1,721,177 research outputs found
A synthesis of the distribution of Mnemiopsis leidyi in European waters
No full textJaspers, Cornelia ... et. al.-- International Council for the Exploration of the Sea Annual Science Conference (ICES ASC 2014), Sustainability in a changing ocean, 15-19 September 2014, La Coruña.-- 2 pagesWe synthesize the distribution of M. leidyi throughout European waters and show that it has established populations through northern and southern Europe reaching as far north as 63.5⁰NPeer Reviewe
Physical oceanography during ALKOR cruise AL544
No full textConductivity-temperature-depth profiles were measured using a CTD during RV ALKOR cruise AL544. The CTD was equipped with duplicate sensors for temperature, conductivity and oxygen. All sensors are calibrated irregularly. Data were connected to the station book of the specific cruise as available in the DSHIP database
Evidence of extraordinary marine species in the SW Baltic Sea
No full textThe presence of an extended salinity gradient of the Baltic Sea reveals a variety of species occur at the limit of their physiological tolerance and preference, i.e. in areas and habitats not representing their marine or fresh water origin. Hence, the Baltic Sea is known for its high share of non-indigenous species, which have established. In this study, we compiled extraordinary sightings of transient, non-native or potentially range expanding species, such as jellyfish, squid, fishes and marine mammals in the SW Baltic Sea for a period from 2001 to 2018. We focused on jellyfish, squid, fishes and marine mammals. Hydrographic conditions, such as water temperature and salinity, obtained from a high spatio-temporally resolved hydrodynamic Baltic Sea model, covering a daily resolved 40-year time series were linked to the sightings of these extraordinary species. Our hydrodynamic modelling results demonstarted that changes in the occurrence of exceptional species reflect the dynamics of water mass exchange between the Kattegat/Skagerrak and the SW Baltic Sea. Our analyses show that these changes could be related to the presence of anomalously high saline water masses. This documents that the hydrographically highly dynamic SW Baltic Sea needs special attention for monitoring of non-indigenous species, as high saline and warm water intrusions are more frequent than currently believed and ii) can be linked to sightings of exceptional species in the SW Baltic Sea
Mesozooplankton abundance and biomass during Alkor cruise AL544 (WP2 net)
No full textA key goal of the AL544 cruise in September 2020 in the Baltic Sea was to enhance our understanding of environmental and zooplankton (especially gelatinous) population fluctuations along an east-west transect. Vertically integrated mesozooplankton abundance and diversity was obtained from plankton net hauls followed by image analysis. Samples were collected using a Hydrobios standard WP2 net (200µm) vertical from bottom to surface. Samples were scanned using an Epson V750 Pro flatbed scanner at 2400dpi, scanned as one size fraction, split sometimes multiple times. Processed using ZooProcess. Image data are available on https://ecotaxa.obs-vlfr.fr/prj/5189 and were sorted into taxonomic categories (examples in AL544_mesozoo_examples.zip). Using the export file (.tsv) individual biomass was calculated based on object area and taxonomic identity according to Lehette and Hernandez-Leon (2009). Abundance and biomass are then aggregated to concentrations (per volume)
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
Ocean current connectivity propelling the secondary spread of a marine invasive comb jelly across western Eurasia
No full textJaspers, Cornelia ... et al.-- 14 pages, 5 figures, 3 tables, supporting information https://doi.org/10.1111/geb.12742.-- All data are available from the Pangaea database (https://doi.org/10.1594/PANGAEA.884403) and GenBank (accession numbers KY204070–KY204083)Aim: Invasive species are of increasing global concern. Nevertheless, the mechanisms driving further distribution after the initial establishment of non-native species remain largely unresolved, especially in marine systems. Ocean currents can be a major driver governing range occupancy, but this has not been accounted for in most invasion ecology studies so far. We investigate how well initial establishment areas are interconnected to later occupancy regions to test for the potential role of ocean currents driving secondary spread dynamics in order to infer invasion corridors and the source–sink dynamics of a non-native holoplanktonic biological probe species on a continental scale. Location: Western Eurasia. Time period: 1980s–2016. Major taxa studied: ‘Comb jelly’ Mnemiopsis leidyi. Methods: Based on 12,400 geo-referenced occurrence data, we reconstruct the invasion history of M. leidyi in western Eurasia. We model ocean currents and calculate their stability to match the temporal and spatial spread dynamics with large-scale connectivity patterns via ocean currents. Additionally, genetic markers are used to test the predicted connectivity between subpopulations. Results: Ocean currents can explain secondary spread dynamics, matching observed range expansions and the timing of first occurrence of our holoplanktonic non-native biological probe species, leading to invasion corridors in western Eurasia. In northern Europe, regional extinctions after cold winters were followed by rapid recolonizations at a speed of up to 2,000 km per season. Source areas hosting year-round populations in highly interconnected regions can re-seed genotypes over large distances after local extinctions. Main conclusions: Although the release of ballast water from container ships may contribute to the dispersal of non-native species, our results highlight the importance of ocean currents driving secondary spread dynamics. Highly interconnected areas hosting invasive species are crucial for secondary spread dynamics on a continental scale. Invasion risk assessments should consider large-scale connectivity patterns and the potential source regions of non-native marine speciesThis work received funding from the Danish Council for Independent Research and the European Commission (Marie‐Curie program) with the DFF‐MOBILEX mobility grant number: DFF‐1325‐00102B (C.J.). Additional support was received from the BIO‐C3 project, funded jointly by the EU, BONUS (Art 185) and the national funding agencies in Germany (BMBF grant no. 03F0682), Denmark, Finland and Poland, as well as the Excellence Cluster Future Ocean (CP1539)Peer Reviewe
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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