1,720,961 research outputs found
Hatching Success of Caretta caretta on a Mediterranean Volcanic Beach: Impacts from Environmental Parameters and Substrate Composition
No full textNew data on the potential impact of environmental parameters and the mineralogical nature of the substrate on the hatching success of the loggerhead sea turtle Caretta caretta on a volcanic beach on Linosa Island in the central Mediterranean Sea are reported. During 2 years of investigation (2018-19), five nests were observed. The temperature and moisture of the nests were determined along with the grain size and mineralogical nature of the substrate. The temperature values of the nests recorded at depths of 5 and 35 cm showed an average temperature incubation of 32.2°C ± 1.4°C and 32.8°C ± 1.6°C, respectively, with peaks close to 37°C. The sedimentological analysis carried out on two cores revealed the prevalence of large sandy particle and sediment moisture of about 35% in the deeper layers. A total of 214 laid eggs were recorded in 2018 with only 44 emerged turtles, whereas 45 turtles emerged from 199 laid eggs in 2019. Both years showed a low hatching success (25%-30%) and a high frequency of anomalies (>60%), which were present in individuals as nonmodal scutes or bifid limbs. Results suggest that environmental parameters such as temperature, sand moisture, and the geological nature of the substrate seem to play an important role in the reproductive success of this species. Some aspects for improving the nesting site and egg development conditions are also discussed
Intra-gear variation in sea turtle bycatch: Implications for fisheries management
No full textIn the Mediterranean Sea, bottom trawl, bottom longline and set nets are the fishing gears with the highest impact on marine turtle populations. These demersal gear types are characterised by a variety of métiers (fishing operations targeting a specific assemblage of species, using specific gear, during a precise period of the year and/or within a specific area). Data on fishing methods, target species and turtle bycatch were collected through interviews in three different study areas in the central Mediterranean. The results show that, even in the same fishing area, different métiers of the same gear can have a different impact on turtles. These findings have several implications. First, traditional turtle bycatch estimations and comparisons based on a fishing gear as a whole may be spatially or temporally biased by spatial and temporal differences in métier composition, respectively. Second, the efficiency of conservation measures may be different according to the métiers involved and caution is needed when measures developed in small areas with certain métiers are exported to a wider scale with possibly very different métiers. Third, conservation measures may induce shifts among métiers that may have an impact on other species, but such shifts are difficult to detect. All this suggests that, in the Mediterranean, a métier-based approach is needed to provide realistic estimates of turtle bycatch, to increase the efficiency of conservation measures by targeting only the most relevant métiers and to predict the changes in target species and effort distribution that can be driven by conservation measures. The variability of fishing methods and métiers implies that the most effective management strategies should be identified at relatively small geographical scales
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
Soundscape of a Mediterranean seashore during loggerhead sea turtle (Caretta caretta) spawning season
No full textThe soundscape is an intrinsic property of an ecosystem and influences the species that live in it. Here, we examined for the first time the soundscape of a beach, one of the most dynamic ecosystems on Earth, where every year the loggerhead sea turtle Caretta caretta lays eggs. The aim of this work was to analyze the acoustic components (biophony, anthropophony and geophony) to which turtles embryos were exposed throughout the development and the post-hatching period. The acoustic monitoring was carried out on the volcanic island of Linosa (central Mediterranean Sea, Strait of Sicily), during the months of July and August 2022, close to two turtle nests. Results revealed that all the acoustic levels (octave bands from 4 Hz to 16 kHz, and total 1–24,000 Hz band) showed lower values in July, and during the night. Furthermore, above 1 kHz the levels decreased and had very little variability. Anthropogenic noise was the main component of the soundscape and consisted of marine and land traffic, that affected sound levels directly or via seismic tremors. When the beach was exposed to the breaking waves, the latters were the first contributor to the noise up to 1 kHz. The only recognized biophony was represented by the shearwater choruses in July (at the frequency band 700–1500 Hz), but they had a negligible weight on the soundscape. Finally, human speech contributed to the soundscape at higher frequencies (1–8 kHz). These outcomes show that the embryos and the post-hatching turtles are exposed to a high anthropogenic noise level, which the effects of are still unknown
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
Detection of Dirofilaria DNA and host blood-meal identification in Culicoides paolae biting-midges
No full textThe vectorial role of blood-sucking arthropods, other than mosquitoes, has been explored for Dirofilaria immitis and Dirofilaria repens which are filarioids of increasing interest due to their zoonotic potential. Given the expansion of canine heartworm infection in southern Europe due to D. immitis and the report of the infection in Linosa Island (Sicily, Italy), we investigated and focused on the potential involvement of Culicoides spp. in Dirofilaria spp. transmission as well as the blood-meal source in Dirofilaria spp. molecularly positive biting midges. Out of 1791 specimens collected 1773 were morphologically and molecularly identified as Culicoides paolae and 18 as Culicoides obsoletus complex. Of the 1596 females, 4 (0.26%) parous C. paolae tested positive for D. immitis and D. repens (i.e. 2 Culicoides specimens for each filarial species), of which D. immitis-positive samples fed on both humans and dogs and D. repens-positive samples fed only on humans. The detection of D. immitis and D. repens DNA in Culicoides midges suggests their potential involvement in the epidemiology of the filarial nematodes, which may be of medical and veterinary importance in hyper-endemic areas. Findings of this study shed new light on the epidemiology of Dirofilaria spp. infections indicating that further investigations are needed
Unveiling the egg microbiota of the loggerhead sea turtle Caretta caretta in nesting beaches of the Mediterranean Sea
Full text linkMicrobes have central roles in the development and health of animals, being the introduction of specific microbial species a potential conservation strategy to protect animals from emerging diseases. Thus, insight into the microbiota of the species and their habitats is essential. In this manuscript, we report for the first time the bacterial composition of all the components (eggshells of hatched and unhatched eggs, internal content of unhatched eggs, intestinal content of hatchling and pipping sea turtles, and sand) of three nesting beaches of Caretta caretta along the Italian coasts of the Mediterranean Sea. The analysis of 26 amplicon samples was carried out using next-generation sequencing analysis, targeting V3–V4 regions of the bacterial 16S rRNA gene. Samples featured mainly Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes, whose percentages depended on the sample type. Our results showed that, although from different sampling sites, the internal content of the unhatched eggs, intestinal content of hatchling and pipping sea turtles share the microbiota, which was yet different from that of eggshells and sand of the same nesting beach. This study suggests the maternal and environmental influence alongside a protective role of eggshells in shaping the egg microbiota of Caretta caretta sea turtles
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
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