Ecosystem modeling to evaluate the ecological sustainability of small-scale fisheries: A case study from El Hierro, Canary Islands

This paper examines various fishery management scenarios based on the recovery of small-scale fisheries (SSF) following a submarine volcanic eruption in 2011 in El Hierro Island (Canary Islands, Spain). After this catastrophic event, the SSF composition of La Restinga fishing community was affected by socio-economic and demographic changes. The uncertainty derived from this situation provides an opportunity to evaluate the fisheries’ sustainability and advice on different management options under an ecosystem-based approach. The Ecopath with Ecosim modeling framework was used to build a model of El Hierro Island, where the versatile and traditional multispecies small-scale fleet of La Restinga operates. Our main goal is to improve traditional fisheries, based on the relevance of key local fisheries and multi-specific fishery strategies in the light of scientific knowledge. Temporal simulations for the next decade were analyzed by creating scenarios of alternative fishing effort distributions based on the fishing trends observed in El Hierro small-scale community of La Restinga after a natural hazard. The outcomes of this modeling prototype show the vulnerability of some littoral and demersal species, the resilience of migratory species, and the sustainability of SSF diversification practices. These results could develop an adaptive and co-management strategy with the local fishing community to preserve the small-scale fishing system and marine resources.En prens

Corrosion study of pipeline carbon steel in sourbrine under turbulent flow conditions at 60°C

This work presents the electrochemical results obtained during the corrosion study of X52 pipeline steel sample, immersed in “sour” solution under turbulent flow conditions at 60°C. In order to obtain information on the corrosion kinetics, weight loss method, linear polarization resistance, impedance and polarization curves were used at different immersion times. In order to control the turbulent flow conditions, a rotating cylinder electrode was used at two different rotation rates, 0 and 1000 rpm. A surface analysis was carried out in order to identify the corrosion morphology and the corrosion product formed on the steel sample. In general, it was found that flow has a considerable influence upon the electrochemical process occurring on the surface of the steel. It was observed as the flow rate increased the corrosion rate also increased. In surface analysis three phases were found, mackinawite (Fe,Ni)  1+xS ,pyrrhothite (Fe(1-x)S) and marcasite (FeS2). In addition, a “localized attack” was found

Geoquímica del extenso depósito de flujo piroclástico hiperalcalino del NW de México, basada en fluorescencia de rayos X convencional y portátil. Implicaciones en un contexto regional

Chemical analyses conducted on the surface of rock slabs under a combination of two X-ray spectrometry methods, wavelength dispersive XRF and energy dispersive XRF, are used to establish a geochemical correlation between the studied samples. This proves to be an excellent method for the characterization of volcanic glasses, particularly when particles of exotic origin are present, because the effect of these is not easily eliminated by conventional whole rock analysis. Analyses of glassy rhyolites (ignimbrites and lava flows) in northwestern Mexico establish a geochemical signature for the samples, providing criteria that allow us to: a) correlate them with a peralkaline volcanic event, previously reported, that occurred during Middle Miocene time; b) distinguish them from other metaluminous varieties in the region and, c) propose a correlation between all the peralkaline vitrophyres that crop out within the studied area, of at least 50.000 km2, validating the hypothesis that they are related to the same volcanic event. Finally, based on the results of this study and previous geological investigations, it is proposed that a distance of more than 100 km between the geographical location of the thickest peralkaline deposits in Sonora, is probably related to a displacement along transtensional dextral faults during the Late Miocene.El análisis químico realizado en secciones de roca bajo la combinación de dos métodos de espectrometría de fluorescencia de rayos x, por dispersión de longitudes de onda y por dispersión de energías, permitió establecer una correlación geoquímica entre las muestras estudiadas, resultando ser un excelente método para la caracterización de vidrios volcánicos, en particular cuando contienen partículas ajenas al magma que no pueden ser eliminadas por el análisis de roca total convencional. Los resultados obtenidos sobre las riolitas vítreas estudiadas (ignimbritas y coladas) del Noroeste de México permiten establecer una firma geoquímica de las muestras que proporciona criterios permitiendo: a) correlacionarlas con un evento volcánico, anteriormente descrito, de tipo hiperalcalino que ocurrió durante el Mioceno medio; b) diferenciarlas de las ignimbritas metaluminosas también presentes en la región y, c) proponer una correlación entre los vitrófiros de la zona estudiada, de al menos 50000 km2, haciendo válida la hipótesis de que todos ellos provienen de una misma erupción. Finalmente, basados en los resultados de este estudio y de trabajos geológicos previos, se propone que una diferencia de hasta más de 100 km en la ubicación geográfica de los depósitos hiperalcalinos de mayor espesor, es probablemente relacionada con un desplazamiento a lo largo de fallas dextrales asociadas a un evento extensivo en transtensión ocurrido durante el Mioceno superior

Distinct fos-expressing neuronal ensembles in the ventromedial prefrontal cortex mediate food reward and extinction memories

In operant learning, initial reward-associated memories are thought to be distinct from subsequent extinction-associated memories. Memories formed during operant learning are thought to be stored in “neuronal ensembles.” Thus, we hypothesize that different neuronal ensembles encode reward- and extinction-associated memories. Here, we examined prefrontal cortex neuronal ensembles involved in the recall of reward and extinction memories of food self-administration.Wefirst trained rats to lever press for palatable food pellets for 7 d (1 h/d) and then exposed them to 0, 2, or 7 daily extinction sessions in which lever presses were not reinforced. Twenty-four hours after the last training or extinction session, we exposed the rats to either a short 15 min extinction test session or left them in their homecage (a control condition). We found maximal Fos (a neuronal activity marker) immunoreactivity in the ventral medial prefrontal cortex of rats that previously received 2 extinction sessions, suggesting that neuronal ensembles in this area encode extinction memories. We then used the Daun02 inactivation procedure to selectively disrupt ventral medial prefrontal cortex neuronal ensembles that were activated during the 15 min extinction session following 0 (no extinction) or 2 prior extinction sessions to determine the effects of inactivating the putative food reward and extinction ensembles, respectively, on subsequent nonreinforced food seeking 2 d later. Inactivation of the food reward ensembles decreased food seeking, whereas inactivation of the extinction ensembles increased food seeking. Our results indicate that distinct neuronal ensembles encoding operant reward and extinction memories intermingle within the same cortical area

Período crítico de competencia de la Zanahoria (Daucus carota L.) y malezas asociadas al cultivo

Las malezas constituyen uno de los problemas fitosanitarios que afectan la rentabilidad de los cultivos. El periodo crítico de competencia con el cultivo (PCC), permite prever el nivel de interferencia de las malezas sobre la producción del cultivo de interés. El objetivo de esta investigación fue determinar el PCC entre zanahoria y las plantas asociadas al cultivo, en el municipio de Ventaquemada, departamento de Boyacá, implementando un diseño en Bloques Completos al Azar, con 12 tratamientos y cuatro repeticiones, el cual incluía un grupo de tratamientos libres de malezas por un periodo de tiempo (10, 20, 30, 40 ó 50 días), al término del cual se permitía el crecimiento de las mismas en el cultivo, de modo que el cultivo estuviese primero libre y luego en competencia (LC) y en el segundo grupo de tratamientos se permitía primero el desarrollo del proceso de competencia entre la maleza y el cultivo por un intervalo de tiempo igual al del grupo anterior y luego se retiraban las malezas. El mayor número de plantas cosechadas se obtuvo en la parcela libre de competencia durante los primeros 50 días después de emergencia. El mayor rendimiento se obtuvo en el tratamiento que se mantuvo limpio durante todo el ciclo de cultivo, con una producción de 5810g m-2, superior en 2252g a la obtenida en el punto crítico de competencia. para las condiciones evaluadas, el periodo crítico de competencia en zanahoria, se sitúa entre los 20 a 45 días, después de la emergencia del cultivo

Geochemistry of the extensive peralkaline pyroclastic flow deposit of NW Mexico, based on conventional and handheld X-ray fluorescence. Implications in a regional context

Chemical analyses conducted on the surface of rock slabs under a combination of two X-ray spectrometry methods, wavelength dispersive XRF and energy dispersive XRF, are used to establish a geochemical correlation between the studied samples. This proves to be an excellent method for the characterization of volcanic glasses, particularly when particles of exotic origin are present, because the effect of these is not easily eliminated by conventional whole rock analysis. Analyses of glassy rhyolites (ignimbrites and lava flows) in northwestern Mexico establish a geochemical signature for the samples, providing criteria that allow us to: a) correlate them with a peralkaline volcanic event, previously reported, that occurred during Middle Miocene time; b) distinguish them from other metaluminous varieties in the region and, c) propose a correlation between all the peralkaline vitrophyres that crop out within the studied area, of at least 50.000 km^2, validating the hypothesis that they are related to the same volcanic event. Finally, based on the results of this study and previous geological investigations, it is proposed that a distance of more than 100 km between the geographical location of the thickest peralkaline deposits in Sonora, is probably related to a displacement along transtensional dextral faults during the Late Miocene

Uso de coberturas vegetales en el manejo sostenible del suelo asociado al cultivo de maíz amiláceo (Zea mays L.)

Soil is a living, dynamic entity and at the same time vulnerable to degradation, if it is not managed with sustainable practices, causing low crop yields. The objective of this research was to determine the effects of plant cover associated with the cultivation of corn on soil properties: bulk density, gravimetric moisture, soil pH and electrical conductivity, organic matter, estimation of nitrogen supply when leaf biomass is incorporated, and finally corn yield. The study was conducted under a randomized complete block experimental design with five treatments: corn without cover crop (control), corn with clover cover crop; corn with vetch cover crop; corn with vetch + oats cover crop and corn with dead cover crop (mulch). The results showed that corn associated with clover, vetch and mulch (dead cover) increased grain yield (kg.ha-1) of corn by 44%, 37% and 38%, respectively, compared to planting corn without any type of cover. Likewise, the use of clover, vetch and vetch cover crops associated with oats increased soil organic matter and soil input by 253, 163 and 149 kg ha-1 of nitrogen if the leaf biomass of the cover crops was incorporated into the soil. Therefore, the corn-clover association is the one that presents the best results to increase yields under sustainable soil management and agroecological principles.El suelo es un ente vivo, dinámico y a la vez vulnerable a la degradación, siempre y cuando no se maneje de manera sostenible ocasionando bajos rendimientos de los cultivos. El objetivo de la presente investigación fue determinar los efectos de las coberturas vegetales asociado al cultivo de maíz amiláceo en las propiedades del suelo: densidad aparente, humedad gravimétrica, pH y conductividad eléctrica del suelo, materia orgánica, estimación del aporte de nitrógeno cuando se incorpora la biomasa foliar y finalmente el rendimiento de maíz. El estudio se realizó bajo un diseño experimental de bloques completos al azar con cinco tratamientos: maíz sin cobertura (testigo), maíz con cobertura de trébol; maíz con cobertura de vicia; maíz con cobertura de vicia + avena y maíz con cobertura muerta-mulch. Los resultados demostraron que, el maíz asociado con coberturas de trébol, vicia y mulch (cobertura muerta) aumentó en 44%, 37% y 38% respectivamente el rendimiento (kg.ha-1) de grano de maíz amiláceo, comparados a la siembra de maíz sin ningún tipo de cobertura. Asimismo, el uso de coberturas de trébol, vicia y avena + vicia incrementan la materia orgánica del suelo y aporta al suelo 253; 163 y 149 kg.ha-1 de nitrógeno siempre y cuando la biomasa foliar de las coberturas se incorpora al suelo. Por lo tanto, la asociación maíz – trébol es la que presenta mejores resultados para incrementar los rendimientos bajo un manejo sostenible del suelo y bajo los principios de la agroecología