1,720,975 research outputs found
Jellyfish as innovative bioindicator for plastic pollution
No full textThe monitoring of plastic pollution through marine biota is a difficult task, which is receiving increasing attention nowadays. A selection of appropriate bioindicator species for plastic ingestion has been proposed, mostly covering benthic filter-feeding organisms or large marine vertebrates. However, monitoring programs involving a broad range of synergetic bioindicators are still missing. Jellyfish have recently been reported as target organisms for marine litter, being able to internalise a number of anthropogenic fragments, from macro- to microplastics. With this perspective, we consider the trophic role of jellyfish and critically discuss its use as a novel bioindicator for plastic pollution on a global scale. Being a widespread energy source in pelagic and deep-sea food webs worldwide and occurring at high densities, jellyfish may represent the invertebrate bioindicator counterpart to monitor plastic pollution in pelagic waters, along with their common predators, and we recommend its inclusion in future monitoring surveys
Molecular Phylogenetics and Systematics of the Bivalve Family Ostreidae Based on rRNA Sequence-Structure Models and Multilocus Species Tree
No full textThe bivalve family Ostreidae has a worldwide distribution and includes species of high economic importance. Phylogenetics
and systematic of oysters based on morphology have proved difficult because of their high phenotypic plasticity. In this
study we explore the phylogenetic information of the DNA sequence and secondary structure of the nuclear, fast-evolving,
ITS2 rRNA and the mitochondrial 16S rRNA genes from the Ostreidae and we implemented a multi-locus framework based
on four loci for oyster phylogenetics and systematics. Sequence-structure rRNA models aid sequence alignment and
improved accuracy and nodal support of phylogenetic trees. In agreement with previous molecular studies, our
phylogenetic results indicate that none of the currently recognized subfamilies, Crassostreinae, Ostreinae, and Lophinae, is
monophyletic. Single gene trees based on Maximum likelihood (ML) and Bayesian (BA) methods and on sequence-structure
ML were congruent with multilocus trees based on a concatenated (ML and BA) and coalescent based (BA) approaches and
consistently supported three main clades: (I) Crassostrea, (II) Saccostrea, and (III) an Ostreinae-Lophinae lineage. Therefore, the
subfamily Crassotreinae (including Crassostrea), Saccostreinae subfam. nov. (including Saccostrea and tentatively Striostrea)
and Ostreinae (including Ostreinae and Lophinae taxa) are recognized. Based on phylogenetic and biogeographical
evidence the Asian species of Crassostrea from the Pacific Ocean are assigned to Magallana gen. nov., whereas an
integrative taxonomic revision is required for the genera Ostrea and Dendostrea. This study pointed out the suitability of the
ITS2 marker for DNA barcoding of oyster and the relevance of using sequence-structure rRNA models and features of the
ITS2 folding in molecular phylogenetics and taxonomy. The multilocus approach allowed inferring a robust phylogeny of
Ostreidae providing a broad molecular perspective on their systematics
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
Abundance, Distribution, and Habitat Preference of Syngnathid Species in Sabaudia Lake (Tyrrhenian Sea)
Full text linkSyngnathids are considered flagship species of estuarine and coastal environments. However, most of the Mediterranean species are still classified as data-deficient (DD) at a global level according to the IUCN Red List of Threatened Species. In central Italy, several areas host potentially suitable habitats for syngnathids but have not been previously reported in the literature; the estimation of population parameters and habitat partitioning at these sites may help to assess their conservation status. In this study, we investigated the abundance, distribution, and habitat preferences of sympatric populations of Hippocampus hippocampus, H. guttulatus, Syngnathus abaster, and Nerophis ophidion in Sabaudia Lake (Tyrrhenian Sea, Italy). While confirming the primary importance of a healthy coastal habitat, we retrieved hints about species ecology and habitat use. The species distribution in the study area highlights the role of habitat complexity in supporting local populations of these sensitive species
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
Pioneer settlement of the cold-water coral Desmophyllum dianthus (Esper, 1794) on plastic
Full text linkLarval settlement is a critical step for sessile benthic species such as corals, whose ability to thrive on diverse natural and anthropogenic substrates may lead to a competitive advantage in the colonization of new environments with respect to a narrow tolerance for a specific kind of substratum. Plastic debris, widespread in marine waters, provides a large, motile, and solid substratum supporting a highly diverse biological community. Here we present the first observation of a floating plastic bottle colonized by the deep-sea coral Desmophyllum dianthus. The density pattern and co-occurring species composition suggest a pioneer behavior of this coral species, whose peculiar morphologic plasticity response when interacting with the plastic substrate (i.e., low density polyethylene) has not been observed before. The tolerance of D. dianthus for such plastic substrate may affect ecological processes in deep water environments, disrupting interspecific substrate competition in the benthic community
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
Relative influence of environmental factors on biodiversity and behavioural traits of a rare mesopelagic fish, Trachipterus trachypterus (gmelin, 1789), in a continental shelf front of the Mediterranean Sea
Full text linkCoastal environments can be influenced by water body masses with particular physical, chemical, and biological properties that create favourable conditions for the development of unique planktonic communities. In this study, we investigated a continental shelf front at Ponza Island (Tyrrhenian Sea) and discussed its diversity and complexity in relation to major environmental parameters. Moon phase and current direction were found to play a significant role in shaping species abundance and behaviour. During in situ observations, we also provided the first data on the behaviour of juveniles of a rare mesopelagic species, Trachipterus trachypterus, suggesting the occurrence of Batesian mimicry
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