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Ecosistemes profunds de la Mediterrània: Biodiversitat, funcionament i vulnerabilitat
No full textMemoria de tesis doctoral presentada por Samuele Tecchio para optar al grado de Doctor en Biodiversidad por la Universitat de Barcelona (UB), realizada bajo la dirección del Dr. Francisco Sardà Amills y de la Dra. Eva Zoe Ramírez Llodra del Institut de Ciències del Mar (ICM-CSIC).-- 138 pagesThe deep sea is the portion of the ocean that stands below 200 m depth, both in the water column and in the benthos (Gage & Tyler 1991). It is the largest biome of planet Earth, with about 90% of the ocean area being deep sea (Ramírez-Llodra et al. 2010a). In the past decades, researchers have loved to refrain that “we know more about the surface of the Moon than about our deep oceans”. To date, this still holds true. The deep sea is considered impenetrable, difficult and expensive to reach and observe. [...]The author has been financed by a JAE pre-doctoral grant from the Spanish Research Council (CSIC), from December 2008 to November 2012. This work has been carried out in the framework of the following research projects:
- BIOFUN (CTM2007-28739-E), from the European Science
Foundation (ESF);
- PROMETEO (CTM2007-66316-C02/MAR), from the
CYCIT, Spain;
- HERMIONE (G.A. 226354), from the European UnionPeer reviewe
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Mediterranean deep-sea ecosystems: Biodiversity, functioning and vulnerability = Ecosistemes profunds de la Mediterrània: Biodiversitat, funcionament i vulnerabilitat
Get PDF[spa] En la presente tesis se han estudiado los patrones de biodiversidad, funcionamiento trófico y ecosistémico de los sistemas bentónicos de gran profundidad en el Mar Mediterráneo. El objetivo principal fue de describir y caracterizar los hábitats profundos, relacionando su biodiversidad y sus procesos de funcionamiento con los gradientes ambientales a lo largo de los ejes longitudinal, batimétrico y estacional. El estudio de la composición de comunidades y la respectiva recogida de muestras para los análisis tróficos se han realizado a través de arrastres profundos. Los resultados de análisis de composición de comunidades hallaron una correlación significativa entre las dinámicas de las capas oceánicas de superficie, la cantidad de alimento disponible en el fondo marino, y la composición de la megafauna estudiada. A escala reducida y considerando las variaciones estacionales, la biomasa bentónica mostró un patrón a U-invertida, con un pico a profundidades de 1000-1400 m. Una posible explicación de este fenómeno podría ser la combinación de forzajes ecológicos ligados a las diferentes distribuciones batimétricas de las especies. Para estudiar las relaciones tróficas en los ejes batimétricos y geográficos de gran escala, se utilizó el análisis de isotopos estables de las componentes bentónicas, de superficie, y de capas pelágicas intermedias. El amplitud de los nichos tróficos de las comunidades bentónicas se encontraron relacionados con indicadores de productividad de superficie, tanto primaria como secundaria. Asimismo, los procesos de utilización mesopelágica del carbono orgánico se hallaron en posición intermedia entre los de superficie y los del bentos profundo. Finalmente, un análisis ecosistémico a través de “Ecopath with Ecosim”, reveló que los ecosistemas de los taludes continentales del Mediterráneo son el resultado de un largo proceso de sucesión ecológica, han alcanzado un estado de estabilidad, y son particularmente vulnerables a factores de impacto humano, entre ellos, la explotación pesquera[eng] The Mediterranean Sea can be considered an excellent natural laboratory for benthic ecologists, due to its peculiar environmental conditions, its broad-scale gradients, and its deep-sea fauna. Primary production levels in the Mediterranean follow a longitudinal gradient, decreasing from west to east. The present thesis focused on the fine-mud benthos habitat of the Mediterranean Sea, on its bathyal and abyssal zones, and the compartment considered was demersal megafauna. The main objective of the present thesis was to describe and characterize the deep habitats of the Mediterranean Sea, relating their biodiversity and ecosystem functioning with the varying environmental conditions along the geographic, bathymetric, and temporal axes. The work was divided into four parts. In the first part, the patterns of distribution, biomass and abundance of bathyal and abyssal megafauna were studied, in relation with environmental variables, along longitudinal and bathymetric gradients. This was a large geographic scale study, across the three basins of the Mediterranean at depths of 1200-3000 m. Benthic biomass strongly decreased with depth and longitude (west-to-east). Results showed a significant correlation between the dynamics of surface layers, the amount of food available on the bottom, and the composition of benthos. In the second part, the seasonal fluctuations of benthic communities in the Catalan continental margin were observed. A highly replicated, multi-period study was conducted at depths of 900-1500 m. Total biomass followed an inverted U-shaped pattern, peaking at depths of 1050-1350 m. Range-related ecological forcings between shallower and deeper species may have caused this biomass accumulation at intermediate slope depths. The arrival of a new water mass from the deep basin to the slope in spring may have also driven an accumulation of biomass at 900-1050 m depth over the same period. An adjacent submarine canyon was also studied, comparing communities between the canyon and the open slope area. Analyses revealed higher diversity, but not biomass, inside the canyon than in the adjacent open slope, and a significantly different assemblage between the habitats. These results strengthen the concept of submarine canyons as hotspots of biodiversity and underline the importance of their conservation as diversity repositories. The third part is a study on trophic relations of deep-sea fauna, over the same large spatial transects considered in the first part, by means of natural-abundances stable isotopes analyses and the use of novel statistical methods to analyse heavy datasets all in once. Bulk-tissue d13C and d15N isotope ratios were analysed for benthic megafauna and associated surface and mesopelagic components from the 3 basins of the Mediterranean Sea. The trophic niche width and the amplitude of primary carbon sources were positively correlated with both primary and secondary surface production indicators. Moreover, mesopelagic organic matter utilization processes showed an intermediate position between surface and deep benthic components. Thus, both primary and secondary production processes taking place at surface layers are key drivers of deep-sea food web structuring. Finally, the fourth part integrates the whole collected dataset into the first ecotrophic model of a deep-water ecosystem in the Mediterranean Sea, evaluating the general ecosystem functioning as well as the degree of vulnerability of these ecosystems. The Ecopath with Ecosim approach was used to model the flows and biomasses of the Catalan Sea continental slope ecosystem at depths of 1000-1400 m. Network analysis identified low levels of consumer biomass cycling and low system omnivory index when compared with expected values of marine ecosystems, and higher cycling and omnivory when compared with available models of shallower areas of the Mediterranean. A simulation of the possible expansion of the red-shrimp benthic trawl fishery that currently operates at shallower depths, showed reductions in fish biomass and that the state of the deep continental slope ecosystem seems to be result of a long-term succession process, which has reached ecological stability, and is particularly vulnerable to human impact and, specifically, to fisheries exploitation
Relating nutritional condition and food of Anchovy Larvae (Engraulis encrasicolus, Linnaeus 1758) in the Gulf of Lions (North-Western Mediterranean)
Get PDFLavoro di internato condotto presso l’Institut de Ciències del Mar di Barcelona, analizzando il contesto del Golfo del Leone e considerando la specie E. encrasicolus (Linnaeus 1758), che rappresenta la specie pelagica economicamente più importante della regione
Una prima analisi ha riguardato la valutazione della condizione nutrizionale delle larve e la loro comparazione per definire se vi fossero differenze rispetto a due periodi diversi di cattura (e quindi ad una diversa condizione trofica e oceanografica)
Relating nutritional condition and food of Anchovy Larvae (Engraulis encrasicolus, Linnaeus 1758) in the Gulf of Lions (North-Western Mediterranean)
Get PDFLavoro di internato condotto presso l’Institut de Ciències del Mar di Barcelona, analizzando il contesto del Golfo del Leone e considerando la specie E. encrasicolus (Linnaeus 1758), che rappresenta la specie pelagica economicamente più importante della regione
Una prima analisi ha riguardato la valutazione della condizione nutrizionale delle larve e la loro comparazione per definire se vi fossero differenze rispetto a due periodi diversi di cattura (e quindi ad una diversa condizione trofica e oceanografica).ope
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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