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Diversity patterns are determined by biogeographic, energetic, and anthropogenic factors, yet few studies have combined them into a large-scale framework in order to decouple and compare their relative effects on fish faunas. Using an empirical dataset derived from 1527 underwater visual censuses (UVC) at 18 oceanic islands (five different marine provinces), we determined the relative influence of such factors on reef fish species richness, functional dispersion, density and biomass estimated from each UVC unit. Species richness presented low variation but was high at large island sites. High functional dispersion, density, and biomass were found at islands with large local species pool and distance from nearest reef. Primary productivity positively affected fish richness, density and biomass confirming that more productive areas support larger populations, and higher biomass and richness on oceanic islands. Islands densely populated by humans had lower fish species richness and biomass reflecting anthropogenic effects. Species richness, functional dispersion, and biomass were positively related to distance from the mainland. Overall, species richness and fish density were mainly influenced by biogeographical and energetic factors, whereas functional dispersion and biomass were strongly influenced by anthropogenic factors. Our results extend previous hypotheses for different assemblage metrics estimated from empirical data and confirm the negative impact of humans on fish assemblages, highlighting the need for conservation of oceanic islands.

DÉCADA (2005-2014) DE LA EDUCACIÓN PARA UN FUTUROSOSTENIBLE

Clipperton Atoll, one of the most isolated coral reefs worldwide, is of great scientific interest due to its geomorphology and high levels of endemism. This study explored the reef fish assemblage structure of Clipperton Atoll and its relationship with live coral cover. Nine stations were sampled at three sites and three depths (6, 12 and 20 m) around the reef, measuring fish species richness and biomass and hermatypic coral cover (at genus level). We evaluated variation in species richness, biomass and diversity of fish assemblages among sites and depths, as well as the relationship between the entire fish assemblage composition and live coral cover. The results showed that species richness and biomass were similar among sites, but differed across depths, increasing with depth. In contrast, diversity differed among sites but not among depths. Multivariate analyses indicated that fish assemblage composition differed among sites and depths in relation to changes in cover of coral of the genera Pocillopora, Porites, Pavona and Leptoseris, which dominate at different depths. The results showed that fish species richness and diversity were low at Clipperton Atoll and that, in isolated coral reefs with a low habitat heterogeneity and low human disturbance, live coral cover has a significant influence on the spatial variation of the reef fish assemblages. This study highlights the importance of coral habitat structure in shaping coral reef fish assemblages.

Los autores desarrollan su modelos de sistema alimentario global, pesentado conceptualmente en anteriores publicaciones, basado en cuatro ejes basicos (disonibilidad, economia, politica y saber) dandole una estructura compresnbile, abierta y en la que se la plica una metodologia matematica que permite conocer la evolucion de los parametros y su prospectiva. Para ello, en el presente trabajo se pasa de los conceptos cualitativos a los cuantitativos. Cada eje se descompine, en tres subejes dando un total de 12, que identifican aspectos especificos de los pirimarios y que definen en este espacio las actividades y conceptos fundmentales del sistema agroalimentario y de tal forma que puedan seguir desarrollandose sus contenidos en aspectos de aun mas detalle, en un desarrollo fractal de base tetraedica. Para cada subeje se propone un primer parametro de evaluacion en base a valores en unidades, obtenibles en unidades de tiempo, habitualmente anos, de datos fiables publicados y compatibles con el modelo de estudios evolutivos y prospectivos presentados en el que se propone una variable vectorial para cada eje que toma valores en el simplex de tres partes y ajuste a un modelo lineal en coordenadas ILR (isometric logratio transformation). El modelo normaliza una estructura que da relieve al espacio agroalimentario global y perminte realizar estrategias propsectivas sobre el mismo en cada parametro y entre ellos. The authors develop their model of global food system, presented conceptually ine arlier publications, based on four basic axes (availability, economy, politics and knowledge) to give it an understandable open structure, and applying a mathematical methodology to it to enable the evolution of the parameters and its prospects to be known. To this end, this current study goes beyond the qualitative concepts to the quantitative ones. Each axis is broken down into three sub-axes giving a total of 12, that identify specific aspects of the primary ones and define the fundamental activities and concepts of the agri-food system in this space and in such a way that their contents can be developed further in even greater detail, in a fractal development on a tetrahedral base. A first evaluation parameter is proposed for each sub-axis based on values in units, that can be obtained, time units, years usually, from reliable published data and compatible with the model of evolutionary and prospective studies presented in which a variable vector for each axis is proposed that takes values in the simplex of three parts and adjusted to a lineal model in ILR ( isometric logratio transformation) coordinates. The model standardises a structure that highlights the global agri-food area and allows prospective strategies to be carried out the same subject, on each parameter or between them.