title: Coupled flow-wave numerical model in assessing the impact of dredging on the morphology of Matakana Banks

authors: Ramli, Andi Yulianti

subjects: ebb-tidal delta

abstract: The short- and long-term impacts of dredging on the Matakana Banks ebb-tidal delta was investigated by numerical modelling using Delft3D. The model covered dredging locations inside Tauranga Harbour and the offshore areas around the Matakana Banks ebb-tidal delta, and was calibrated by an extensive field programme to measure hydrodynamic processes and sediment characteristics, and high resolution bathymetric surveys. The impacts of dredging was then investigated by modelling three different conditions: (1) before dredging started in 1968, using 1967 bathymetry; (2) the present situation using 2013 bathymetry with existing dredging and dumping; and (3) future scenarios using 2013 bathymetry with alternative offshore disposal locations. 
The field data and hydrodynamic model results showed that the ebb-tidal delta can be separated into two main regions that are dominated by tidal processes or wave processes. Overall, the wave influence becomes more dominant as the distance from the entrance channel (main ebb jet) increases, and vice versa for tidal processes. Sediment transport pathways were inferred using spatial patterns of erosion and accretion from bathymetric surveys and cross-sectional profiles along the shoreline. The pathways reflected the interactions between the identified wave and tide processes. 
A month-long time series of wave conditions were used to force a wave model coupled with the hydrodynamic model for the 2013 bathymetry to simulate the present day situation. The results showed that the sediment volume of the ebb-tidal delta fluctuated with tidal range; accretion occurred during neap tides and erosion during spring tides. To assess the long term impact, the morphological factor (morfac) tool in Delft3D was used. Morfac of 60 was applied for 12 days simulation time and the results will be presented in this paper

text: Coupled flow-wave numerical model in assessing the impact of dredging on the morphology of Matakana Banks The short- and long-term impacts of dredging on the Matakana Banks ebb-tidal delta was investigated by numerical modelling using Delft3D. The model covered dredging locations inside Tauranga Harbour and the offshore areas around the Matakana Banks ebb-tidal delta, and was calibrated by an extensive field programme to measure hydrodynamic processes and sediment characteristics, and high resolution bathymetric surveys. The impacts of dredging was then investigated by modelling three different conditions: (1) before dredging started in 1968, using 1967 bathymetry; (2) the present situation using 2013 bathymetry with existing dredging and dumping; and (3) future scenarios using 2013 bathymetry with alternative offshore disposal locations. 
The field data and hydrodynamic model results showed that the ebb-tidal delta can be separated into two main regions that are dominated by tidal processes or wave processes. Overall, the wave influence becomes more dominant as the distance from the entrance channel (main ebb jet) increases, and vice versa for tidal processes. Sediment transport pathways were inferred using spatial patterns of erosion and accretion from bathymetric surveys and cross-sectional profiles along the shoreline. The pathways reflected the interactions between the identified wave and tide processes. 
A month-long time series of wave conditions were used to force a wave model coupled with the hydrodynamic model for the 2013 bathymetry to simulate the present day situation. The results showed that the sediment volume of the ebb-tidal delta fluctuated with tidal range; accretion occurred during neap tides and erosion during spring tides. To assess the long term impact, the morphological factor (morfac) tool in Delft3D was used. Morfac of 60 was applied for 12 days simulation time and the results will be presented in this paper

year: 2015

title: An investigation of low diastase activity in mānuka honey

authors: Bell, Amber

subjects: Mānuka honey

abstract: Mānuka honey with high non-peroxide antibacterial (NPA) activity is a valuable export product in the multi-million-dollar New Zealand honey export industry, with monofloral mānuka honey accounting for 68% (NZ$290 million) of the total export value (NZ$425 million) for the 2019/20 season. Exported honey must meet strict export regulations. Diastase enzyme (alpha amylase) activity is a quality control indicator of detrimental storage conditions (excessive heat treatment or prolonged storage), decreasing over time. International export requires honey to have high diastase activity (Diastase Number, DN > 8). Medium to high NPA mānuka honeys often fail the diastase test, despite careful storage. It is important to determine the cause of low diastase activity in mānuka honey to prevent revenue loss for New Zealand honey exports. Bioactive compounds in the honey were hypothesised to inhibit alpha-amylase, therefore reducing diastase activity.
A database of fresh mānuka and non-mānuka honeys were analysed for various chemical parameters (including moisture content, mānuka chemical marker compounds, dihydroxyacetone (DHA), methylglyoxal (MGO), 5-hydroxymethylfurfural (HMF) and diastase activity) to determine if any correlations were present with diastase activity. Parameters between and within floral honey types varied largely, however no correlations were observed to diastase activity. 
Storage experiments (20 °C, 161 days; 27 °C, 198 days) of selected database honeys showed the mānuka marker compounds were stable. However, the rates of change observed for DHA, MGO, HMF and diastase activity were reliant on intrinsic honey characteristics (not identified). While time and temperature had significant impact on loss of diastase activity in honey, correlation was observed between changes in diastase activity and DHA, MGO and mānuka marker 3-phenyllactic acid (3-PLA) concentrations.
Additionally, a clover honey matrix was perturbed with single bioactive compounds (DHA (MGO-precursor), MGO, mānuka markers compounds, methyl syringate and tannic acid) to observe the effect on diastase activity over time (185 days) and at 20, 27 and 34 °C. MGO and 3 PLA caused diastase activity to decrease at a significantly faster rate than other compounds. The half-life of diastase at 27 °C for the control sample was 590 days compared to the much shorter half-life of diastase in the MGO (440 days) and 3 PLA (380 days) perturbed samples. The mechanism by which these two compounds decrease diastase activity is unknown, however MGO is a highly reactive molecule and has been reported to inhibit other enzymes. Time and temperature were also significant drivers of diastase activity loss; diastase half-life at 20 °C was more than eight times greater than it was at 34 °C (1340 vs. 160 days). 
The experiments indicate that diastase activity is highly variable between fresh honeys and the rate at which it decreases may be dependent not only on temperature and time honey is stored at, but on intrinsic honey compounds and physico-chemical parameters suggesting that diastase activity regulations may not be suitable for mānuka honey.

text: An investigation of low diastase activity in mānuka honey Mānuka honey with high non-peroxide antibacterial (NPA) activity is a valuable export product in the multi-million-dollar New Zealand honey export industry, with monofloral mānuka honey accounting for 68% (NZ$290 million) of the total export value (NZ$425 million) for the 2019/20 season. Exported honey must meet strict export regulations. Diastase enzyme (alpha amylase) activity is a quality control indicator of detrimental storage conditions (excessive heat treatment or prolonged storage), decreasing over time. International export requires honey to have high diastase activity (Diastase Number, DN > 8). Medium to high NPA mānuka honeys often fail the diastase test, despite careful storage. It is important to determine the cause of low diastase activity in mānuka honey to prevent revenue loss for New Zealand honey exports. Bioactive compounds in the honey were hypothesised to inhibit alpha-amylase, therefore reducing diastase activity.
A database of fresh mānuka and non-mānuka honeys were analysed for various chemical parameters (including moisture content, mānuka chemical marker compounds, dihydroxyacetone (DHA), methylglyoxal (MGO), 5-hydroxymethylfurfural (HMF) and diastase activity) to determine if any correlations were present with diastase activity. Parameters between and within floral honey types varied largely, however no correlations were observed to diastase activity. 
Storage experiments (20 °C, 161 days; 27 °C, 198 days) of selected database honeys showed the mānuka marker compounds were stable. However, the rates of change observed for DHA, MGO, HMF and diastase activity were reliant on intrinsic honey characteristics (not identified). While time and temperature had significant impact on loss of diastase activity in honey, correlation was observed between changes in diastase activity and DHA, MGO and mānuka marker 3-phenyllactic acid (3-PLA) concentrations.
Additionally, a clover honey matrix was perturbed with single bioactive compounds (DHA (MGO-precursor), MGO, mānuka markers compounds, methyl syringate and tannic acid) to observe the effect on diastase activity over time (185 days) and at 20, 27 and 34 °C. MGO and 3 PLA caused diastase activity to decrease at a significantly faster rate than other compounds. The half-life of diastase at 27 °C for the control sample was 590 days compared to the much shorter half-life of diastase in the MGO (440 days) and 3 PLA (380 days) perturbed samples. The mechanism by which these two compounds decrease diastase activity is unknown, however MGO is a highly reactive molecule and has been reported to inhibit other enzymes. Time and temperature were also significant drivers of diastase activity loss; diastase half-life at 20 °C was more than eight times greater than it was at 34 °C (1340 vs. 160 days). 
The experiments indicate that diastase activity is highly variable between fresh honeys and the rate at which it decreases may be dependent not only on temperature and time honey is stored at, but on intrinsic honey compounds and physico-chemical parameters suggesting that diastase activity regulations may not be suitable for mānuka honey.

year: 2022

title: Dying to research: An autoethnographic exploration of researching Māori and whānau experiences of end-of-life care

authors: Moeke-Maxwell, Tess

subjects: indigenous

abstract: The authors critically reflect on the autoethnographic process involved in navigating a smooth pathway towards investigating dying, death and bereavement for Māori whānau (families) in a way that supports and gives voice to their experience. This study, based in the Māori & Psychology Research Unit at The University of Waikato, is supported by a Health Research Council Erihapeti Rehu-Murchie Career Development Award. It explores the “end-of-life” journeys of Māori and their whānau in South Auckland and Waikato, through the dying process and subsequent challenges of bereavement. The researcher’s journey from novice to someone fully enmeshed in the struggles and triumphs of conducting research with Māori is examined. There is reflection on the challenges and issues that have emerged since settling on this research topic. These include ethical concerns, and the processes and outcomes associated with negotiating tensions between a shifting academic objectivity and the development of a methodology requiring subjective reflexivity.

text: Dying to research: An autoethnographic exploration of researching Māori and whānau experiences of end-of-life care The authors critically reflect on the autoethnographic process involved in navigating a smooth pathway towards investigating dying, death and bereavement for Māori whānau (families) in a way that supports and gives voice to their experience. This study, based in the Māori & Psychology Research Unit at The University of Waikato, is supported by a Health Research Council Erihapeti Rehu-Murchie Career Development Award. It explores the “end-of-life” journeys of Māori and their whānau in South Auckland and Waikato, through the dying process and subsequent challenges of bereavement. The researcher’s journey from novice to someone fully enmeshed in the struggles and triumphs of conducting research with Māori is examined. There is reflection on the challenges and issues that have emerged since settling on this research topic. These include ethical concerns, and the processes and outcomes associated with negotiating tensions between a shifting academic objectivity and the development of a methodology requiring subjective reflexivity.

year: 2010