of recent commercial interest as sources of metabolites with biomedical potential, such as Dysidea avara, which is considered endangered due to a pressing demand for the industrial extraction of chemicals it produces ( e.g . Avarol). The wild harvesting of new target sponges is also discussed, together with a proposal for a rational, sustainable, long-term strategy for Mediterranean sponge management. Sponge culture in situ is suggested as a useful approach that may allow eco-compatible management and conservation of this natural resource.  相似文献   

Klaus Ruetzler. A tribute     

Jörg Ott  Maurizio Pansini  & Renata Manconi 《Marine Ecology》2008,29(2):143-145

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