1,721,012 research outputs found
Importance of the natural flow regime to an amphidromous shrimp: A case study
No full textAmphidromous shrimp inhabiting large river systems are thought to migrate downstream to hatch larvae close to the estuary or sea. Recent work on Macrobrachium spinipes in northern Australia challenged this hypothesis, with the discovery of abundant females in reproductive condition over 400km upstream. We investigated the early life history of M. spinipes by using a combination of field sampling, laboratory experiments and modelling. We determined the spatial and temporal production of larvae, larval salinity requirements, and, finally, the potential for transport of larvae to the estuary during the wet season. Larvae occurred in high abundances across a 400-km river reach. However, successful larval development was contingent on access, by drift, to saltwater within 7 days. This interval is longer than that found for the majority of amphidromous shrimp species and we propose that larvae in the study river are able to successfully moult through the early stages in freshwater. Large, wet-season discharge events were critical for transporting larvae from all sampled sites to the estuary. The present study confirmed the amphidromous life history of M. spinipes, highlighted the importance of natural flows for maintaining existing populations and provided evidence of a novel type of amphidromous life-history strategy. Journal compilationNo Full Tex
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
Do upstream migrating, juvenile amphidromous shrimps, provide a marine subsidy to river ecosystems?
No full textThe upstream migration of juvenile amphidromous shrimps has been proposed as a source of marine or estuarine-derived nutrients into fresh water. Little is known about the size and ecological importance of any such subsidy as there have been few observational or empirical studies on the topic. We investigated the upstream migration of the amphidromous shrimp, Macrobrachium spinipes (Palaemonidae) in the Daly River, of tropical northern Australia, to determine migration phenology, estimate migration biomass and determine whether migrating shrimps transport marine-derived energy and nutrients upstream. Field observations over 2 years revealed that juvenile M. spinipes migrate upstream en masse during extended periods of declining discharge over a period of 4–6 weeks during the wet season (March–May). In addition, juvenile atyid shrimps from the genus Caridina were also observed migrating upstream during the same period. Fine-scale sampling using fyke nets over 2 years (2013 and 2014) consistently found discharge to be the strongest predictor of M. spinipes and Caridina spp. biomass, while moon illumination and cloud cover were also important predictors. An estimated 10–20 million shrimps migrated upstream during each wet season, transporting c. 100 kg of carbon and c. 28 kg of nitrogen per year. Muscle sulphur stable isotopes (δ34S) and exoskeleton strontium isotope ratios (87Sr/86Sr) were used to establish if marine carbon was transported upstream by the juvenile M. spinipes. Isotope data from migratory M. spinipes were compared to the non-migratory freshwater Macrobrachium bullatum. No evidence of a marine signature in body tissue or exoskeleton was found using either technique, suggesting very rapid turnover of body tissues This study provides key insights into the migration phenology of amphidromous shrimps and, importantly, suggests that migrating M. spinipes do not transport significant amounts of marine-derived energy and nutrients across the marine/freshwater ecotone.Full Tex
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
Ontogenetic shifts in habitat use during the dry season by an amphidromous shrimp in a tropical lowland river
No full textCaridean shrimp have considerable effects on ecosystem processes and, thus, understanding their use of key habitats is important for determining their potential ecological effect. The present study examined the meso-habitat use of Macrobrachium spinipes, a large-bodied and important amphidromous species, in the Daly River, northern Australia. We examined shrimp abundance at four common meso-habitat types; sand bank, rock bars, undercut and structurally complex banks and mid-channel areas at five sites on three occasions during the dry season (May to October). We found that habitat use changed considerably first, with ontogeny, and, second, with the colonisation of habitats with algae and macrophytes as the dry season progressed. As juveniles, their habitat use was strongly associated with well structured bank environments early in the dry season. By the mid-dry season, juveniles were more abundant within sand habitats recently colonised with macrophytes and filamentous algae. Females showed little change in habitat use, whereas large-bodied dominant males generally favoured rock bars and heavily structured bank environments. The present study has provided significant insights into the changes in use of key riverine habitats throughout the dry season by an ecologically important species. This information will be of considerable value to the determination of environmental flow requirements and food-web investigations.No Full Tex
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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