1,720,959 research outputs found
Assessing the relationship between the Lake Habitat Survey and littoral macroinvertebrate communities in European lakes
No full textImplementation of the EU Water Framework Directive (WFD) has drawn much attention to hydromorphological alterations of surface waters. The Lake Habitat Survey (LHS) protocol provides a method for characterising and assessing the physical habitats of lakes and reservoirs. Two metrics were developed based on this method: the Lake Habitat Modification Score (LHMS) and the Lake Habitat Quality Assessment (LHQA), as measures of lake modification and habitat value, respectively. However, the use of these metrics to predict measures of ecological quality remains largely untested. Thus, we assessed the relationships between LHS metrics and the littoral macroinvertebrate community in 42 lakes across Europe. A significant relationship was found between littoral macrophyte descriptors and riparian natural land cover variables of the LHQA score and macroinvertebrate community composition in 2 out of 4 European regions. No relationship was found between macroinvertebrate community composition and the LHMS. Some significant correlations were found between selected macroinvertebrate metrics and the LHS scores, but this pattern was not consistent across regions, and no relationship was found with the overall LHMS or LHQA scores. This demonstrates that the LHS metrics do not consistently predict the quality of littoral macroinvertebrate communities across Europe, and a region specific approach may be necessary. However, we could demonstrate a relationship between the site specific LHS variables and the macroinvertebrate community at the site level, and in some cases at the regional level. Therefore, although the LHS metrics do not appear to be a useful for relating habitat quality and pressure to littoral macroinvertebrate communities, selected LHS variables may exhibit stronger relationships with the biota.</p
Distinctiveness of macroinvertebrate communities in turloughs (temporary ponds) and their response to environmental variables
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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
Morphological alterations of lake shores in Europe: A multimetric ecological assessment approach using benthic macroinvertebrates
No full textBesides pollution, lakes are affected by human alterations of lake-shore morphology. However, ecological effects of such alterations have rarely been studied systematically. Hence, we developed tools to assess the ecological effects of anthropogenic morphological alterations on European lake-shores based on pressure-specific response patterns of littoral macroinvertebrate community composition. Littoral invertebrates were sampled from 51 lakes in seven European countries. Sampling covered a range of natural to heavily morphologically degraded sites including natural shorelines, recreational beaches, ripraps and retaining walls. Biological data were supplemented by standardized morphological data that were collected via a Lake Habitat Survey (LHS) protocol and subsequently used to develop a morphological stressor index. Two biotic multimetric indices were developed based on habitat-specific samples (Littoral Invertebrate Multimetric based on HAbitat samples, LIMHA) and composite samples (Littoral Invertebrate Multimetric based on COmposite samples, LIMCO) through correlations with the morphological stressor index. Similarity analyses showed strong spatial differences in macroinvertebrate community composition between four main geographical regions, i.e. Western, Northern, Central and Southern Europe. The morphological stressor index as well as LIMCO and LIMHA have been developed for each geographical region specifically, thereby optimizing correlations of LIMCO and LIMHA with the respective morphological stressor index. The metric composition of LIMCO and LIMHA and their correlation coefficients with the morphological stressor index are comparable to existing national and regional methods that assess morphological lakeshore degradation via macroinvertebrate communities. Hence, LIMCO and LIMHA indices constitute a new stressor-specific assessment tool that enables comparable lake morphology assessment across Europe, as it has been developed involving a uniform methodology followed by regionalized optimization. These tools fulfil the standards of the EU Water Framework Directive and thus may complement existing assessment approaches used in lake monitoring focusing solely on lake eutrophication so far. (c) 2013 Elsevier Ltd. All rights reserved
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