1,720,962 research outputs found
Composition and seasonality of a heterobranch assemblage in a sublittoral, unconsolidated, wave-disturbed community in the Mediterranean Sea.
No full textThe habitat preferences of the Mediterranean heterobranchs are generally well known; however, some environments, especially those considered poorly structured or of modest biodiversity, have been scarcely studied. Here we evaluate the annual variations in species composition, seasonality and diet preferences of the sea-slug assemblage in an environment of gravel and coarse sand at Noli Cape (northwestern Ligurian Sea), an unconsolidated wave-disturbed community, between 5 m and 20m depth. The assemblage, studied by means of 64 scuba-diving surveys from January 2015 to December 2016, was found to be extremely rich in terms of biodiversity, reaching 45 recorded species in just 3,000m2 (including six new records for the Ligurian Sea), of a total richness, in the entire basin, of about 150 species. Seasonality is a strong feature of the studied species, showing a high frequency of species appearance in winter; overall, 60% of the recorded sea slugs showed a cold affinity, even though the most common species were chiefly endemic ones. An expected finding, in view of the dominant environment, was that most of the species were typical of hard-bottom communities. Despite the high total species richness, the main feature characterizing the assemblage was the poor representation of sponge-eaters (13%), while the majority of the species were cnidarian-eaters (29%), or omnivorous and true predators (24%). Some common sponge-eaters were absent or very rare, because of the lack of their prey. The species composition of the Noli Cape heterobranch assemblage appears strongly related to the presence of their prey which, in turn, directly depends on the effect of hydrodynamism that can be considered the primary constraint. At the same time, the presence of many boreal species, and the evident seasonality with peaks of biodiversity during cold periods, suggest that temperature is also a significant variable
Northernmost record of Godiva quadricolor (Gastropoda: Nudibranchia) in the SCI “Fondali Noli – Bergeggi” (Ligurian Sea).
No full textThe northernmost record of the alien nudibranch Godiva quadricolor is reported here, about 400 km farther north than the previously published one and the farthest to be recorded from the equator. It is also the second published record of this species along the Italian coasts and the first record from the Ligurian Sea. A single specimen was reported during a scuba dive, crawling on small stones inside the Site of Community Importance 'Fondali Noli - Bergeggi SCI', at a depth of 3.5 m. The species, described in 1927 in South Africa, is considered to be rapidly expanding its original areal distribution thanks to maritime traffic. A review of the known actual distribution is also reported here
First records from the Ligurian Sea of the cold water species Okenia aspersa and Doto koenneckeri (Gastropoda: Nudibranchia).
No full textOkenia aspersa is a north-eastern Atlantic species, only previously recorded as Okenia quadricornis from the Malta Archipelago in the Mediterranean Sea, and in juvenile forms, from Sicily and the Gulf of Naples. A second adult specimen is recorded in the present paper, which was found along the Noli Cape coast, in the western Ligurian Sea (Italy). It was found on pebbles at a depth of 10 m. In the same area, at a depth of 5.5 m, two specimens of Doto koenneckeri and three of their egg masses were found. This species, also described from Norway and Ireland, was only previously known to occur in the Mediterranean Sea off Spain and France. It is likely that the cold winter temperatures of the Ligurian Sea allowed this species to live and reproduce
Shallow-water sea fans: the exceptional assemblage of Leptogorgia sarmentosa (Anthozoa: Gorgoniidae) in the Genoa harbour (Ligurian Sea)
No full textAn exceptional assemblage of the sea fan Leptogorgia sarmentosa (Anthozoa: Gorgoniidae) was observed inside the Genoa harbour, which represents one of the major Mediterranean ports. The studied assemblage is confined in a shaded portion of a floating dock thriving in extremely shallow water, with specimens even touching the sea surface. It represents the shallowest population of this species and of this genus known worldwide. A total of 188 specimens were observed and measured: the maximum density of 45 specimens m−2 was reached in the most shaded part of the dock, where the maximum height of colonies (30 cm) was also recorded. Light measurements showed that the illuminance along the dock was comparable to that observed outside the harbour at 20 m depth, where the nearest colonies of L. sarmentosa were recorded for this region. This suggests that high levels of incident light might be putatively interpreted as the limiting factor in the upper bathymetrical distribution of the species. Despite the extremely shallow distribution, however, the population cannot be defined as intertidal as the floating dock avoids exposing the gorgonians to air. The chance to grow far from the silted bottom, but still in a turbid, sciaphilous and nutrient-enriched environment, probably enhanced the settling and growth of the colonies and allowed the formation of a dense and healthy population
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
Prove sperimentali di allevamento in cattività di APHIA MINUTA MEDITERRANEA De Buen, 1931, a scopo di studiarne la biologia
No full textDispelling 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
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