title: Community composition and distribution of macroinvertebrates on natural and artificial substrates in North Island lakes and ponds

authors: Taitibe, Heather

subjects: Community composition

abstract: Artificial structures in freshwater ecosystems are becoming increasingly common. The introduction of these structures in marine systems lead to changes in the physical structure and the biotic assemblages. Even though artificial structures provide hard substrates for species to colonize and settle on, they are commonly shown to support a smaller number of taxa than natural substrates and are also known to facilitate the settlement of disproportionate numbers of non-native species. Nevertheless, little is known of their effects in freshwaters. 
In the second chapter of my thesis, I compare macroinvertebrate communities on three substrate types, macrophytes, sediments and artificial structures, among twenty-two ponds, to identify differences in community composition and distribution of macroinvertebrates between natural and artificial substrates. In addition, I investigated whether non-native macroinvertebrates prefer artificial substrates more than natural substrates. The similarities between artificial substrates and macrophytes can be attributed to the habitat structure, i.e., hard surfaces and the provision of refugia for macroinvertebrates from their predators. The differences between sediments and macrophytes, and artificial substrates were attributed to the difference in habitat structure and the fauna they supported (i.e., sediments contained large proportions of infauna). Non-native species that were collected in my study did not show preference for any of the habitats that were sampled.  
In the third chapter of my thesis, I identified important environmental factors that affect the distribution of macroinvertebrates communities across the twenty-two ponds sampled. The most important factor identified was temperature, nutrient gradients, pH and dissolved oxygen levels.  
Both chapters of my thesis offer an understanding of how existing artificial substrates and environmental variables in lakes and ponds on the North Island, New Zealand, affect macroinvertebrate community composition and distribution in relation to natural substrates.

text: Community composition and distribution of macroinvertebrates on natural and artificial substrates in North Island lakes and ponds Artificial structures in freshwater ecosystems are becoming increasingly common. The introduction of these structures in marine systems lead to changes in the physical structure and the biotic assemblages. Even though artificial structures provide hard substrates for species to colonize and settle on, they are commonly shown to support a smaller number of taxa than natural substrates and are also known to facilitate the settlement of disproportionate numbers of non-native species. Nevertheless, little is known of their effects in freshwaters. 
In the second chapter of my thesis, I compare macroinvertebrate communities on three substrate types, macrophytes, sediments and artificial structures, among twenty-two ponds, to identify differences in community composition and distribution of macroinvertebrates between natural and artificial substrates. In addition, I investigated whether non-native macroinvertebrates prefer artificial substrates more than natural substrates. The similarities between artificial substrates and macrophytes can be attributed to the habitat structure, i.e., hard surfaces and the provision of refugia for macroinvertebrates from their predators. The differences between sediments and macrophytes, and artificial substrates were attributed to the difference in habitat structure and the fauna they supported (i.e., sediments contained large proportions of infauna). Non-native species that were collected in my study did not show preference for any of the habitats that were sampled.  
In the third chapter of my thesis, I identified important environmental factors that affect the distribution of macroinvertebrates communities across the twenty-two ponds sampled. The most important factor identified was temperature, nutrient gradients, pH and dissolved oxygen levels.  
Both chapters of my thesis offer an understanding of how existing artificial substrates and environmental variables in lakes and ponds on the North Island, New Zealand, affect macroinvertebrate community composition and distribution in relation to natural substrates.

year: 2019

title: Al-doped Zinc Oxide as a Transparent Conductive Material

authors: Linklater, Rachael Annette

subjects: Zinc Oxide

abstract: ZnO powders containing from 1-8 atom% aluminium ions were prepared from aqueous citrate-aminoalcohol-based gels calcined at 500◦C. The powders were characterized using 27Al NMR, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Solid state 27Al NMR clearly distinguished between different Al environments and was effective in determining the relative amounts of incorporation of Al dopant ions into the different Zn lattice sites in the zincite structure. A degree of control over dopant placement is demonstrated by modifying sol precursors and processing parameters, which allowed a syn- thesis protocol to be developed to optimise the doping effectiveness. Relatively minor variations in processing conditions can influence the degree and mode of Al incorporation. Thin films (ca 100 nm) were fabricated by spin-coating the Al-doped Zinc citrate sol-gels onto glass and quartz substrates, followed by a drying step and annealing at 500◦C. The degree of crystal alignment in thin films, deter- mined by X-ray diffraction studies, was found to be influenced by both the dopant level and the heating profile. Resistivity measurements showed films with 0.5-1atom %Al and multiple layers which had been heated at 90◦C before annealing at 500◦C, and subjected to post-annealing treatment under vacuum displayed the lowest resistivities. Further post-annealing treatment at 500◦C under H2/N2 reduced resistivities by an order of magnitude. Transparencies for all films were above 80% in the visible range, and thicker multi-layer films generally demonstrated lower transmittances. Preferential c-axis orientation was observed for all films, but showed higher intensities with increasing film thickness, and for films subjected to directional heating on a hotplate. Increased film thickness gave films with lower resistivities, but also lower transparencies

text: Al-doped Zinc Oxide as a Transparent Conductive Material ZnO powders containing from 1-8 atom% aluminium ions were prepared from aqueous citrate-aminoalcohol-based gels calcined at 500◦C. The powders were characterized using 27Al NMR, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Solid state 27Al NMR clearly distinguished between different Al environments and was effective in determining the relative amounts of incorporation of Al dopant ions into the different Zn lattice sites in the zincite structure. A degree of control over dopant placement is demonstrated by modifying sol precursors and processing parameters, which allowed a syn- thesis protocol to be developed to optimise the doping effectiveness. Relatively minor variations in processing conditions can influence the degree and mode of Al incorporation. Thin films (ca 100 nm) were fabricated by spin-coating the Al-doped Zinc citrate sol-gels onto glass and quartz substrates, followed by a drying step and annealing at 500◦C. The degree of crystal alignment in thin films, deter- mined by X-ray diffraction studies, was found to be influenced by both the dopant level and the heating profile. Resistivity measurements showed films with 0.5-1atom %Al and multiple layers which had been heated at 90◦C before annealing at 500◦C, and subjected to post-annealing treatment under vacuum displayed the lowest resistivities. Further post-annealing treatment at 500◦C under H2/N2 reduced resistivities by an order of magnitude. Transparencies for all films were above 80% in the visible range, and thicker multi-layer films generally demonstrated lower transmittances. Preferential c-axis orientation was observed for all films, but showed higher intensities with increasing film thickness, and for films subjected to directional heating on a hotplate. Increased film thickness gave films with lower resistivities, but also lower transparencies

year: 2011

title: The Māori Data Privacy Framework: How useful is it for hapū?

authors: Clark, Vanessa

abstract: This brief is a part of a series, produced for the Tikanga in Technology (TiNT) research programme, that provides a hapū perspective on data sovereignty, data governance, and data privacy. In this brief we focus on the Māori Data Privacy Framework developed by the TiNT team and assess how useful it is for hapū. To do so, we draw on a case study with Ngāti Tiipa, one of the 33 iwi and hapū of the Waikato confederation (Kukutai, Whitehead & Kani, 2022). This brief should be read in conjunction with TiNT Brief #2 Protecting hapū data privacy: A Ngāti Tiipa case study of technology considerations.

text: The Māori Data Privacy Framework: How useful is it for hapū? This brief is a part of a series, produced for the Tikanga in Technology (TiNT) research programme, that provides a hapū perspective on data sovereignty, data governance, and data privacy. In this brief we focus on the Māori Data Privacy Framework developed by the TiNT team and assess how useful it is for hapū. To do so, we draw on a case study with Ngāti Tiipa, one of the 33 iwi and hapū of the Waikato confederation (Kukutai, Whitehead & Kani, 2022). This brief should be read in conjunction with TiNT Brief #2 Protecting hapū data privacy: A Ngāti Tiipa case study of technology considerations.

year: 2025-02-11