4 resultados para Semantisk webb

em Acceda, el repositorio institucional de la Universidad de Las Palmas de Gran Canaria. España


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Tesis realizada en el Jardín Botánico Canario "Viera y Clavijo" en colaboración con el Departamento de Biología de la Universidad de Las Palmas de GRan Canaria, dentro del Programa de Doctorado: Biodiversidad y Conservación Vegetal

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[EN] Marine N2 fixing microorganisms, termed diazotrophs, are a key functional group in marine pelagic ecosystems. The biological fixation of dinitrogen (N2) to bioavailable nitrogen provides an important new source of nitrogen for pelagic marine ecosystems 5 and influences primary productivity and organic matter export to the deep ocean. As one of a series of efforts to collect biomass and rates specific to different phytoplankton functional groups, we have constructed a database on diazotrophic organisms in the global pelagic upper ocean by compiling about 12 000 direct field measurements of cyanobacterial diazotroph abundances (based on microscopic cell counts or qPCR 10 assays targeting the nifH genes) and N2 fixation rates. Biomass conversion factors are estimated based on cell sizes to convert  abundance data to diazotrophic biomass. The database is limited spatially, lacking large regions of the ocean especially in the Indian Ocean. The data are approximately log-normal distributed, and large variances exist in most sub-databases with non-zero values differing 5 to 8 orders of magnitude. 15 Lower mean N2 fixation rate was found in the North Atlantic Ocean than the Pacific Ocean. Reporting the geometric mean and the range of one geometric standard error below and above the geometric mean, the pelagic N2 fixation rate in the global ocean is estimated to be 62 (53–73) TgNyr−1 and the pelagic diazotrophic biomass in the global ocean is estimated to be 4.7 (2.3–9.6) TgC from cell counts and to 89 (40–20 200) TgC from nifH-based abundances. Uncertainties related to biomass conversion factors can change the estimate of geometric mean pelagic diazotrophic biomass in the global ocean by about ±70 %. This evolving database can be used to study spatial and temporal distributions and variations of marine N2 fixation, to validate geochemical estimates and to parameterize and validate biogeochemical models. The database is 25 stored in PANGAEA (http://doi.pangaea.de/10.1594/PANGAEA.774851).

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[ES]El presente proyecto se centra en aplicar técnicas de biología molecular, demográficas y de biología reproductiva en cuatro endemismos canarios amenazados que se encuentran total o parcialmente localizados en los parques nacionales de Canarias: Silene nocteolens Webb & Berthel. (Parque Nacional del Teide, Tenerife); Ilex perado ssp. lopezlilloi (G. Kunkel) A. Hansen & Sunding (Parque Nacional Garajonay, La Gomera), Sorbus aria (L.) Crantz (Parque Nacional de la Caldera de Taburiente, La Palma) y Bencomia exstipulata Svent. (parques nacionales del Teide y Caldera de Taburiente). Se estableció un estudio genético a través de marcadores moleculares hipervariables, microsatélites, y se determinó para cada taxón la variación genética de sus poblaciones, para su posterior aplicación en la gestión en el ámbito de la Biología de la conservación de estos taxones.