Diel and seasonal variability in the fish community structure of a mud‐bottom estuarine habitat in the Gulf of Mexico     

Manuel Castillo‐Rivera  Rocío Zárate‐Hernández  Selene Ortiz‐Burgos  José Zavala‐Hurtado 《Marine Ecology》2010,31(4):633-642

We hypothesized that temporal variation in fish species composition and community structure in a low complexity habitat in the Pueblo Viejo Lagoon, Mexico, is influenced by diel light/dark cycles and tidal stage, and by seasonal changes in salinity and temperature. We collected a total of 17,661 individuals during 2‐h interval sampling over six bi‐monthly 24‐h sampling cycles representing 53 species, of which 11 (～20%) were previously unknown in the system. Diel variation indicated that significantly higher numbers of individuals and species were caught at night, whereas diversity and evenness were higher during the day. Species richness was significantly higher in July and January, whereas diversity and evenness peaked around May; both were correlated with temperature. Diel variation in species composition was influenced primarily by the light/dark cycle. Cluster analyses of each diel cycle separated fish assemblages from midday samples from those of nocturnal samples, separated by an extended wide transition period as fish moved at dawn and during the late afternoon/dusk. Significant shifts (as determined by MANOVA) in assemblage structure occurred between months. Canonical correspondence analysis showed that temperature and day/night effects were the most important environmental variables structuring the fish community. This constrained ordination also defined species with specific habitat preferences as follows: (i) diurnal, warm temperature species (mainly planktivores) (Brevoortia gunteri, Cetengraulis edentulus, Diapterus auratus, and Membras martinica); (ii) nocturnal, warm temperature species (mainly predators) (Citharichthys spilopterus, Cathorops melanopus, and Bairdiella spp.); and (iii) low temperature, diurnal species (Brevoortia patronus and Mugil curema) or those with twilight and nocturnal distributions (Anchoa mitchilli, the most numerically abundant species). Our results indicate that diel and seasonal changes in fish community structure were mainly related to day/night cycles and temperature regimes.  相似文献   

Structural evolution of the Orange Basin gravity-driven system,offshore Namibia     

Jose de Vera  Pablo GranadoKen McClay 《Marine and Petroleum Geology》2010

The Orange Basin records the development of the Late Jurassic to present day volcanic-rifted passive margin of Namibia. Regional extension is recorded by a Late Jurassic to Lower Cretaceous Syn-rift Megasequence, which is separated from a Cretaceous to present day post-rift Megasequence by the Late Hauterivian (ca. 130 Ma) break-up unconformity. The Late Cretaceous Post-rift evolution of the basin is characterized by episodic gravitational collapse of the margin. Gravitational collapse is recorded as a series of shale-detached gravity slide systems, consisting of an up-dip extensional domain that is linked to a down-dip zone of contraction domain along a thin basal detachment of Turonian age. The extensional domain is characterized by basinward-dipping listric faults that sole into the basal detachment. The contractional domain consists of landward-dipping listric faults and strongly asymmetric basinward-verging thrust-related folds. Growth stratal patterns suggest that the gravitational collapse of the margin was short-lived, spanning from the Coniacian (ca. 90 Ma) to the Santonian (ca. 83 Ma). Structural restorations of the main gravity-driven system show a lack of balance between up-dip extension (24 km) and down-dip shortening (16 km). Gravity sliding in the Namibian margin is interpreted to have occurred as a series of episodic short-lived gravity sliding between the Cenomanian (ca. 100 Ma) and the Campanian (ca. 80 Ma). Gravity sliding and spreading are interpreted to be the result of episodic cratonic uplift combined with differential thermal subsidence. Sliding may have also been favoured by the presence of an efficient detachment layer in Turonian source rocks.  相似文献   

Geophysical and geochemical constraints on the age and paleoclimate implications of Holocene lacustrine cores from the Andes of central Chile          下载免费PDF全文

Rachel J. Tiner  Robert M. Negrini  Jose L. Antinao  Eric McDonald  Antonio Maldonado 《第四纪科学杂志》2018,33(2):150-165

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Anelastic Rayleigh Wave Attenuation In the Iberian Peninsula   总被引：1，自引：0，他引：1  

Jose A. Canas  Fernando De  Miguel†  Francisco Vidal†  Gerardo Alguacil† 《Geophysical Journal International》1988,95(2):391-396

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Petrology of pumices of April 1993 eruption of Lascar (Atacama, Chile)     

Bernard Déruelle  Oscar Figueroa A.  Eduardo Medina T.  Jose Viramonte G.  Mario Maragaño C. 《地学学报》1996,8(2):191-199

Lascar Volcano (Atacama, Chile) erupted on 18–20 April 1993. Several sub-Plinian explosions occurred, and some were mushroom-shaped. The highest column rose up to 23 km. Ash clouds crossed South America eastwards. Dacite pumice falls made of blocks and ashes were deposited on the flanks of the volcano as a result of collapsed columns. The pumice contains phenocrysts of plagioclase, enstatite, augite, biotite, magnetite and ilmenite and small crystals of apatite. The 1992 previous andesite dome inside the crater was destroyed. Banded blocks resulting from mingling of the dacitic pumice and andesite from the dome are found in the pumice flow. Both the lava dome and the pumice are representative of the Lascar high-K magma unit. Dacitic pumice is a product of crystal fractionation of the andesitic magma.  相似文献   

A warm-season comparison of WRF coupled to the CLM4.0, Noah-MP,and Bucket hydrology land surface schemes over the central USA     

Matthew?S.?Van Den BroekeEmail authorView author&#;s OrcID profile  Andrew?Kalin  Jose?Abraham?Torres?Alavez  Robert?Oglesby  Qi?Hu 《Theoretical and Applied Climatology》2018,134(3-4):801-816

In climate modeling studies, there is a need to choose a suitable land surface model (LSM) while adhering to available resources. In this study, the viability of three LSM options (Community Land Model version 4.0 [CLM4.0], Noah-MP, and the five-layer thermal diffusion [Bucket] scheme) in the Weather Research and Forecasting model version 3.6 (WRF3.6) was examined for the warm season in a domain centered on the central USA. Model output was compared to Parameter-elevation Relationships on Independent Slopes Model (PRISM) data, a gridded observational dataset including mean monthly temperature and total monthly precipitation. Model output temperature, precipitation, latent heat (LH) flux, sensible heat (SH) flux, and soil water content (SWC) were compared to observations from sites in the Central and Southern Great Plains region. An overall warm bias was found in CLM4.0 and Noah-MP, with a cool bias of larger magnitude in the Bucket model. These three LSMs produced similar patterns of wet and dry biases. Model output of SWC and LH/SH fluxes were compared to observations, and did not show a consistent bias. Both sophisticated LSMs appear to be viable options for simulating the effects of land use change in the central USA.  相似文献   

Multivariate analysis of contamination in the mining district of Linares (Jaén, Spain)     

J. Martínez Lpez  J. Llamas Borrajo  E. De Miguel García  J. Rey Arrans  Ma C. Hidalgo Estvez  A.J. Sez Castillo 《Applied Geochemistry》2008,23(8):2324-2336

Historically, a significant level of mining activity has taken place in the batholite-related metalogenic enclave of Linares (Jaén province, Spain), associated with Pb–Ag, Cu, Zn and Fe sulphides and Ba sulphate mineralization, though mining here has now been abandoned. Additionally, the area features a significant amount of urban, industrial and agricultural activities. These considerations, taken together, explain the need to assess the levels of concentration of trace elements and to determine their relationship with geogenic and anthropogenic factors. For geochemical characterisation of the soil, the region has been divided into 126 grid squares with an area of 1 km². For each grid square, 32 trace elements have been analysed. Elemental concentrations of Cu, Pb, Zn, As and Mn have been included in statistical analyses. According to the reference levels established by the Regional Government (Junta de Andalucía), soils in a large part of the study area require amendment applications. The comparison of the mean content for each grid square with the reference levels reveals a significant degree of contamination of the soil by Cu (719 mg kg⁻¹), Pb (22,964 mg kg⁻¹) and As (100 mg kg⁻¹) in those grid squares affected by metallurgic activities. By means of factor analysis, four scores have been identified which together account for 80% of the variance observed. The first score is highly correlated with the logarithms of the variables Fe, Th, La, Ti, Al, Na, K, Zr, Y, Nb, Be and Sc. It is a “natural” factor that indicates the type of soil matrix (fundamentally granites and, to a lesser degree, Triassic materials). The second score shows high correlation with the logarithms of the variables Mo, Cu, Pb, Zn, Ag, Co, Mn, As, Cd, Sb, Ba, W and Sn, and is the “metallization” factor related to the mineralization that has been exploited. The third score is mainly determined by the logarithms of the variables Sr, Ca and Mg. This is a “natural” factor that indicates a type of carbonate soil matrix (Miocene). Finally, the fourth factor groups the logarithms of the variables Ni, V and Cr, elements that are associated with the combustion of fossil fuels. Analysis of the patterns of each of the factors identified enabled achieving a global characterisation of the study area. Cluster analysis of the observations showed there to be five clusters relating to the grid squares, differentiated by lithologies and degrees of contamination. These clusters are used to determine the background of granite and to calculate the anomalous load.  相似文献   

Selected ore deposits of Brazil     

Steffen Hagemann  Jose Carlos Frantz  Hardy Jost 《Mineralium Deposita》2008,43(2):127-128

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Optimal Stopping Location of a High Speed Train using GIS and Multicriteria Decision‐making          下载免费PDF全文

Roberto Sañudo  Jose Luis Moura  Ruben Cordera  Angel Ibeas 《Transactions in GIS》2017,21(1):151-168

This article develops a methodology using a Geographical Information System (GIS) to evaluate the best location to stop a high speed passenger train when faced with an undesired event. The proposed method is based on multicriteria decision‐making where different stretches of line which could be chosen as the stopping point are ranked depending on the characteristics of the line, the surrounding area and its accessibility for equipment. The method was integrated into the GIS to develop an expert support system for decision makers faced with different kinds of undesired events. It has been applied to a case study on the high speed line between Valladolid and Madrid (Spain). The proposed method is new and has not previously been applied to high speed railway networks and could be adapted to other case studies. The speed of the algorithm provides an almost instantaneous reply within seconds of an emergency situation occurring. The method can therefore be part of an overall support system for decision making in undesired rail events.  相似文献   

Effects of Unstable Thermal Stratification on Vertical Fluxes of Heat and Momentum in Urban Areas     

Andres Simón-Moral  Jose Luis Santiago  Alberto Martilli 《Boundary-Layer Meteorology》2017,163(1):103-121

A Reynolds-averaged Navier–Stokes microscale model is used for the simulation of the effect of unstable thermal stratification on the flow within an aligned configuration of building-like cubes as used in Santiago et al. (Urban Clim 9:115–133, 2014). The spatially-averaged results show increased dispersive fluxes, turbulent length scales and sectional drag coefficient. An extension of K-theory is presented to parametrize the sum of the turbulent and dispersive fluxes, and the length scale and drag coefficient increases are parametrized as functions of the ratio of buoyant and inertial forces. This approach improves the results of urban canopy parametrization simulations inside and above the urban canyon and represents the first attempt to account for the dispersive fluxes and the effect of solar radiation on the flow.  相似文献