1,721,015 research outputs found
Caulerpa taxifolia C. Agardh
No full text<i>Caulerpa taxifolia</i> <p> Research effort on the ecological impacts of <i>Caulerpa taxifolia</i> decreased relative to other invasive macroalgae, and the geographic focus shifted in large part from the Mediterranean Sea (1 study in this review) to Australia (12 studies in this review). However, this species continued to affect the diversity (Gallucci et al. 2012, Bishop and Kelaher 2013), growth, condition, and survival (Gribben et al. 2009) of invertebrates. Gribben et al. (2013) found that faunal impacts varied by community: <i>C. taxifolia</i> had a negative effect on infauna but a positive effect on epifauna. It also affected higher trophic levels by providing a less attractive food source to herbivores (Gollan and Wright 2006, Burfeind et al. 2009) and a less attractive fish habitat (York et al. 2006) relative to native macroalgae.</p>Published as part of <i>Davidson, Alisha D., Campbell, Marnie L., Hewitt, Chad L. & Schaffelke, Britta, 2015, Assessing the impacts of nonindigenous marine macroalgae: an update of current knowledge, pp. 55-79 in Botanica Marina (Warsaw, Poland) (Warsaw, Poland) 58 (2)</i> on page 62, DOI: 10.1515/bot-2014-0079, <a href="http://zenodo.org/record/11208773">http://zenodo.org/record/11208773</a>
Codium fragile subsp. tomentosoides P. C. Silva
No full text<i>Codium fragile</i> ssp. <i>tomentosoides</i> <p> <i>Codium fragile</i> ssp. <i>tomentosoides</i> maintained its dominance in many areas of the northwest Atlantic because it is a superior competitor after disturbance events (Scheibling and Gagnon 2006, Kelly et al. 2011). However, several studies reported greater macrofaunal and epiphyte diversity associated with <i>C. fragile</i> ssp. <i>tomentosoides</i> (Schmidt and Scheibling 2006, 2007), which may be due to increased adaptation of the local community to this species (Harris and Jones 2005). A single study outside the northwest Atlantic showed that <i>C. fragile</i> ssp. <i>tomentosoides</i> increased the recruitment of the mussel <i>Mytilus galloprovincialis</i> Lamarck (Bulleri et al. 2006).</p>Published as part of <i>Davidson, Alisha D., Campbell, Marnie L., Hewitt, Chad L. & Schaffelke, Britta, 2015, Assessing the impacts of nonindigenous marine macroalgae: an update of current knowledge, pp. 55-79 in Botanica Marina (Warsaw, Poland) (Warsaw, Poland) 58 (2)</i> on page 64, DOI: 10.1515/bot-2014-0079, <a href="http://zenodo.org/record/11208773">http://zenodo.org/record/11208773</a>
Sargassum muticum Fensholt
No full text<i>Sargassum muticum</i> <p> Several of the case studies of the impacts of <i>Sargassum muticum</i> introductions showed negative effects, such as being an undesirable food source for herbivores (Monteiro et al. 2009), suppression of native algal assemblages (Olabarria et al. 2009), and space monopolization (Thomsen et al. 2006). However, several of the studies had ambiguous results, with some taxonomic groups showing increased abundance and some showing decreased abundance (Lang and Buschbaum 2010, Gestoso et al. 2012). <i>Sargassum muticum</i> also enhanced epibiotic diversity in soft-bottom environments (Buschbaum et al. 2006), and at time scales of <1 week after colonization (Rodil et al. 2008). This species was a preferred forage material for the snail <i>Lacuna vincta</i> Montagu (Britton-Simmons et al. 2011), and its presence increased overall faunal abundance (Strong et al. 2006).</p>Published as part of <i>Davidson, Alisha D., Campbell, Marnie L., Hewitt, Chad L. & Schaffelke, Britta, 2015, Assessing the impacts of nonindigenous marine macroalgae: an update of current knowledge, pp. 55-79 in Botanica Marina (Warsaw, Poland) (Warsaw, Poland) 58 (2)</i> on page 64, DOI: 10.1515/bot-2014-0079, <a href="http://zenodo.org/record/11208773">http://zenodo.org/record/11208773</a>
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
Comparing competitive interactions and settlement success among native and non-indigenous species in marine hard bottom communities of colonial ascidians, from the Bay of Plenty, New Zealand
Full text linkThe requirement for space in marine hard bottom assemblages is paramount for life. Due to the crowded nature and demand for space in these sessile assemblages, bare space that is freed is quickly occupied. The intense push and pull for space within these assemblages is represented by heavy overgrowth interactions. These competitive interactions often result in the displacement of native species and the formation of competitive hierarchies amongst species, with some individuals settling as epibionts and causing the mortality or stress of those beneath them.
Ascidian invasions have become more frequently reported on a global scale, becoming an emerging issue on many coastlines. Colonial ascidians (the key phylogenetic class of this study) and their ability to dominate and occupy vast amounts of space, has landed them their reputation as notorious marine invaders. With urbanization comes the general increase in anthropogenic activity, which in turn has been known to coincide with the increase in the translocations of nonindigenous species. Vectors such as interoceanic trade and travel have contributed heavily to the spread of nonindigenous ascidians, allowing them to overcome geographic barriers. Unmanaged populations of nonindigenous colonial ascidians heavily foul much of the submerged substrate in the Tauranga Harbour, threatening the biodiversity, population structure and function of native communities as well as fouling of marina and port substrates (wharves, pylons, ropes, boat hulls).
The framework of this research infers that the competitive abilities of non-indigenous colonial ascidians through their rapid occupation of substrate is a key determinant in their invasion success. Ex-situ manipulative experiments were used to examine potential competition (epibiotic or bare space settlement) recruiting species may have on nonindigenous and native ascidians. Simultaneously, we examined if the status (nonindigenous or native) of the test species impacted the settlement of the nonindigenous and native recruiting species. Few studies have attempted the novel process of rearing ascidian cultures ex-situ, where manipulation and control can be maximized. We attempted to develop a robust ascidian culture system to better study ascidian species.
The lines of evidence provided by these experiments revealed that nonindigenous colonial ascidians are often opportunistic settlers and can largely determine the dynamics of native sessile communities, as they settled the most as both epibionts and bare space recruits on the experimental plates in this study.
Experimental results found most recruits to prefer settling on bare substrate than on the surfaces of other organisms, supportive of the concept that surface microtopography and secondary metabolite release may play a role in recruit settlement.
Findings bring focus to the unrivalled ability of nonindigenous species to exert settlement pressures on existing sessile communities, illustrated by their competitive power. Introduced species’ ability to settle heavily as both basibionts and epibionts allows them to litter submerged substrates with larvae, illustrative of high propagule pressures found in this study. Experimental results offer managers to better utilise biosecurity management resources when dealing with nonindigenous incursions in the future
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