1,720,970 research outputs found
YOUMARES 8 – Oceans Across Boundaries: Learning from each other
Get PDFThis open access book presents the proceedings volume of the YOUMARES 8 conference, which took place in Kiel, Germany, in September 2017, supported by the German Association for Marine Sciences (DGM). The YOUMARES conference series is entirely bottom-up organized by and for YOUng MARine RESearchers. Qualified early career scientists moderated the scientific sessions during the conference and provided literature reviews on aspects of their research field. These reviews and the presenters’ conference abstracts are compiled here. Thus, this book discusses highly topical fields of marine research and aims to act as a source of knowledge and inspiration for further reading and research
YOUMARES 9 - The Oceans: Our Research, Our Future
Get PDFThis open access book summarizes peer-reviewed articles and the abstracts of oral and poster presentations given during the YOUMARES 9 conference which took place in Oldenburg, Germany, in September 2018. The aims of this book are to summarize state-of-the-art knowledge in marine sciences and to inspire scientists of all career stages in the development of further research. These conferences are organized by and for young marine researchers. Qualified early-career researchers, who moderated topical sessions during the conference, contributed literature reviews on specific topics within their research field
YOUMARES – A Conference from and for YOUng MARine RESearchers
Get PDFYOUMARES is an annual early-career scientist conference series. It is an initiative of the German Society for Marine Research (DGM) and takes place in changing cities of northern Germany. The conference series is organized in a bottom-up structure: from and for YOUng MARine RESearchers. In this chapter, we describe the concept of YOUMARES together with its historical development from a single-person initiative to a conference venue of about 200 participants. Furthermore, the three authors added some personals experiences and insights, what YOUMARES means to them
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Die eingeschleppte Seescheide Styela clava im Ökosystem Wattenmeer - Bedrohung oder Gewinn?
No full textDispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
INVASIVES PLANKTON : Konsequenzen durch und für Ballastwassermanagement
No full textInvasive species are one of the biggest threats to our world’s oceans. The man-aided introduction of non-native organisms via a vector into new areas and their successful establishment as invasive species pose risks to native biodiversity, ecosystem services, and human health. To develop effective strategies in case of negative environmental and economic impacts, detailed knowledge about the invasion process is required.
A new comprehensive stage-transition framework is presented. It unifies invasion theories which were inconsistent in the use of terminology and it provides a mechanistic understanding of the invasion process. That makes it applicable for the development of management strategies and as a tool for scientists and decision makers. The new framework consists of three stages: introduction, establishment, and dominance. Each stage is preceded by a transition: transport, survival, and spread. Successful invaders pass these intermediate transitions which are influenced by factors like propagule pressure, invasiveness, and invasibility.
‘Invasive species’ are defined encompassing the major process events: non-native species which were transported via a vector and by that experienced a human-mediated introduction outside their normal distribution followed by dominant abundance in the recipient ecosystem. That definition excludes, however, the invader’s possible (positive or negative) impact.
The first transition in the framework is the transport via a vector and that is the best moment to mitigate introductions of species with invasive and harmful potential. Marine organisms are mainly transported via ballast water of vessels and many are able to survive in the dark tanks. In order to reduce the risk of invasions, different technologies were developed to treat ballast water according to the Ballast Water Convention adopted by the International Maritime Organization. The effectiveness of a UV-based ballast water treatment system is tested in incubation experiments over 20 days.
Long-term incubation experiments proved to be a valuable testing tool and after an initial decline in cell numbers, re-growth could be observed. Surviving phytoplankton taxa were identified for the first time: namely, the diatoms Thalassiosira, Skeletonema, Chaetoceros, Pseudo-nitzschia, and Nitzschia (order represents rank of abundance). The conclusion is that a variety of taxa are able to survive UV-treatment. Despite approved treatment according to IMO’s D-2 standard, phytoplankton species can become invasive and might become harmful by producing toxins (e.g. Pseudo-nitzschia species) or anoxic conditions following their blooms. Thalassiosira could be a suitable indicator organism for testing the efficiency of UV-units.
Methods for phytoplankton detection are used and compared: flow cytometry, cluster analysis, microscopy, and DNA-sequencing. Flow cytometry is preferable for fast organism counts. Cluster analysis and DNA-sequencing seemed unreliable to identify phytoplankton species. Results of microscopy indicate, even at species level, the re-growing phytoplankton - including species smaller than 10 µm in minimum dimension. These small organisms are so far not included in the D-2 Ballast Water Performance Standard which restricts organism counts per size class after treatment. However, they account for over 90 % of the overall phytoplankton in land-based ballast water treatment system testing, show the main re-growth after UV-treatment and electrolytic chlorination, and include harmful species. It is therefore recommended to include organisms smaller than 10 µm in minimum dimension into the D-2 standard.
This thesis showed why invasive plankton is the reason for ballast water management and in turn treatment seems to have implications for plankton invasions. Invasive plankton and ballast water management were examined based on the new framework of invasion theory. As further perspective, more research is suggested to study if ballast water treatment according to D-2 is sufficient or if amendments are needed (especially regarding smaller organisms) and if ballast water treatment is creating tough invaders.Invasive Arten sind eine der größten Bedrohungen für unsere Weltmeere. Durch die Einschleppung gebietsfremder Organismen und deren erfolgreiche Invasion werden die heimische Biodiversität und Ökosystemdienstleistungen gefährdet, wobei einige invasive Arten auch gesundheitsschädlich sind. Um mögliche Kosten und öko-logische Schäden zu begrenzen, ist ein grundlegendes Verständnis des Invasions-prozesses notwendig.
Das neue konzeptionelle Modell erklärt nicht nur den Invasionsprozess, sondern vereinheitlicht auch ältere, zum Teil widersprüchliche, Prozessmodelle und die Terminologie. Dadurch kann es zur Entwicklung von Maßnahmen beitragen und Wissenschaftler und Entscheidungsträger bei ihrer Arbeit unterstützen. Das neue Modell besteht aus drei Stufen: Einschleppung, Ansiedlung und Dominanz. Jeder Stufe geht ein Zwischenschritt voraus: Transport, Überleben und Verbreitung. Erfolgreiche invasive Arten durchlaufen diese Prozessschritte unter Einflussnahme von Faktoren, wie Einschleppungsfrequenz und Volumen, den Eigenschaften der Art und des Zielhabitats.
Invasive Arten werden auf Basis des neuen Modells definiert als gebietsfremde Arten, die über einen Vektor außerhalb ihres normalen Lebensraumes eingeschleppt werden und sich im Zielhabitat dominant ansiedeln. Diese Definition bezieht jedoch nicht die möglichen positiven oder negativen Folgen der Invasion mit ein.
Der erste (Zwischen-)Schritt in dem Modell ist der Transport durch den Vektor. An diesem Schritt kann deshalb besonders gut interveniert werden, um die Einschleppung möglicher schädlicher invasiven Arten zu verhindern. Meeres-organismen werden hauptsächlich durch Ballastwasser von Frachtschiffen in andere Gebiete transportiert und können dabei auch mehrere Tage im dunklen Tank überleben. Um die Einschleppung gebietsfremder Arten zu reduzieren, wurden Ballastwasserbehandlungsanlagen entwickelt – nach den Richtlinien des Ballast-wasser-Übereinkommens der Internationalen Seeschifffahrts-Organisation (IMO). Die Effektivität einer Behandlungsanlage, die UV-Strahlung zur Desinfizierung einsetzt, wurde im Rahmen von Inkubationsexperimenten über 20 Tage getestet.
Die Inkubationsexperimente erwiesen sich als sehr sinnvoll und zeigten nach einer anfänglichen Abnahme der Phytoplankton-Zellen erneutes Wachstum. Phyto-plankton-Taxa, die überlebt haben, wurden erstmals identifiziert: Thalassiosira, Skeletonema, Chaetoceros, Pseudo-nitzschia und Nitzschia (wobei die Reihenfolge ihrer Abundanz entspricht). Die Schlussfolgerung ist also, dass verschiedene Phytoplankton-Taxa die UV-Behandlung überleben. Trotz Behandlung mit einem zertifizierten System nach dem D-2 Standard der IMO verbleiben Möglichkeiten, dass Phytoplankton-Arten invasiv werden und Schäden verursachen können (z.B. durch Planktonblüten oder Toxine bildende Pseudo-nitzschia Arten). Dabei scheint Thalassiosira ein guter Testorganismus für die Effektivität von Ballastwasser-behandlungsanlagen zu sein.
Methoden zur Untersuchung von Phytoplankton wurden verglichen: Durchfluss-zytometrie, Software zur Daten-Gruppenerkennung, Mikroskopie und DNS-Sequenzierung. Um Zellzahlen zu ermitteln, erwies sich die Durchflusszytometrie als bestes Verfahren. Die Identifizierung der Arten war durch die Software zur Daten-Gruppenerkennung und die DNS-Sequenzierung nur unzuverlässig gewährleistet. Mikroskopie war die beste Methode, um Arten zu ermitteln. Dadurch war es sogar möglich, die kleineren überlebenden Phytoplankton-Gruppen zu ermitteln (kleiner als 10 µm). Bisher sind diese kleinen Organismen nicht in dem D-2 Standard enthalten, welcher die erlaubten Zellanzahlen per Größenklasse im Auspumpwasser regelt. Allerdings machen diese kleinen Organismen den größten Teil des Phytoplanktons bei den Landtests der Behandlungsanlagen aus. Sie zeigen außerdem die höchste Überlebens- und (Wiederwachstums-)Rate nach Behandlung mit UV-Strahlung oder elektrolytischer Chlorierung und beinhalten schädliche Arten. Deshalb wird empfohlen, Phytoplankton mit einer Größe kleiner als 10 µm in den D-2 Standard zu integrieren.
Diese Dissertation hat gezeigt, warum invasives Plankton der Grund für die Entwicklung von Ballastwassermanagement ist, welches wiederum Plankton-invasionen beeinflusst. Invasives Plankton und Ballastwassermanagement wurden im Rahmen des neuen Prozessmodells analysiert. Als Folgeschritt ist zu empfehlen, weiter zu untersuchen, ob der D-2 Standard des Ballastwasser-Übereinkommens ausreicht oder Änderungen im Speziellen bezüglich kleinerer Organismen notwendig sind und ob das heutige Ballastwassermanagement besonders resistente invasive Arten hervorbringt
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