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Life history strategies in reef-building coral communities: evidence from spatial patterns, population trends and demographic rates
No full textLife history strategies in reef-building coral communities: evidence from spatial patterns, population trends and demographic rates
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Global assessment of the status of coral reef herbivorous fishes : : evidence from fishing effects
Get PDFHerbivores provide important ecological services across ecosystems where they influence productivity and plant community composition. On coral reefs, herbivorous fishes consume benthic primary producers and regulate competition between fleshy algae and reef-building corals. Many of these species are also important fishery targets yet little is known about their global status. Using a worldwide synthesis of herbivorous reef fishes we show that biomass is more than twice as high at sites not accessible to fishing relative to fished sites, independent of regional effects. Further, fishing alters community structure by disproportionately reducing biomass of larger-bodied functional groups while increasing that of smaller territorial damselfishes. This fishing down the herbivore guild likely alters the effectiveness of these fishes to regulate algal abundance on reefs. Our study reveals that herbivores are systematically affected by fishing and provides insights and baselines for herbivore assemblages which can be used for developing informed management targets globall
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Life history strategies in reef-building coral communities: evidence from spatial patterns, population trends and demographic rates
No full textUnderstanding the intrinsic drivers of change in high diversity systems such as coral reefs is of fundamental importance to both ecological theory and conservation. Across four chapters, I explore the role of life history strategy in shaping spatial patterns, population trends, and variability in reef-building coral communities. I first tested whether differences in spatial dispersion among coral taxa reflect ecological strategy. Using spatial point pattern analysis, I found that nearly all coral taxa exhibit clustered distributions. Variation in the degree of clustering corresponded with life history characteristics of the taxa, and was largely driven by patterns of recruitment and fragmentation. I next explored whether these temporally stationary patterns scale to differences in populations through time, and determined if the net effect of these differences drive patterns of community abundance. I found a tendency for asynchronous population fluctuations to contribute to overall community stability under background conditions. Importantly, these effects were shown to be driven by statistical averaging, rather than consistent patterns of covariation, consistent with portfolio effects. However, this effect reversed under intense disturbance, and a large decline in community abundance was associated with net synchrony among populations. Next, I explored the causal mechanisms of demographic variation and developed a robust growth model for a well-studied taxon, Pocillopora. I found growth in Pocillopora to be well described by a simple model of radial growth, and while growth and survivorship rates varied through time and space, they were generally stable between sites. Chapter 4 extends this framework to a multi-species context, and I compare patterns growth and survivorship across four dominant coral groups. There were strong similarities in the functional form of growth, but important differences in rate and temporal variability. These differences, however, only partially align with life history expectations, suggesting a need to revise how coral strategies are defined. Together, these chapters offer one of the most detailed empirical assessments of coral community variability to date, advancing our understanding of how vital rates vary across taxa, time, and space, and how this variation shapes coral reef community dynamics
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
Dispelling 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
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