Community structure and functional traits of mollusks associated with coastal reef macroalgae in Northeastern Brazil     

Dbora Ferreira Barbosa  Thelma Lúcia Pereira Dias  Srgio de Faria Lopes  Rafaela Cristina de Souza Duarte  Fernanda Maria Duarte do Amaral 《Marine Ecology》2019,40(5)

This study investigated the community structure and functional traits of the mollusk fauna associated with macroalgae with different thallus morphologies in a reef environment in Northeastern Brazil. A total of 15 individuals of each species of macroalgae adhered to natural substrate and 15 individuals of Padina gymnospora detached from the substrate were collected. The structural complexity of algal habitats was measured and the associated malacofauna screened and identified. All three macroalgae differed significantly in the complexity of their habitat, with Sargassum polyceratium being the most complex. A total of 823 specimens of mollusks belonging to 22 species and 11 families were recorded, of which Columbellidae was the most represented with six species. The functional trait “size” revealed that micromollusks smaller than 10 millimeters were predominant in the community; however, individuals of larger sizes (up to 24.54 millimeters) belonging to young stages of other species were also present. Eight functional trophic groups were identified, of which “carnivorous” stood out with seven species. Six functional groups of microhabitats were identified, with intra‐specific variation in habitats, while habitat expansion was documented for species not yet recorded in association with macroalgae. The structure of the molluskan community differed among the three algae species with the greatest richness, abundance, and diversity of mollusks and functional traits occurring with S. polyceratium. Community structure differed between algae adhered to natural substrate and detached algae, with the latter having lower mollusk richness and diversity, but with greater abundance of some species that remained on algal fronds after release from the reef environment. This study reinforces the importance of algal habitat for marine invertebrate fauna, especially for micromollusks that spend their entire life cycle, or part of it, in association with macroalgae.  相似文献   

Decentralized water supply by reservoir network reduces power demand for water distribution in a semi-arid basin     

Antônia Tatiana Pinheiro do Nascimento  Natália Holanda Maia Cavalcanti  Bruno Parente Leitão de Castro 《水文科学杂志》2019,64(1):80-91

In the Brazilian semi-arid region, thousands of small dams have been built over time to enhance water availability, accumulating water and hydraulic energy at high altitudes. Simulations were performed in this study to assess how the arrangement of reservoirs impacts on the power demand for water distribution in the Banabuiú River Basin (19?800 km²), Brazil. The power required to pump water from 1405 reservoirs to all districts with diffuse demands is 6.5 GWh/year, whereas in the scenario with only the 12 larger strategic reservoirs, the power demand reached 45.3 GWh/year. Alone, the largest reservoir in the basin can supply water to all districts. Nonetheless, in that scenario, the power demand would reach 195 GWh/year, which is 30 times the power required in the real reservoir arrangement. Thus, decentralization by small reservoirs not only promotes more democratic access to water, but also increases energy efficiency by storing it at higher altitudes and closer to the diffuse demands.  相似文献   

Estimating quality factor from surface seismic data: A comparison of current approaches     

Bonnie Ives de Castro Nunes  Walter Eugênio de Medeiros  Aderson Farias do Nascimento  José Antonio de Morais Moreira 《Journal of Applied Geophysics》2011,75(2):161-170

The performances of the spectral ratio (SR), frequency centroid shift (FCS), and frequency peak shift (FPS) methods to estimate the effective quality factor Q are compared. These methods do not demand true amplitude data and their implementations were done following an “as simple as possible” approach to highlight their intrinsic potentials and limitations. We use synthetic zero-offset seismic data generated with a simple layer-cake isotropic model. The methods can be ranked from simple to complex in terms of automation as: FPS, FCS and SR. This is a consequence of: (i) peak identification consists basically of a sorting procedure, (ii) centroid estimation involves basically the evaluation of two well-behaved integrals, and (iii) implementation of the SR method involves at least choosing a usable frequency bandwidth and fitting a gradient. The methods can be ranked from robust to sensitive in the presence of noise content in the sequence SR, FCS, and FPS. This is consequence of: (i) the gradient estimate associated to the SR method averages out the noise content in the entire usable frequency bandwidth, (ii) in the presence of moderate-to-high noise level, the centroid estimation is biassed towards overestimating Q due to noise contribution in the tail of the amplitude spectrum, and (iii) peak identification is unstable due to local noise fluctuation in the amplitude spectrum around the peak frequency. Regarding the stability of the estimates relative to the attenuation amount, SR and FCS methods show similar behaviours, whereas FPS method presents an inferior performance. This fact is an indirect consequence of the sensitivity of FPS method to the noise content because the higher is the attenuation the lower is the signal-to-noise ratio. Finally, regarding the robustness of the methods to the presence of dipping layers, only SR and FCS methods provide good estimates, at least to typical dips in non-faulted sedimentary layers, with the estimates obtained with SR method being more accurate that those obtained with FCS method. Except in relation to the automation complexity, which is less important than the performances of the methods, SR method was superior or showed similar performance to FCS method in all scenarios we tried.  相似文献   

Extended Barcelona Basic Model for unsaturated soils under cyclic loadings     

Dorival M. Pedroso  Marcio M. Farias 《Computers and Geotechnics》2011

The Barcelona Basic Model (BBM) is an extension of the Cam clay model that has become popular in applications involving unsaturated soils and, in particular, in simulations using the finite element method. Partially saturated soils can be loaded in different ways, for instance, mechanically and/or hydraulically. In addition, cycles of loading and unloading can be applied. The present work introduces a modification of the BBM in order to simplify its computer implementation and also to allow the simulation of elastoplastic behaviour during cycles of both mechanical and hydraulic loading. A unique smooth yield surface is introduced and a two-yield surfaces concept is applied in order to represent the cyclic behaviour. The influence of the intermediate principal stress on the strength is also accounted for. Finally, the numerical integration (stress update) of the extended BBM is briefly discussed.  相似文献   

On the Effect of Thermally Induced Stresses in Failures of Some Rock Slopes in Rio de Janeiro, Brazil   总被引：1，自引：0，他引：1  

Euripedes do Amaral Vargas Jr.  Raquel Quadros Velloso  Leonardo Erik Chávez  Luiz Gusmão  Claudio Palmeiro do Amaral 《Rock Mechanics and Rock Engineering》2013,46(1):123-134

Previous studies have indicated that many rock slope failures in Rio de Janeiro, Brazil, occur during relatively dry periods when there is little, if any, rainfall. In the present paper, we describe these events and propose possible mechanisms for their occurrence. It is believed that daily fluctuations in temperature may create thermally induced stresses of enough magnitude to propagate fractures already existing in the rock mass. Laboratory experiments were conducted in order to measure temperature variations in a fractured rock system. Using the experimentally obtained data, we carried out numerical analyses in order to verify whether temperature-related stresses were indeed able to propagate fractures existing in the rock mass. The results obtained indicate that cycles of temperature change over time, especially during the colder months of the year can indeed create stress conditions in the rock mass able to propagate existing non-persistent joints, and ultimately lead to failure of the rock slope.  相似文献   

Juvenile contribution of the Neoproterozoic Rio Negro Magmatic Arc (Ribeira Belt,Brazil): Implications for Western Gondwana amalgamation     

Miguel Tupinambá  Monica Heilbron  Claudio Valeriano  Rubem Porto Júnior  Fátima Blanco de Dios  Nuno Machado  Luiz Guilherme do Eirado Silva  Júlio Cesar Horta de Almeida 《Gondwana Research》2012,21(2-3):422-438

The ca. 790–600 Ma Rio Negro Complex (RNC) of the Ribeira belt (Brazil) consists of a plutonic portion of a magmatic arc built by the E-vergent subduction of the ESE border of the São Francisco paleoplate during the amalgamation of Western Gondwana.The plutonic series comprises low- to medium-K granitoids (ca. 790–620 Ma) and high-K granitoids and shoshonite rocks (ca. 610–605). The age span of 185 m.y. is suggestive of a long history of arc-related magmatism, continuously or not in time. The Nd isotopic signatures of the RNC consist of εNd(t) ratios from ? 3 to + 5 for the medium-K series shoshonite series and from ? 14 to ? 3 for the younger high-K group. This time-dependent trend of Nd isotopes is indicative of progressive maturity of the arc over time. The same evolution is indicated by Sr data, as the medium-K rocks have ⁸⁷Sr/⁸⁶Sr initial ratios < 0.705 while the high-K rocks yield values between 0.705 and 0.710. The predominance of intermediate rocks over mafic ones suggests an initial intra-oceanic to transitional stage, possibly developed in a distal portion of a passive margin, such as the Japanese arc, evolving to a more developed, differentiated felsic rock associations.The role of transform fault zones, such as the Luanda shear zone, is emphasized in order to explain the consumption of a wide oceanic plate in the inner portion of Western Gondwana.  相似文献   

Cr and Zn biosorption by <Emphasis Type="Italic">Aspergillus niger</Emphasis>     

Maria do Socorro Vale  Ronaldo Ferreira do Nascimento  Renato Carrhá Leitão  Sandra Tédde Santaella 《Environmental Earth Sciences》2016,75(6):462

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Trace metal distribution in white shrimp (<Emphasis Type="Italic">Litopenaeus schmitti</Emphasis>) tissues from a Brazilian coastal area     

Juliana Ribeiro Nascimento  Edison Dausacker Bidone  Denise Rolão-Araripe  Karina Annes Keunecke  Elisamara Sabadini-Santos 《Environmental Earth Sciences》2016,75(11):990

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Animal thermal comfort index for the state of Paraíba,Brazil: trend,influencing factors,and mitigating measures     

da Silva  Valquiria Cordeiro  de Sousa Nascimento  Robson  Neto  José Pinheiro Lopes  de Melo Lopes  Fernanda Fernandes  Miranda  Jaciara Ribeiro  Furtado  Dermeval Araújo 《Theoretical and Applied Climatology》2022,147(1-2):523-534

Theoretical and Applied Climatology - The present work had the objective to determine the tendency and the influence percentage of climatic variables on the Temperature and Humidity Index (THI) in...  相似文献   

Influence of Weathering on the Strength and Hoek–Brown Parameters of a Kinzigite Gneiss     

Gomes Marques  Eduardo Antonio  do Amaral Vargas Júnior  Eurípedes  Pereira  Luana Cláudia  Leão  Marcio Fernandes 《Geotechnical and Geological Engineering》2021,39(5):3995-4008

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