Masters Theses
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The Masters Theses collection contains digital copies of AUT University masters theses deposited with the Library since 2002 and made available open access. From 2007 onwards, all theses for masters degrees awarded are required to be deposited in Tuwhera Open Theses & Dissertations unless subject to an embargo.
For theses submitted prior to 2007, open access was not mandatory, so only those theses for which the author has given consent are available in Tuwhera Open Theses & Dissertations. Where consent for open access has not been provided, the thesis is usually recorded in the AUT Library catalogue where the full text, if available, may be accessed with an AUT password. Other people should request an Interlibrary Loan through their library.
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Browsing Masters Theses by Supervisor "Alfaro, Andrea C."
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- ItemAn investigation into the reuse of organic waste produced by the New Zealand mussel industry(Auckland University of Technology, 2004-01-01) Barnaby, ClaireManagement of organic waste is a major problem for the New Zealand Mussel Industry. Currently most waste is discarded, and this represents a potential loss of both resources and revenue, unless an alternative use for this waste could be developed. Waste types were first identified, then quantified, first seasonally, then annually, to provide an estimate of total industry-wide waste production. Possible uses for this waste were then identified. Little investigative research has been undertaken on identifying alternative uses for mussel industry organic waste. The uses of organic waste as organic fertilizers, and the economic benefit of adding treated waste products to cement mix to improve its compressive strength and thermal insulation, are two primary objectives of this dissertation. The possibility of using mussel shell in agricultural liming as a substitute is also explored. The potential value of pre-grade waste as an organic fertilizer was explored by addition of decomposed tissue to tomato seedlings and by monitoring plant development and condition. Growth of treatment and control seedlings was monitored by counting the number of branches, stem heights, leaf numbers and total biomass. Analyses prove Perna canaliculus pre-grade organic waste has the potential to be exploited as an expensive, effective organic fertilizer, whereas Mytilus galloprovincialis pre-grade organic waste may not. Moreover, there is further potential to develop P. canaliculus pre-grade organic waste into an odourless, chemically stable fertilizer product. The potential value of post-grade waste in cement mixes to improve compressive strength was explored by addition of shell aggregate to cement mix. Analyses indicate that, as an aggregate, mussel shell has little to no structural potential, but does have latent thermal insulating properties. Recommendations are made to: - Separate Perna and Mytilus pre-grade waste products. - Further explore the thermal insulating potential of mussel-shell concrete. - Further explore techniques for treatment of Perna pre-grade waste as a fertilizer. - Further explore the use of crushed mussel shell as a potential limestone or sand substitute for agricultural, construction and engineering purposes. - Explore markets for Mytilus potential export, to reduce pre-grade waste production and problems of resettlement.
- ItemAquatic invertebrate fauna of Matapouri, Northland.(Auckland University of Technology, 2008) Pohe, Stephen RobertA study of the aquatic invertebrate communities from two locations (Location 1 and Location 2) within the Matapouri catchment in Northland, New Zealand, was conducted to assess community structure in differing local-scale habitats. Four data collection methods were utilised generating 33,058 adult or larval invertebrates. The sampling methods comprised benthic kick-sampling, sticky trapping, light trapping, and emergence trapping. For the sticky trapping and light trapping, sampling was carried out at three different sites (Sites 1–3) within each location. The sites were situated within three habitat types; native forest, native forest-fringe, and raupo wetland. Emergence trapping also commenced within the three sites, at both locations, but was discontinued after two months, due to the equipment being destroyed by consecutive flooding events (method described in Appendix 1). Benthic sampling was carried out within the Forest and Forest-fringe habitats. Benthic sampling, sticky trapping, and light trapping were carried out following a monthly schedule between June and November 2005. Conductivity, pH, and water temperature measurements were taken concurrently with benthic sampling on a monthly basis, while water velocity and substrate measurements were taken once to assist in habitat characterisation. Overall, 71 taxa were recorded by benthic sampling over the six month period, with a mean of approximately 30 taxa per site per month. In comparison with similar studies elsewhere in New Zealand, a figure of around 30 taxa per sample was high. The benthic macroinvertebrate fauna at all sites was dominated by Trichoptera (19 taxa), Diptera (16 taxa) and Ephemeroptera (10 taxa). This pattern of diversity is similar to that reported in other New Zealand studies. However, in contrast to previous studies, the leptophlebiid mayfly genus Deleatidium was not numerically dominant over the rest of the community, and other leptophlebiid genera (Acanthophlebia, Atalophlebioides, Mauiulus and Zephlebia) were equally represented, possibly reflecting niche partitioning between the groups. The genus Nesameletus was not recorded at any site, despite being one of the core mayfly species in New Zealand streams. The rare mayfly Isothraulus abditus was recorded at one of the forest locations. There are no published records of this species from Northland. Although acknowledged as another of the core New Zealand benthic taxa, the hydropsychid caddisfly Aoteapsyche was not recorded during the study. However, another hydropsychid, Orthopsyche, was commonly recorded, and these may be filling a similar niche to the Aoteapsyche genus. In contrast to the Trichoptera, Diptera, and Ephemeroptera, the Plecoptera fauna was relatively depauperate, probably reflecting the warmer climate of the region and lack of temperature-buffered spring-fed streams. Surprisingly, Zelandobius, a core New Zealand genus, was absent but is regularly recorded in Northland. A species of conservation interest, Spaniocercoides watti, currently recognised as a Northland endemic, was recorded in low numbers. There were no apparent trends in diversity or abundance of benthic invertebrates over time. Also, there were no significant differences in species diversity between the two locations. However, in many cases, taxa were more abundant at Location 2. This may have been due to steeper gradients at Location 2, and the consequent effects on substrate size and streambed stability, as all other physical factors appeared similar between locations. Although several significant differences of individual benthic taxa were recorded, no broad effect of habitat (sites) on species diversity was observable. However, at Location 2, abundances were significantly higher at Site 3 (Forest) compared to Site 2 (Forest-fringe). The reasons were uncertain, but may be attributed to higher retention of allochthonous organic materials, trapped by in-stream cover and larger substrates. Investigations of adult stages by sticky traps supported benthic results recording community compositions and abundances dominated by Trichoptera and Diptera. Plecoptera were poorly represented. Location 2 recorded higher abundances of taxa, particularly Ephemeroptera and Plecoptera. Investigations of adult stages by light traps however did not produce any statistically significant differences in abundances between sites, between locations, or between sites across locations, and it is believed to be due to limited sampling replication combined with some biases of light trapping. This study indicates that the aquatic invertebrate community at Matapouri is diverse but also reasonably representative. Several rare or uncommon insects inhabit the catchment. It is therefore important that Iwi and the local Landcare Group, who invited and supported this research, together with the Department of Conservation, continue their efforts in protecting these areas. The resident fauna have the capacity to restock areas downstream, which are intended to be improved and restored through sediment control and riparian management.
- ItemBenthic invertebrate assemblages and sediment characteristics(Auckland University of Technology, 2009) Boyd, ShereeCold seep ecosystems in the deep sea are fuelled by chemosynthetic processes based on methane emission to the sediment surface from gas hydrate disassociation, methanogenesis or thermogenic processes. While cold seep ecosystems have been studied in the last three decades worldwide, little is known about New Zealand’s cold seep habitats and associated fauna. A joint German-New Zealand cruise to the Hikurangi Margin in early 2007 enabled biological and sediment sampling to investigate the biological and sedimentological relationships and variability of seeps and their faunal diversity. Multi-disciplinary approaches were employed that included Xray radiography, stratigraphic descriptions, lebensspuren traces analysis, sediment grain size analysis, determination of total organic content, carbonate content and its stable isotopic composition, and analysis of benthic invertebrate assemblages of seep habitats. The results of this study revealed three distinctive habitats and associated fauna based on the sediment characteristics and faunal type. Habitat 1 includes all sites pertaining to Omakere Ridge, a seep-related habitat comprised of layers of very poorly sorted, sandy silt, shell hash and bands of methane-derived authigenic aragonitic carbonate nodules with low total organic content (TOC). Due to the characteristics of the sediments and death assemblages of molluscs, it is inferred that Habitat 1 methane seepage is actively diffusive, waning or dormant. Habitat 2 describes sites that are either non-seep or relic and applies to those at Bear’s Paw and Kaka. Habitat 2 constituted of shell hash overlain with very poorly sandy silt, and low carbonates content and low to medium TOC. Habitat 3 describes non-seep related habitats, and includes all sites of the Wairarapa region and one reference site from Kaka also falls into this category. Sediments for Habitat 3 constituted poorly sorted silt with high TOC and low carbonate content which can be explained by their close proximity to land and converging sea currents. The mineral components of the background siliciclastic sediments for all sites studied originated in the Tertiary mudstone of the East Coast Basin. The characteristics of seep habitats of the Hikurangi Margin were comparable to that of the Northern Hemisphere modern seep counterparts, although the abundance and distributions of seep fauna were low. Results from this research have enhanced our understanding on the spatial and variability of methane fluxes and their affects on the duration of cold seep ecosystems, especially for New Zealand. However, more such studies are essential to increase our understanding of seep sediments and explain disturbance-sediment-benthic invertebrate interactions.
- ItemHeavy metal concentrations in the Pacific oyster Crassostrea gigas(Auckland University of Technology, 2004-01-01) Perera, PercyHeavy metals present in high concentrations in aquatic habitats are bioaccumulated within the tissues of intertidal organisms. The chemical analyses of animal tissues and sediments provide an indication of bioavailability of heavy metals in the environment. Monitoring of the coastal pollution using organisms is widely practiced all over the world.Chemical analysis of the tissues of Pacific oyster, Crassostrea gigas, and river sediments were used in this study to monitor the environmental concentrations, of cadmium, copper, lead and zinc of shallow coastal areas near to the river mouths of Mahurangi, Awaruku, Waiake, Taiorahi and Wairau. All of these river mouths are situated along the northeastern coast of Auckland. Each month, during the period of November 2002 to October 2003, three replicate samples of oysters, and sediments were collected from each of the river mouths for analysis. Three additional replicate samples of oysters were collected separately, in each month in order to calculate the condition index of oysters. Oyster tissues and sediments were analysed with Inductively Coupled Atomic Plasma Emission Spectrometer to detect the concentration levels of cadmium, copper, lead and zinc.The highest level of copper and zinc concentrations in the oyster tissues was observed in the river mouth of Wairau. Wairau river mouth receives water from heavily urbanised and industrialised catchments. A higher concentration of cadmium was observed in the oysters of the river mouth of Mahurangi than in the oysters in the other sites. The reason for this difference could be due to the heavy use of cadmium contaminated fertilizers at the pasture lands situated around the Mahurangi estuary. Therefore, the relationship between the land use of the catchments and the degree of pollution of the estuarine habitats could be established from the data obtained from this study. Higher concentrations of heavy metals were found in the sediments of Waiake, Taiorahi and Wairau compared to the sediments of Mahurangi and Awaruku. Significantly higher level of copper was observed in the sediments of Awaruku. However no clear co-relation was found between heavy metal concentration in oysters and in sediments. Variations of the condition of oysters were closely related to seasonal changes of the life cycle of the oysters. No clear relationship was found between the condition of the oysters and the heavy metal concentration of the river mouth habitats.This study provides evidence that Pacific oysters are good organisms to use as bioindicators of environmental heavy metal levels in shallow coastal waters. The results of this study suggest a clear relationship between the heavy metal concentration in river waters and the land use of the catchment areas of those rivers. The results may be useful in management strategies of the northeastern coastal areas of Auckland.
- ItemNutrition and broodstock conditioning of the New Zealand Pipi, Paphies australis(Auckland University of Technology, 2010) Mamat, Nawwar Z.The New Zealand pipi, Paphies australis, occurs widely around the coast of New Zealand and belonging to the family Mesodesmatidae. Pipi form a part of the recreational bivalve fishery, and there is also an annual restriction of the total commercial harvest. Previous investigations have examined the biological and ecological aspects of pipi in the wild. However, neither of them studied the nutritional requirements of pipi under hatchery conditions. This thesis discusses the feeding requirements of pipi collected from Waiwera Beach and Onehunga Harbour, during their growing and maturing stages. A series of studies on the cell clearance rates, feeding trials, proximate analysis, and broodstock conditioning of pipi clams were conducted over 15 months (September 2008 until December 2009) at the AUT Aquaculture Laboratory. In the cell clearance rates study, the rates for microalgal diets in descending order were Thalassiosira pseudonana > Isochrysis galbana > Chaetoceros muelleri > Tetraselmis suecica > Pavlova lutheri. It is inferred that pipi are capable of filtering a variety of microalgal species while at the same time being a selective filter feeder. The same microalgal species tested in the aforementioned study were fed to pipi of different size classes (spat, juveniles, and adults) in the feeding trials experiment. Three processed diets (baker's yeast, wheat flour, and corn flour) also were tested on the pipi clams. This study was carried out to test the effect of different diets on growth and survivality, and body composition of spat, juvenile, and adult pipi. There were positive relationships between the growth performance (length and weight) and dietary lipid content for spat and juveniles. For adult pipi, the carbohydrate content in the diets was positively related to pipi shell growth. However, proximate analyses of adult pipi at the end of the experiment indicated an overall depletion of carbohydrates in the tissues, while proteins and lipids were accumulated. These results suggest that the gonadal development have initiated during the breeding season. Based on the results of the present study, it is suggested that baker's yeast would be a good substitute of spat and juvenile feeds, and wheat and corn flours would be good substitutes for adult feeds. In the conditioning experiment, broodstock pipi were conditioned with three different diets: exclusively P. lutheri, exclusively corn flour, and a mixed diet composed of P. lutheri and corn flour in 1:1 ration. On days 21 and 28, following the conditioning period, broodstock were induced to spawn by temperature shock treatment. Although both spawning induction trials failed to bring broodstock pipi into spawning condition, maturity was apparent for brooodstock fed the mixed diet of P. lutheri and corn flour, indicating that P.lutheri-corn flour may be a better food source compared to P. lutheri or corn flour alone for pipi broodstock conditioning.