558 research outputs found

    Plasticidad del crecimiento larvario entre atún rojo y melva modulado por sus interacciones tróficas.

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    ECOlogía trófica comparativa de LArvas de aTUN rojo atlántico (Thunnus thynnus) de las áreas de puesta del Medterraneo-NO y el Golfo de México.ECOLATU

    Maternal transference of isotopic signature (δ15N, δ13C) and Its evolution during ontogenic development of reared bluefin larvae (Thunnus thynnus)

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    An experimental rearing experiment of bluefin tuna larvae was undertaken in the Spanish Oceanographic Institution (IEO) based in the aquaculture plant of Murcia that started June 24, 2013 when caged bluefin spawned naturally. Bluefin tuna eggs were transferred to rearing tanks and where hatched larvae were sampled regularly every 2 days till 15dph. After this period, larvae were sampled every 3 days till 37dph (Temperature range 22-26ºC). The standard length (SL) of larvae were measured after frozen and conserved deep-frozen in a -80ºC for undertaking posterior nitrogen (N) and carbon (C) stable isotope analysis. The results of the experiment showed very high initial values of δ15N and δ13C in the eggs and lecitotrophic larvae till 4dph, explaining a transgenerational transference of the heavy isotopes through maternal inheritance. After this time lapse, the stable isotope values declined progressively till 12dph and maintained this low level till 15dph. This period coincides with the notochord post-flexion development established at a mean SL of 6,7mm (±0,57) measured. Coinciding with this ontogenic stage, larvae were started to be fed with newly hatched larvae of aquaculture-bred gilt-head seabream whose δ15N and δ13C values were consequently enriched. This diet produced an increasing trend in the δ15N and δ13C values till 24dph reaching similar values of the initial developmental times. The results show that pre-flexion larvae of bluefin have high δ15N and δ13C signature as a result of their maternal transference. A similar decreasing pattern was also observed in field-based research on bluefin larvae which justified the need to carry out this rearing experiment. The data acquired in this experiment allows to formulate an estimate of the maternal δ15N and δ13C signatures from larvae between 3-6mm SL which opens research horizons in the estimation of maternal trophic qualities that may relate to larval growth and condition potentials. This work was financed by the project ATAME CTM2011-29525-C04-02

    Pathways to Equitable and Sustainable Education through the Inclusion of Roma Students in Learning Mathematics

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    Education is a key feature in the development of an agenda for a sustainable world. Education usually is associated with developing a responsible and ethical citizenship, aware of the main challenges for a sustainable development. Mathematics used to play a role as gatekeeper to achieve good educational performance. This article explores six case studies of Roma developing successful learning stories in learning mathematics. We identify five main characteristics in their educational trajectories that may explain Roma students' success in the school. This article moves forward previous studies characterizing Roma cultural features of mathematics learning, reporting stereotypes towards Roma in school. We conclude that in order to promote educational inclusion, successful stories may inform effective educational programs that, ultimately, may lead towards a sustainable education, including students from the most disadvantaged groups, as in the case of the Roma people

    Biophysical Processes Determining the Connectivity of the Alboran Sea Fish Populations

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    This chapter revises biogeophysical issues of connectivity processes for fish populations in the Alboran Sea—Strait of Gibraltar—Gulf of Cadiz area. Connectivity of early life history stages between distant spawning grounds is crucial to incorporate vital developmental rates that condition survival probabilities at critical ontogenic stages. Hydrodynamics is pivotal to the process and most particular for pelagic species originating from adult fish adapted to recurrent patterns. Therefore, special focus has been placed on the hydrodynamics of the region, particularly on the Alboran Sea where the swift and energetic eastward-flowing Atlantic Jet entering the basin from the Strait of Gibraltar determines the surface circulation patterns. The Jet establishes an obvious zonal west-to-east connectivity, prevents the one in the opposite east-to-west direction and works as a hydrodynamic barrier that hampers the north-to-south connectivity. The chapter addresses these processes, discusses possible mechanisms to achieve connectivity between north and south shores, which have to overcome the hydrodynamic barrier, and assesses the feasibility of east-to-west connectivity by means of intermediate-depth currents. Implications on the populations and ecosystems of the Alboran Sea and on the three main harvested species potentially affected by hydrodynamic connectivity in the basin (European hake, the sardine, and the blackspot seabream) are also commented.Preprin

    Biomass-modulated fire dynamics during the last glacial-interglacial transition at the central pyrenees (Spain)

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    Understanding long-term fire ecology is essential for current day interpretation of ecosystem fire responses. However palaeoecology of fire is still poorly understood, especially at high-altitude mountain environments, despite the fact that these are fire-sensitive ecosystems and their resilience might be affected by changing fire regimes. We reconstruct wildfire occurrence since the Lateglacial (14.7. cal. ka BP) to the Mid-Holocene (6. cal. ka BP) and investigate the climate-fuel-fire relationships in a sedimentary sequence located at the treeline in the Central Spanish Pyrenees. Pollen, macro- and micro-charcoal were analysed for the identification of fire events (FE) in order to detect vegetation post-fire response and to define biomass-fire interactions. mean fire intervals (mfi) reduced since the Lateglacial, peaking at 9-7.7. cal. ka BP while from 7.7 to 6. cal. ka BP no fire is recorded. We hypothesise that Early Holocene maximum summer insolation, as climate forcing, and mesophyte forest expansion, as a fuel-creating factor, were responsible for accelerating fire occurrence in the Central Pyrenees treeline. We also found that fire had long-lasting negative effects on most of the treeline plant communities and that forest contraction from 7.7. cal. ka BP is likely linked to the ecosystem's threshold response to high fire frequencies.This research has been funded by the projects DINAMO (CGL2009-07992) (funding EGPF — grant ref. BES-2010-038593 and MSC), DINAMO2 (CGL2012-33063), ARAFIRE (2012 GA LC 064), GRACCIE-CONSOLIDER (CSD2007-00067). GGR was funded by the Juan de la Cierva Program (grant ref. JCI2009-04345) and JAE-Doc CSIC Program, LLM was supported by a postdoctoral MINT fellowship funded by the Institute for the Environment (Brunel University), AMC is a Ramón y Cajal fellow (ref: RYC-2008-02431), APS holds a grant funded by the Aragon Government (ref. 17030G/5423/480072/14003) and JAE holds a grant funded by the Basque Country Government (BFI-2010-5)

    Developing a coding scheme for analysing classroom dialogue across educational contexts

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    The research reported sought to develop a framework for systematically analysing classroom dialogue for application across a range of educational settings. The paper outlines the development and refinement of a coding scheme that attempts to represent and operationalise commonalities amongst some key theorists in the field concerning productive forms of educational dialogue. The team has tested it using video recordings from classroom settings in the UK and Mexico, across age phases, subject areas, and different interactional contexts including whole class, group and paired work. Our Scheme for Educational Dialogue Analysis (SEDA) is situated within a sociocultural paradigm, and draws on Hymes' Ethnography of Communication to highlight the importance of context. We examined how such a tool could be used in practice. We found that concentrating on the ‘communicative act’ to explore dialogue between participants was an appropriate level of granularity, while clustering the 33 resulting codes according to function of the acts helped to highlight dialogic sequences within lessons. We report on the application of the scheme in two different learning contexts and reflect on its fitness for purpose, including perceived limitations. Development of specialised sub-schemes and a version for teachers is underway

    SEDIMENTACIÓN Y DISTRIBUCIÓN SUPERFICIAL DE PALINOMORFOS EN CUEVAS DEL SE IBÉRICO. IMPLICACIONES EN PALEOECOLOGÍA

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    Pollen from several karstic caves of Mediterranean Spain has been studied in order to understand taphonomic processes affecting cave systems. Results confirm the palaeoecological potential of cave sediments, which show pollen spectra that may reflect external vegetation from both local and regional catchment areas. Pollen distribution, deposition, and preservation are not homogeneous throughout the cave surface, but they are greatly influenced by cave morphology, and stochastic processes. The aridity is a positive factor for pollen preservation, thus enhancing the use of cave deposits as sources of palaeoenvironmental information.Se ha realizado un análisis polínico del sedimento superficial de varias cavidades kársticas de la España mediterránea con el fin de conocer los procesos tafonómicos que afectan al polen en este contexto sedimentario. Los resultados confirman el potencial paleoecológico de los depósitos de cuevas. Los espectros polínicos reflejan la vegetación que crece en los alrededores de la cueva, así como, parcialmente, la vegetación regional. La distribución, deposición y preservación polínicas no son homogéneas en el interior de las cuevas, estando influenciadas por la morfología de la cueva y diversos procesos estocásticos. La aridez se confirma como un factor positivo para la preservación polínica y, por tanto, resulta una garantía en estudios de reconstrucción paleoambiental
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