1,720,980 research outputs found
Climate Variability and Change, their Impacts on Marine Life and Ecosystems
No full textThroughout its 4,500 MY history, the Earth has gone through many changes. Some of these have implied such radical transformations as the coalescence of a crust and the relative movement and redistribution of tectonic plates (the Wilson cycle described in Chapter 1), the advent of life, the transition from a reducing to an oxidizing atmosphere during the Great Oxidation Event, and finally, with the creation of an atmosphere, the establishment of the climatic system as we know it today. In other words, planet Earth is used to changes and transformations. But with the advent of modern civilization, anthropic (i.e., from the Greek ánthrōpos = human) activities, largely related to agricultural and industrial development and based on fossil fuels as an energy source, have significantly altered biogeochemical cycles, leading to an accelerated change in many of Earth¨s processes.Fil: Pan, Jeronimo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Maenza, Reinaldo Agustín. Instituto Nacional de Investigaciones y Desarrollo Pesquero; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin
Introduction to the Marine Environment from Physical and Chemical Perspectives
No full textThe oceans and the atmosphere exchange heat, salt, water, and momentum, and most physical andchemical processes in the oceans result from this interaction. Winds blowing over the ocean transfer energy to the surface layers allowing for the development of ocean currents. Solar radiation can evaporate water, removing heat from the ocean that is transferred to the atmosphere when water vapor is condensed into clouds. Evaporation and freezing, both resulting from the ocean-atmosphere interaction, turn liquid water saltier, but rainfall dilutes the salt concentration of the surface ocean. As mentioned, there are many feedback mechanisms between the oceans and the atmosphere. In the next sections, we will introduce some of the physical and chemical properties of the marine environment that result from the ocean atmosphere coupling and are relevant for marine life. Our coverage of these topics is by no means exhaustive, nor at length, but rather aiming to provide the basics anyone interested in marine biology should be familiar with. Those readers interested in more thorough and quantitative treatments of these topics should refer to specific oceanography and biogeochemistry textbooks.Fil: Pratolongo, Paula Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; ArgentinaFil: Pan, Jeronimo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin
Soft-bottom Marine Benthos
No full textThe term benthos applies to the organisms that inhabit ocean bottoms. Benthos distribution is controlled by a combination of factors such as sediment granulometry, dissolved O2, OM content, as well as disturbance and pollution. Functional classifications of soft-bottom marine benthos may follow different criteria, namely, size (micro-, meio- and macrobenthos); habitat preference (epifauna, infauna); feeding strategies (shredders, grazers, suspension- and deposit feeders); type of carnivory (predators and scavengers); or their contribution to sediment stability and/or erodibility (stabilizers and bioturbators). Deep-sea benthic ecosystems harbor a high biological diversity and several hypotheses have been invoked to explain such diversity and distribution patterns. Deep-sea ecosystems may be divided into two major groups, heterotrophic and chemosynthetic habitats, in relation to the energy fuelling them. Soft-bottom ecosystems play a major role in nutrient regeneration, through the processing of OM coming from different sources. The pelagic and benthic sub-systems are interconnected through physical or biologically-mediated processes, collectively known as benthic-pelagic coupling (BPC). Suspension-feeding, an example of biological BPC, is an energy-acquisition strategy convergently evolved among many phyla of marine organisms, that targets a profit from the large amount of particles suspended in seawater. There is no analogous mechanism to suspension-feeding in terrestrial ecology.Fil: Pan, Jeronimo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Pratolongo, Paula Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentin
Top-down effects of an exotic serpulid polychaete on natural plankton assemblage of estuarine and brackish systems in the SW Atlantic
Get PDFThe invasive reef-building polychaete Ficopomatus enigmaticus (Fauvel, 1923) has become well-established in many temperate brackish waters. To analyze preferences for different planktonic food sources, short-term (~1.5 h), grazing microcosm experiments were performed in situ (n ¼ 3), at two water bodies, a coastal lagoon (Mar Chiquita, MC) and the mixohaline stretches of a coastal creek (La Tigra, LT), Argentina, in January 2007. Relative clearance rates of phytoplankton were assessed for chlorophyll a size-fractions and for different groups of nanoplanktonic and microplanktonic protists. The two locations showed significant differences in plankton community structure. Nanoeukaryotes were the dominant group at both locations; the second most-abundant groups were diatoms at MC and ciliates at LT. There were significant differences in chlorophyll-based clearance rates in relation to phytoplankton size-fraction. Clearance rates for pennate diatoms were significantly higher than for any other planktonic prey (2.3 l h1 g DW1 ). Ficopomatus enigmaticus presented relatively high clearance rates for heterotrophic ciliates (1.5 l h1 g DW1 ). Biomass removal by F. enigmaticus was high (.50% of initial standing stocks for all components), indicating that the serpulid was capable of regulating planktonic biomass. Significant differences in clearance for different components of the community suggest that F. enigmaticus has the potential to promote changes in plankton community structure and, hence, exerts strong top-down controls.Fil: Pan, Jeronimo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Universidad Nacional de Mar del Plata. Facultad de Cs.exactas y Naturales. Departamento de Cs.marinas. Estación "j.j.nagera" Grupo Medusas; ArgentinaFil: Marcoval, Maria Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentina. Universidad Nacional de Mar del Plata. Facultad de Cs.exactas y Naturales. Departamento de Cs.marinas. Estación "j.j.nagera" Grupo Medusas; Argentin
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
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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