1,721,061 research outputs found
Modelling the influence of flow and other environmental variables on the migration of atlantic salmon (Salmo salar) in a UK chalk stream
No full textThe Atlantic salmon (Salmo salar L.) is a species of substantial cultural, economic and ecological importance. Named “Salmo”, meaning ‘leaper’, by the Romans (Stolte, 1981; Sutterby and Greenhalgh, 2005), the fish is synonymous with persistence and power. The unique nature of the species’ anadromous life cycle is perhaps why the Atlantic salmon is so iconic. Juveniles habituate the freshwater environment during their early development, then migrate to the marine environment to feed and grow, before returning to rivers as mature adults to spawn (Netboy, 1958; Jonsson et al., 1991; Aas et al., 2011). Adult migrations upstream have provided societies with sport, commerce and food for centuries (Hendry and Cragg-Hine, 2003; Susdorf et al., 2017), and are the foundation for the vastly popular salmon angling industry. There are estimated to be 843,000 game anglers in the UK, which contribute to the salmon fishery, which across England and Wales, is thought to be worth £10 million per year (Hinkley, 1995; Environment Agency, 2009). Fished salmon have historically provided communities with a commodity for trade, whilst also offering a proteinrich food source (Thorstad et al., 2008). Ecologically, salmon act as an indicator species for the assessment of riverine health (Parrish et al., 1998), and downstream migrating juveniles in particular provide food for a range of predators such as other freshwater fish species, land and aquatic mammals, and native birds (Metcalfe et al., 1987; Jepsen et al., 1998). Evidence for the protection of Atlantic salmon in legislation dates back to the 13th century, largely owing to recognition for its primary value both as a commodity and as a food source (Netboy, 1958). Modern conservation has evolved to protect the species’ cultural and ecological worth, as well as economic benefits. The Atlantic salmon is acknowledged as a ‘priority species’ for conservative action in the UK Biodiversity Action Plan, and is listed in annex II of the European Union’s Habitat Directive (Hampshire Biodiversity Partnership, 2000; Hendry and Cragg-Hine, 2003). Furthermore, the presence of Atlantic salmon in UK rivers heavily influences the selection of Special Areas of Conservation (SAC), where site management is obligated to comply with the specific ecological requirements of listed species. Due to the nature and scale of migrations, however, international cooperation is key to ensure effective management. The North Atlantic Salmon Conservation Organisation (NASCO) is an inter-governmental organisation that was founded for this purpose, and has greatly reduced marine harvests of the species through the implementation of prohibited fishing zones in large portions of the North Atlantic (NASCO, 2019). Despite protective efforts, however, populations of Atlantic salmon are in decline throughout their native range (Parrish et al., 1998; Windsor et al., 2012; Sundt-Hansen et al., 2018) (Figure 1). Catch-rates and the mean weights Chapter 1 2 of caught fish are deteriorating globally (Welton et al., 1999; ICES, 2015). In 2001, 57% of global salmon populations were classified as extinct, at risk of extinction, endangered, or vulnerable (WWF, 2001). The pattern of population decline is mirrored in UK, where between 1983 and 1998 the total declared salmon catch in England and Wales deteriorated by approximately 64% (Environment Agency, 1999), and the estimated total pre-fisheries abundance of salmon is estimated to have approximately halved since the early 1970s (Environment Agency, 2016). Populations in Southern and Central England are identified as the most endangered in the UK, considered extirpated, compared to those of Northern Ireland (stable), Scotland (stable), Wales (deteriorating) and Northern England (deteriorating) (Parrish et al., 1998). Figure 1 The endemic range of the Atlantic salmon (Source: Jonsson and Jonsson, 2009) One of the main challenges to the survival of Atlantic salmon are anthropogenic activities and their impact on freshwater environments. Humans have historically had a profoundly negative impact on the freshwater environment via; overexploitation of resources, water pollution, flow modification, the destruction and degradation of habitats, and the facilitation of invasive species (Revenga et al., 2005; Dudgeon et al., 2006; Thorstad et al., 2008). An increase of these pressures, specifically on freshwater ecosystems, has occurred over the last century, which echoes the decline in salmon populations for the same period. This increase is largely owing to rises in human populations, which have consequently lead to greater competition for freshwater resources and an increased demand for services such as hydropower, domestic water supply, flood control, irrigation and recreation (Arthington et al., 2006; Alcamo et al., 2007; Murchie et al., 2008; Godfray et al., 2010). These services directly impact aquatic fauna, such as the Atlantic salmon, in a variety of ways. Dams and low head weirs which allow for the provision of hydropower often create channel Chapter 1 3 obstructions with no available means for passage (Poff and Hart, 2006; De Leaniz, 2008). Channel modification for the establishment of water abstraction plants and other infrastructures can drastically alter the physical environment and degrade habitats (Petts, 1996; Ward et al., 1999). Furthermore, increases in human population leads to greater stress on aquatic fauna through more frequent recreation and leisure purposes, such as fishing and water sports. (Parrish et al., 1998; Lackey, 2005). The UK salmon population comprises a significant proportion of the total European stock (JNCC, 2019). Of the 49 rivers in England that support ‘major’ Atlantic salmon populations, 5 are chalk streams (Environment Agency, 2018; Ikediashi, 2018). The chalk streams of southern England are stable, with small annual variations in the physical and chemical environment, resulting in highly productive settings for aquatic fauna and flora (Solomon, 1978a; Welton et al., 2002; Riley et al., 2002; Grapes et al., 2005). Whilst beneficial for fauna such as Atlantic salmon, chalk streams are attractive for a wide range of human activities that can result in ecological damage. The characteristics of chalk geology render groundwater aquifers highly important across northern Europe (Edmunds et al., 1987), and the most important in the UK (MacDonald and Allen, 2001). Both surface and ground water abstractions from chalk rivers are key for domestic demand across the south of England, and have been extensively developed for public water supply (Edmunds et al., 1987; Macdonald and Allen, 2001; Environment Agency, 2004), and consequently, conflicts between land drainage, land use and ecological requirements are commonplace (Mann, 1989). Moreover, recreational fishing is highly popular on chalk streams due to the prevalence of desirable game and coarse fish. During the close season for salmon and trout (Salmo trutta), species such as the European eel (Anguilla Anguilla), grayling (Thymallus thymallus) and pike (Esox lucius) are often targeted by anglers (Mann, 1989). Salmon are negatively impacted upon through illegal stocking, negative habitat management for the benefit of anglers, and poor handling and angling practice (Netboy, 1958; Mann, 1989). In addition to increasing human population exerting stress on freshwater ecosystems, anthropogenically driven climate change stands to exacerbate these pressures (Whitehead et al., 2009; Vörösmarty et al., 2010). Increasing global temperatures and alterations to precipitation and runoff will inevitably both increase the demand for water whilst simultaneously reducing the available supply. The influence of climate change on freshwater ecosystems is thought to be more severe in the South and East of England, as they are the most populated and most intensely-farmed regions of England, resulting in larger competition for water resources (WWF, 2017). In addition, the temperate climate of the South of England is predicted to experience a greater impact from increasing summer temperatures, than the comparatively cooler North (Watts and Anderson, 2016). Groundwater-fed streams, such as chalk streams, are particularly sensitive to extended Chapter 1 4 periods of drought, given that available water is vastly dependent on aquifer levels (Wood and Petts, 1999). Chalk aquifers account for 60% of the groundwater and 20% of the total water used in England and Wales (UK Groundwater Forum, 1998), and 70% of the public drinking water supply for the south-east region (Stewart and Smedley, 2009; WWF-UK, 2014). As such, chalk environments and the services derived from them are considered particularly vulnerable to the forecast changes in climate. Understanding the ecological requirements of river flora and fauna is a fundamental prerequisite for setting conservation objectives (Hendry and Cragg-Hine, 2003).The mechanics by which environmental factors can influence the migrations of fish are broadly understood, though precise effects will differ between rivers and specific reaches (Thorstad et al., 2008). The physical characteristics of a gravel bed river in Scotland, for instance, will have considerably different characteristics in terms of hydrological lag time following precipitation events, channel morphology and temperature regimes, when compared with the typically stable nature of chalk streams. Given the pressures associated with increasing human population and impacts deriving from anthropogenic climate change, improved understanding of the environmental variables that influence migrations of Atlantic salmon would be of significant value (Hodgson and Quinn, 2002). Such understanding is imperative for ensuring the effective conservation of the species, through the development of scientifically-supported legislation (Hodgson and Quinn, 2002)
Taxonomic studies on Malagasy Dalbergia (Fabaceae). II. A new name for D. mollis and the reinstatement of D. chermezonii
No full textWilding, Nicholas, Phillipson, Peter B., Crameri, Simon (2021): Taxonomic studies on Malagasy Dalbergia (Fabaceae). II. A new name for D. mollis and the reinstatement of D. chermezonii. Candollea 76 (2): 251-257, DOI: 10.15553/c2021v762a5, URL: http://dx.doi.org/10.15553/c2021v762a
Fig. 6. – Dalbergia obcordata N in Taxonomic studies on Malagasy Dalbergia (Fabaceae). I. Two new species from northern Madagascar, and an emended description for D. manongarivensis
No full textFig. 6. – Dalbergia obcordata N. Wilding, Phillipson & Crameri. Inflorescence and leaflets.Published as part of Wilding, Nicholas, Phillipson, Peter B., Crameri, Simon, Andriambololonera, Sylvie, Andriamiarisoa, Roger L., Andrianarivelo, Sandratra A. F., Bernard, Roger, Rakotonirina, Nivo, Rakotovao, Charles, Randrianaivo, Richard I., Razakamalala, Richard & Lowry Ii, Porter P., 2021, Taxonomic studies on Malagasy Dalbergia (Fabaceae). I. Two new species from northern Madagascar, and an emended description for D. manongarivensis, pp. 237-249 in Candollea 76 (2) on page 248, DOI: 10.15553/c2021v762a4, http://zenodo.org/record/718293
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
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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