Life history of the bathyal octopus Pteroctopus tetracirrhus (Mollusca,Cephalopoda) in the Mediterranean Sea     

Antoni Quetglas  Francesc Ordines  María González  Ignacio Franco 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(8):1379-1390

The life cycle of the deep-sea octopus Pteroctopus tetracirrhus was studied from monthly samples obtained throughout the year in different areas of the western Mediterranean (mainly around the Balearic Islands and along the coast of the Iberian Peninsula). A total of 373 individuals (205 females, 168 males) were analyzed; females ranged from 4.5 to 14.0 cm mantle length (ML) and males from 4.5 to 11.5 cm ML. There were few small-sized octopuses (<7 cm ML) in the samples, which might indicate that these individuals inhabit rocky grounds that are not accessible to trawlers or waters deeper than the maximum depth sampled (800 m). The species occurred more frequently around the Balearic Islands than along the Iberian Peninsula as they appeared in 20% and 7%, respectively, of the hauls in these areas. The octopus inhabits the lower continental shelf and upper slope in both areas, primarily between 200 and 500 m depth. Modal lengths were followed from autumn, when recruits were caught by trawlers, to summer, when reproduction took place. Females grew from 8 to 10 cm ML from winter to spring, but this modal size did not increase further in summer; males grew from 7 to 9 cm ML from winter to spring. The total disappearance of large individuals after summer suggests a life cycle lasting a single year. The evolution of the monthly mean sizes showed that the growth was best described by log-linear functions in both sexes. The length at first maturity was clearly higher in females (12 cm ML) than in males (8 cm ML). A total of 30 different prey items, belonging to four major taxonomic groups (crustaceans, osteichthyes, cephalopods and gastropods), were identified in the stomach contents. The diet of the octopus was based on crustaceans and teleosts, which accounted for 75% and 23% of the prey items, respectively. Cephalopods and gastropods were accessory prey as they only represented 1.6% and 0.7%, respectively, of the total. The octopus showed a marked preference for the benthic fish Symphurus nigrescens and the endobenthic crustacean Alpheus glaber. The bathymetric distribution of P. tetracirrhus coincides with those of these two main prey, which suggests that the distribution of the octopus might be strongly linked to its trophic resources.  相似文献   

Multifractal analysis as a tool for validating a rainfall model     

A. P. García‐Marín  F. J. Jiménez‐Hornero  J. L. Ayuso‐Muñoz 《水文研究》2008,22(14):2672-2688

A multifractal analysis was carried out in order to validate the simulation of hourly rainfall records of a local climate model for the Iberian Peninsula. Observed and simulated hourly rainfall data from four locations in Andalusia (southern Spain) were used to carry out the study. In order to detect the influence of the length of the data series on the results, two different sizes were used for the real data: 4 years, and 20 years. The results show that algebraic tails are required to fit the probability distribution of extreme rain event sizes, and rain and dry event durations for both kinds of rainfall data. Similar results are found for the extreme rain event sizes and dry event durations fits when the real and synthetic data are considered. Nevertheless, some differences appear in the cases of rain event durations. The detection of the presence of a first‐order multifractal phase transition associated with a critical moment in the empirical moment scaling exponent function and the results of the extreme rain event sizes fits, reveal that real rainfall is a self‐organized criticality (SOC) process. That behaviour is less evident in the simulated rainfall series. The same ‘synoptic maximum’ value was found for each place with both types of rainfall data. A time clustering analysis was carried out applying the count‐based periodogram and the Fano factor methods. Some periodicities have been detected in the periodograms, especially for the longest real rainfall data series. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Introduction     

María dos Santos Afonso  Miguel A. Blesa 《Aquatic Geochemistry》2010,16(2):223-224

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Linking geomorphology and hydrodynamics: a case study from Península Valdés, Patagonia, Argentina   总被引：1，自引：0，他引：1  

María del Pilar Alvarez  Nilda E. Weiler  Mario A. Hernández 《Hydrogeology Journal》2010,18(2):473-486

A case study is presented to assess the relevance of geomorphology in hydrogeological phenomena in an arid coastal area in the Argentinean extra-Andean Patagonia (Península Valdés) with an average rainfall of 232 mm/year and a soil moisture deficit of about 472 mm/year. Various geomorphic units were identified by interpreting Landsat 7 satellite images processed with ER Mapper software and then surveyed in the field, as well as by geological characterization. The hydrodynamic analysis was based on a survey of 89 wells, the construction of equipotential maps, and the interpretation of pumping-test results by a non-equilibrium method. The hydrochemical characterization was based on chemical tests analyzed with the Easy_Quim 6.0 application. The combination of geomorphological, geological, hydrodynamic and hydrochemical elements allowed the definition of hydromorphological units that are typical of recharge, circulation and discharge areas, the latter both for coastal and inland areas in wetlands (salt pans) with elevations to ?40 m relative to sea level. These units and the criteria used for their definition allow immediate recognition of hydrogeological phenomena in arid regions such as the extra-Andean Patagonia, with low information density but with near-optimal satellite imaging of landforms due to the lack of vegetation cover.  相似文献   

Dynamics of negative hydraulic barriers to prevent seawater intrusion     

María Pool  Jesús Carrera 《Hydrogeology Journal》2010,18(1):95-105

Negative hydraulic barriers that intercept inflowing saltwater by pumping near the coast have been proposed as a corrective measure for seawater intrusion in cases where low heads must be maintained. The main disadvantage of these barriers is that they pump a significant proportion of freshwater, leading to contamination with saltwater at the well. To minimize such mixing, a double pumping barrier system with two extraction wells is proposed: an inland well to pump freshwater and a seawards well to pump saltwater. A three-dimensional variable density flow model is used to study the dynamics of the system. The system performs very efficiently as a remediation option in the early stages. Long-term performance requires a well-balanced design. If the pumping rate is high, drawdowns cause saltwater to flow along the aquifer bottom around the seawater well, contaminating the freshwater well. A low pumping rate at the seawards well leads to insufficient desalinization at the freshwater well. A critical pumping rate at the seawater well is defined as that which produces optimal desalinization at the freshwater well. Empirical expressions for the critical pumping rate and salt mass fraction are proposed. Although pumping with partially penetrating wells improves efficiency, the critical pumping rates remain unchanged.  相似文献   

Modelling shallow landslide susceptibility: a new approach in logistic regression by using favourability assessment   总被引：2，自引：0，他引：2  

María José Domínguez-Cuesta  Montserrat Jiménez-Sánchez  Ana Colubi  Gil González-Rodríguez 《International Journal of Earth Sciences》2010,99(3):661-674

A new method for estimating shallow landslide susceptibility by combining Geographical Information System (GIS), nonparametric kernel density estimation and logistic regression is described. Specifically, a logistic regression is applied to predict the spatial distribution by estimating the probability of occurrence of a landslide in a 16 km² area. For this purpose, a GIS is employed to gather the relevant sample information connected with the landslides. The advantages of pre-processing the explanatory variables by nonparametric density estimation (for continuous variables) and a reclassification (for categorical/discrete ones) are discussed. The pre-processing leads to new explanatory variables, namely, some functions which measure the favourability of occurrence of a landslide. The resulting model correctly classifies 98.55% of the inventaried landslides and 89.80% of the landscape surface without instabilities. New data about recent shallow landslides were collected in order to validate the model, and 92.20% of them are also correctly classified. The results support the methodology and the extrapolation of the model to the whole study area (278 km²) in order to obtain susceptibility maps.  相似文献   

Soil and vegetation seasonal changes in the grazing Andean Mountain grasslands     

MU?OZ María ángeles  FAZ ángel 《山地科学学报》2014,11(5):1123-1137

Andean grasslands ecosystems are fragile environments with rigorous climatologic conditions and low and variable food for the grazing. The Apolobamba area is located in the Bolivian Andean Mountains. Its high grasslands provide a natural habitat for wild and domestic camelids such as vicuna（Vicugna vicugna） and alpaca（Lama pacos）. The botanical diversity plays an essential role in maintaining vital ecosystem functions. The objectives of this research were to determine the seasonal changes in soil properties, to study the vegetation changes during the wet and dry seasons and the influence of soil properties and camelid densities on the vegetation in the Apolobamba grasslands. Four zones with different vicuna populations were selected to be studied. The following soil parameters were determined： total organic carbon, total nitrogen, available phosphorous, cation exchange capacity, exchangeable cations, pH and texture. The vegetation season changes were studied through botanical identification, above-ground biomass, plant cover and species richness. Results showed that some soil properties such as C/N ratio, CEC, silt and clay percentages kept stable against the seasonal changes. Generally, soil nutrients were relatively higher during the dry season in the surface and subsurface. The results did not point out the predominant vegetation growth during the wet season. The seasonal vegetation growth depended on each species. Thegood soil fertility corresponded to the highest plant cover. Soil fertility presented no influence on the above-ground biomass of the collected species. The negative influence of camelid grazing on soil properties could not be assessed. However, overgrazing could affect some plant species. Therefore, protection is needed in order to preserve the biodiversity in the Andean mountain grasslands.  相似文献   

Geochemical aspects of accumulation of macroelements in the subcolloidal fraction of bottom sediments at the Razdol’naya River-Amur Bay cross-section (the Sea of Japan)     

D. M. Polyakov  A. V. Mozherovskii  A. A. Mar’yash 《Russian Meteorology and Hydrology》2014,39(10):697-704

The concentration of Si, Al, Mg, K, Ca, Na, Sr, and Ba in the subcolloidal fraction of sediments at the Razdol’naya River-Amur Bay cross-section is determined using the atomic emission spectroscopy method. Computed is the mean content of studied elements in the soil and river bottom sediments (to the mixing zone). Revealed are river bottom sediments with the high concentration of macroelements corresponding to the zone of mixing of fresh river water and salt sea water. It is demonstrated that the additional accumulation of macroelements (Ca, Na, and Sr) in these sediments is associated with the formation of hydroxides of Fe and Mn and processes of sorption (Mg, Ca, Na, K, Sr, and Ba) on clay minerals (hydromica and smectites).  相似文献   

Technical, financial and location criteria for the design of land application system treatment     

Juana María Sanz  Ángel de Miguel  Irene de Bustamante  Alberto de Tomás  José Luis Goy 《Environmental Earth Sciences》2014,71(1):13-21

Conventional water treatments when downsized to cover the demands of small and scattered populations are costly and ineffective. In fact, many small towns cannot afford the high average treatment costs nor provide the skill and complex management requirements. Even when these facilities are available, waste water might not be properly treated. Land application system treatments (LAST) have been shown to be preferable on the basis of their technical effectiveness and financial viability. The recently approved Spanish regulations (RDL 1620/2007, pp 50369–50661) represent an opportunity for the implementation of well-designed LASTs. This paper presents an assessment methodology for the design of LASTs by combining technical, financial and location criteria. The method is applied to the design of LASTs to cover the water disposal demand of twelve municipalities located within the protected natural landscape, and surrounding areas of ‘El Rebollar’, Salamanca, Spain.  相似文献   

Modeling heavy metal concentration distributions in estuarine waters: an application to Suances Estuary (Northern Spain)     

María Luisa Sámano  Andrés García  José Antonio Revilla  César Álvarez 《Environmental Earth Sciences》2014,72(8):2931-2945

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