Individual differences in dominance-related traits drive dispersal and settlement in hatchery-reared juvenile brown trout

Effective management of exploited populations is based on an understanding of population dynamics and evolutionary processes. In spatially structured populations, dispersal is a central process that ultimately can affect population growth and viability. It can be influenced by environmental conditions, individual phenotypes, and stochastic factors. However, we have a limited knowledge of the relative contribution of these components and its interactions, and which traits can be used as reliable predictors of the dispersal ability. Here, we conducted a longitudinal field experiment aimed to identify traits which can be used as proxy for dispersal in juvenile brown trout (Salmo trutta L.). We measured body size and standard metabolic rates, and estimated body shapes for 212 hatchery-reared juvenile fish that were marked with individual codes and released in a small coastal stream in northwest Spain. We registered fish positions and distances to the releasing point after 19, 41, 60 and 158 days in the stream. We detected a high autocorrelation of dispersal distances, demonstrating that most individuals settle down relatively soon and then hold stable positions over the study period. Body size and fish shape were reliable predictors of dispersal, with bigger and more robust-set individuals being more likely to settle closer to the release site than smaller and more elongated fish. In addition, the analysis of spacing and spatial patterns indicated that the dispersal of introduced fish could affect the distribution of resident conspecifics. All together, these results suggest that stocking programs aimed to the enhancement of overexploited populations at fine spatial scales can be optimized by adjusting the size and shape of the introduced fish to specific management targets and environmental conditions.This study was supported by grants CN-07-164 (Principality of Asturias), MEC-CGL2004-03239/BOS and MMA/86-2003-1 to A.G. Nicieza, and a FICYT PhD fellowship (BP04-147) to J.R. Sánchez-González

Dimension and support of underground slate mines

[Abstract] We've studied the conditions about dimensions and support ofan underground mine of roofing slate in Galice, worked by rooms with continuous pillars. The rock mass was characterized by the empiric and analitic methods, calculating the stable pillar wide along the mine by the theory of attributed area and by a model of finite elements, where the breaking criterion ofHoek and Brown was applied. The result was a parabolic relationship between pillar wide and mine length. Stability studies in an isolated stope give an elastic performance on the periphery of the room, without tractions. Although the stability ofthe mine is good, a systematic support is recommended on the basis of bolts, that will be reinforced with projected concret at the top, and a singular treatment of the detected wedges

The computer in a roofing slate quarry

[Resumen] Sencillas configuraciones informáticas en base a ordenadores personales con programas comerciales de modelización y diseño asistido por ordenador, facilitan el reiterativo trabajo de planificación minera de una explotación de pizarra a cielo abierto. Su utilización es aplicable a tres fases del proyecto minero: Modelización del yacimiento (investigación), proyecto de explotación (viabilidad) y labores mineras (ejecución).[Abstract] Simple integrated systems based on personal computers and cornmercial programmes about modelling and CAD, make easy the reiterative work on exploitation planning in roofing slate quarries. We can use this systems in the three phases of the mining project: bed modelling (Research), exploitation (Viability)wand mining (Performance)

LA COBERTURA PERIODÍSTICA DE DESASTRES NATURALES. SISTEMATIZACIÓN TEÓRICA SOBRE EL TRATAMIENTO EN LOS MEDIOS DE COMUNICACIÓN

La presente revisión bibliográfica deviene una aproximación a la cobertura periodística de desastres naturales y el rol que asumen los medios de comunicación en el tratamiento de estas contingencias. Se plantean los fundamentos conceptuales y enfoques referentes al protagonismo de las organizaciones periodísticas en el abordaje mediático de siniestros. Desde una perspectiva cualitativa se asume un método de este diseño metodológico y se aplica la técnica revisión documental y el instrumento análisis de contenido. El objetivo es identificar los principales postulados teóricos relacionados con la cobertura periodística de desastres naturales tema latente en los mass media ante el incremento de los eventos climatológicos

Contrasting effects of environmental factors during larval stage on morphological plasticity in post-metamorphic frogs

In organisms with complex life cycles, environmentally induced plasticity across sequential stages can have important consequences on morphology and life history traits such as developmental and growth rates. However, previous research in amphibians and other ectothermic vertebrates suggests that some morphological traits are generally insensitive to environmental inductions. We conducted a literature survey to examine the allometric responses in relative hind leg length and head shape of post-metamorphic anuran amphibians to induced environmental (temperature, resource level, predation and desiccation risk) variation operating during the larval phase in 44 studies using 19 species. To estimate and compare plastic responses across studies, we employed both an index of plasticity and effect sizes from a meta-analysis. We found contrasting trait responses to different environmental cues. Higher temperatures increased development more than growth rate and induced smaller heads but not overall shifts in hind leg length. In contrast, an increment in resource availability increased growth more than development, with a parallel increase in hind leg length but no change in head shape. Increases in predation risk decreased both development and growth rates and slightly reduced relative hind leg length, but there was no change in head shape. Pond desiccation induced quick development and low growth rates, with no changes in morphology. Across environments, both hind leg and head shape plasticity were positively correlated with growth rate plasticity. However, plasticity of developmental rate was only correlated with head shape plasticity. Overall, these results suggest that environmental trends predicted by global warming projections, such as increasing pond temperature and accelerating pond desiccation, will significantly influence hind leg and head morphology in metamorphic frogs, which may affect performance and, ultimately, fitness.Fil: Tejedo, Miguel. Consejo Superior de Investigaciones Científicas. Estación Biológica de Doñana; EspañaFil: Marangoni, Federico. Consejo Superior de Investigaciones Científicas. Estación Biológica de Doñana; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Materiales de Misiones. Universidad Nacional de Misiones. Facultad de Ciencias Exactas Químicas y Naturales. Instituto de Materiales de Misiones; ArgentinaFil: Pertoldi, Cino. University Aarhus; DinamarcaFil: Richter-Boix, Alex. Uppsala University; SueciaFil: Laurila, Anssi. Uppsala University; SueciaFil: Orizaola, Germán. Uppsala University; SueciaFil: Nicieza, Alfredo G.. Universidad de Oviedo; EspañaFil: Álvarez, David. Universidad de Oviedo; EspañaFil: Gomez Mestre, Iván. Universidad de Oviedo; España. Consejo Superior de Investigaciones Científicas. Estación Biológica de Doñana; Españ

Características, procesamiento proteolítico y papel en el desarrollo de nucleasas exocelulares de streptomyces antibioticus

Se realizó un estudio en S. antibioticus, con el fin de analizar la presencia de actividades nucleolíticas distintas a la previamente descrita en el periplasma de la bacteria. Se detectaron dos nucleasas exocelulares, de 34 kDa y 18 kDa, que fueron purificadas y caracterizadas bioquímicamente. Ambos enzimas presentan actividad endo-exonucleolítica. Hidrolizan ADN y ARN, y dejan como productos finales una mezcla de mono y oligonucleótidos. Aparecen desde el inicio del desarrollo del microorganismo y alcanzan niveles máximos en la fase de micelio aéreo. Las dos nucleasas parecen tener su origen en un precursor inactivo de 74 kDa; que sufre un procesamiento proteolítico, llevado a cabo por una proteasa de tipo tripsina (TLP). La secuencia amino-terminal de la DNasa de 18 kDa es homologa a la de otras proteinas de la familia de las ciclofilinas; y la DNasa de 18 kDa presenta actividad isomerasa; lo que sugiere su relación con estas proteinas. Se propone el papel de estas nucleasas en el proceso de diferenciación del microorganismo, y la homología de estos procesos con algunos acontecimientos bioquímicos que tienen lugar durante los procesos de apoptosis de células eucariotas