1,720,992 research outputs found
Northern futures: threats and opportunities for freshwater ecosystems
No full text[Extract] The absence of extensive broad-scale intensive agriculture across northern Australia has left a vast area of tropical savanna largely intact. With less than 5% of the region having undergone landscape transformation, most catchment vegetation and associated riparian zones remain uncleared (although in most cases modified by weeds, changed fire regimes, feral animals and cattle grazing). The unregulated river conditions ensure important ecological connections are maintained between the catchment, river, fioodplain and the estuary (Chapter 3; Douglas et al. 2005). Overall, these systems are considered to be the most biologically diverse and "healthy" aquatic ecosystems in Australia (NLWRA 2002, Australian Tropical Rivers Group 2004). This was one of the few larger regions of the world identified by Vörösmarty et al (2010) to have a low level of threat to river ecosystems from both a human and biodiversity perspective. The rivers represent the highest concentration of free-fiowing systems in the world (Australian Tropical Rivers Group 2004), with only 23 water storages with a capacity greater than 1 GL across the entire region (Cresswell et al 2009)
Freshwater fish
No full text[Extract] Fish are an important component of the fauna of aquatic ecosystems of northern Australia. They contribute substantially to the overall biodiversity in the region and are critical components of riverine and wetland food webs. Fish occur at all secondary levels of food webs, consuming primary production (algae, terrestrial detritus and fruits) and planktonic and epibenthic insects and crustaceans, as well as other fish. They also figure prominently in the diet of other aquatic or semiaquatic organisms, such as snakes and monitor lizards, waterbirds, crocodiles and, of course, people. Fish also shift carbon produced in one area (e.g. floodplains) to other areas as they move between upstream tributaries or downstream estuaries and near-shore marine environments. Fish are economically important (e.g. the commercial and recreational barramundi fisheries of northern Australia), as well as spiritually and culturally vital in the lives of Indigenous people of the north
Condition, impacts and threats to aquatic biodiversity
No full text[Extract] The aquatic systems that support the distinctive and diverse biodiversity of northern Australia are in relatively good ecological condition because of the region's low population density and limited land and water use (NLWRA 2002, Woinarski et al 2007). Nonetheless, a range of existing and potential threats impinge on the natural values of these ecosystems and may reduce their future capacity to sustain aquatic biodiversity. In this chapter, we first evaluate and discuss the known current condition of aquatic ecosystems of northern Australia. We then discuss the current condition of different catchments in the region and identify a broad range of potential threats. Next, we elaborate on the nature of these threats and describe the manner in which future human activities and climate change may intensify and multiply the range of threats. It needs to be stressed that, although there are currrent threats to the rich aquatic biodiversity of northern Australia, they are frequently diffuse in distribution and intensity. Such a situation may not continue into the future, however. Remediation or control of these threats is needed now to prevent more widespread damage
The social, cultural and economic significance of tropical aquatic ecosystems: a diversity of values
No full text[Extract] Australia's tropical aquatic ecosystems and the rich biodiversity they support are of social, cultural and economic value to residents, visitors and the international community (Stoeckl et al 2006a). These natural areas are of
intrinsic value and, because they are in generally good health, they also provide many important ecological services upon which a range of human activities depend (Greiner et al 2009). The predominant regional industries-pastoral grazing, mining, Indigenous enterprises, fishing and tourism-all use and rely on the region's water resources and aquatic ecological processes in different ways. These industries, along with people's livelihoods and lifestyle practices-such as camping, swimming and
fishing-are thus linked by land and water: they all need to consider the region's resources and biodiversity, with regard to access, quality, use and changes
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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