title: Brews and blooms: Development of a novel seaweed biostimulant supporting sustainable primary industry practices

authors: Robertson, Holly A.

abstract: With a growing global population and increasing needs for environmentally friendly food production, novel technologies and products are required to increase food production sustainably. In this regard, seaweed biostimulants are an innovative tool to improve crop growth and yield. However, seaweed biomass is typically obtained through wild harvest or collection of beach cast, with challenges around the consistency of quality and reliability of supply. Furthermore, common manufacturing methods can have issues with high chemical input, loss of potentially important compounds, and cost. Therefore, this thesis aims to develop a seaweed biostimulant utilising the cultivated seaweed Ulva stenophylloides and a novel low-input fermentation method. This research covers optimisation of fermentation parameters and detailed compositional characterisation of the resulting products (Chapter 2), and the quantification of the effect of selected ferments on growth and yield in plants in hydroponics systems (Chapter 3) and in potted soil (Chapter 4).
The fermentation parameters: biomass loading, sucrose input, and incubation temperature were optimised. The initial sucrose input had the largest impact on fermentation progression and success, and was the main driver in resulting glucose content, total dissolved solids, pH, and pellicle yield. Excluding treatments with low biomass loadings, treatments with low and medium sucrose inputs reached completion and treatments with high sucrose inputs did not. As indicated by residual glucose, high biomass loadings provided valuable nutrients for microbial growth and high incubation temperatures were optimal for microbial growth. A range of nutrients were extracted from the seaweed biomass, but concentrations were insufficient as a sole nutrient source for plants based on chemical analyses. High biomass loadings were the main driver in the yield of protein and the sulfated polysaccharide ulvan, which both may modulate gene expression and induce metabolic changes in plants. High incubation temperature was the main driver for the yield of the auxin phenylacetic acid and indicates the production of other possible plant growth stimulating microbial biochemicals at high temperatures. 
Of the four ferments selected for further testing by ferment progression and chemical composition, ferment four (high biomass loading, mid-range sucrose loading, and high incubation temperature) was the best performing biostimulant tested on mung bean seedlings in hydroponics; at a 1 % (v/v) dose, plant fresh and dry weight were increased by 15 and 16 %, respectively, and the most root growth was generated. An auxin-like effect was not detected at any biostimulant dose. At a 1 % dose, an interactive effect with fertiliser was demonstrated in tomato seedling root number. A 2 % dose of biostimulant had adverse impacts on root growth over multiple root growth assays. When applied to potted tomato plants, inconclusive results were obtained in growth and yield due to sub-optimal application volumes and growing conditions that require further method development and retesting.
Overall, this thesis advances knowledge in seaweed biostimulant manufacturing utilising U. stenophylloides with a fermentation production method. These results warrant further investigation into refinement of plant assays and growing conditions, the composition of the ferments through metabolomics and microbial identification, and the biostimulant effects on soil.

text: Brews and blooms: Development of a novel seaweed biostimulant supporting sustainable primary industry practices With a growing global population and increasing needs for environmentally friendly food production, novel technologies and products are required to increase food production sustainably. In this regard, seaweed biostimulants are an innovative tool to improve crop growth and yield. However, seaweed biomass is typically obtained through wild harvest or collection of beach cast, with challenges around the consistency of quality and reliability of supply. Furthermore, common manufacturing methods can have issues with high chemical input, loss of potentially important compounds, and cost. Therefore, this thesis aims to develop a seaweed biostimulant utilising the cultivated seaweed Ulva stenophylloides and a novel low-input fermentation method. This research covers optimisation of fermentation parameters and detailed compositional characterisation of the resulting products (Chapter 2), and the quantification of the effect of selected ferments on growth and yield in plants in hydroponics systems (Chapter 3) and in potted soil (Chapter 4).
The fermentation parameters: biomass loading, sucrose input, and incubation temperature were optimised. The initial sucrose input had the largest impact on fermentation progression and success, and was the main driver in resulting glucose content, total dissolved solids, pH, and pellicle yield. Excluding treatments with low biomass loadings, treatments with low and medium sucrose inputs reached completion and treatments with high sucrose inputs did not. As indicated by residual glucose, high biomass loadings provided valuable nutrients for microbial growth and high incubation temperatures were optimal for microbial growth. A range of nutrients were extracted from the seaweed biomass, but concentrations were insufficient as a sole nutrient source for plants based on chemical analyses. High biomass loadings were the main driver in the yield of protein and the sulfated polysaccharide ulvan, which both may modulate gene expression and induce metabolic changes in plants. High incubation temperature was the main driver for the yield of the auxin phenylacetic acid and indicates the production of other possible plant growth stimulating microbial biochemicals at high temperatures. 
Of the four ferments selected for further testing by ferment progression and chemical composition, ferment four (high biomass loading, mid-range sucrose loading, and high incubation temperature) was the best performing biostimulant tested on mung bean seedlings in hydroponics; at a 1 % (v/v) dose, plant fresh and dry weight were increased by 15 and 16 %, respectively, and the most root growth was generated. An auxin-like effect was not detected at any biostimulant dose. At a 1 % dose, an interactive effect with fertiliser was demonstrated in tomato seedling root number. A 2 % dose of biostimulant had adverse impacts on root growth over multiple root growth assays. When applied to potted tomato plants, inconclusive results were obtained in growth and yield due to sub-optimal application volumes and growing conditions that require further method development and retesting.
Overall, this thesis advances knowledge in seaweed biostimulant manufacturing utilising U. stenophylloides with a fermentation production method. These results warrant further investigation into refinement of plant assays and growing conditions, the composition of the ferments through metabolomics and microbial identification, and the biostimulant effects on soil.

year: 2024

title: Competition between native bees and honey bees on mānuka flowers in New Zealand

authors: Fale, Grant

abstract: Humans have introduced the European subspecies of the Western honey bee (Apis mellifera) to every other continent except Antarctica, resulting in the presence of this generalist forager many ecosystems that honey bees are not native to. The impacts of introduced honey bees on these ecosystems are still not well understood. Honey bees were introduced to New Zealand in 1839, and are common visitors to native flowers throughout the country. As honey bees are generalist flower visitors and can present at high abundances, they could potentially be competing with and displacing native flower visitors. The aim of this study was to investigate interactions and possible competition between European-derived honey bees (A. mellifera sspp.) and native bee species (Leioproctus spp) for mānuka (Leptospermum scoparium) floral resources in New Zealand. I assessed a) temporal overlap in activity, b) abundances across time of day, and c) foraging behaviours of honey bees and Leioproctus bees. In a combination of field observations and behaviour experiments I found that a) temporal niche partitioning occurs daily and seasonally and b) both Leioproctus sp and honey bees display behavioural changes in the presence of the other. My observations suggest that competition does occur between honey bees and Leioproctus sp and that both alter their foraging behaviour and activity to reduce this competition. However, more research is required to assess this interspecific competition is great enough to adversely affect either species. Evidence-based understanding of the impacts of honey bees in native ecosystems is critical to our ability to improve honey bee management strategies and/or mitigate adverse effects of honey bee competition to endemic species where honey bees have been introduced.

text: Competition between native bees and honey bees on mānuka flowers in New Zealand Humans have introduced the European subspecies of the Western honey bee (Apis mellifera) to every other continent except Antarctica, resulting in the presence of this generalist forager many ecosystems that honey bees are not native to. The impacts of introduced honey bees on these ecosystems are still not well understood. Honey bees were introduced to New Zealand in 1839, and are common visitors to native flowers throughout the country. As honey bees are generalist flower visitors and can present at high abundances, they could potentially be competing with and displacing native flower visitors. The aim of this study was to investigate interactions and possible competition between European-derived honey bees (A. mellifera sspp.) and native bee species (Leioproctus spp) for mānuka (Leptospermum scoparium) floral resources in New Zealand. I assessed a) temporal overlap in activity, b) abundances across time of day, and c) foraging behaviours of honey bees and Leioproctus bees. In a combination of field observations and behaviour experiments I found that a) temporal niche partitioning occurs daily and seasonally and b) both Leioproctus sp and honey bees display behavioural changes in the presence of the other. My observations suggest that competition does occur between honey bees and Leioproctus sp and that both alter their foraging behaviour and activity to reduce this competition. However, more research is required to assess this interspecific competition is great enough to adversely affect either species. Evidence-based understanding of the impacts of honey bees in native ecosystems is critical to our ability to improve honey bee management strategies and/or mitigate adverse effects of honey bee competition to endemic species where honey bees have been introduced.

year: 2023

title: Place attachment of Ngāi Te Ahi to Hairini Marae

authors: Teddy, Lani

subjects: Hairini

abstract: Twelve members of Ngāi Te Ahi, a hapū from Tauranga, were interviewed to explore how they talk about their place attachment to Hairini Marae.  This was organized around five key dimensions of place attachment taken from the literature—continuity, distinctiveness, symbolism, attachment and familiarity.  We found that in discussing all dimensions, place attachment was equally about social and cultural relationships, history, and socialization.  Place attachment for groups such as Māori is complex because it encompasses all social relationships past and present.  The implication for those working with Māori is to take seriously the wider connotations of place when talking to Māori about marae, traditional homelands, and their land.

text: Place attachment of Ngāi Te Ahi to Hairini Marae Twelve members of Ngāi Te Ahi, a hapū from Tauranga, were interviewed to explore how they talk about their place attachment to Hairini Marae.  This was organized around five key dimensions of place attachment taken from the literature—continuity, distinctiveness, symbolism, attachment and familiarity.  We found that in discussing all dimensions, place attachment was equally about social and cultural relationships, history, and socialization.  Place attachment for groups such as Māori is complex because it encompasses all social relationships past and present.  The implication for those working with Māori is to take seriously the wider connotations of place when talking to Māori about marae, traditional homelands, and their land.

year: 2008