School of Science

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Research at AUT's School of Science is focused on key scientific issues with regional and global significance. The common theme connecting all research areas is sustainability – in the broadest sense as it relates to environmental and human health. Our research is closely allied to teaching and learning opportunities at undergraduate and postgraduate level within the school. Research is organised in three thematic areas:


Recent Submissions

Now showing 1 - 5 of 249
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    Propagating Uncertainty in Predicting Individuals and Means Illustrated with Foliar Chemistry and Forest Biomass
    (Springer Science and Business Media LLC, 2024-01-22) Yanai, RD; Drake, JE; Buckley, HL; Case, BS; Lilly, PJ; Woollons, RC; Gamarra, JGP
    Quantifying uncertainty is important to establishing the significance of comparisons, to making predictions with known confidence, and to identifying priorities for investment. However, uncertainty can be difficult to quantify correctly. While sampling error is commonly reported based on replicate measurements, the uncertainty in regression models used to estimate forest biomass from tree dimensions is commonly ignored and has sometimes been reported incorrectly, due either to lack of clarity in recommended procedures or to incentives to underestimate uncertainties. Even more rarely are the uncertainty in predicting individuals and the uncertainty in the mean both recognized for their contributions to overall uncertainty. In this paper, we demonstrate the effect of propagating these two sources of uncertainty using a simple example of calcium concentration of sugar maple foliage, which does not require regression, then the mass of foliage and calcium content of foliage, and finally an entire forest with multiple species and tissue types. The uncertainty due to predicting individuals is greater than the uncertainty in the mean for studies with few trees—up to 30 trees for foliar calcium concentration and 50 trees for foliar mass and calcium content in the data set we analyzed from the Hubbard Brook Experimental Forest. The most correct analysis will take both sources of uncertainty into account, but for practical purposes, country-level reports of uncertainty in carbon stocks can safely ignore the uncertainty in individuals, which becomes negligible with large enough numbers of trees. Ignoring the uncertainty in the mean will result in exaggerated confidence in estimates of forest biomass and carbon and nutrient contents.
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    Interactive Effects of Elevated Temperature and Photobacterium swingsii Infection on the Survival and Immune Response of Marine Mussels (Perna canaliculus): A Summer Mortality Scenario
    (Elsevier BV, 2024-02-03) Azizan, Awanis; Venter, Leonie; Zhang, Jingjing; Young, Tim; Ericson, Jessica A; Delorme, Natalí J; Ragg, Norman LC; Alfaro, Andrea C
    The New Zealand Greenshell™ mussel (Perna canaliculus) is an economically important aquaculture species. Prolonged increases in seawater temperature above mussel thermotolerance ranges pose a significant threat to mussel survival and health, potentially increasing susceptibility to bacterial infections. Using challenge experiments, this study examined the combined effects of increased seawater temperature and bacterial (Photobacterium swingsii) infection on animal survival, haemocyte and biochemical responses of adult mussels. Mussels maintained at three temperatures (16, 20 and 24 °C) for seven days were either not injected (control), injected with sterile marine broth (injection control) or P. swingsii (challenged with medium and high doses) and monitored daily for five days. Haemolymph and tissue samples were collected at 24, 48, 72, 96, 120 h post-challenge and analysed to quantify bacterial colonies, haemocyte responses and biochemical responses. Mussels infected with P. swingsii exhibited mortalities at 20 and 24 °C, likely due to a compromised immune system, but no mortalities were observed when temperature was the only stressor. Bacterial colony counts in haemolymph decreased over time, suggesting bacterial clearance followed by the activation of immune signalling pathways. Total haemocyte counts and viability data supports haemocyte defence functions being stimulated in the presence of high pathogen loads at 24 °C. In the gill tissue, oxidative stress responses, measured as total antioxidant capacity and malondialdehyde (MDA) levels, were higher in infected mussels (compared to the controls) after 24h and 120h post-challenge at the lowest (16 °C) and highest temperatures (24 °C), indicating the presence of oxidative stress due to temperature and pathogen stressors. Overall, this work confirms that Photobacterium swingsii is pathogenic to P. canaliculus and indicates that mussels may be more vulnerable to bacterial pathogens under conditions of elevated temperature, such as those predicted under future climate change scenarios.
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    Physicochemical and Antioxidant Properties of Chilli Sauce Incorporated with Fermented Kappaphycus spp. Extracts
    (Rynnye Lyan Resources, 2023-11-11) Norakma, MN; Zaibunnisa, AH; Wan Razarinah, WAR; Sobah, A; Hamid, N; Astuti, PD
    In this study, three distinct Kappaphycus spp. var. Green Flower (GF), var. White Giant (WG), and var. Purple Giant (PG) were subjected to solid-state fermentation (SSF) for four days at 30°C using Aspergillus oryzae (10% inoculum). The fermented seaweed extracts were incorporated into chilli sauce to increase its nutritional quality and were characterised in terms of proximate composition, antioxidant activity, viscosity and serum separation. The results obtained indicated that samples incorporated with fermented seaweed extracts contained significantly lower carbohydrates and higher ash content in comparison to control. The addition of fermented seaweed extracts significantly (p<0.05) increased the antioxidant activity. Serum separation was observed only in the control sample after eight weeks of storage. Therefore, adding fermented seaweeds can be incorporated into chilli sauce to increase the antioxidant properties and storage stability.
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    Effects of Insect Meal and Grape Marc in the Nutritional Profile, Growth, and Digestibility of Juvenile New Zealand Farmed Abalone
    (Springer Science and Business Media LLC, 2023-08-21) Bullon, N; Seyfoddin, A; Hamid, N; Manivannan, M; Alfaro, AC
    Generally, one of the most significant bottlenecks of land-based abalone aquaculture is the high cost of the feed, which is associated with the use of wild fish stocks to produce fish meal. Fish meal is a key ingredient used in aquaculture feeds due to its nutritional profile and palatability. Alternative ingredients, such as insect meal and grape marc, are potential candidates to be included in aquafeeds due to their suitable nutritional profile and more sustainable production. This study aimed to evaluate the effect of insect meal and grape marc on growth and nutritional profile using abalone as an animal model in a feeding trial for 165 days. Proximate analyses were used to identify nutritional variations in abalone tissue and faecal matter, and liquid chromatography-mass spectrometry and gas chromatography mass-spectrometry analyses were utilised to characterise amino acid and fatty acid composition. Results showed a 95% survival for all treatments. The inclusion of insect meal and grape marc did not affect the protein proportions of abalone tissues, but differences were found in the carbohydrate and lipid proportions. The inclusion of insect meal and grape marc significantly affected levels of amino acids L-histidine, L-methionine, and L-phenylalanine, and fatty acids oleic acid, linoleaidic acid, palmitic acid, palmitoleic acid, and α-linolenic suggesting a correlation between the feed source and fatty acid tissue composition. This work provides promising results for future optimisation of abalone diets including more affordable and sustainable alternative ingredients.
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    Application of Multiple Intake Temporal Check All That Apply: A Case Study of Strawberry Yoghurt Formulated with Alternative Sweeteners.
    (Wiley, 2023-12-12) Chadha, Diksha; Hamid, Nazimah; Kantono, Kevin
    BACKGROUND: It is crucial to reduce the high sugar content of fruit yoghurts in response to the excessive weight gain epidemic. The use of alternative sweeteners in yoghurts is often associated with the negative sensory attributes that can have an impact on yoghurt liking. The main objective of this research was to investigate the effect of alternative sweeteners and strawberry puree addition on the temporal sensory profile of yoghurt using multiple-intake temporal check all that apply (TCATA). A novel approach to the statical analysis of the temporal sensory data was employed by using Aligned Rank Transformation (ART)-ANOVA to investigate the differences between sensory attributes within different product and within different intakes. RESULTS: Results showed that attributes sweet and fruity decreased when the concentration of fruit puree was increased at low concentration of sucrose. Interestingly, when the concentration of fruit puree was increased fruitiness increased and mouthcoating decreased at low concentration of stevia. With successive intakes, attributes sweet, sour, creamy and fruity significantly decreased in yoghurts sweetened with sucrose, xylitol and stevia. Yoghurts containing low concentration of sucrose or xylitol and fruit puree were liked the most. However, stevia-sweetened yoghurts varying in sweetener and puree concentration were not significantly different in liking. In order to investigate the consumer acceptance of yoghurts, a novel approach was used i.e., utilising TCATA temporal data to investigate temporal drivers of liking for each yoghurt type. CONCLUSION: The use of multiple statistical analysis to analyse temporal data suggested that both sweetener and puree concentration need to be considered when developing products using alternative sweeteners. This article is protected by copyright. All rights reserved.
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