Big fish (and a smallish skate) eat small fish: diet variation and trophic level of Sympterygia acuta,a medium‐sized skate high in the food web          下载免费PDF全文

Santiago A. Barbini  Luis O. Lucifora 《Marine Ecology》2016,37(2):283-293

The bignose fanskate, Sympterygia acuta, is a small‐to‐medium‐sized species endemic to shallow coastal waters of the Southwest Atlantic. Sympterygia acuta displays a clear seasonal reproductive cycle, characterized by maximum egg‐laying activity in spring and hatching in summer. We hypothesized that diet and feeding activity change with maturity stage and season and that, given its smallish size, the trophic level is low. Using a multiple‐hypothesis modeling approach, the diet of S. acuta in relation to sex, body size, maturity stage, region (i.e. north and south) and season was analysed; and a potential relationship between feeding activity and the seasonal reproductive cycle was assessed. Sympterygia acuta fed on a broad spectrum of prey, but teleosts were more important (47.97% index of relative importance, %IRI), followed by decapods (39.84%IRI), cumaceans (8.31%IRI) and isopods (1.89%IRI). Maturity stage was a strong determinant of the ontogenetic diet shift of S. acuta, and relationships between number of prey consumed with season and region were found.. Feeding activity was higher in the cold season than in the warm season, and was less important in the south region than in the north region. Unexpectedly, the specific trophic level was high (3.87). Sympterygia acuta shifts its diet with maturity stage, possibly by a combination of an improved ability to capture prey and a change in energy demand of mature individuals. Despite being a small‐to‐medium‐sized skate, S. acuta showed a trophic level similar to that of large‐bodied marine predators. It reduces its feeding activity seasonally because in the warm season this species may experience an increased predation risk from large sharks.  相似文献   

Geoarchaeology and Construction of the La Chabola de la Hechicera Megalithic Tomb,Elvillar, Northern Spain     

Luis M. Martínez‐Torres  Javier Fernndez‐Eraso  Jos A. Mujika‐Alustiza  lvaro Rodríguez‐Miranda  Jos M. Valle‐Meln 《Geoarchaeology》2014,29(4):300-311

La Chabola de la Hechicera, a Neolithic collective tomb which was first used at ca. 3850 B.C., has been re‐excavated for interpretation and stabilization. Information about the sources, handling, and placement of building materials allowed determination of the methods used to construct the dolmen monument. All of the rocks used in the structure are local Miocene sandstones, and the slabs were probably taken directly from the base of natural slopes near the monument. The chamber slabs were not carved, but some passage slabs were retouched to level the cover slabs. Fragments for the tumulus were obtained by mechanical fracturing. All of the slabs are imbricated, making it possible to determine the order in which they were placed. Thus, the identification of building materials and their mode of placement allows for the reconstruction of each stage of the building of the monument, providing unusually rich data for understanding the geoarchaeology and building archaeology of a dolmenic structure.  相似文献   

Groundwater–wetlands interaction in coastal lagoon of Almería (SE Spain)     

Francisco Sánchez-Martos  Luis Molina-Sánchez  Juan Gisbert-Gallego 《Environmental Earth Sciences》2014,71(1):67-76

Water resources management in coastal wetlands requires the degree of interdependence between groundwater and terrestrial ecosystems to be known. This is especially so in semiarid areas where surface inflows are restricted, marine influence is marked and the evaporation rate is high. Thus, chemistry of surface waters is very variable in the Cerrillos-Punta Entinas wetlands system. Using classical hydrogeochemical tools, the main processes that favor a diversity of water types were described, related to: presence of salt deposits on the lagoon beds, marine origin of the water, and local influence of groundwater. All these factors make it difficult to establish what reference conditions should be used to define “good” water quality of the surface waters—as required by the Water framework directive—and to understand the influence of groundwater on these coastal wetlands. Knowledge about the influence of the different interaction of these factors on the hydrogeochemical dynamics is required for the sustainable management of this protected natural site.  相似文献   

CONSTAnT – A Conceptual Data Model for Semantic Trajectories of Moving Objects     

Vania Bogorny  Chiara Renso  Artur Ribeiro de Aquino  Fernando de Lucca Siqueira  Luis Otavio Alvares 《Transactions in GIS》2014,18(1):66-88

Several works have been proposed in the last few years for raw trajectory data analysis, and some attempts have been made to define trajectories from a more semantic point of view. Semantic trajectory data analysis has received significant attention recently, but the formal definition of semantic trajectory, the set of aspects that should be considered to semantically enrich trajectories and a conceptual data model integrating these aspects from a broad sense is still missing. This article presents a semantic trajectory conceptual data model named CONSTAnT, which defines the most important aspects of semantic trajectories. We believe that this model will be the foundation for the design of semantic trajectory databases, where several aspects that make a trajectory “semantic” are taken into account. The proposed model includes the concepts of semantic subtrajectory, semantic points, geographical places, events, goals, environment and behavior, to create a general concept of semantic trajectory. The proposed model is the result of several years of work by the authors in an effort to add more semantics to raw trajectory data for real applications. Two application examples and different queries show the flexibility of the model for different domains.  相似文献   

Shallow Miocene basaltic magma reservoirs in the Bahia de Los Angeles basin, Baja California, Mexico     

Luis A. Delgado-Argote  Juan García-Abdeslem 《Journal of Volcanology and Geothermal Research》1999,88(1-2)

The basement in the Bahía de Los Angeles basin consists of Paleozoic metamorphic rocks and Cretaceous granitoids. The Neogene stratigraphy overlying the basement is formed, from the base to the top, by andesitic lava flows and plugs, sandstone and conglomeratic horizons, and Miocene pyroclastic flow units and basaltic flows. Basaltic dikes also intrude the whole section. To further define its structure, a detailed gravimetric survey was conducted across the basin about 1 km north of the Sierra Las Flores. In spite of the rough and lineal topography along the foothills of the Sierra La Libertad, we found no evidence for large-scale faulting. Gravity data indicates that the basin has a maximum depth of 120 m in the Valle Las Tinajas and averages 75 m along the gravimetric profile. High density bodies below the northern part of the Sierra Las Flores and Valle Las Tinajas are interpreted to be part of basaltic dikes. The intrusive body located north of the Sierra Las Flores is 2.5 km wide and its top is about 500 m deep. The lava flows of the top of the Sierra Las Flores, together with the distribution of basaltic activity north of this sierra, suggests that this intrusive body continues for 20 km along a NNW-trending strike. Between the sierras Las Flores and Las Animas, a 0.5-km-wide, 300-m-thick intrusive body is interpreted at a depth of about 100 m. This dike could be part of the basaltic activity of the Cerro Las Tinajas and the small mounds along the foothills of western Sierra Las Animas. The observed local normal faulting in the basin is inferred to be mostly associated with the emplacement of the shallow magma reservoirs below Las Flores and Las Tinajas.  相似文献   

Robust Mean Traveltime Curves in 2D Transmission Tomographic Surveys     

Juan L. Fernández Martínez  Luis M. Pedruelo González  James W. Rector 《Mathematical Geosciences》2010,42(4):377-400

  相似文献   

Dynamics of contaminants in phosphogypsum of the fertilizer industry of Huelva (SW Spain): From phosphate rock ore to the environment     

Rafael Pérez-López  José Miguel Nieto  Israel López-Coto  Juan Luis Aguado  Juan Pedro Bolívar  María Santisteban 《Applied Geochemistry》2010

The dynamics of trace elements from phosphate rock ore to the environment in a phosphoric acid plant located in SW Spain and the impact of phosphogypsum wastes were investigated through total digestion and BCR-sequential extraction. Based on total concentration, element transfer factors as criteria for examining the potential environmental risk of waste with respect to ore rock were calculated, and it was observed that most trace elements are only transferred into phosphogypsum at rates of 2–12%. However, based on those concentrations that are likely to be most readily mobile in the environment, phosphogypsum acts as a higher emission source of contaminants than the original rock. About 100 million tonnes of phosphogypsum are stack-piled in a dump of 1200 ha over salt-marshes of an estuary formed by the confluence of the Tinto and Odiel rivers. Phosphogypsum has been applied, at the recommended rate of 20–25 t/ha since 1978–2001, to improve fertility and reduce Na saturation in agricultural soils of the Guadalquivir river valley (140 km²). Phosphogypsum capacity as a source of mobile contaminants in three environmental scenarios (water leaching, exposure to oxidising and reducing conditions) was quantified by combining sequential extraction and waste mass. The amounts of mobile contaminants that could be released for every tonne of phosphogypsum are approximately 7 × 10² g Sr, 1.1 × 10² g Fe, 55 g Y, 30 g Ce, 12 g Cr, 11 g Ti, 5 g Zn, 4 g each of Cu and Pb, 3 g each of V and Cd, 2 g each of As and Ni and 1 g U. Multiplying these amounts by 100 Mt and 20–25 t/ha, it is possible to calculate risk assessments of phosphogypsum for both estuarine zones, e.g. in a hypothetical stack collapse and waste spilling, and agricultural soils, respectively.  相似文献   

Experimental simulation of melt migration in stromatic metatexite migmatites     

Marcos García-Arias  Luis Guillermo Corretgé  Antonio Castro 《Mineralogy and Petrology》2010,99(3-4):153-164

Melting experiments on a gneissic protolith using the diamond trap technique produced an accumulation of crystals of biotite in the boundary of the diamond trap. Several hypotheses can be inferred to explain this feature, but textural evidence and calculations of the settling and drag velocities of the crystals suggest a model of extraction of melt due to a pressure gradient inside the capsule as the most likely origin of this biotite layer. This biotite layer and the trapped melt resemble the melanosome and leucosome, respectively, of stromatic metatexite migmatites. The melt extraction model developed is similar to the “filter pressing” model for migmatite formation. The diamond trap technique is a suitable method to develop migmatites experimentally.  相似文献   

Uranium minerals from the San Marcos District, Chihuahua, Mexico   总被引：1，自引：0，他引：1  

Manuel Reyes-Cortés  Luis Fuentes-Cobas  Enrique Torres-Moye  Hilda Esparza-Ponce  María Elena Montero-Cabrera 《Mineralogy and Petrology》2010,99(1-2):121-132

The mineralogy of the two uranium deposits (Victorino and San Marcos I) of Sierra San Marcos, located 30 km northwest of Chihuahua City, Mexico, was studied by optical microscopy, powder X-ray diffraction with Rietveld analysis, scanning electron microscopy with energy dispersive X-ray analysis, inductively coupled plasma spectrometry, and gamma spectrometry. At the San Marcos I deposit, uranophane Ca(UO₂)₂Si₂O₇·6(H₂O) (the dominant mineral at both deposits) and metatyuyamunite Ca(UO₂)(V₂O₈)·3(H₂O) were observed. Uranophane, uraninite (UO_2+x), masuyite Pb(UO₂)₃O₃(OH)·3(H₂O), and becquerelite Ca(UO₂)₆O₄(OH)₆ ·(8H₂O) are present at the Victorino deposit. Field observations, coupled with analytical data, suggest the following sequence of mineralization: (1) deposition of uraninite, (2) alteration of uraninite to masuyite, (3) deposition of uranophane, (4) micro-fracturing, (5) calcite deposition in the micro-fractures, and (6) formation of becquerelite. The investigated deposits were formed by high-to low-temperature hydrothermal activity during post-orogenic evolution of Sierra San Marcos. The secondary mineralization occurred through a combination of hydrothermal and supergene alteration events. Becquerelite was formed in situ by reaction of uraninite with geothermal carbonated solutions, which led to almost complete dissolution of the precursor uraninite. The Victorino deposit represents the second known occurrence of becquerelite in Mexico, the other being the uranium deposits at Peña Blanca in Chihuahua State.  相似文献   

Improving the descendant relationship of cluster galaxies at z < 1     

Cleivison Souza de Jesus  Andre Luis Batista Ribeiro  Christine Cordula Dantas 《Astronomische Nachrichten》2024,345(1):e220081

In this work, we study how to improve well-known techniques for detecting progenitors/descendants of galaxies, such as the NDpredict program, when applied to galaxies in clusters. The improvement of this particular method is based on the use of the red sequence of galaxies in those environments. Objects close to the red sequence in the color and magnitude diagram are more likely to belong to the cluster. This defines a probability scale which is then combined with the one generated by NDpredict. This procedure is optimized for the study of galaxies in clusters over different epochs. Our main result is that, for a sample composed of $120$ clusters, with masses greater than ${10}^{13.25}{M}_{\odot }$, selected from the IllustrisTNG simulations (namely, the TNG100 runs). In $99\%$ of the cases (i.e., $119$ systems), we obtain better performance with the red sequence method in comparison to the original NDpredict, and the average gain obtained is $28\%$ in the identification of descendants for this sample of cluster galaxies.  相似文献