Patterns in the spatial distribution of Peruvian anchovy (Engraulis ringens) revealed by spatially explicit fishing data   总被引：1，自引：0，他引：1  

Sophie Bertrand  Erich Díaz  Matthieu Lengaigne 《Progress in Oceanography》2008,79(2-4):379

Peruvian anchovy (Engraulis ringens) stock abundance is tightly driven by the high and unpredictable variability of the Humboldt Current Ecosystem. Management of the fishery therefore cannot rely on mid- or long-term management policy alone but needs to be adaptive at relatively short time scales. Regular acoustic surveys are performed on the stock at intervals of 2 to 4 times a year, but there is a need for more time continuous monitoring indicators to ensure that management can respond at suitable time scales. Existing literature suggests that spatially explicit data on the location of fishing activities could be used as a proxy for target stock distribution. Spatially explicit commercial fishing data could therefore guide adaptive management decisions at shorter time scales than is possible through scientific stock surveys. In this study we therefore aim to (1) estimate the position of fishing operations for the entire fleet of Peruvian anchovy purse–seiners using the Peruvian satellite vessel monitoring system (VMS), and (2) quantify the extent to which the distribution of purse–seine sets describes anchovy distribution. To estimate fishing set positions from vessel tracks derived from VMS data we developed a methodology based on artificial neural networks (ANN) trained on a sample of fishing trips with known fishing set positions (exact fishing positions are known for approximately 1.5% of the fleet from an at-sea observer program). The ANN correctly identified 83% of the real fishing sets and largely outperformed comparative linear models. This network is then used to forecast fishing operations for those trips where no observers were onboard. To quantify the extent to which fishing set distribution was correlated to stock distribution we compared three metrics describing features of the distributions (the mean distance to the coast, the total area of distribution, and a clustering index) for concomitant acoustic survey observations and fishing set positions identified from VMS. For two of these metrics (mean distance to the coast and clustering index), fishing and survey data were significantly correlated. We conclude that the location of purse–seine fishing sets yields significant and valuable information on the distribution of the Peruvian anchovy stock and ultimately on its vulnerability to the fishery. For example, a high concentration of sets in the near coastal zone could potentially be used as a warning signal of high levels of stock vulnerability and trigger appropriate management measures aimed at reducing fishing effort.  相似文献   

Impacts of Kelvin wave forcing in the Peru Humboldt Current system: Scenarios of spatial reorganizations from physics to fishers   总被引：2，自引：1，他引：1  

Sophie Bertrand  Boris Dewitte  Jorge Tam  Erich Díaz  Arnaud Bertrand   《Progress in Oceanography》2008,79(2-4):278

Because climate change challenges the sustainability of important fish populations and the fisheries they support, we need to understand how large scale climatic forcing affects the functioning of marine ecosystems. In the Humboldt Current system (HCS), a main driver of climatic variability is coastally-trapped Kelvin waves (KWs), themselves originating as oceanic equatorial KWs. Here we (i) describe the spatial reorganizations of living organisms in the Humboldt coastal system as affected by oceanic KWs forcing, (ii) quantify the strength of the interactions between the physical and biological component dynamics of the system, (iii) formulate hypotheses on the processes which drive the redistributions of the organisms, and (iv) build scenarios of space occupation in the HCS under varying KW forcing. To address these questions we explore, through bivariate lagged correlations and multivariate statistics, the relationships between time series of oceanic KW amplitude (TAO mooring data and model-resolved baroclinic modes) and coastal Peruvian oceanographic data (SST, coastal upwelled waters extent), anchoveta spatial distribution (mean distance to the coast, spatial concentration of the biomass, mean depth of the schools), and fishing fleet statistics (trip duration, searching duration, number of fishing sets and catch per trip, features of the foraging trajectory as observed by satellite vessel monitoring system). Data sets span all or part of January 1983 to September 2006. The results show that the effects of oceanic KW forcing are significant in all the components of the coastal ecosystem, from oceanography to the behaviour of the top predators – fishers. This result provides evidence for a bottom-up transfer of the behaviours and spatial stucturing through the ecosystem. We propose that contrasting scenarios develop during the passage of upwelling versus downwelling KWs. From a predictive point of view, we show that KW amplitudes observed in the mid-Pacific can be used to forecast which system state will dominate the HCS over the next 2–6 months. Such predictions should be integrated in the Peruvian adaptive fishery management.  相似文献   

The diffusion of ICT in France: infrastructures,services, and uses     

Sophie Houzet 《GeoJournal》2007,68(1):5-17

How does the organization of space interfere in the numerical development of territories? Our hypothesis is that information and communication technologies (ICT) are organized by taking into account the existing spatial structures, compared to constraints of distance, spatial position and urban hierarchy. In the context of the liberalization of the sector of telecommunications, ICT spread according to an economic logic of profitability. The concern of network operators collides with the principle of territorial equity in planning policies. To understand the diffusion of ICT in France, a cartographic analysis of their distribution is proposed. It derives from the notion of networks at three levels: infrastructures, services and uses. The research takes into account the difference between regional configurations to identify the spatial factors of the digital divide. For each level, the diffusion of ICT follows a different logic, and characterizes territories with different orientations. Areas with a high density of population and activities are quickly equipped. The democratization of the use of the Internet, notably with the diffusion of public access to the Internet, is present to a greater degree in low-density areas.  相似文献   

Barriers perceived to engaging with climate change among the UK public and their policy implications   总被引：6，自引：2，他引：6  

Irene Lorenzoni  Sophie Nicholson-Cole  Lorraine Whitmarsh 《Global Environmental Change》2007,17(3-4):445-459

This paper reports on the barriers that members of the UK public perceive to engaging with climate change. It draws upon three mixed-method studies, with an emphasis on the qualitative data which offer an in-depth insight into how people make sense of climate change. The paper defines engagement as an individual's state, comprising three elements: cognitive, affective and behavioural. A number of common barriers emerge from the three studies, which operate broadly at ‘individual’ and ‘social’ levels. These major constraints to individual engagement with climate change have implications for achieving significant reductions in greenhouse gases in the UK. We argue that targeted and tailored information provision should be supported by wider structural change to enable citizens and communities to reduce their carbon dependency. Policy implications for effective engagement are discussed.  相似文献   

Reconstitution des apports en éléments traces métalliques et bilan de leur migration dans un Luvisol sableux soumis à 100 ans d'irrigation massive par des eaux usées brutes     

Christelle Dère  Isabelle Lamy  Folkert van Oort  Denis Baize  Sophie Cornu 《Comptes Rendus Geoscience》2006,338(8):565-573

Raw wastewaters were massively spread on sandy luvisols near Paris from 1899 to 2002, leading to high trace metals (TM) pollution of soils. Mass balance calculations were performed on a soil profile to assess vertical migration of TM. The contamination was estimated by subtracting the natural pedo-geochemical background of the horizons. TM inputs were estimated using Cr as an invariant. It is shown that Pb and Cr remained in the surface horizon, while Ni, Cd, Cu and Zn migrated downward, being more or less trapped depending on the physicochemical properties of the horizons. To cite this article: C. Dère et al., C. R. Geoscience 338 (2006).  相似文献   

Localisation of lunar acoustic energy     

J. A. Bastin 《Earth, Moon, and Planets》1970,1(4):449-450

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Infrared observations of the moon and their interpretation   总被引：3，自引：0，他引：3  

M. J. Pugh  J. A. Bastin 《Earth, Moon, and Planets》1972,5(1-2):16-30

The lunar spectrum, resulting from both the directly scattered solar radiation and the Moon's intrinsic thermal radiation, is described. The variations of the thermal component with latitude and phase, and during eclipse conditions, are described and compared with a plane homogeneous model of temperature-independent thermal constants. A review is given of that data appropriate to the lunar crust which may be obtained, both from comparison of this model with observation and from those modifications of the model, which explain otherwise anomalous measurements. Finally, a discussion of the various methods of determining the vertical temperature gradient at the surface leads to a mean value of about 2Km^–1, although the heat flux associated with these results is much less than the recent direct measurement.  相似文献   

Testing climate models using an impact model: what are the advantages?     

Marc Stéfanon  Nicolas K. Martin-StPaul  Paul Leadley  Sophie Bastin  Alessandro Dell’Aquila  Philippe Drobinski  Clemente Gallardo 《Climatic change》2015,131(4):649-661

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Determination of the Concentration of Carbonic Species in Natural Waters: Results from a World‐Wide Proficiency Test          下载免费PDF全文

Mahendra P. Verma  Enrique Portugal  Sophie Gangloff  María Aurora Armienta  Dornadula Chandrasekharam  Mayela Sanchez  Roberto E. Renderos  Miguel Juanco  Robert van Geldern 《Geostandards and Geoanalytical Research》2015,39(2):233-255

The results of an international interlaboratory proficiency test for the determination of carbonic species are presented. Eight laboratories analysed twelve water samples (four synthetic waters, one lake water, four geothermal waters, one seawater and two petroleum waters) by two methods: (a) individual laboratory analytical procedure and (b) acid–base titration curves in tabular form following a standardised protocol. In case (b), the concentrations of carbonic species were calculated by the organiser using the (1) Hydrologists' method, (2) Geochemists' method and/or (3) initial pH and total alkalinity method. For synthetic waters, the averaged % trueness and precision of measurement of the two methods were (trueness = 7.6, precision = 9.4) and (9.0, 3.4) for total alkalinity, and (6.6, 31.0) and (7.8, 6.1) for carbonic alkalinity, respectively. This indicates that the total alkalinity calculation procedure is in general correct in the individual laboratory method, but the carbonic alkalinity calculation procedure has serious problems. The measurements of total alkalinity for lake and seawaters were in agreement in both the methods; however, the individual laboratory measurement method for geothermal and petroleum waters was conceptually incorrect. Thus, the analytical procedures for the determination of carbonic species were reviewed. To apply the Hydrologists' and/or Geochemists' methods, the location of NaHCO₃EP and H₂CO₃EP is necessary, even for samples with pH lower than that of NaHCO₃EP, and a backward titration curve after complete removal of CO₂ must be performed. The initial pH and total alkalinity method is appropriate where a complete analysis of species that contribute to the alkalinity is known.  相似文献   

Soil moisture-temperature feedbacks at meso-scale during summer heat waves over Western Europe     

Marc Stéfanon  Philippe Drobinski  Fabio D’Andrea  Cindy Lebeaupin-Brossier  Sophie Bastin 《Climate Dynamics》2014,42(5-6):1309-1324

This paper investigates the impact of soil moisture-temperature feedback during heatwaves occurring over France between 1989 and 2008. Two simulations of the weather research and forecasting regional model have been analysed, with two different land-surface models. One resolves the hydrology and is able to simulate summer dryness, while the other prescribes constant and high soil moisture and hence no soil moisture deficit. The sensitivity analysis conducted for all heatwave episodes highlights different soil moisture-temperature responses (1) over low-elevation plains, (2) over mountains and (3) over coastal regions. In the plains, soil moisture deficit induces less evapotranspiration and higher sensible heat flux. This has the effect of heating the planetary boundary layer and at the same time of creating a general condition of higher convective instability and a slight increase of shallow cloud cover. A positive feedback is created which increases the temperature anomaly during the heatwaves. In mountainous regions, enhanced heat fluxes over dry soil reinforce upslope winds producing strong vertical motion over the mountain slope, first triggered by thermal convection. This, jointly to the instability conditions, favors convection triggering and produces clouds and precipitation over the mountains, reducing the temperature anomaly. In coastal regions, dry soil enhances land/sea thermal contrast, strengthening sea-breeze circulation and moist cold marine air advection. This damps the magnitude of the heatwave temperature anomaly in coastal areas, expecially near the Mediterranean coast. Hence, along with heating in the plains, soil dryness can also have a significant cooling effect over mountains and coastal regions due to meso-scale circulations.  相似文献