32 research outputs found
Hábitos alimenticios y la razón de isotopos estables de carbono (δ13 C) y nitrógeno (δ15 N) del tiburón Sphyrna lewini, (Griffith y Smith 1834) capturado en el área de Mazatlán, Sinaloa, México
No full textimpreso y digitalSphyrna lewini es un recurso importante en la pesca de tiburón para la zona de Mazatlán México, el objetivo de este estudio es conocer su dieta, establecer su posición trófica y llevar a cabo una comparación entre la dieta consumida (evaluada por contenido estomacal) y la dieta asimilada (estimada con δ13C Y δ15N). Durante los muestreos de octubre 2000 a abril 2004 se colectaron 556 estómagos correspondientes a tiburones entre 48 - 160 centímetros. de estos 449 estómagos presentaron alimento. En la evaluación del contenido estomacal se identificaron 88 especies presas. De acuerdo al índice de importancia relativa (IIR), la dieta estuvo constituida por el cefalópodo Loliolopsis dimedeae (IIR) = 49 %), y por lo peces de la familia carangidae ( IIR = 26 %) y gerreidae (iir = 7 %). De manera general se observo un valor bajo de amplitud de dieta (0.15). El índice Morisita-Horn indico un alto traslapo trófico entre sexos (C2 = 0.95), y traslapo medio al comparar la dieta entre tiburones mayores a 100 cm. y menores a 100 cm. (c2 = 0.44). para S. lewini los valores promedio (± 1.01 ‰ y -14.89 ± 0.44 ‰ y en hígado : 17.21 ± 1.03 ‰; y -17.46 ±1.71 ‰ respectivamente. al comparar el valor promedio de δ15n de S. lewini con el de sus presas más probables, se observo en el tiburón un enriquecimiento de aproximadamente 3 ‰ los cambios mensuales observados en el número de especies presa se reflejaron directamente en la variación del valor del índice de amplitud de dieta, el cual a su vez se reflejo en el valor de la desviación estándar de los valores del δ15N con retraso de un mes, es decir a valores altos de amplitud de dieta correspondió el mes siguiente un valor alto de desviación estándar y viceversa. a pesar de que los valores de amplitud de dieta en general fueron bajos, los cambios mensuales permiten plantear que S. lewini puede ser considerado como un depredador oportunista, con comportamiento de alimentación poco selectivo influenciado por la abundancia y disponibilidad de sus presas en el medio.
Finalmente se observo que los tiburones al inicio de la temporada presentan un valor promedio de δ15n bajo con respecto al enriquecimiento esperado de acuerdo a las presas encontradas en el contenido estomacal. Después del primer mes, el enriquecimiento es proporcional a las presas consumidas el mes anterior, lo que finalmente se mantiene a lo largo de la temporada; lo que nos permite suponer que la zona de Mazatlán es un área de alimentación y crianza para S. lewiInstituto Politécnico Nacional. Centro Interdisciplinario de Ciencias MarinasMaestría en Manejo de Recursos Marinosxiv, 107 h
Hábitos alimenticios y la razón de isotopos estables de carbono (δ13 C) y nitrógeno (δ15 N) del tiburón Sphyrna lewini, (Griffith y Smith 1834) capturado en el área de Mazatlán, Sinaloa, México
No full textimpreso y digita
The social class struggles concept with an interdisciplinary approach: a paramount concept for research in library and information science (LIS)
No full textThis paper analyses the social class struggles concept with an interdisciplinary approach to be used by theorists and practitioners of library and information science (LIS). This concept emerged as part of the theoretical framework employed by the author in his doctoral thesis (Muela-Meza, 2010): An Application of Community Profiling to Analyse Community Information Needs, and Providers: Perceptions from the People of the Broomhall Neighbourhood of Sheffield, UK. This concept is complemented from philosophy (Marx and Engels, [1848] 1976a), and the natural sciences (Hauser, 2006; Sagan and Druyan, 1992), and it served the author to understand better the bigger dimensions of the underlying issues behind social classes and human conflicts. It also served to understand better the contradictions between people (e.g. LIS users with contradictory and mutually exclusive information needs to be provided by libraries and other institutions of information recorded in documents), and how these intensify when these are interrelated with the social class they belong to (Muela-Meza, 2007). This paper also criticises some competing views whose proponents by pretending fallaciously and deceitfully to deny the presence of social class divides in society, such as those rhetorical ploys of post-modernism that propose capitalist-class-driven ideologues of “community cohesion” based on “social capital” (Putnam, 1999). It shows evidence of how those followers (e.g. Pateman, 2006; Contreras Contreras, 2004; Bryson, Usherwood and Proctor, 2003) of capitalist-class ideologues, by doing so they aligned their discourse to that of dominance hierarchies and hegemony against working class people, in LIS and other sciences, and the humanities. It also criticises the postmodern pseudoscience because it pretends to undermine the logical rationality fundamental in LIS and all other sciences. It recommends that LIS theorists and practitioners employ the social class struggles concept as configured here in order to understand better contradictions, conflicts, and struggles within LIS theory and practice, and also to search for broader epistemological aims such as justice and wisdom (Fleissner and Hofkirchner, 1998), concealed by the capitalist or bourgeois and middle classes for their benefit against working class
Reproductive cycle of the sea cucumber Holothuria floridana in the littorals of Campeche, Mexico
No full textThe Eco-classroom project: Fostering student participation through education for sustainability
No full textThis thesis investigates learning and other outcomes in participants, particularly students (9-11 years), as a result of their involvement in an education for sustainability (EfS) co-design and build project at their primary school, in New Zealand, which was conducted within the Enviroschools Programme. The research focused on four areas that distinguished the project: sustainability learning as the issue, participatory practice as the method, design as the process and community partnerships as the sphere of involvement. Each of these was considered in terms of its influence on learning that was either cognitively-based (knowledge), psychomotor (skills) or affective (attitudes and values). This led to the set-up of a matrix to collect qualitative data that was gathered using a narrative inquiry method of collecting participants stories. This included focus groups with students who were part of the Eco-building Working Party, interviews with key adults from the school and the wider community, survey questionaires to parents of the focus group students, and other observations and materials. Findings demonstrated a correlation between the set-up and execution of the eco-classroom project and the Danish-developed pedagogical EfS concept of Action Competence. This was indicated through the authentic, relevant and democratic action-taking focus of the eco-classroom project that is linked to making learning transformations, which have been established as being more likely to lead to genuine changes in behaviour towards the environment. Also in agreement with an action competence approach was the strong focus in the project on both individual and collective learning. This was partly a result of the process-focused nature of the project, which was related to the learning mandate and commitment to a democratic process with students. The project ran for a number of years with annually changing groups of students, who all had different experiences. The teacher used ‘peer education’ and reflective tools to manage the ‘changeover’ positively, give depth and breadth to learning and ensure the project was truly collaborative. Student learning occurred in all three learning domains and included EfS learning (particularly about aspects of architecture and the built environment), learning about the process of design, and cross-disciplinary learning that included skills such as leadership, teamwork and public speaking. Adult participants also gained from their involvement in the project. The embedding of learning in the project within the New Zealand Curriculum, provided evidence of the flexible and multidisciplinary nature of EfS. Finally, a number of key characteristics were identified as contributing significantly to learning in the project
Crítica Bibliotecológica: Revista de las Ciencias de la Información Documental, Vol. 2 No. 2 y Vol. 3 No. 1 Julio 2009-Julio 2010.
No full textPublication of the journal Library and Information Science Critique: Journal of the Sciences of Information Recorded in Documents, corresponding to the double issue corresponding to the Vol. 2 No. 2 y Vol. 3 No. 1 from July 2009 to July 2010
A global perspective on the trophic geography of sharks
No full textSharks are a diverse group of mobile predators that forage across varied spatial scales and have the potential to influence food web dynamics. The ecological consequences of recent declines in shark biomass may extend across broader geographic ranges if shark taxa display common behavioural traits. By tracking the original site of photosynthetic fixation of carbon atoms that were ultimately assimilated into muscle tissues of 5,394 sharks from 114 species, we identify globally consistent biogeographic traits in trophic interactions between sharks found in different habitats. We show that populations of shelf-dwelling sharks derive a substantial proportion of their carbon from regional pelagic sources, but contain individuals that forage within additional isotopically diverse local food webs, such as those supported by terrestrial plant sources, benthic production and macrophytes. In contrast, oceanic sharks seem to use carbon derived from between 30° and 50° of latitude. Global-scale compilations of stable isotope data combined with biogeochemical modelling generate hypotheses regarding animal behaviours that can be tested with other methodological approaches
Data from: A global perspective on the trophic geography of sharks
No full textSharks are a diverse group of mobile predators that forage across varied spatial scales and have the potential to influence food web dynamics. The ecological consequences of recent declines in shark biomass may extend across broader geographic ranges if shark taxa display common behavioural traits. By tracking the original site of photosynthetic fixation of carbon atoms that were ultimately assimilated into muscle tissues of 5,394 sharks from 114 species, we identify globally consistent biogeographic traits in trophic interactions between sharks found in different habitats. We show that populations of shelf-dwelling sharks derive a substantial proportion of their carbon from regional pelagic sources, but contain individuals that forage within additional isotopically diverse local food webs, such as those supported by terrestrial plant sources, benthic production and macrophytes. In contrast, oceanic sharks seem to use carbon derived from between 30° and 50° of latitude. Global-scale compilations of stable isotope data combined with biogeochemical modelling generate hypotheses regarding animal behaviours that can be tested with other methodological approaches. </span
