title: A Survey of Dihydroxyacetone in Nectar of Leptospermum Scoparium from Several Regions of New Zealand

authors: Williams, Simon Douglas

subjects: dihydroxyacetone

abstract: Mānuka honey has been identified as having non-peroxide antimicrobial activity (NPA). This medical benefit has led to mānuka honey becoming a major export for New Zealand. Hives are currently located in preserved or regenerating mānuka bush. With the growth in the mānuka honey industry, interest has arisen to determine why mānuka trees produce the non-peroxide active honey. Identification of this reason will allow mānuka plantations to be planted that are expected to provide honey with a high level of non-peroxide activity. These plantations will also allow marginal land to become more productive due to mānuka being a resilient plant able to grow under harsh conditions.

It has been shown that the majority of the non-peroxide activity arises from the presence of methylglyoxal (MGO). In fresh honey a minimal amount of MGO was present, but a large amount of dihydroxyacetone (DHA) was found. Previous work has shown that DHA can undergo chemical conversion into MGO under the correct conditions. A similar conversion is postulated to take place in honey, testing suggests that this conversion is a non-enzymatic reaction. Preliminary surveys have been carried out which have identified DHA in the nectar of mānuka owers.

This thesis describes a wider survey of mānuka trees around New Zealand.The trees were sampled in the flowering seasons of 2009 and 2010 between October and January. Flowers were picked and frozen for processing and an aqueous soaking method was developed to extract the DHA and sugar from a pooling of 20 owers. Analyses of the samples were carried out by gas chromatography with flame ionisation detection. This method was further improved to include the nectar extraction and measurement of DHA levels within a single flower.

To allow the DHA to be related back to honey, it was measured in ratio to the total sugar (Tsugar) in the nectar to give the ratio DHA/Tsugar. It was confirmed that DHA/Tsugar measured in the nectar of the mānuka flower does vary within and between the regions surveyed. Suggested causes of within region variation are the age of the tree, micro-environments and possibly genetics. Variation between regions is strongly suggested to be genetically linked. Using the work by Adam set al.(2008, 2009), it was possible to predict honey NPA values based upon the DHA/Tsugar found in the nectar and these values were comparable with the measured NPA of the honey as supplied by beekeepers. Only a poor correlation of DHA/Tsugar was found with the soil components measured by Kiefer(2010);  with the leaf oil components measured by Janusch(2010) some correlation was found, when these were correlated across all the sampled regions. When each region was correlated individually, the correlation proved much stronger, suggesting a link, though most likely indirect, to the mānuka oil chemotype. Using these survey results, mānuka trees have been identified for the purpose of breeding and on-going study.

text: A Survey of Dihydroxyacetone in Nectar of Leptospermum Scoparium from Several Regions of New Zealand Mānuka honey has been identified as having non-peroxide antimicrobial activity (NPA). This medical benefit has led to mānuka honey becoming a major export for New Zealand. Hives are currently located in preserved or regenerating mānuka bush. With the growth in the mānuka honey industry, interest has arisen to determine why mānuka trees produce the non-peroxide active honey. Identification of this reason will allow mānuka plantations to be planted that are expected to provide honey with a high level of non-peroxide activity. These plantations will also allow marginal land to become more productive due to mānuka being a resilient plant able to grow under harsh conditions.

It has been shown that the majority of the non-peroxide activity arises from the presence of methylglyoxal (MGO). In fresh honey a minimal amount of MGO was present, but a large amount of dihydroxyacetone (DHA) was found. Previous work has shown that DHA can undergo chemical conversion into MGO under the correct conditions. A similar conversion is postulated to take place in honey, testing suggests that this conversion is a non-enzymatic reaction. Preliminary surveys have been carried out which have identified DHA in the nectar of mānuka owers.

This thesis describes a wider survey of mānuka trees around New Zealand.The trees were sampled in the flowering seasons of 2009 and 2010 between October and January. Flowers were picked and frozen for processing and an aqueous soaking method was developed to extract the DHA and sugar from a pooling of 20 owers. Analyses of the samples were carried out by gas chromatography with flame ionisation detection. This method was further improved to include the nectar extraction and measurement of DHA levels within a single flower.

To allow the DHA to be related back to honey, it was measured in ratio to the total sugar (Tsugar) in the nectar to give the ratio DHA/Tsugar. It was confirmed that DHA/Tsugar measured in the nectar of the mānuka flower does vary within and between the regions surveyed. Suggested causes of within region variation are the age of the tree, micro-environments and possibly genetics. Variation between regions is strongly suggested to be genetically linked. Using the work by Adam set al.(2008, 2009), it was possible to predict honey NPA values based upon the DHA/Tsugar found in the nectar and these values were comparable with the measured NPA of the honey as supplied by beekeepers. Only a poor correlation of DHA/Tsugar was found with the soil components measured by Kiefer(2010);  with the leaf oil components measured by Janusch(2010) some correlation was found, when these were correlated across all the sampled regions. When each region was correlated individually, the correlation proved much stronger, suggesting a link, though most likely indirect, to the mānuka oil chemotype. Using these survey results, mānuka trees have been identified for the purpose of breeding and on-going study.

year: 2012

title: Beyond transformation and regulation: Productive tensions and the analytics of inclusion

authors: Simon-Kumar, Rachel

subjects: inclusion

abstract: The inclusion of marginal groups is increasingly becoming part of contemporary governance. Critical appraisals categorize inclusionary mechanisms either as politically transformative or as regulative and part of the state's broader agenda of social control. In this article, we argue against both these positions and propose instead that inclusion is simultaneously regulative and transformative, that is, it is practiced in a state of—what Chantal Mouffe calls—“productive tension.” The article is divided into two parts: the first critically examines the theoretical literature on the tensions written into inclusive practices. The second part illustrates productive tensions in the case of inclusive strategies between ethnic/migrant groups and the government in Aotearoa/New Zealand. The article urges the reconceptualization of tensions and contradictions as part of the broader contours of contemporary radical democracy wherein erasures, assimilations, resistance, and transformations exist simultaneously.

text: Beyond transformation and regulation: Productive tensions and the analytics of inclusion The inclusion of marginal groups is increasingly becoming part of contemporary governance. Critical appraisals categorize inclusionary mechanisms either as politically transformative or as regulative and part of the state's broader agenda of social control. In this article, we argue against both these positions and propose instead that inclusion is simultaneously regulative and transformative, that is, it is practiced in a state of—what Chantal Mouffe calls—“productive tension.” The article is divided into two parts: the first critically examines the theoretical literature on the tensions written into inclusive practices. The second part illustrates productive tensions in the case of inclusive strategies between ethnic/migrant groups and the government in Aotearoa/New Zealand. The article urges the reconceptualization of tensions and contradictions as part of the broader contours of contemporary radical democracy wherein erasures, assimilations, resistance, and transformations exist simultaneously.

year: 2011

title: The modification of toheroa habitat by streams on Ripiro Beach

authors: Cope, Jane

abstract: Habitat modification and loss are key factors driving the global extinction and displacement of species. The scale and consequences of habitat loss are relatively well understood in terrestrial environments, but in marine ecosystems, and particularly soft sediment ecosystems, this is not the case. The characteristics which determine the suitability of soft sediment habitats are often subtle, due to the apparent homogeneity of sandy environments. This can make it difficult to detect habitat change in the first place let alone understand ecological consequences. Subtle differences in habitat quality are even harder to detect on dynamic surf beaches which are controlled by the interactions between the wave climate and the beach sands, and experience frequent and large changes. The exposed surf beaches of northern New Zealand, are home to toheroa (Paphies ventricosa), an endemic surf clam and New Zealand‘s most protected shell fish species. Over the course of the 20th century, toheroa were harvested to the point of collapse resulting in the closure of an important cultural, recreational and commercial fishery. Despite more than 40 years of protection, toheroa populations have failed to recover with populations in most locations continuing to decline. 

In northern New Zealand toheroa distribution is strongly associated with the small streams which flow across the toheroa beaches. A reduction in the flow of fresh water to the beach via these streams has been suggested as one possible factor which may be preventing the recovery of toheroa. However, little is known about the characteristics of the habitat, and the mechanism driving this toheroa-stream relationship has not received specific attention. The objective of this research was to better understand the effect of streams on beach habitat in the hope of determining the drivers of toheroa distribution. Specifically, I investigated how sediment type, topography, water table depth and sediment temperatures varied across exposed intertidal sediments adjacent to and away from streams. Sampling took place at four sites along Ripiro Beach during the summer, the season when toheroa are most susceptible to thermal stress and streams are thought to provide some protection from dissipation and heat stress. Grainsize distributions from the sampled sediment cores were processed using a Malvern Mastersizer 3000 laser diffractometer (Malvern, UK). The surface elevation and sediment temperature profiles of the subaerial beach was measured using a theodolite CDN pro accurate waterproof thermometers (Model DTW450L). Temperatures were measured at five sediment depths (2cm, 4cm, 7.5cm, 10.5cm, 20.5cm) throughout the sampling period. 

The effect of the streams on the grain size distribution of intertidal sediments appeared to be limited to the high tide, where the proportion of fine sediments was highest in stream adjacent sediments. Greater variations in grain size occurred along the beach, but the greatest difference in sediment sizes occurred when contrasting current day beach grain size distributions with sediment data collected in 1974. Beach sediments from 2017 contained 26661% time more medium sediment indicating the beach is now much coaster than it was 44 years ago. However, as no time series is available for sediment composition at Ripiro it is uncertain whether this change in beach make up is indicative of year-to-year variation or a long term trend. Beach topography varied consistently in the vicinity of streams. The elevation and slope of the beach face was lowest in the path of streams. Along the upper beach, low elevation in the path of the stream lead to the formation of deep bowl like features. As a result of this topography, adjacent to the stream, the water table remained close to the sediment surface throughout the sampling period (< 20 cm), in contrast to point‘s away from the stream where the water table was below the sampling depth. 

The hypothesis that streams would provide a thermal refuge for toheroa was one of the key questions of this thesis. What I found was that stream driven difference in sediment temperatures were only apparent in the upper intestinal, the area occupied by juvenile toheroa when they first recruit to the beach. Temperatures away from streams were significantly higher (> 3.5 °C) than stream adjacent sediments. However, in the middle intestinal, the area occupied by adult toheroa, the seep face exerted a greater influence on sediment temperatures than the stream and temperatures were no different regardless of stream proximity. The findings of this study suggest that the toheroa-stream relationship is not a direct response to the presence of freshwater, but rather is driven by the modification of the intertidal sediments by the streams. The increased erosion in these areas reduces the distance between the sediment surface and the water table, increasing the moisture content of the sediments. Additionally, the formation of the basin like depressions in the upper intertidal may act to aggregate spat and juvenile toheroa through the effect of this topography on the beach swash regime. At mid-tide areas adjacent to streams, the depth of the water table was such that adult toheroa are likely to be either fully or partially immersed throughout the low tide. Away from streams, the water table is beyond the burrowing depth of toheroa. For both juveniles and adults, stream associated areas may provide important protection against desiccation, through increasing moisture content of the sediments and for juveniles through reduced sediment temperatures. 

Evidently, streams do modify beach habitat in a way that makes it inhabitable for toheroa. Just not in the way that was anticipated. This study has increased our knowledge of beach characteristics that provide good toheroa habitat. Further research is required to test these hypotheses and better understand the effects of climate and terrestrial land use on beach state and therefore the suitability of the beach for toheroa.

text: The modification of toheroa habitat by streams on Ripiro Beach Habitat modification and loss are key factors driving the global extinction and displacement of species. The scale and consequences of habitat loss are relatively well understood in terrestrial environments, but in marine ecosystems, and particularly soft sediment ecosystems, this is not the case. The characteristics which determine the suitability of soft sediment habitats are often subtle, due to the apparent homogeneity of sandy environments. This can make it difficult to detect habitat change in the first place let alone understand ecological consequences. Subtle differences in habitat quality are even harder to detect on dynamic surf beaches which are controlled by the interactions between the wave climate and the beach sands, and experience frequent and large changes. The exposed surf beaches of northern New Zealand, are home to toheroa (Paphies ventricosa), an endemic surf clam and New Zealand‘s most protected shell fish species. Over the course of the 20th century, toheroa were harvested to the point of collapse resulting in the closure of an important cultural, recreational and commercial fishery. Despite more than 40 years of protection, toheroa populations have failed to recover with populations in most locations continuing to decline. 

In northern New Zealand toheroa distribution is strongly associated with the small streams which flow across the toheroa beaches. A reduction in the flow of fresh water to the beach via these streams has been suggested as one possible factor which may be preventing the recovery of toheroa. However, little is known about the characteristics of the habitat, and the mechanism driving this toheroa-stream relationship has not received specific attention. The objective of this research was to better understand the effect of streams on beach habitat in the hope of determining the drivers of toheroa distribution. Specifically, I investigated how sediment type, topography, water table depth and sediment temperatures varied across exposed intertidal sediments adjacent to and away from streams. Sampling took place at four sites along Ripiro Beach during the summer, the season when toheroa are most susceptible to thermal stress and streams are thought to provide some protection from dissipation and heat stress. Grainsize distributions from the sampled sediment cores were processed using a Malvern Mastersizer 3000 laser diffractometer (Malvern, UK). The surface elevation and sediment temperature profiles of the subaerial beach was measured using a theodolite CDN pro accurate waterproof thermometers (Model DTW450L). Temperatures were measured at five sediment depths (2cm, 4cm, 7.5cm, 10.5cm, 20.5cm) throughout the sampling period. 

The effect of the streams on the grain size distribution of intertidal sediments appeared to be limited to the high tide, where the proportion of fine sediments was highest in stream adjacent sediments. Greater variations in grain size occurred along the beach, but the greatest difference in sediment sizes occurred when contrasting current day beach grain size distributions with sediment data collected in 1974. Beach sediments from 2017 contained 26661% time more medium sediment indicating the beach is now much coaster than it was 44 years ago. However, as no time series is available for sediment composition at Ripiro it is uncertain whether this change in beach make up is indicative of year-to-year variation or a long term trend. Beach topography varied consistently in the vicinity of streams. The elevation and slope of the beach face was lowest in the path of streams. Along the upper beach, low elevation in the path of the stream lead to the formation of deep bowl like features. As a result of this topography, adjacent to the stream, the water table remained close to the sediment surface throughout the sampling period (< 20 cm), in contrast to point‘s away from the stream where the water table was below the sampling depth. 

The hypothesis that streams would provide a thermal refuge for toheroa was one of the key questions of this thesis. What I found was that stream driven difference in sediment temperatures were only apparent in the upper intestinal, the area occupied by juvenile toheroa when they first recruit to the beach. Temperatures away from streams were significantly higher (> 3.5 °C) than stream adjacent sediments. However, in the middle intestinal, the area occupied by adult toheroa, the seep face exerted a greater influence on sediment temperatures than the stream and temperatures were no different regardless of stream proximity. The findings of this study suggest that the toheroa-stream relationship is not a direct response to the presence of freshwater, but rather is driven by the modification of the intertidal sediments by the streams. The increased erosion in these areas reduces the distance between the sediment surface and the water table, increasing the moisture content of the sediments. Additionally, the formation of the basin like depressions in the upper intertidal may act to aggregate spat and juvenile toheroa through the effect of this topography on the beach swash regime. At mid-tide areas adjacent to streams, the depth of the water table was such that adult toheroa are likely to be either fully or partially immersed throughout the low tide. Away from streams, the water table is beyond the burrowing depth of toheroa. For both juveniles and adults, stream associated areas may provide important protection against desiccation, through increasing moisture content of the sediments and for juveniles through reduced sediment temperatures. 

Evidently, streams do modify beach habitat in a way that makes it inhabitable for toheroa. Just not in the way that was anticipated. This study has increased our knowledge of beach characteristics that provide good toheroa habitat. Further research is required to test these hypotheses and better understand the effects of climate and terrestrial land use on beach state and therefore the suitability of the beach for toheroa.

year: 2018