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Struttura e dinamica dei popolamenti macrofouling in relazione al periodo di insediamento nel bacino centrale della laguna di Venezia.
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Indagini biometriche su Hediste diversicolor O.F.Muller (Polychaeta: Nereididae) nella laguna di Venezia.
No full textMercury in sediments and Nassarius reticulatus (Gastropoda Prosobranchia) in the southern Venice Lagoon
No full textThe southern basin of the Venice Lagoon has been the focus of fewer studies concerning contamination from heavy metals than the northern and central basins. A recent increase in urban waste waters from Chioggia town, as well as dockyards, shipping and fishing activities, affect this part of the lagoon. The aim of this study was to investigate the total mercury (THg) incidence in sediments and Nassarius reticulatus gastropods in order to assess its distribution and evaluate the level of contamination. THg concentration measured in bottom sediments ranged between 0.1 and 3.4 mg/kg d. wt. The enrichment factor (EF) showed high values (avg. 30, max 49) near the dockyards of Chioggia; the lowest (avg. 9, max 17) were found in the coastal marine sediments near the port entrance of the southern basin. THg in marine scavenger gastropods accumulated in N. reticulatus with concentrations falling within the range of 0.3–1.3 mg/kg d. wt. A positive correlation was found between THg concentration in sediments and in N. reticulatus in all sites, excluding the dockyards. A first local cause for mercury pollution might be attributed to the antifouling paints used in great quantity inthe recent past near the town of Chioggia. Moreover, fine suspended sediments associated with tidal flushing are suggested as possibly being the vehicle for pollutant dispersal from the Marghera industrial area to the whole of Venice’s lagoon
Changes in Macrozoobenthos Community after Aquatic Plant Restoration in the Northern Venice Lagoon (IT)
Full text linkResponses of the macrozoobenthic community to an ecological restoration activity in the northern Venice lagoon were studied, within the scope of the project LIFE SEagrass RESTOration aimed at recreating aquatic phanerogam meadows largely reduced in recent decades. Transplants were successful in almost all project areas. Macrozoobenthos was sampled in eight stations before (2014) and after (2015, 2016, 2017) transplanting activities. An increase in abundance and fluctuations in richness and univariate ecological indices (Shannon’s, Margalef’s, Pielou’s indices) resulted during the years. Comparing non-vegetated and vegetated samples in 2017, every index except Pielou’s increased in the latter. Multivariate analysis (hierarchical cluster analysis, MDS, PERMDISP, SIMPER) grouped samples by localization rather than years, with differences between stations due to the abundance of common species. In 2017, results were also grouped by the presence or absence of aquatic plants, with differences in the abundance of grazer and filter-feeding species. Results of ecological index M-AMBI depicted conditions from moderate to good ecological status (sensu Dir.2000/60/EC) with similar fluctuations, as presented by univariate indices from 2014 to 2017. Responses of the macrozoobenthic community were more evident when comparing vegetated and non-vegetated samples, with the vegetated areas sustaining communities with greater abundance and diversity than non-vegetated samples, thus demonstrating the supporting function of aquatic plants to benthic communities
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
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