Feeding ecology of elasmobranch fishes in coastal waters of the Colombian Eastern Tropical Pacific

<p>Abstract</p> <p>Background</p> <p>Stomach contents of 131 specimens of five elasmobranch species (<it>Mustelus lunulatus</it>, <it>Dasyatis longa</it>, <it>Rhinobatos leucorhynchus</it>, <it>Raja velezi </it>and <it>Zapteryx xyster</it>) caught in the central fishing zone in the Pacific Ocean of Colombia were counted and weighed to describe feeding habits and dietary overlaps.</p> <p>Results</p> <p>Twenty-one prey items belonging to four major groups (stomatopods, decapods, mollusks and fish) were identified. Decapod crustaceans were the most abundant prey found in stomachs. The mantis shrimp <it>Squilla panamensis </it>was the main prey item in the diet of <it>M. lunulatus</it>; tiger shrimp <it>Trachypenaeus </it>sp. was the main prey item in the diet of <it>Rhinobatos leucorhynchus </it>and <it>Raja velezi</it>, and Penaeidae shrimp were the main prey items in the diet of <it>Z. xyster</it>. Furthermore, fish were important in the diet of <it>Raja velezi, Z. xyster </it>and <it>D. longa</it>. The greatest diet breadth corresponded to <it>Z. xyster </it>whereas <it>M. lunulatus </it>was the most specialized predator. Finally, four significant diet overlaps between the five species were found, attributable mainly to Squillidae, Penaeidae and Fish.</p> <p>Conclusion</p> <p>Shrimps (Penaeidae and stomatopods) and benthic fishes were the most important food types in the diet of the elasmobranch species studied. Diet breadth and overlap were relatively low. Determination of food resource partitioning among the batoid species studied was not possible. However, we identified partitions in other niche axes (time of feeding activity and habitat utilization). It is possible to assume that diffuse competition could be exceeding the biunivocal competition among the studied species. Therefore, this assemblage would have a strong tendency to trophic guild formation.</p

Challenges for ecolabeling growth: lessons from the EU Ecolabel in Spain

Purpose The European Ecolabel (EU Flower) has the mission to encourage cleaner production and influence consumers to promote Europe's transition to a circular economy. Nonetheless, little is known about EU Ecolabel evolution; it is not clear what the drivers that encourage its implementation are. Thus, this study aims to assess the growing acceptance of the EU Ecolabel in the European Union, and Spain more specifically, by examining product and service categories and geographical regions. Methods The methodological approach taken in this study is a mixed methodology based on the triangulation method by consulting the EU Ecolabel scheme database, EU Ecolabel delegates from some autonomous regions, and the academic literature. Also, a geographic analysis was run in the ArcGIS Software with data about the accumulation of licenses assigned in 2016. Results and discussion The analysis shows that most products in Spain that have been awarded the EU Ecolabel belong to the following categories: Do-It-Yourself Products (paint and varnish), Paper Products, Cleaning Up Products, and Electronic Equipment. At the same time, the study showed that this ecolabel faces significant obstacles in its diffusion, such as the competition with environmental labels launched previously in Europe and other regional labels. Conclusions The results of this study indicate the existence of five drivers that may encourage the implementation of EU Flower in a region: (1) public management, (2) communication strategy, (3) sustainable public procurement criteria, (4) local income per capita, and (5) international trade incentives. Finally, this study provides essential recommendations for policymakers to trigger ecolabeling practices such as the need to improve the understanding of the EU ecolabel impact in different levels of activity, which means countries, regions, industrial clusters, firms, and consumers. Also, this investigation identifies areas for further research, and it expresses the need to develop business case studies about ecolabeling with the objective to visualize this phenomenon as an eco-innovation process

Evaluación de técnicas de tinción para la observación de bandas de crecimiento en vértebras de elasmobranquios tropicales

The aim of this study was to assess the suitability of different vertebrae staining techniques for the visualization and counting of growth bands in tropical species of batoids (Narcine leoparda, Urotrygon aspidura, Hypanus longus, Potamotrygon magdalenae) and sharks (Alopias pelagicus, Carcharhinus falciformis, Sphyrna lewini, Sphyrna corona and Mustelus lunulatus). Different cutting thicknesses and staining protocols were tested, analysing the precision and bias of each combination to identify the most accurate technique for estimating age. Vertebral sections of 0.4 mm were more suitable for batoids, except for Narcine leoparda; for this species and for all the shark species assessed, sections of 0.5 mm are recommended. Different combinations of stain and exposure time were required to achieve the best visualizations of vertebral growth band pair for the shark and ray species. Intraspecific variation occurred among vertebrae size of batoids. Our results confirm the importance of defining a suitable species-specific protocol for sectioning and staining hard structures before carrying out an age and growth study to improve the reliability of the age estimates.El objetivo de este estudio fue evaluar la efectividad de diferentes técnicas de tinción de vértebras en la visualización y el conteo de bandas de crecimiento en especies tropicales de batoideos (Narcine leoparda, Urotrygon aspidura, Hypanus longus, Potamotrygon magdalenae) y tiburones (Alopias pelagicus, Carcharhinus falciformis, Sphyrna lewini, Sphyrna corona y Mustelus lunulatus). Se probaron diferentes espesores de corte y protocolos de tinción, analizando la precisión y el sesgo de cada combinación para identificar la técnica más precisa para estimar la edad. Las secciones vertebrales de 0,4 mm fueron más adecuadas para batoideos, excepto para Narcine leoparda; para esta especie y para todas las especies de tiburones evaluadas, se recomiendan secciones de 0,5 mm. Se identificaron diferentes combinaciones de tinción y tiempo de exposición para lograr las mejores visualizaciones de las bandas de crecimiento vertebral en las especies de tiburones y rayas. En los batoideos se identificó variación intraespecífica de acuerdo con el tamaño de las vértebras. Nuestros resultados confirman la importancia de definir un protocolo especie-específico adecuado para cortar y teñir las estructuras duras antes de realizar un estudio de edad y crecimiento y así incrementar la confiabilidad de las estimaciones de edad

Eficiencia de la respuesta superovulatoria del ganado Brahman al protocolo P-24

Objetivo. Evaluar la eficiencia de la respuesta superovulatoria del ganado Brahman al protocolo P-24. Materiales y métodos. Se utilizaron doce vacas Brahman donadoras con más de 60 días postparto, a las cuales se les realizó un total de 21 tratamientos superovulatorios con base en el protocolo P-24. Se realizó la colecta de los embriones a través del método convencional y los embriones fueron clasificados (IETS). Resultados. Se obtuvo un promedio de 9.1 estructuras, 4.4 embriones transferibles, 3.7 embriones congelables y 3.2 embriones degenerados recuperados por colecta. Los estadíos de desarrollo que predominaron fueron mórula (32.6%), blastocisto temprano (38%) y blastocisto (18.5%). Se presentó efecto (p0.05) sobre las demás variables estudiadas. Se presentó efecto (p0.05) de la producción promedio de embriones degenerados y ovocitos sin fecundar entre ambos grupos. No obstante, la proporción de éstos fue mayor en las donadoras con una menor producción de embriones transferibles (50 y 22.4%) vs. las donadoras con mayor producción (39.3 y 14%) para embriones degenerados y ovocitos sin fecundar respectivamente. Conclusiones. El ganado Brahman tuvo una respuesta superovulatoria eficiente al protocolo P-24 para transferencia de embriones a tiempo fijo

Prediction of the water/oil interfacial tension from molecular simulations using the coarse-grained SAFT-γ Mie force field

This work is framed within the Ninth Industrial Fluid Properties Simulation Challenge, with the aim of assessing the capability of molecular simulation methods and force fields to accurately predict the interfacial tension of oil + water mixtures at high temperatures and pressures. The challenge focused on predicting the liquid-liquid interfacial tension of binary mixtures of dodecane + water, toluene + water and a 50:50 (wt%) mixture of dodecane:toluene + water at 1.825 MPa (250 psig) and temperatures from 110 to 170 °C. In our entry for the challenge, we employed coarse-grained intermolecular models parametrized via a top-down technique in which an accurate equation of state is used to link experimentally observed macroscopic properties of fluids with the force-field parameters. The state-of-the-art version of the statistical associating fluid theory (SAFT) for potentials of variable range as reformulated in terms of the Mie potential is employed here. Interfacial tensions are calculated through a direct method, where an elongated simulation cell is sampled through molecular dynamics in the isobaric-isothermal constant area ensemble (NPzzAT). The coarse-grained nature of the force field allows for the accelerated calculation of relatively large systems. The binary interaction parameters that describe the cross-interactions have been obtained in previous works by fitting to interfacial tensions of the constituent binaries at lower pressures and temperatures; these are taken as constant for all conditions and mixtures studied. After disclosure of the challenge results, we observe that the interfacial properties of the mixtures are described with an error of less than 5 mN/m over the whole range of conditions, demonstrating the accuracy and transferability of the top-down SAFT-γ Mie force field approach

Construcción de un sistema para el modelado de una lámina de acero flexible suspendida magnéticamente

En este artículo se presenta el análisis del modelamiento de una lámina flexible la cual se suspende en el espacio por la acción de fuerzas magnéticas que actúan sobre ella. Dadas las características de la planta se emplean técnicas especiales para el modelado de sistemas altamente no lineales y los resultados obtenidos son utilizados con el fin de describir la dinámica del sistema. Los datos analíticos son comparados con lo obtenidos a partir del modelo real

Control de posición de una lámina de acero flexible suspendida magnéticamente

En este artículo se presenta los resultados obtenidos a partir del diseño de un controlador para la suspensión magnética de una lámina flexible ferromagnética, tomando como base el modelo matemático obtenido de un prototipo construido en una primera fase. El trabajo se centra en el diseño de un control robusto usando la función de sensibilidad calculada para la planta