title: Visualisation of Parallel Data Streams with Temporal Mosaics

authors: Luz, Saturnino

subjects: computer science

abstract: Despite its popularity and widespread use, timeline visualisation suffers from shortcomings which limit its use for displaying multiple data streams when the number of streams increases to more than a handful. This paper presents the TemporalMosaic technique for visualisation of parallel time-based streams which addresses some of these shortcomings. Temporal mosaics provide a compact way of representing parallel streams of events by allocating a fixed drawing area to time intervals and partitioning that area according to the number of concurrent events. A user study is presented which compares this technique to a standard timeline representation technique in which events are depicted as horizontal bars and multiple streams are drawn in parallel along a vertical axis. Results of this user study show that users of the temporal mosaic visualisation perform significantly better at detecting concurrency, interval overlaps and inactivity than users of standard timelines.

text: Visualisation of Parallel Data Streams with Temporal Mosaics Despite its popularity and widespread use, timeline visualisation suffers from shortcomings which limit its use for displaying multiple data streams when the number of streams increases to more than a handful. This paper presents the TemporalMosaic technique for visualisation of parallel time-based streams which addresses some of these shortcomings. Temporal mosaics provide a compact way of representing parallel streams of events by allocating a fixed drawing area to time intervals and partitioning that area according to the number of concurrent events. A user study is presented which compares this technique to a standard timeline representation technique in which events are depicted as horizontal bars and multiple streams are drawn in parallel along a vertical axis. Results of this user study show that users of the temporal mosaic visualisation perform significantly better at detecting concurrency, interval overlaps and inactivity than users of standard timelines.

year: 2007

title: The role of Chaetopterus sp. in reshaping sediment characteristics and benthic communities in Queen Charlotte Sound

authors: Scott-Simmonds , Thomas

abstract: Soft-sediment habitats are critical to marine ecosystems, supporting diverse benthic communities and key processes such as nutrient cycling, sediment stabilisation, and energy transfer. Among these habitats, tube-building polychaetes like Chaetopterus act as ecosystem engineers, modifying sediment properties and influencing community structure and functioning. This study investigated the ecological impacts of Chaetopterus in East Bay, Queen Charlotte Sound, focusing on its role in sediment modification, macrofaunal biodiversity, and functional group composition. 

Field surveys were conducted across ten paired Chaetopterus and control sites, selected to capture a gradient in tube mat density and depth. At each site, five sediment and macrofaunal samples were collected using coring techniques, enabling a robust comparison of Chaetopterus-modified and unmodified habitats. 

Results showed significantly higher organic content (3.1% ± 0.2 vs. 2.0% ± 0.1) and mud content (19.8% ± 2.0 vs. 7.7% ± 0.5) in Chaetopterus habitats, highlighting its role in sediment enrichment and stabilisation. Macrofaunal communities exhibited significantly greater species richness (20.0 ± 0.8 vs. 14.5 ± 0.7 species per core) and diversity (Shannon diversity: 2.48 ± 0.05 vs. 2.16 ± 0.06), driven by increased structural complexity and organic matter retention. 

Functional group analysis revealed a shift towards surface-oriented taxa in Chaetopterus habitats, including increased surface-feeding deposit feeders (e.g., amphipods) and scavengers (e.g., Halicarcinus cookii), alongside a relative reduction in deeper-burrowing taxa such as bioturbating polychaetes (Prionospio multicristata) and burrowing bivalves (Tawera spissa). This suggests that Chaetopterus tube mats promote surface-associated processes like organic matter turnover and detritus retention, while potentially suppressing sediment-mixing and oxygenation functions. 

Chaetopterus habitats exhibited significantly lower dispersion (PERMDISP), indicating more functionally homogeneous assemblages compared to control sites, where greater within-group variability reflected a broader range of functional traits, including suspension feeders and opportunistic burrowers (e.g., Phoxocephalidae amphipods). Chaetopterus density was significantly correlated with macrofaunal community composition, reinforcing the role of tube mats as a key driver of functional trait distributions. However, the extent of these effects varied across sites, suggesting that local environmental factors, particularly sediment properties (mud content, organic matter) and Chaetopterus density, mediate its influence on benthic communities. 

These findings advance understanding of habitat-modifying polychaetes by demonstrating that Chaetopterus effects are highly context-dependent, shaped by habitat × site interactions and environmental conditions. While previous studies have identified Chaetopterus as a biodiversity enhancer, this study highlights its dual role as both a facilitator of surfacedominated processes and a potential suppressor of deeper sediment functions. These findings provide critical insights into its ecological role within New Zealand's coastal ecosystems and underscore the need for site-specific management strategies that balance local biodiversity benefits with broader ecosystem functions.

text: The role of Chaetopterus sp. in reshaping sediment characteristics and benthic communities in Queen Charlotte Sound Soft-sediment habitats are critical to marine ecosystems, supporting diverse benthic communities and key processes such as nutrient cycling, sediment stabilisation, and energy transfer. Among these habitats, tube-building polychaetes like Chaetopterus act as ecosystem engineers, modifying sediment properties and influencing community structure and functioning. This study investigated the ecological impacts of Chaetopterus in East Bay, Queen Charlotte Sound, focusing on its role in sediment modification, macrofaunal biodiversity, and functional group composition. 

Field surveys were conducted across ten paired Chaetopterus and control sites, selected to capture a gradient in tube mat density and depth. At each site, five sediment and macrofaunal samples were collected using coring techniques, enabling a robust comparison of Chaetopterus-modified and unmodified habitats. 

Results showed significantly higher organic content (3.1% ± 0.2 vs. 2.0% ± 0.1) and mud content (19.8% ± 2.0 vs. 7.7% ± 0.5) in Chaetopterus habitats, highlighting its role in sediment enrichment and stabilisation. Macrofaunal communities exhibited significantly greater species richness (20.0 ± 0.8 vs. 14.5 ± 0.7 species per core) and diversity (Shannon diversity: 2.48 ± 0.05 vs. 2.16 ± 0.06), driven by increased structural complexity and organic matter retention. 

Functional group analysis revealed a shift towards surface-oriented taxa in Chaetopterus habitats, including increased surface-feeding deposit feeders (e.g., amphipods) and scavengers (e.g., Halicarcinus cookii), alongside a relative reduction in deeper-burrowing taxa such as bioturbating polychaetes (Prionospio multicristata) and burrowing bivalves (Tawera spissa). This suggests that Chaetopterus tube mats promote surface-associated processes like organic matter turnover and detritus retention, while potentially suppressing sediment-mixing and oxygenation functions. 

Chaetopterus habitats exhibited significantly lower dispersion (PERMDISP), indicating more functionally homogeneous assemblages compared to control sites, where greater within-group variability reflected a broader range of functional traits, including suspension feeders and opportunistic burrowers (e.g., Phoxocephalidae amphipods). Chaetopterus density was significantly correlated with macrofaunal community composition, reinforcing the role of tube mats as a key driver of functional trait distributions. However, the extent of these effects varied across sites, suggesting that local environmental factors, particularly sediment properties (mud content, organic matter) and Chaetopterus density, mediate its influence on benthic communities. 

These findings advance understanding of habitat-modifying polychaetes by demonstrating that Chaetopterus effects are highly context-dependent, shaped by habitat × site interactions and environmental conditions. While previous studies have identified Chaetopterus as a biodiversity enhancer, this study highlights its dual role as both a facilitator of surfacedominated processes and a potential suppressor of deeper sediment functions. These findings provide critical insights into its ecological role within New Zealand's coastal ecosystems and underscore the need for site-specific management strategies that balance local biodiversity benefits with broader ecosystem functions.

year: 2025

title: Investigating the Social Supports of Successful Māori Undergraduate Appellants at the University of Waikato

authors: Diamond, Danielle Jade

subjects: Social Supports

abstract: Educational disparities between Māori and non-Māori tertiary students are evident in regards to participation, retention, and completion rates at secondary and tertiary levels. Instead of focusing on negative statistics, it was of interest to investigate Māori students who had failed sufficient papers to initially be denied re-entry to university study, yet continued to attain their degrees, as a result of a successful appeal. Māori undergraduate students, who had successfully appealed from 2003-2012, were recruited for my research. The availability and utilisation of social supports were investigated, along with the decision to make an appeal, the role of cultural expectations, and barriers experienced by participants. A mixed method approach was utilised in this research through use of an adapted overarching Kaupapa Māori framework, statistical analysis, and 13 interviews. My research found that social supports were beneficial for participants throughout their appeal, as they provided: emotional, instrumental, appraisal, and informational support. Although the social supports utilised by participants were satisfactory, barriers to accessing formal supports were also found, which included: perceived stigma having failed their papers, pride, as well as being whakamā. The appeal process was a beneficial intervention from the University of Waikato, which provided participants another opportunity to overcome the factors that contributed to their initial failure. Post appeal, participants implemented strategies to address and reduce their factors in order to become academically engaged. Participants were deemed to be resilient from their continued pursuit of degree attainment, implementation of their strategies, and their use of perceived social supports.

text: Investigating the Social Supports of Successful Māori Undergraduate Appellants at the University of Waikato Educational disparities between Māori and non-Māori tertiary students are evident in regards to participation, retention, and completion rates at secondary and tertiary levels. Instead of focusing on negative statistics, it was of interest to investigate Māori students who had failed sufficient papers to initially be denied re-entry to university study, yet continued to attain their degrees, as a result of a successful appeal. Māori undergraduate students, who had successfully appealed from 2003-2012, were recruited for my research. The availability and utilisation of social supports were investigated, along with the decision to make an appeal, the role of cultural expectations, and barriers experienced by participants. A mixed method approach was utilised in this research through use of an adapted overarching Kaupapa Māori framework, statistical analysis, and 13 interviews. My research found that social supports were beneficial for participants throughout their appeal, as they provided: emotional, instrumental, appraisal, and informational support. Although the social supports utilised by participants were satisfactory, barriers to accessing formal supports were also found, which included: perceived stigma having failed their papers, pride, as well as being whakamā. The appeal process was a beneficial intervention from the University of Waikato, which provided participants another opportunity to overcome the factors that contributed to their initial failure. Post appeal, participants implemented strategies to address and reduce their factors in order to become academically engaged. Participants were deemed to be resilient from their continued pursuit of degree attainment, implementation of their strategies, and their use of perceived social supports.

year: 2013