title: New Zealand seagrass (Zostera muelleri) response to acute sedimentation: Linking non-structural carbohydrate reserves to resilience

authors: Soerensen, Stine Tang

subjects: seagrass

abstract: Seagrass meadows form healthy near-coastal marine environments that provide a wide range of ecosystem services in New Zealand and Australia. However, seagrass habitats are declining regionally and globally. It is therefore essential that research fills the current knowledge gaps associated with seagrass disturbance-response regimes and develops standardised methods to measure seagrass health and resilience. Sedimentation associated with increased human activity is a major environmental stressor to seagrass; yet little is known about how sedimentation affects New Zealand’s only seagrass species, Zostera muelleri. This thesis, therefore explores how Z. muelleri responds to catastrophic burial (acute) events in Tauranga Harbour, New Zealand. 

Non-structural carbohydrates (NSC) are synthesised and stored in seagrass tissues when photosynthetic outputs exceed metabolic demands and, in turn, are mobilised when photosynthesis is unable to meet metabolic demands. Hence, NSC reserves can be used to measure the impact of a disturbance and/or the resilience of seagrass. A literature review in Chapter 2 illustrates that multiple methods are used to estimate NSC reserves. Experimental comparisons of a selection of these methods demonstrate that NSC estimates by different analytical methods cannot be compared. The outcome of Chapter 2 is the development of a 5-step standard analytical protocol for the quantitation of NSC reserves in seagrass (specifically Z. muelleri). The implementation of a standardised protocol will enable researchers to compare and synthesise results and, thus, increase the application of NSC as a seagrass health measure. 

Chapter 3 investigates the effects of acute sedimentation (i.e. burial) on Z. muelleri. In situ manipulative experiments across three sites in Tauranga Harbour, New Zealand were used to assess the spatial variation in resilience (i.e. resistance and recovery) to burial. Resistance and recovery following burial varied significantly between the three distinct morphotypes that existed in the three sites; a large, a small and an intermediate morphotype that overlapped with the small and the large morphotypes. These morphometric differences were believed to be phenotypic responses to site-specific environmental conditions. Having a large morphotype maximises the potential to capture light and store reserves and presumably an acclimation of Z. muelleri existing in a chronically impacted environment (high sediment mud/organic matter (SOM) and low sediment grain size). The largest seagrass displayed high resistance to both single and repeated burial events of 2 cm (no significant effects). In contrast, the smaller seagrass had low resistance and the slowest ability to recover following burial (up to 251 days), whereas, the intermediate morphotype displayed a faster ability to recover (up to 168 days). Results, therefore, suggest that the resilience to burial events increases in populations that have acclimated to a chronically impacted environment. It is, however, noted that a degraded environment will eventually reach a limiting threshold from which recovery is not plausible and results should therefore be interpreted with some caution. 

While rhizome NSC reserves were not affected by burial treatments, these varied significantly throughout a full growing year across the three locations. NSC reserves were at the lowest levels in winter and spring, consistent with seasonal trends. Sucrose levels at the peak of the growing season (February) were significantly related to relative shoot cover the following winter (r² = 0.54, P < .001) and spring (r² = 0.66, P < .001). As such, chapter 3 also documented a link between seagrass cover and sucrose reserves.

Estimates of NSC reserves from the literature vary greatly, presumably due to the wide variety of analytical methods used. Chapter 4 explores the variability of Z. muelleri NSC reserves and the specific partitioning of carbohydrate groups (sucrose and starch) across different spatial scales (within meadow, between sites, between regions), including temperate (Port Phillip Bay) and tropical populations (Townville and Magnetic Island) in Australia. When measured in spring, the total NSC reserves were similar across all spatial scales (193.59 ± 10.88 mg g⁻¹ DW); however, the proportional contents of sucrose and starch varied significantly at different spatial scales. Sucrose contents varied at site level and were best explained by a combination of sediment pH and aboveground to belowground biomass ratio (r² = 0.49, P <0.001). Starch contents varied between regions, with seagrass in the tropical Townsville containing significantly higher starch levels and as such lower sucrose to starch ratios. The best model for starch included only one variable; sediment surface temperature (r² = 0.33, P < 0.001) and results therefore suggest that starch is influenced by large-scale processes linked to climatic processes. The adaptive strategies of seagrass to moderate NSC allocation appear to be of particular importance to seagrass’ ability to acclimate to a diverse range of environments. 

Chapter 5 synthesises the results of the three research chapters and provides recommendations for best practices. Of particular importance, is the method that was developed to ensure accurate measurements of NSC reserves in seagrasses, allowing this measure to be used as a monitoring tool of potential resilience and health of seagrass meadows. This thesis clearly illustrates that the partitioning of NSC groups (sucrose/starch) vary spatially and temporally and that these are influenced by distinct processes. Furthermore, it demonstrates that the phenotypic plasticity of Z. muelleri in New Zealand enhances their resilience to acute sedimentation events (i.e. burial). It is therefore suggested that the timing and location of human-induced disturbances (i.e. catchment developments, dredging of harbours and ports) should match optimum seagrass resilience (e.g., high sucrose reserves and consideration of phenotypic expression), as this is likely to increase the survival rates of the impacted seagrass meadows. The new insights gained from this research provides crucial information to ensure sustainable management of Z. muelleri into the future.

text: New Zealand seagrass (Zostera muelleri) response to acute sedimentation: Linking non-structural carbohydrate reserves to resilience Seagrass meadows form healthy near-coastal marine environments that provide a wide range of ecosystem services in New Zealand and Australia. However, seagrass habitats are declining regionally and globally. It is therefore essential that research fills the current knowledge gaps associated with seagrass disturbance-response regimes and develops standardised methods to measure seagrass health and resilience. Sedimentation associated with increased human activity is a major environmental stressor to seagrass; yet little is known about how sedimentation affects New Zealand’s only seagrass species, Zostera muelleri. This thesis, therefore explores how Z. muelleri responds to catastrophic burial (acute) events in Tauranga Harbour, New Zealand. 

Non-structural carbohydrates (NSC) are synthesised and stored in seagrass tissues when photosynthetic outputs exceed metabolic demands and, in turn, are mobilised when photosynthesis is unable to meet metabolic demands. Hence, NSC reserves can be used to measure the impact of a disturbance and/or the resilience of seagrass. A literature review in Chapter 2 illustrates that multiple methods are used to estimate NSC reserves. Experimental comparisons of a selection of these methods demonstrate that NSC estimates by different analytical methods cannot be compared. The outcome of Chapter 2 is the development of a 5-step standard analytical protocol for the quantitation of NSC reserves in seagrass (specifically Z. muelleri). The implementation of a standardised protocol will enable researchers to compare and synthesise results and, thus, increase the application of NSC as a seagrass health measure. 

Chapter 3 investigates the effects of acute sedimentation (i.e. burial) on Z. muelleri. In situ manipulative experiments across three sites in Tauranga Harbour, New Zealand were used to assess the spatial variation in resilience (i.e. resistance and recovery) to burial. Resistance and recovery following burial varied significantly between the three distinct morphotypes that existed in the three sites; a large, a small and an intermediate morphotype that overlapped with the small and the large morphotypes. These morphometric differences were believed to be phenotypic responses to site-specific environmental conditions. Having a large morphotype maximises the potential to capture light and store reserves and presumably an acclimation of Z. muelleri existing in a chronically impacted environment (high sediment mud/organic matter (SOM) and low sediment grain size). The largest seagrass displayed high resistance to both single and repeated burial events of 2 cm (no significant effects). In contrast, the smaller seagrass had low resistance and the slowest ability to recover following burial (up to 251 days), whereas, the intermediate morphotype displayed a faster ability to recover (up to 168 days). Results, therefore, suggest that the resilience to burial events increases in populations that have acclimated to a chronically impacted environment. It is, however, noted that a degraded environment will eventually reach a limiting threshold from which recovery is not plausible and results should therefore be interpreted with some caution. 

While rhizome NSC reserves were not affected by burial treatments, these varied significantly throughout a full growing year across the three locations. NSC reserves were at the lowest levels in winter and spring, consistent with seasonal trends. Sucrose levels at the peak of the growing season (February) were significantly related to relative shoot cover the following winter (r² = 0.54, P < .001) and spring (r² = 0.66, P < .001). As such, chapter 3 also documented a link between seagrass cover and sucrose reserves.

Estimates of NSC reserves from the literature vary greatly, presumably due to the wide variety of analytical methods used. Chapter 4 explores the variability of Z. muelleri NSC reserves and the specific partitioning of carbohydrate groups (sucrose and starch) across different spatial scales (within meadow, between sites, between regions), including temperate (Port Phillip Bay) and tropical populations (Townville and Magnetic Island) in Australia. When measured in spring, the total NSC reserves were similar across all spatial scales (193.59 ± 10.88 mg g⁻¹ DW); however, the proportional contents of sucrose and starch varied significantly at different spatial scales. Sucrose contents varied at site level and were best explained by a combination of sediment pH and aboveground to belowground biomass ratio (r² = 0.49, P <0.001). Starch contents varied between regions, with seagrass in the tropical Townsville containing significantly higher starch levels and as such lower sucrose to starch ratios. The best model for starch included only one variable; sediment surface temperature (r² = 0.33, P < 0.001) and results therefore suggest that starch is influenced by large-scale processes linked to climatic processes. The adaptive strategies of seagrass to moderate NSC allocation appear to be of particular importance to seagrass’ ability to acclimate to a diverse range of environments. 

Chapter 5 synthesises the results of the three research chapters and provides recommendations for best practices. Of particular importance, is the method that was developed to ensure accurate measurements of NSC reserves in seagrasses, allowing this measure to be used as a monitoring tool of potential resilience and health of seagrass meadows. This thesis clearly illustrates that the partitioning of NSC groups (sucrose/starch) vary spatially and temporally and that these are influenced by distinct processes. Furthermore, it demonstrates that the phenotypic plasticity of Z. muelleri in New Zealand enhances their resilience to acute sedimentation events (i.e. burial). It is therefore suggested that the timing and location of human-induced disturbances (i.e. catchment developments, dredging of harbours and ports) should match optimum seagrass resilience (e.g., high sucrose reserves and consideration of phenotypic expression), as this is likely to increase the survival rates of the impacted seagrass meadows. The new insights gained from this research provides crucial information to ensure sustainable management of Z. muelleri into the future.

year: 2020

title: Recording and Tracking Design Decisions in Interactive System Development

authors: Yang, Wanying

subjects: Interactive system design

abstract: Experience economy is prompting the innovation of traditional product design. The design concept - "user-centered design" has received wide recognition. In the face of many professional or non-professional users, the priority of interaction design is to ensure the usability of the interactive product, and then a good user experience of the product. The user interface is an intermediary between human and computer. Users exchange information with the computer via the user interface. The user interface is an important part of a computer system. It is a big part of the software development. The quality of the user interface directly affects the performance of the software. For most users, the user interface is all they know from a product. So for these users, a program with a good interior design but a bad user interface design is a bad program. 
	In this project we investigate different ways of recording design decisions in interactive system development which may allow us to think of the different variants and alternatives that are possible (within a design space) in some formal notation, which then allows us to either reason about their suitability or record the decisions made to understand the impact of decisions and how well they support the given criteria. The goal of this project will involve finding out what the influences are which help drive the design process; considering the effects of individual vs. team design; deciding how and when decisions occur; thinking about useful ways to record decisions and their influences; and investigating the usefulness of the approach through the working examples identified as case studies

text: Recording and Tracking Design Decisions in Interactive System Development Experience economy is prompting the innovation of traditional product design. The design concept - "user-centered design" has received wide recognition. In the face of many professional or non-professional users, the priority of interaction design is to ensure the usability of the interactive product, and then a good user experience of the product. The user interface is an intermediary between human and computer. Users exchange information with the computer via the user interface. The user interface is an important part of a computer system. It is a big part of the software development. The quality of the user interface directly affects the performance of the software. For most users, the user interface is all they know from a product. So for these users, a program with a good interior design but a bad user interface design is a bad program. 
	In this project we investigate different ways of recording design decisions in interactive system development which may allow us to think of the different variants and alternatives that are possible (within a design space) in some formal notation, which then allows us to either reason about their suitability or record the decisions made to understand the impact of decisions and how well they support the given criteria. The goal of this project will involve finding out what the influences are which help drive the design process; considering the effects of individual vs. team design; deciding how and when decisions occur; thinking about useful ways to record decisions and their influences; and investigating the usefulness of the approach through the working examples identified as case studies

year: 2016

title: A new beginning for indigenous wellbeing - Guest editorial

authors: Nikora, Linda Waimarie

abstract: Three members of the editorial board of the Journal of Indigenous Wellbeing – Te Mauri: Pimatisiwin and the Editor reflect on the genesis of the journal, comment on its journey over time, review its mission moving forward and introduces the first edition of the journal August 2016. The authors of this article include the current editorial board’s chairperson, two board members – one a past editor of the journal, the other, the journal’s present patron and the current editor.

text: A new beginning for indigenous wellbeing - Guest editorial Three members of the editorial board of the Journal of Indigenous Wellbeing – Te Mauri: Pimatisiwin and the Editor reflect on the genesis of the journal, comment on its journey over time, review its mission moving forward and introduces the first edition of the journal August 2016. The authors of this article include the current editorial board’s chairperson, two board members – one a past editor of the journal, the other, the journal’s present patron and the current editor.

year: 2016