The functionality of riparian zones in flat sandy catchments

Intermittent streams and flat sandy catchments are common throughout the world. In south Western Australia, Ellen Brook provides a model landscape for the study of water quality issues associated with managing flat sandy coastal catchments, where the highly permeable sands have limited capacity to intercept and store nutrients arising from agricultural activity. Revegetating riparian zones is universally used as a best-management practice to intercept nutrients and improve stream condition. However, the riparian zone can only be effective in nutrient removal if there is interaction between runoff and riparian vegetation. Key elements driving this interaction are slope, providing flow through the riparian zone and a mechanism for uptake and storage of nutrients (e.g. reactive soils). In addition, riparian vegetation is known to provide a suite of environmental benefits, however, there is little information on the influence of riparian vegetation on in-stream biota of intermittent streams. The questions posed in this thesis are 1) can vegetated riparian zones effectively ameliorate nutrient inputs in flat sandy catchments (no slope and unreactive soils) and 2) do riparian zones on intermittent streams in flat sandy catchments influence in-stream biological communities? This thesis compares hydrology and nutrient dynamics between an intermittent stream in a flat sandy landscape (Bingham Creek) and a perennial stream in a nearby landscape with slope and reactive soils (Lennard Brook). Nutrient stores within groundwater, soil and vegetation were analysed. A column experiment was undertaken to determine how the vertical rise and fall of groundwater affected nutrient dynamics in paddock and riparian soils and compared the effect of nutrient addition from fertiliser and cow manure. The thesis also examined the ecological condition of riparian vegetation and its influence on in-stream biota amongst a wider range of intermittent and perennial streams in this catchment. In flat sandy catchments, the lack of slope and unreactive soils reduced the capacity for riparian vegetation to intercept and store nutrients. The dominant flow path was the vertical rise and fall of groundwater in response to rainfall, which limited the interaction of groundwater with the active root zone of riparian soils, reducing the potential for nutrient assimilation. However, slow (0.23-0.3 m/day) horizontal groundwater flow through riparian zone, results in extended residence times (106-141 days), allowed nutrient transformations to occur. Riparian and paddock soils at Bingham Creek had a poor nutrient holding capacity, resulting in nutrients being stored in the groundwater (e.g. filterable reactive phosphorus (FRP) 48-600 μg/L-1) and not the soil (e.g. 4-510 mg.P/kg). Whereas at Lennard Brook the improved soil characteristics (increased iron oxides and clay) provided a greater opportunity for nutrient interception and storage by the soils (e.g. 29-1037 mg.P/kg) and groundwater flow to the stream was low in phosphate (e.g. FRP 10-74 μg/L-1). The riparian vegetation had a similar community structure at both sites and contributed comparable amounts of litterfall (369 and 404 g/m2) and nutrients per unit area (0.8-1.5 and 0.5-1 mg.P/m2) at Bingham Creek and Lennard Brook, respectively. This enhanced the organic matter content of underlying riparian soils that in turn slowed the rate of water movement (paddock 0.08-0.7 L/hr, riparian 0.04-0.24 L/hr), improved the phosphorus binding capacity of the soil and promoted loss of mineral nitrogen, probably by denitrification. However, the increased carbon content also supported a greater microbial community and the input of extra nutrients (including labile carbon) increased microbial respiration, leading to release of iron-bound phosphorus into groundwater. In the Ellen Brook catchment, flow regime (Global R = 0.444, P < 0.001) and the presence/absence of riparian vegetation (Global R = 0.407, P < 0.001) were the most influential factors associated with invertebrate assemblage composition. On average there were more invertebrate families in vegetated (30 ± 1.4) streams than unvegetated (27 ± 3.2) streams. Riparian vegetation helped shape and improve in-stream biological communities through the provision of organic matter for food and habitat and by limiting algal growth in stream water through shading. This was illustrated by a higher proportion of algal grazers (Chironominae and Physidae) in unvegetated streams and more detrital feeders (Leptoceridae, Gripopterygidae, Ceinidae) in vegetated streams. A conceptual model of hydrology and nutrient dynamics for riparian zones in flat sandy catchments was developed, which describes the key points of difference to the hydrological and nutrient dynamics in sloped catchments with reactive soils. Riparian vegetation appears to be acting similarly between catchment types but the capacity for riparian zones to remove nutrients in flat sandy catchments is limited due to soil type and hydrology. However, in these catchments, riparian zones are also the only sink contributing to a reduction in nutrient export from the catchment and so still have value in regulating nutrient dynamics. Clearly, riparian vegetation alone across the catchment alone cannot stem the flow of nutrients in flat sandy catchments. Instead, a multi-pronged approach is required to reduce nutrient export and improve the nutrient holding capacity of soils. Furthermore, riparian vegetation helps maintain and improve in-stream biological communities in intermittent and perennial streams in sandy catchments with low relief. Overall, riparian vegetation increased the retention of nutrients, improved soils and in-stream biodiversity, warranting the protection and rehabilitation of riparian zones in flat sandy catchments

Investigations into some important fish larvae in the south east Atlantic in relation to the hydrological environment

Includes bibliographies at end of chapters.The following objectives are covered in the study: (i) the description of the seasonal hydrological changes in the survey area and a comparison between years. (ii) an examination of the seasonal distribution and abundance of the larval stages in relation to hydrological conditions. (iii) the determination of the preferential temperature and salinity ranges for the larvae. (iv) an examination of seasonal shift in location and intensity of spawning from the geographic distribution, abundance and size composition of the larvae. (v) the establishment of dispersal trends of developing larvae from the spawning grounds. (vi) the provision of information on the identity and development of important fish eggs and larvae. (vii) the determination of diurnal changes in abundance and size composition of various larval species. The results reported are regarded as scientifically significant in view of the paucity of basic information on the early life history of any fish species off South West Africa. Many aspects such as identity, development, distribution, abundance, hydrological affinities, diurnal variation and dispersal are given for the first time. The findings make a positive contribution not only to knowledge of the early stages and biology of the species but also provide an insight into the general ecology of fish larvae in what is probably the most productive and lucrative fishing grounds in the South East Atlantic

Characterising live cell behaviour: traditional label-free and quantitative phase imaging approaches

Label-free imaging uses inherent contrast mechanisms within cells to create image contrast without introducing dyes/labels, which may confound results. Quantitative phase imaging is label-free and offers higher content and contrast compared to traditional techniques. High-contrast images facilitate generation of individual cell metrics via more robust segmentation and tracking, enabling formation of a label-free dynamic phenotype describing cell-to-cell heterogeneity and temporal changes. Compared to population-level averages, individual cell-level dynamic phenotypes have greater power to differentiate between cellular responses to treatments, which has clinical relevance e.g. in the treatment of cancer. Furthermore, as the data is obtained label-free, the same cells can be used for further assays or expansion, of potential benefit for the fields of regenerative and personalised medicine

Characterising live cell behaviour: traditional label-free and quantitative phase imaging approaches

Label-free imaging uses inherent contrast mechanisms within cells to create image contrast without introducing dyes/labels, which may confound results. Quantitative phase imaging is label-free and offers higher content and contrast compared to traditional techniques. High-contrast images facilitate generation of individual cell metrics via more robust segmentation and tracking, enabling formation of a label-free dynamic phenotype describing cell-to-cell heterogeneity and temporal changes. Compared to population-level averages, individual cell-level dynamic phenotypes have greater power to differentiate between cellular responses to treatments, which has clinical relevance e.g. in the treatment of cancer. Furthermore, as the data is obtained label-free, the same cells can be used for further assays or expansion, of potential benefit for the fields of regenerative and personalised medicine

Dietary fibre modulates the gut microbiota

peer-reviewedDietary fibre has long been established as a nutritionally important, health-promoting food ingredient. Modern dietary practices have seen a significant reduction in fibre consumption compared with ancestral habits. This is related to the emergence of low-fibre “Western diets” associated with industrialised nations, and is linked to an increased prevalence of gut diseases such as inflammatory bowel disease, obesity, type II diabetes mellitus and metabolic syndrome. The characteristic metabolic parameters of these individuals include insulin resistance, high fasting and postprandial glucose, as well as high plasma cholesterol, low-density lipoprotein (LDL) and high-density lipoprotein (HDL). Gut microbial signatures are also altered significantly in these cohorts, suggesting a causative link between diet, microbes and disease. Dietary fibre consumption has been hypothesised to reverse these changes through microbial fermentation and the subsequent production of short-chain fatty acids (SCFA), which improves glucose and lipid parameters in individuals who harbour diseases associated with dysfunctional metabolism. This review article examines how different types of dietary fibre can differentially alter glucose and lipid metabolism through changes in gut microbiota composition and function

SME investment report 2019: Developments between 2016 and 2018. ESRI Survey and Statistical Report Series 86 October 2020.

This report provides a statistical review of the data collected in a specific SME investment module on the Department of Finance Credit Demand Survey. The report presents survey data for the year 2018, with reference to 2016 and 2017 for context and comparison

A comparison of two computer-based face identification systems with human perceptions of faces

The performance of two different computer systems for representing faces was compared with human ratings of similarity and distinctiveness, and human memory performance, on a specific set of face images. The systems compared were a graphmatching system (e.g. Lades et al., 1993) and coding based on Principal Components Analysis (PCA) of image pixels (e.g. Turk & Pentland, 1991). Replicating other work, the PCA-based system produced very much better performance at recognising faces, and higher correlations with human performance with the same images, when the images were initially standardised using a morphing procedure and separate analysis of "shape" and "shape-free" components then combined. Both the graph-matching and (shape + shape-free) PCA systems were equally able to recognise faces shown with changed expressions, both provided reasonable correlations with human ratings and memory data, and there were also correlations between the facial similarities recorded by each of the computer models. However, comparisons with human similarity ratings of faces with and without the hair visible, and prediction of memory performance with and without alteration in face expressions, suggested that the graph-matching system was better at capturing aspects of the appearance of the face, while the PCA-based system seemed better at capturing aspects of the appearance of specific images of faces