1,720,956 research outputs found
The ecological effects of physical habitat restoration in English chalk streams
No full textChalk streams are globally rare and unique systems that have been extensively subjected to physical modification. This has contributed to the widespread degradation of ecological communities in chalk streams and failures to adhere to legislation (e.g. Water Framework Directive). Physical restoration has emerged as a key strategy to improve the condition of chalk streams, but a current lack of evidence for its effectiveness constrains the development of sound practice. This thesis aimed to develop understanding of the effects of restoration on physical habitat and ecology in English chalk streams. A series of case study appraisals were undertaken to understand: (1) the physical and ecological effects of different techniques (i.e. weir removal and gravel augmentation); (2) the influence of time since restoration; (3) the effects of restoration on different ecological groups. Additionally, (4) a methodological approach for non-invasively evaluating fish populations was developed to help improve monitoring capabilities in chalk streams. Weir removal rapidly altered habitat and ecological communities, especially directly upstream which became more lotic. Little evidence of sediment-pulse related impacts downstream of the weir was found, possibly due to additional silt-management methods which facilitated recovery. Gravel augmentation desirably altered habitat and ecology over the timescale studied (e.g. enhanced macroinvertebrate diversity). However, variability between sites, time periods and ecological groups signifies widespread uncertainties in restoration outcomes and the need to develop a better understanding of the drivers behind these. Time was a key factor influencing the observed effects of restoration (e.g. due to lag-effects). Furthermore, responses varied considerably between ecological groups, where changes in macroinvertebrates (e.g. increased diversity) and fish (e.g. increased brown trout sightings) were not reciprocated in macrophytes. These findings highlight the need for appraisals to take place at commensurate temporal scales and ideally using a multi-taxa approach to understand responses more accurately. Remote underwater video proved a useful tool for assessing fish communities and population size. Given the adaptability and utility of the technique, as well as its potential application as a citizen science methodology, it may prove useful for monitoring at chalk stream restoration projects and requires further investigation. Overall, this thesis contributes valuable evidence suggesting restoration can be an effective tool for desirably altering habitat and ecological communities in chalk streams. However, the need to conduct more robust appraisals to consolidate knowledge is highlighted and emphasises the need to fund the development of flagship case studies to guide and inspire future restoration efforts. <br/
Dataset supporting the publication 'Chalk stream restoration: physical and ecological responses to gravel augmentation'
No full textDataset supporting the manuscript by Dolman et al. 'Chalk stream restoration: physical and ecological responses to gravel augmentation'.
This dataset contains:
- Gravel_augmentation_study_dataset_East_Lodge.xlsx
-Gravel_augmentation_study_dataset_Home_Stream.xlsx
See Readme file for more information on each tab within each document.
This research was funded by the Environment Agency and EPSRC through the CDT-SIS programme (EP/L01582X/1)
Data Licence: CC BY
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Dataset supporting the University of Southampton Doctoral Thesis: 'the ecological effects of physical habitat restoration in English chalk streams' by Lewis Adam Dolman
No full textDataset supporting the University of Southampton Doctoral Thesis: 'The ecological effects of physical habitat restoration in English chalk streams' by Lewis Adam Dolman.
This dataset contains data (excel files) for:
CHAPTER 5 - 'Quantifying the environmental impacts of low-head weirs and their removal in low power chalk streams'. This includes physical habitat and ecological monitoring data collected at a case study weir removal on the River Test (Hampshire, UK) and data collated from the Environment Agency's 'Fish and Ecology Data Explorer'.
CHAPTER 6 - 'Chalk stream restoration - physical and ecological responses to gravel augmentation'. This includes physical habitat and ecological monitoring data collected at two case study gravel augmentation restoration sites on the River Test and Itchen (Hampshire, UK).
CHAPTER 7 - 'Restoration over time - the physical and ecological responses to restoration in an English chalk stream'. This includes physical habitat and ecological monitoring data collected at two case study instream physical habitat restoration sites on the River Test (Hampshire, UK). Additionally, control macroinvertebrate datasets collated from the Environment Agency 'Fish and Ecology Data Explorer' and 'SmartRivers' dataset.
CHAPTER 8 - 'Non-invasive population estimates of freshwater fishes using remote underwater video'. This includes data from an experiment aiming to understand whether it is possible to identify individual fish from unique identifiable features (e.g. spots, stripes) and morphometrics (i.e. body measurements) from photographs and underwater video. This is followed by an experiment exploring the accuracy of non-invasive population estimates created using mark-recapture estimates from underwater video and unique identifiable features.
For further details on this dataset, see the 'README' file.
This PhD was funded by the Engineering and Physical Sciences Research Council (EP/L01582X/1) and Environment Agency.
Data Licence: CC BY</span
Chalk stream restoration: Physical and ecological responses to gravel augmentation.
No full textTo mitigate the morphological and ecological impacts of direct (e.g. dredging) and indirect (e.g. damaged river function) sediment loss, gravel augmentation is commonly practiced in river systems globally. Despite this, the effectiveness of this practice remains poorly understood, especially in less often considered systems such as chalk streams which present uncommon conditions (e.g. low stream power, stable flow) and may respond to interventions in ways that differ from systems more commonly studied. This study quantified immediate (0-1 years) and short-term (1-2 years) physical and ecological responses to gravel augmentation at two English chalk stream restoration sites: Home Stream (HS; River Test) and East Lodge (EL; River Itchen). We quantified habitat (depth, velocity, substrate composition), cover of different macrophytes, and macroinvertebrate (before-after-control-impact) abundance and community structure. Restoration reduced depth and increased gravel cover in both sites and decreased the cover of filamentous green algae in HS. Macroinvertebrate communities became more dominated by silt-intolerant taxa, while abundance [HS only] and taxon richness increased 1-2 years post-restoration. Whilst the responses found were generally positive in light of the restoration goals, the effects varied across sites, post-restoration time periods and ecological groups, emphasising the need for the more holistic monitoring of restoration projects considering community-level responses at different sites and systems over ecologically relevant timescales. This will help inform on the generality and longevity of responses and provide the evidence needed to develop sound restoration practice
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
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