Community structure and dynamics of deep-water decapod assemblages from Le Danois Bank (Cantabrian Sea, NE Atlantic): Influence of environmental variables and food availability   总被引：1，自引：0，他引：1  

Joan E. Cartes  Alberto Serrano  Francisco Velasco  Santiago Parra  Francisco Snchez 《Progress in Oceanography》2007,75(4):797-816

The community structure of the decapod crustaceans inhabiting Le Danois Bank (Cantabrian Sea, NE Atlantic Ocean) was studied on two cruises performed in October 2003 and April 2004. Otter and beam-trawls were used to collect this fauna. At depths ranging between 455 and 1048 m, we found distinct decapod assemblages on the bank summit and deeper in the inner basin (between the bank and the continental shelf). The faunal discontinuity between these groups appeared at around 600 m (e.g. between 612 and 642 m in the basis of species replacement). The summit assemblage was characterized by low diversity (in terms of number and relative abundances of species) and by the dominance of hermit crabs (Pagurus alatus, Anapagurus laevis, Pagurus excavatus), the crangonid Pontophilus spinosus and the squat lobster Munida sarsi. Species characterizing the deeper assemblage, which was richer in terms of diversity, were Munida tenuimana, Parapagurus pilosimanus, Pontophilus norvegicus, the crab Geryon trispinosus and a number of bathypelagic shrimps (Sergia robusta, Acanthephyra pelagica and Pasiphaea tarda). Changes in decapod composition characterized by multidimensional scaling analyses were correlated with different variables, e.g. %mud and %organic matter (OM), temperature and salinity close to the bottom. Among those the %OM and %mud in sediments affected decapod distributions the most. The summit of the bank was covered by fine sediments with low proportion of mud (13.9–29.3%) and OM (2.55–3.50%). By contrast, sediment of the inner basin had a higher proportion of OM and mud (64.1–84.2%; 6.26–7.00%, respectively). The low proportion of mud at the summit of Le Danois Bank may explain the absence or scarcity of burrowing species (e.g. the lobster Nephrops norvegicus, the shrimps Calocaris macandreae and Alpheus glaber and the crab Goneplax rhomboides), that are dominant at similar depths (400–500 m) in the upper muddy assemblage on the mainland-continental slope in the Bay of Biscay (44–46°N). The dominance of certain species on the summit of submarine mounts can probably be related to their biology and feeding ecology. For example, pagurids are deposit feeders, even consuming marine snow (e.g. Chl-a identified in guts of Pagurus alatus), and they have low gut fullness (probably indicating a capacity to withstand long periods under starvation), that would favour their adaptability to a rather unpredictable habitat such as Le Danois Bank summit. Regarding prey availability, zooplankton/micronekton and infauna distributed around Le Danois Bank showed different depth-related patterns. Among zooplankton, mesopelagic decapods, mysids, and fishes were absent at the bank summit, while euphausiids exhibited high abundances over the summit. No significant trends with depth were found for infauna abundance, and for instance polychaete densities were similar both at the summit and the inner basin. Therefore, prey availability was lower for summit assemblages regarding zooplankton/micronekton. Patterns in mean size vs. depth were species specific for decapods, and the possible role of the bank summit as a recruitment area was not general for the whole decapod assemblage.  相似文献   

Phosphate adsorption and desorption in a tropical estuary (Maracaibo system)     

D. López-Hernández  T. Herrera  F. Rotondo 《Marine environmental research》1980,4(2):153-163

The Maracaibo Estuary is of particular interest because of its location in the tropics, its large size (over 12,000 km²), the economic importance of its underlying hydrocarbon deposits and its increasing rate of pollution. Sediments from this estuary were studied in order to characterise their capacity to adsorb and desorb phosphorus. Considerable variability in capacity for phosphate sorption was found among the seventeen samples studied. This variability can be attributed first to the differences among the samples in total P content and, secondly, to their differences in free iron content. Also, it appears that P retention contributes to the control of P concentration in the water and therefore the sediments serve as a buffer in controlling P eutrophication in the estuary.  相似文献   

Flotation of oxidized minerals of copper using a new synthetic chelating reagent as collector     

M. Barbaro  R. Herrera Urbina  C. Cozza  D. Fuerstenau  A. Marabini 《International Journal of Mineral Processing》1997,50(4):275-287

A new synthetic reagent containing a mixed aliphatic-aromatic structure, with a hydrocarbon chain and an aminothiophenol chelating group, has proven to be an effective collector for the flotation of chrysocolla minerals. The flotation is optimum in the narrow pH range of 5.5 to 6, falls sharply at pH 5, and is moderate in the pH range 7 to 11. Infrared spectra indicate that copper aminothiophenolate chelates are formed on the surface of the chrysocolla under the conditions of maximum flotation.  相似文献   

Daily precipitation statistics in a EURO-CORDEX RCM ensemble: added value of raw and bias-corrected high-resolution simulations     

A. Casanueva  S. Kotlarski  S. Herrera  J. Fernández  J. M. Gutiérrez  F. Boberg  A. Colette  O. B. Christensen  K. Goergen  D. Jacob  K. Keuler  G. Nikulin  C. Teichmann  R. Vautard 《Climate Dynamics》2016,47(3-4):719-737

  相似文献   

Comparison of water-level,extensometric, DInSAR and simulation data for quantification of subsidence in Murcia City (SE Spain)     

S. Tessitore  J. A. Fernández-Merodo  G. Herrera  R. Tomás  M. Sanabria  J. Duro  J. Mulas  D. Calcaterra 《Hydrogeology Journal》2016,24(3):727-747

Subsidence due to groundwater overexploitation has been recognized in the metropolitan area of Murcia (25 km²) in south-eastern Spain since the early 1990s. Previous published works have focused their attention on land subsidence that occurred during the drought period between 1995 and 2008. This work first analyzes the groundwater recovery that has occurred since 2008 and then determines the kind of associated ground deformation detected by the new extensometric data. Subsequently, subsidence time series are computed on 24 geotechnical boreholes scattered throughout the study area by means of a hydro-mechanical finite element code and a linear-elastic constitutive law. A spatio-temporal interpolation of the numerically modeled surface displacements is performed over the whole domain and compared with extensometers and DInSAR-derived displacement maps in two different periods: the drought period from 2004 to 2008, and the recovery period from 2008 to 2012. In spite of the limited information on the geomechanical parameters characterizing the modelled geological formations, the proposed approach is able to discriminate areas where the soils have an elastic behavior (small differences in the comparisons) or an elasto-plastic behavior (large differences in the comparisons). This zonation enhances the understanding of the subsidence phenomenon in Murcia City and could prevent, from a quantitatively point of view, future severe subsidence due to aquifer overexploitation.  相似文献   

An integrated GIS-based tool for aquifer test analysis     

R. Criollo  V. Velasco  E. Vázquez-Suñé  A. Serrano-Juan  M. Alcaraz  A. García-Gil 《Environmental Earth Sciences》2016,75(5):391

  相似文献   

Hydrogeology and sustainable future groundwater abstraction from the Agua Verde aquifer in the Atacama Desert,northern Chile   总被引：1，自引：0，他引：1  

Javier Urrutia  Jorge Jódar  Agustín Medina  Christian Herrera  Guillermo Chong  Harry Urqueta  José A. Luque 《Hydrogeology Journal》2018,26(6):1989-2007

The hyper-arid conditions prevailing in Agua Verde aquifer in northern Chile make this system the most important water source for nearby towns and mining industries. Due to the growing demand for water in this region, recharge is investigated along with the impact of intense pumping activity in this aquifer. A conceptual model of the hydrogeological system is developed and implemented into a two-dimensional groundwater-flow numerical model. To assess the impact of climate change and groundwater extraction, several scenarios are simulated considering variations in both aquifer recharge and withdrawals. The estimated average groundwater lateral recharge from Precordillera (pre-mountain range) is about 4,482 m³/day. The scenarios that consider an increase of water withdrawal show a non-sustainable groundwater consumption leading to an over-exploitation of the resource, because the outflows surpasses inflows, causing storage depletion. The greater the depletion, the larger the impact of recharge reduction caused by the considered future climate change. This result indicates that the combined effects of such factors may have a severe impact on groundwater availability as found in other groundwater-dependent regions located in arid environments. Furthermore, the scenarios that consider a reduction of the extraction flow rate show that it may be possible to partially alleviate the damage already caused to the aquifer by the continuous extractions since 1974, and it can partially counteract climate change impacts on future groundwater availability caused by a decrease in precipitation (and so in recharge), if the desalination plant in Taltal increases its capacity.  相似文献   

Site scale modeling of slow-moving landslides,a 3D viscoplastic finite element modeling approach     

G. Bru  J.A. Fernández-Merodo  J.C. García-Davalillo  G. Herrera  J. Fernández 《Landslides》2018,15(2):257-272

This paper presents an advanced 3D numerical methodology to reproduce the kinematics of slow active landslides, more precisely, to reproduce the nearly constant strain rate (secondary creep) and the acceleration/deceleration of the moving mass due to hydrological changes. For this purpose, finite element analyses are performed in a large area covering a long time-span (12 years), in order to exhibit different interacting slope movements. First, we perform a stability analysis using the shear strength reduction (SSR) technique with a Mohr-Coulomb failure criteria. It is done in order to compute factors of safety (FS) and to identify two different scenarios, the first one being stable (FS > 1) and the second one being unstable (FS < 1). In the studied test case, the Portalet landslide (Central Spanish Pyrenees), the first scenario corresponds to an initial stable configuration of the slope and the second one to an unstable excavated configuration. Second, taking the first scenario as an initial condition, a time-dependent analysis is performed using a coupled formulation to model solid skeleton and pore fluids interaction, and a simplified ground water model that takes into account daily rainfall intensity. In this case, a viscoplastic constitutive model based on Perzyna’s theory is applied to reproduce soil viscous behavior and the delayed creep deformation due to the excavation. The fluidity parameter is calibrated to reproduce displacements measured by the monitoring systems. Our results demonstrate that 3D analyses are preferable to 2D ones for reproducing in a more realistic way the slide behavior. After calibration, the proposed model is able to simulate successfully short- and medium-term predictions during stages of primary and secondary creep.  相似文献   

Upwelling-enhanced seasonal stratification in a semiarid bay     

Peng Cheng  Arnoldo Valle-Levinson  Clinton D. Winant  Aurelien L.S. Ponte  Guillermo Gutierrez de Velasco  Kraig B. Winters 《Continental Shelf Research》2010,30(10-11):1241-1249

The role of wind-driven upwelling in stratifying a semiarid bay in the Gulf of California is demonstrated with observations in Bahía Concepción, Baja California Sur, Mexico. The stratification in Bahía Concepción is related to the seasonal heat transfer from the atmosphere as well as to cold water intrusions forced by wind-driven upwelling. During winter, the water column is relatively well-mixed by atmospheric cooling and by northwesterly, downwelling-favorable, winds that typically exceed 10 m/s. During summer, the water column is gradually heated and becomes stratified because of the heat flux from the atmosphere. The wind field shifts from downwelling-favorable to upwelling-favorable at the beginning of summer, i.e., the winds become predominantly southeasterly. The reversal of wind direction triggers a major cold water intrusion at the beginning of the summer season that drops the temperature of the entire water column by 3–5 °C. The persistent upwelling-favorable winds during the summer provide a continuous cold water supply that helps maintain the stratification of the bay.  相似文献   

A contribution to the ore genesis of the magnesite deposit of Eugui,Navarra (Spain)     

F. Velasco  A. Pesquera  R. Arce  F. Olmedo 《Mineralium Deposita》1987,22(1):33-41

In the area of the magnesite deposits of Eugui (Navarra, Spain) studies on illite crystallinity, the degree of graphitization of carbonaceous material, measurements of vitrinite reflectivity, and fluid inclusions have been carried out on dolomites, magnesites, schists, and carbonaceous matter. These rocks have suffered metamorphism of very low to low grade.The magnesite appears generally concordant with the Namurian dolomitic rocks showing a typically banded structure. The genetic model proposed involves an early Mg concentration during sedimentation (syndiagenetic dolomitization), lateral circulation of saline solutions, and formation of diagenetically crystallized rhythmites (DCR), and final compaction. The formation of magnesite took place under the conditions of low pressure and temperatures close to 150°C, very similar to all strata-bound ore deposits. Deformation and regional metamorphism only caused minor removal, recrystallization, and transformation of the clay minerals and carbonaceous matter.  相似文献