Matrix composition and patch edges influence plant-herbivore interactions in marine landscapes

38 páginas, 4 figuras, 3 tablas.1. The functioning of ecosystems can be strongly driven by landscape attributes. Despite its importance, however, our understanding of how landscape influences ecosystem function derives mostly from species richness and abundance patterns, with few studies assessing how these relate to actual functional rates. 2. We examined the influence of landscape attributes on the rates of herbivory in seagrass meadows, where herbivory has been identified as a key process structuring these relatively simple systems. The study was conducted in three representative Posidonia oceanica meadows. The principal herbivores in these meadows are the fish Sarpa salpa and the sea urchin Paracentrotus lividus, and we hypothesised that differences in their interaction with landscape attributes would significantly influence herbivory rates. 3. We measured herbivore abundance, herbivory rates, primary production and plant quality (C:N) in seagrass patches embedded either in rock or in sand (matrix attribute), in patches either near or far from a rocky reef (distance attribute) and at the edges and interior of meadows. 4. Our results show that matrix and meadow edges significantly affected the actual levels of herbivory. Herbivory rates were higher in seagrass patches embedded in a rocky matrix compared to those on sand, and herbivory at the centre of seagrass meadows was higher than at the edges. In contrast, patch distance to rocky reefs did not affect herbivory. Neither herbivore abundance nor food quality explained the patterns across different landscape attributes. This suggests that variation in herbivory across the landscape may be related much more to behavioural differences between species in their evaluation of risk, movement, and food preference in relation to the landscape structure. 5. Our results indicate that richness and abundance patterns may mask critical interactions between landscape attributes and species responses, which result in considerable heterogeneity in the way key functional processes like herbivory are distributed across the ecosystem mosaic.The Spanish Ministry of Science and Innovation funded this research (projects CTM2010-22273-C02-01 and 02). The Spanish Ministry of Education supported JP (scholarship AP2008-01601) and the Spanish National Research Council supported AG (scholarship JAEPre_08_00466).Peer reviewe

Matrix composition and patch edges influence plant-herbivore interactions in marine landscapes

38 páginas, 4 figuras, 3 tablas.1. The functioning of ecosystems can be strongly driven by landscape attributes. Despite its importance, however, our understanding of how landscape influences ecosystem function derives mostly from species richness and abundance patterns, with few studies assessing how these relate to actual functional rates. 2. We examined the influence of landscape attributes on the rates of herbivory in seagrass meadows, where herbivory has been identified as a key process structuring these relatively simple systems. The study was conducted in three representative Posidonia oceanica meadows. The principal herbivores in these meadows are the fish Sarpa salpa and the sea urchin Paracentrotus lividus, and we hypothesised that differences in their interaction with landscape attributes would significantly influence herbivory rates. 3. We measured herbivore abundance, herbivory rates, primary production and plant quality (C:N) in seagrass patches embedded either in rock or in sand (matrix attribute), in patches either near or far from a rocky reef (distance attribute) and at the edges and interior of meadows. 4. Our results show that matrix and meadow edges significantly affected the actual levels of herbivory. Herbivory rates were higher in seagrass patches embedded in a rocky matrix compared to those on sand, and herbivory at the centre of seagrass meadows was higher than at the edges. In contrast, patch distance to rocky reefs did not affect herbivory. Neither herbivore abundance nor food quality explained the patterns across different landscape attributes. This suggests that variation in herbivory across the landscape may be related much more to behavioural differences between species in their evaluation of risk, movement, and food preference in relation to the landscape structure. 5. Our results indicate that richness and abundance patterns may mask critical interactions between landscape attributes and species responses, which result in considerable heterogeneity in the way key functional processes like herbivory are distributed across the ecosystem mosaic.The Spanish Ministry of Science and Innovation funded this research (projects CTM2010-22273-C02-01 and 02). The Spanish Ministry of Education supported JP (scholarship AP2008-01601) and the Spanish National Research Council supported AG (scholarship JAEPre_08_00466).Peer reviewe

Changes in heart rate recovery index after a programme of strength/endurance training in hypoxia

Objective To determine whether twelve sessions of resistance training on lower limbs at simulated altitude (2500m) were efficient to elicit an improvement in heart rate recovery index in the first 3min of recovery after a maximal jump test. Materials and methods Twelve young physically active subjects were divided in two balanced groups for training in hypoxia (HYP) and normal oxygen (NOR). The subjects were assigned to each group based on previous test results in the 60s counter-movement jump test (CMJ60). Results Both groups performed identical strength training (volume, intensity, character and effort conditions) on the lower limbs (squats, half-squats and jumps) for 4 weeks. Both groups improved the measured parameters in all cases. We analyzed the time course of heart rate during the CMJ60 test and the subsequent 3min recovery period. HYP group (n=5) improved the heart rate recovery index as compared to NOR group (Student's t-test) at minute 2 (P=0.03) and minute 3 (P=0.05). Conclusions We conclude that a protocol of resistance training on lower limbs (12 sessions in 4 weeks) at a simulated altitude could improve heart rate recovery index compared to the same training performed at sea level

Valoració de la freqüència cardíaca de recuperació després d'un programa d'entrenament de força/resistència en hipòxia

Objectiu: Dotze subjectes joves físicament actius van ser dividits en dos grups equilibrats per poder ser entrenats en hipòxia (HYP) i normòxia (NOR). Material i mètodes: Els subjectes foren assignats a cada grup en base als resultats en una prova prèvia de salt en contramoviment de 60 s (CMJ60). Ambdós grups realitzaren durant 4 setmanes un entrenament idèntic de força (volum, intensitat, caràcter i condicions d’esforç) a les extremitats inferiors (esquat, mig esquat i salts). Resultats: Ambdós grups van millorar en tots els casos. S’analitzà l’evolució temporal de la freqüència cardíaca durant la prova CMJ60 i el posterior període de recuperació de 3 min. El grup HYP (n = 5) reflecteix una millora de l’índex de recuperació de la freqüència cardíaca en comparació amb el grup NOR (prova t de Student) després de 2 (p = 0,03) i 3 (p = 0,05) minuts d’haver finalitzat el test de salts. Conclusions: Concloem que un protocol d’entrenament de la resistència (12 sessions en 4 setmanes) de les extremitats inferiors en altitud simulada podria millorar l’índex de recuperació de la freqüència cardíaca en comparació amb el mateix entrenament realitzat a nivell del mar

¿Afecta el sildenafilo a la capacidad física en altitud? Evidencias científicas en la actualidad

  El sildenafilo ha demostrado eficacia reduciendo la hipertensión pulmonar provocada por la vasoconstricción pulmonar hipóxica. Su papel como posible factor para aumentar el rendimiento en el ejercicio en condiciones de hipoxia está por demostrar, pero el uso de sildenafilo ha aumentado entre los montañeros, no como un fármaco preventivo del edema pulmonar de gran altitud, sino como un medio que podría ayudar a mejorar el rendimiento físico a gran altura geográfica. Varios estudios han tratado de abordar este tema, con resultados contradictorios. Actualmente, a pesar de que no hay datos concluyentes, ni en altitud simulada, ni real, y con la clara evidencia de que en normoxia el sildenafilo no mejora el rendimiento físico, se continúa utilizando esta sustancia (a veces en exceso) por personas que suben a altas cumbres. Tal potencial mejora de rendimiento dependería del grado de hipoxemia en altitud y de la capacidad de respuesta individual a este medicamento. El presente artículo revisa el conocimiento actual sobre este tema

Valoración de la Frecuencia Cardíaca de Recuperación después de un programa de entrenamiento de fuerza-resistencia en hipoxia

Objetivo Doce sujetos jóvenes físicamente activos se dividieron en dos grupos equilibrados para entrenar en hipoxia (HYP) y normoxia (NOR). Material y métodos Los sujetos fueron asignados a cada grupo en base a los resultados en una prueba previa de salto en contramovimiento de sesenta segundos (CMJ60). Ambos grupos realizaron durante 4 semanas un entrenamiento idéntico de fuerza (volumen, intensidad, carácter y condiciones de esfuerzo) en las extremidades inferiores (squat, half-squat y saltos). Resultados Ambos grupos mejoraron en todos los casos. Se analizó la evolución temporal de la frecuencia cardiaca durante la prueba CMJ60 y el posterior período de recuperación de tres minutos. El grupo HYP (n=5) refleja una mejoría del índice de recuperación de la frecuencia cardiaca en comparación con el grupo NOR (prueba t de Student) después de 2 (p=0,03) y 3 (p=0,05) minutos de finalizar el test de saltos. Conclusiones Concluimos que un protocolo de entrenamiento de fuerza resistencia (12 sesiones en 4 semanas) de las extremidades inferiores en altitud simulada podría mejorar el índice de recuperación de la frecuencia cardiaca en comparación con el mismo entrenamiento realizado a nivel del mar

Can sildenafil improve physical performance at altitude? Current scientific evidence

  Sildenafil has proven to efficiently reduce the increase in pulmonary artery pressure provoked by hypoxic pulmonary vasoconstriction. However, its role as a possible factor in increasing exercise performance under hypoxic conditions remains to be demonstrated. The use of sildenafil has increased among mountaineers, not as a high altitude pulmonary edema preventive drug, but as a means that could help to improve performance. Several studies have attempted to address this issue, with conflicting results. Currently, despite the inconclusive data at simulated or real altitude, and with the clear evidence that, in normoxia, sildenafil does not improve performance, this drug is being used (and sometimes overused) by people who climb high peaks. However, such potential performance improvement would depend on the degree of hypoxemia (altitude) and the individual responsiveness to this drug. This paper reviews the current knowledge on this matter

Stigmatella aurantiaca, un mixobacteri amb aspecte de mixomicet, trobat al Parc de Collserola (Catalunya)

Stigmatella allrantiaca, un mixobacteri amb aspecte de mixomicet, trobat al Parc de Collserola (Catalunya). Stigmatella aurantiaca ha estat trobada sobre restes vegetals recol·lectades a Collserola, prop de Barcelona (Catalunya). Es tracta d'un mixobacteri que rarament es pot veure formant cossos fructífers a la natura i es pot confondre fàcilment amb un mixomicet immadur. Forma grups de cossos fructífers molt petits, de color taronja, portats per pedicels blancs.Stigmatella allrantiaca, a myxomycete-looking myxobacterium, found in Collserola Park (Catalonia). Stigmatella aurantiaca has been found on plant debris collected in ColIserola, near Barcelona (Catalonia). It belongs to myxobacteria, a group of procariotes rarely found fonuing fruiting bodies in the nature, where it may easily be confused with an immature myxomycete. It forms clusters of tiny fruiting bodies, orange coloured, on white stalks.Stigmatella aurantiaca, una mixobacteria con aspecto de mixomicete, hallada en el Parque de Collserola (Cataluña). Stigmatella aurantiaca ha sido encontrada sobre restos vegetales recolectados en Collserola, cerca de Barcelona (Cataluña). Se trata de una mixobacteria que raramente se puede ver formando cuerpos fructíferos en la naturaleza y que fácilmente se puede confundir con algún mixomicete inmaduro. Forma grupos de diminutos cuerpos fructíferos de color naranja, sostenidos por pedicelos blancos

La formación en didáctica de las ciencias sociales del profesorado de secundaria : del CAP al CCP

El trabajo plantea una revisión de la situación en que se encuentra la formación inicial del profesorado de secundaria en el área de Ciencias Sociales, revisión que incide de forma especial en las investigaciones realizadas sobre el tema y en la escasa importancia cuantitativa de estas investigaciones dentro del panorama general de la universidad española. Se aporta el análisis de dos ejemplos concretos: la Universidad Autónoma de Barcelona y la Universidad de La Rioja, diferentes en tradición y realidad formativa actual. Por último, se incorpora un esquema de lo que pensamos deben ser los elementos organizadores de una formación inicial del profesorado de secundaria en Ciencias Sociales coherente con el desarrollo científico-didáctico en el mundo actual.This essay proposes a revision of the present situation regarding the initial preparation of Secondary School Teachers in the social sciences, stressing in particular research carried out on the subject to date and the relatively high importance of this research within the broader panorama of Spanish Universities. The analysis makes use of two concrete examples: the Autonamous University of Barcelona and the University of La Rioja, two universities with differing traditions and current formative position. Lastly, several ideas about the future Course of Pedagogical Grading are offered, along with some suggestions for a preparation of Secondary School Social Science teachers that takes into account current scientific-didactic development and the complexities of teaching