1,721,042 research outputs found
The analysis of contaminants of emerging concern and trace elements in Louisiana red swamp crayfish suggests its possible exploitation trough sustainable applications
No full textLouisiana red swamp crayfish (Procambarus clarkii) is one of the most widely introduced freshwater species in the world, raising concerns about its impact on native aquatic biota [1]. Despite the important nutritional properties of freshwater decapods and their potential use as a source of bioactive molecules, there are potential health risks associated with their consumption due to their ability to accumulate contaminants [1].
In the present work, we aimed to analyze muscle and exoskeleton of P. clarkii and environmental matrices (water and sediment) for the presence of trace elements (TEs), pesticides, per- and polyfluoroalkyl substances, phthalates, antibiotics and cyanotoxins in three epresentative Sicilian aquatic ecosystems. P. clarkii samples were divided into five pools to collect the necessary amounts of muscle and exoskeleton, and to increase the homogeneity and representativeness of measurements. After dissection of muscle (with and without intestine) and exoskeleton (with and without cephalothoracic region) samples were weighed, homogenized, and frozen at -20 °C until freeze-drying.
All extraction and analytical procedures were adapted to the type of matrix and analytes. Except for TEs, all samples showed concentrations below the detection limit for all contaminant classes. The bioaccumulation factor and the biotic sediment accumulation factor for TEs were, except in a few cases, below the EU bioaccumulative criterion. In addition, the PERMANOVA, PCA and HCA statistical analysis showed significant differences between the contamination profiles observed both between sites and between matrices, confirming that P. clarkii is a good bioindicator of TEs contamination. Nevertheless, the levels of TEs detected were comparable or lower than those reported in the literature [2] and below the maximum levels allowed by current European
environmental and food safety legislation (EU Regulation 2023/915). However, these results are specific to these selected sites, time of sampling and contaminants and should be confirmed by further periodic sampling and analysis.
Based on these results, Sicilian P. clarkii individuals removed as part of monitoring, management or eradication activities required by EU and Italian legislation could be used as a resource in various sectors. Only in this exceptional case, the meat could be suitable for food or feed, while the exoskeleton, could be a valuable resource in various industries, such as the production of commercially valuable substances like chitin or chitosan. This would prevent the carcasses, which are considered waste, from having to be disposed of at additional environmental and economic costs, while also helping to cover the costs of managing this invasive species. In this context, the exploitation of P. clarkii could help to promote the policies and regulations necessary for more economically sustainable actions by local management authorities.
References
[1] C. Souty Grosset, P. Anastácio, L. Aquiloni, et al., The red swamp crayfish Procambarus clarkii in Europe: Impacts on aquatic ecosystems and human well-being, Limnologica 2016 58, 78 – 93.
[2] A. Anandkumar, J. Li, K. Prabakaran, et al., Accumulation of toxic elements in an invasive crayfish species (Procambarus clarkii) and its health risk assessment to humans, J. Food Compos. Anal. 2020, 88, 103449
Predation of a waterfrog (genus Pelophylax) by the freshwater crab Potamon fluviatile in Sicily, Italy
Full text linkOn the occurrence of Eudiaptomus gracilis (G.O. Sars, 1863) (Copepoda: Diaptomidae) in Madeira (Portugal)
Full text linkCalanoid copepods belonging to the diaptomid genus Eudiaptomus Kiefer, 1932 were collected in an artificial water body on the island of Madeira, Portugal. The morphological and molecular identification of the collected specimens unequivocally proved that they belong to the allochthonous species Eudiaptomus gracilis (G. O. Sars, 1863), possibly unwarily introduced along with fish stockings or ornamental aquatic plants. In the sampled site, the species co-occurred with the non-native cyclopoid copepod Acanthocyclops americanus (Marsh, 1893) and some anomopod species. This is the first record of the species for Portugal and the whole Macaronesia, whereas the possible presence of E. gracilis in the Iberian Peninsula should
be verified.Copépodos calanoides pertenecientes al género de diaptómido Eudiaptomus Kiefer, 1932 fueron recolectados en una masa de agua artificial en la isla de Madeira, Portugal. Las identificaciones morfológicas y moleculares de los especímenes recolectados demostraron inequívocamente que pertenecían a la especie alóctona Eudiaptomus gracilis (G. O. Sars, 1863), posiblemente introducida inadvertidamente con introducciones de peces o plantas acuáticas ornamentales. En la localidad muestreada, la especie coexistía con el copépodo ciclopoide no nativo Acanthocyclops americanus (Marsh, 1893) y algunas especies de anomopodos. Esta es la primera cita de la especie para Portugal y para Macaronesia, aunque la posible presencia de E. gracilis en la Península Ibérica necesita verificación
First data on the genetic structure of Trachemys scripta populations in Sicily (Testudines: Emydidae)
Full text linkThe pond slider Trachemys scripta is one of the most widespread alien turtle species in the world. Its
unregulated trade and the consequent uncontrolled releases into the wild led to negative impacts on the native turtles of
the invaded areas. In Italy, alien pond sliders are widely spread, and the occurrence of hatchlings and well-established
populations is known in some areas. However, to date in Sicily, only a single female of Trachemys scripta laying eggs was
reported. Besides that, nothing is known about the actual reproduction success and establishment of self-sustaining
T. scripta populations in Sicily. Therefore, based on 14 previously characterised highly polymorphic microsatellite loci,
we aimed to unravel if the alien turtles successfully reproduce in Sicily, in both natural and semi-natural areas (i.e., lake
“Biviere di Gela” and “Parco d’Orléans”, respectively). Our results show a clear structuring of the two studied
populations. Several full-sibling relationships between the sampled turtles were found, suggesting actual reproduction in
the wild of the pond sliders in Sicily. However, further sampling is desirable since no parent-offspring relationships were
observed in the studied populations. Due to our results, systematic monitoring of alien pond sliders in the whole of Sicily
is crucial for better planning of mitigation strategies in order to protect the native biota of Sicilian inland waters
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
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