title: An Investigation of Factors that Contribute to Dihydroxyacetone Variation Observed in New Zealand Leptospermum scoparium

authors: King, Jessica

abstract: Honey derived from Leptospermum scoparium (commonly known as mānuka) is known to have anti-bacterial activity that is not entirely accounted for by the presence of hydrogen peroxide.1 This is known as non-peroxide activity (NPA). The discovery of this medical benefit has led to mānuka honey being a major export for New Zealand. In order to assure supply, mānuka trees are being investigated to determine why certain specimens yield honeys with a greater NPA than others. This might result in plantations of L. scoparium that would yield honey with a consistently high NPA. 
The compound responsible for the NPA is a 1,2-dicarbonyl known as methylglyoxal (MGO).2 The precursor to this molecule was found in nectar of the mānuka flowers and was identified as dihydroxyacetone (DHA).3 An investigation of DHA in the nectar of L. scoparium across different regions of New Zealand was carried out by Williams (2012).4 It was confirmed that trees vary within and between regions across New Zealand. 
This thesis describes different investigations into why the variation of DHA observed in various mānuka flowers is so great. Flowers were collected during flowering periods from 2011-2013 and were frozen prior to processing. The extraction method used ten flowers (10F) and samples were analysed by gas chromatography with flame ionisation detection (GC-FID). The DHA quantity was expressed with respect to the total sugar (Tsugar) in the nectar (DHA/Tsugar) in order to allow for comparison between samples.
The study by Williams (2012) was extended to include the Northland region.4 Wild L. scoparium var. incanum specimens were collected from this region and it was determined that these trees only produced a low to moderate amount of DHA/Tsugar. Williams (2012) also investigated the DHA variability of trees in close proximity to each other as these are supposed to be genetically similar.4 This study was repeated in a different region and the findings were the same; that is trees that were in close proximity to each other can have different DHA/Tsugar. 
One possibility of why DHA is observed in mānuka flowers is that it is used to combat stress as a compatible osmolyte. This was tested using chemical additives and it was found that the DHA/Tsugar varied as a result of the Tsugar as opposed to the amount of DHA. This response was cultivar dependent.
Different flower physiologies were also investigated. This included the andromonoecious nature of mānuka and the specific colour change in the hypanthium of the flower. Male flowers were found to have a larger amount of DHA/Tsugar as a result of a higher level of DHA than hermaphrodite flowers. This could suggest that DHA is being used in the hermaphrodite flowers for processes such as seed production. The DHA/Tsugar of flowers with different hypanthium colour was shown to be dependent on the variety type. The source and reason for DHA still remains unclear and therefore further study is required.

text: An Investigation of Factors that Contribute to Dihydroxyacetone Variation Observed in New Zealand Leptospermum scoparium Honey derived from Leptospermum scoparium (commonly known as mānuka) is known to have anti-bacterial activity that is not entirely accounted for by the presence of hydrogen peroxide.1 This is known as non-peroxide activity (NPA). The discovery of this medical benefit has led to mānuka honey being a major export for New Zealand. In order to assure supply, mānuka trees are being investigated to determine why certain specimens yield honeys with a greater NPA than others. This might result in plantations of L. scoparium that would yield honey with a consistently high NPA. 
The compound responsible for the NPA is a 1,2-dicarbonyl known as methylglyoxal (MGO).2 The precursor to this molecule was found in nectar of the mānuka flowers and was identified as dihydroxyacetone (DHA).3 An investigation of DHA in the nectar of L. scoparium across different regions of New Zealand was carried out by Williams (2012).4 It was confirmed that trees vary within and between regions across New Zealand. 
This thesis describes different investigations into why the variation of DHA observed in various mānuka flowers is so great. Flowers were collected during flowering periods from 2011-2013 and were frozen prior to processing. The extraction method used ten flowers (10F) and samples were analysed by gas chromatography with flame ionisation detection (GC-FID). The DHA quantity was expressed with respect to the total sugar (Tsugar) in the nectar (DHA/Tsugar) in order to allow for comparison between samples.
The study by Williams (2012) was extended to include the Northland region.4 Wild L. scoparium var. incanum specimens were collected from this region and it was determined that these trees only produced a low to moderate amount of DHA/Tsugar. Williams (2012) also investigated the DHA variability of trees in close proximity to each other as these are supposed to be genetically similar.4 This study was repeated in a different region and the findings were the same; that is trees that were in close proximity to each other can have different DHA/Tsugar. 
One possibility of why DHA is observed in mānuka flowers is that it is used to combat stress as a compatible osmolyte. This was tested using chemical additives and it was found that the DHA/Tsugar varied as a result of the Tsugar as opposed to the amount of DHA. This response was cultivar dependent.
Different flower physiologies were also investigated. This included the andromonoecious nature of mānuka and the specific colour change in the hypanthium of the flower. Male flowers were found to have a larger amount of DHA/Tsugar as a result of a higher level of DHA than hermaphrodite flowers. This could suggest that DHA is being used in the hermaphrodite flowers for processes such as seed production. The DHA/Tsugar of flowers with different hypanthium colour was shown to be dependent on the variety type. The source and reason for DHA still remains unclear and therefore further study is required.

year: 2013

title: Investigating the socio-economic impacts of the introduced Asian paddle crab, Charybdis japonica, on New Zealand’s native paddle crab fishery

authors: Weaver, Shannon Jaine

subjects: Invasive species

abstract: Despite the body of scientific research that exists on Charybdis japonica since it’s discovery in New Zealand in 2000, an investigation into the socio-economic impacts this introduced species may have was lacking. This study focuses on the potential socio-economic impacts from C. japonica on NZ’s native paddle crab (Ovalipes catharus) fishery. Charybdis japonica has spread steadily throughout the North Island of NZ, predominantly in an area that coincides with the main commercial fishing area for O. catharus (federally managed and defined as ‘PAD1’). Fishers perceptions of change and impacts in the fishery were investigated across the commercial and recreational sectors within this focus area. Qualitative, semi-structured interviews with commercial crab fishers covered three main areas: (1) background information on the O. catharus fishery, (2) perceptions of change in the fishery, (3) knowledge of C. japonica and perceived impact. Surveys with recreational fishers also covered these areas, with additional questions on their perceptions of the value of certain coastal environmental aspects (i.e., safety, cleanliness, biodiversity). 

Commercial fisheries catch data for the five main O. catharus fishing regions was also analysed to assess if a significant change in catch rates pre- and post- the arrival of C. japonica in NZ had occurred. Results showed significant changes in PAD1, PAD7 and PAD8 fisheries management areas. Given C. japonica has not yet been found in PAD7 and PAD8, catch rate changes within these three areas are likely due to other unmeasured variables. Commercial fishers predominantly suggested C. japonica had not yet had an observable impact on the O. catharus fishery. Recreational fishers that participated in this study had only had a short-term exposure to the fishery (the majority had started fishing for crabs less than a year ago), thus they had limited perceptions of change within the fishery. Commercial and recreational fishers were also tested on their ability to accurately identify the two crab species. Both sectors accurately identified O. catharus 95% of the time and C. japonica 55% of the time from a series of four images, with no statistically significant difference in accuracy between the two sectors. 
Despite some evidence of self-reported awareness of C. japonica in this study, further sustained public education to enable identification of this introduced species is needed if the public are to be incorporated into the management of this species. Commercial fishers highlighted the potential impact C. japonica may have on the flatfish fishery, an area requiring further investigation. Further research on the impacts C. japonica could have on other species of ecological, social, cultural and economic importance in NZ is required.

text: Investigating the socio-economic impacts of the introduced Asian paddle crab, Charybdis japonica, on New Zealand’s native paddle crab fishery Despite the body of scientific research that exists on Charybdis japonica since it’s discovery in New Zealand in 2000, an investigation into the socio-economic impacts this introduced species may have was lacking. This study focuses on the potential socio-economic impacts from C. japonica on NZ’s native paddle crab (Ovalipes catharus) fishery. Charybdis japonica has spread steadily throughout the North Island of NZ, predominantly in an area that coincides with the main commercial fishing area for O. catharus (federally managed and defined as ‘PAD1’). Fishers perceptions of change and impacts in the fishery were investigated across the commercial and recreational sectors within this focus area. Qualitative, semi-structured interviews with commercial crab fishers covered three main areas: (1) background information on the O. catharus fishery, (2) perceptions of change in the fishery, (3) knowledge of C. japonica and perceived impact. Surveys with recreational fishers also covered these areas, with additional questions on their perceptions of the value of certain coastal environmental aspects (i.e., safety, cleanliness, biodiversity). 

Commercial fisheries catch data for the five main O. catharus fishing regions was also analysed to assess if a significant change in catch rates pre- and post- the arrival of C. japonica in NZ had occurred. Results showed significant changes in PAD1, PAD7 and PAD8 fisheries management areas. Given C. japonica has not yet been found in PAD7 and PAD8, catch rate changes within these three areas are likely due to other unmeasured variables. Commercial fishers predominantly suggested C. japonica had not yet had an observable impact on the O. catharus fishery. Recreational fishers that participated in this study had only had a short-term exposure to the fishery (the majority had started fishing for crabs less than a year ago), thus they had limited perceptions of change within the fishery. Commercial and recreational fishers were also tested on their ability to accurately identify the two crab species. Both sectors accurately identified O. catharus 95% of the time and C. japonica 55% of the time from a series of four images, with no statistically significant difference in accuracy between the two sectors. 
Despite some evidence of self-reported awareness of C. japonica in this study, further sustained public education to enable identification of this introduced species is needed if the public are to be incorporated into the management of this species. Commercial fishers highlighted the potential impact C. japonica may have on the flatfish fishery, an area requiring further investigation. Further research on the impacts C. japonica could have on other species of ecological, social, cultural and economic importance in NZ is required.

year: 2017

title: Ka Māpuna: Towards a rangatiratanga framework for the governance of waterways

authors: Martin, Betsan

abstract: Rangatiratanga is thenavigational courseforthis research, the aspiration that guides a frameworkfor thegovernance which, in respect ofwaterways and Te Taiao secures mauri, ecosystem health, and water for domestic and commercial use. Rangatiratanga encompasses mana whakahaeredecision-making throughout all relevantgovernance systems. In respect of resource governance, this needs to be achieved through mana whenua authorities and co-governance institutions and procedures.

text: Ka Māpuna: Towards a rangatiratanga framework for the governance of waterways Rangatiratanga is thenavigational courseforthis research, the aspiration that guides a frameworkfor thegovernance which, in respect ofwaterways and Te Taiao secures mauri, ecosystem health, and water for domestic and commercial use. Rangatiratanga encompasses mana whakahaeredecision-making throughout all relevantgovernance systems. In respect of resource governance, this needs to be achieved through mana whenua authorities and co-governance institutions and procedures.

year: 2021