title: Consequences of shellfish die-offs on seafloor biodiversity

authors: Crosbie, Caleb

abstract: Coastal soft sediment habitats contain highly productive benthic communities that provide numerous ecological services. Many of these functions, processes and services are underpinned by the behaviour, density and diversity of the resident macrofaunal community. Climate change has caused heat waves to become more regular and extreme, causing die-off’s of functionally important shellfish beds, potentially generating large shifts in benthic community structure and functioning. Recent studies of the New Zealand intertidal cockle (Austrovenus stutchburyi) dieoff events have focused on cockle population recovery, but there is very little understanding of how the rest of the macrofaunal community responds. To understand how the macrofaunal communities respond to cockle-die offs, a manipulative experiment was undertaken at 23 sites in four estuaries on the northeast coast of the North Island. In late summer, at each site we established a 9m2 control and 9m2 exclusion plot. One year later, we sampled all plots for macrofauna and sediment properties. Results indicate a strong relationship between treatment type and community composition, with none of the exclusion treatments returning to predisturbance community compositions. Furthermore, that recovery was largely estuary specific and community composition following disturbance was highly variable within exclusion treatments. Statistical analysis highlighted that exposure to high intensity wind-wave activity and polychaete dominance within estuaries could explain the relatively improved recovery of Ongare sites within Tauranga harbour. Additionally, there are observable variations in cockle recruitment between sites for both adults and juveniles. This experiment explores whether the removal of cockles, as key habitat forming species, selects for a different macrofaunal community type. The observed changes in community structure can be linked to shifts in ecosystem functioning in these soft sediment habitats.

text: Consequences of shellfish die-offs on seafloor biodiversity Coastal soft sediment habitats contain highly productive benthic communities that provide numerous ecological services. Many of these functions, processes and services are underpinned by the behaviour, density and diversity of the resident macrofaunal community. Climate change has caused heat waves to become more regular and extreme, causing die-off’s of functionally important shellfish beds, potentially generating large shifts in benthic community structure and functioning. Recent studies of the New Zealand intertidal cockle (Austrovenus stutchburyi) dieoff events have focused on cockle population recovery, but there is very little understanding of how the rest of the macrofaunal community responds. To understand how the macrofaunal communities respond to cockle-die offs, a manipulative experiment was undertaken at 23 sites in four estuaries on the northeast coast of the North Island. In late summer, at each site we established a 9m2 control and 9m2 exclusion plot. One year later, we sampled all plots for macrofauna and sediment properties. Results indicate a strong relationship between treatment type and community composition, with none of the exclusion treatments returning to predisturbance community compositions. Furthermore, that recovery was largely estuary specific and community composition following disturbance was highly variable within exclusion treatments. Statistical analysis highlighted that exposure to high intensity wind-wave activity and polychaete dominance within estuaries could explain the relatively improved recovery of Ongare sites within Tauranga harbour. Additionally, there are observable variations in cockle recruitment between sites for both adults and juveniles. This experiment explores whether the removal of cockles, as key habitat forming species, selects for a different macrofaunal community type. The observed changes in community structure can be linked to shifts in ecosystem functioning in these soft sediment habitats.

year: 2024

title: Gait analysis of pedestrians with the aim of detecting disabled people

authors: Mukhtar, Amir

abstract: Gait classification is an effective and non-intrusive method for human identification and it has received significant attention in the recent years due to its applications in visual surveillance and monitoring systems. We analyse gait signatures using spatio-temporal motion characteristics of a person to answer the question ``is there a discriminating feature in the gait signal that can help to categorise a disabled person from healthy?''. The procedure has three steps: detection of a pedestrian using YOLO followed by the silhouette extraction using the Gaussian Mixture Model (GMM). Finally, skeletonization from the silhouette image to estimate head and torso locations and their angles with the vertical axis. Furthermore, velocity and acceleration signals were recorded to look for accelerating behaviour of person walking with a limp. Manual segmentations shows that the gait signal has information about unusual walking patterns but existing pedestrian detectors lack accuracy in extracting an accurate gait signal due to localization errors.

text: Gait analysis of pedestrians with the aim of detecting disabled people Gait classification is an effective and non-intrusive method for human identification and it has received significant attention in the recent years due to its applications in visual surveillance and monitoring systems. We analyse gait signatures using spatio-temporal motion characteristics of a person to answer the question ``is there a discriminating feature in the gait signal that can help to categorise a disabled person from healthy?''. The procedure has three steps: detection of a pedestrian using YOLO followed by the silhouette extraction using the Gaussian Mixture Model (GMM). Finally, skeletonization from the silhouette image to estimate head and torso locations and their angles with the vertical axis. Furthermore, velocity and acceleration signals were recorded to look for accelerating behaviour of person walking with a limp. Manual segmentations shows that the gait signal has information about unusual walking patterns but existing pedestrian detectors lack accuracy in extracting an accurate gait signal due to localization errors.

year: 2018

title: 'Thinking-through-Complicity' with Te Iwi o Ngāti Hauiti: Towards a Critical Use of Participatory Video for Research

authors: Kindon, Sara Louise

subjects: human geography

abstract: This thesis explores some of the seductions and dangers of participatory video for research (PVR) involving Indigenous Māori and Pākehā research partners. The project within which PVR was used focused on exploring relationships between place, identity and social cohesion within ‘remote’ rural communities. It involved about 15 members of the Potaka whānau of Te Iwi o Ngāti Hauiti in the central Rangitīkei district of the North Island, Aotearoa New Zealand. A small group of iwi members, myself and an audiovisual specialist and trainer negotiated the project’s focus, process and ethics during 1998. A different group of iwi members were then trained in video production and community research methods later that year and supported to produce their own productions, and carry out video research interviews with other iwi members. The entire process of negotiation, training and collaborative research was filmed for archival and research purposes with everyone’s consent, and several collaborative publications and presentations have been produced since 1999.

The discursive space opened up by Ngāti Hauiti’s engagement with, and use of, video provides an opportunity to attend to the ‘cultural mediations’ that occurred throughout the research partnership and to inquire into the possible ‘empire building effects’ of visual technologies within participatory research more generally. The focus on PVR within a Māori context also prompts questions about the visual’s transformative potential within geographic research, and the implications of working through the use of a visual medium for rethinking disciplinary practices and knowledges, particularly when working cross-culturally. 

In the thesis, I first review the evolution and attendant challenges associated with both the use of participation and video within research contexts. I trace their similar origins in modernist attempts to ‘know’ and ‘empower’ marginalised others, and highlight the ongoing marginalisation of Indigenous perspectives within mainstream debates. I then engage with conceptualisations of complicity and develop an analytical framework that expands on current discursive and ideological discussions to also attend to its material, embodied and spatial dimensions.

Using this framework and a complementary autoethnographic and ‘hyper-self-reflexive’ approach, I track aspects of my own power, complicity and desire within my research practice in the PVR project during the period 1998-2001. This approach involves the development of a particular reading position to focus on critical incidents of my research practice and a means of grappling productively with the polyvalent nature of my audiovisual and other information sources. I discuss these critical incidents within three processes associated with the research: facilitation, production and reception, attending to the complex and multifaceted interplay of audiovisual texts, their producers and their audiences throughout. 

Such a thesis is expedient given that powerful and often uncritical rhetoric that besets participatory research and development is fast taking hold within geography. It is also timely given the proliferation of affordable and accessible audiovisual technology and its increasing use within geography and other social sciences. As geographers respond to calls to embrace more visual, tactile and other methods, this thesis offers possibilities for the repoliticisation of participatory discourse within social geography, through a more considered engagement with participatory action research, Indigenous research practices and audiovisual media such as video. I offer cautionary insights into the ‘power-full’ effects of these ways of working.

text: 'Thinking-through-Complicity' with Te Iwi o Ngāti Hauiti: Towards a Critical Use of Participatory Video for Research This thesis explores some of the seductions and dangers of participatory video for research (PVR) involving Indigenous Māori and Pākehā research partners. The project within which PVR was used focused on exploring relationships between place, identity and social cohesion within ‘remote’ rural communities. It involved about 15 members of the Potaka whānau of Te Iwi o Ngāti Hauiti in the central Rangitīkei district of the North Island, Aotearoa New Zealand. A small group of iwi members, myself and an audiovisual specialist and trainer negotiated the project’s focus, process and ethics during 1998. A different group of iwi members were then trained in video production and community research methods later that year and supported to produce their own productions, and carry out video research interviews with other iwi members. The entire process of negotiation, training and collaborative research was filmed for archival and research purposes with everyone’s consent, and several collaborative publications and presentations have been produced since 1999.

The discursive space opened up by Ngāti Hauiti’s engagement with, and use of, video provides an opportunity to attend to the ‘cultural mediations’ that occurred throughout the research partnership and to inquire into the possible ‘empire building effects’ of visual technologies within participatory research more generally. The focus on PVR within a Māori context also prompts questions about the visual’s transformative potential within geographic research, and the implications of working through the use of a visual medium for rethinking disciplinary practices and knowledges, particularly when working cross-culturally. 

In the thesis, I first review the evolution and attendant challenges associated with both the use of participation and video within research contexts. I trace their similar origins in modernist attempts to ‘know’ and ‘empower’ marginalised others, and highlight the ongoing marginalisation of Indigenous perspectives within mainstream debates. I then engage with conceptualisations of complicity and develop an analytical framework that expands on current discursive and ideological discussions to also attend to its material, embodied and spatial dimensions.

Using this framework and a complementary autoethnographic and ‘hyper-self-reflexive’ approach, I track aspects of my own power, complicity and desire within my research practice in the PVR project during the period 1998-2001. This approach involves the development of a particular reading position to focus on critical incidents of my research practice and a means of grappling productively with the polyvalent nature of my audiovisual and other information sources. I discuss these critical incidents within three processes associated with the research: facilitation, production and reception, attending to the complex and multifaceted interplay of audiovisual texts, their producers and their audiences throughout. 

Such a thesis is expedient given that powerful and often uncritical rhetoric that besets participatory research and development is fast taking hold within geography. It is also timely given the proliferation of affordable and accessible audiovisual technology and its increasing use within geography and other social sciences. As geographers respond to calls to embrace more visual, tactile and other methods, this thesis offers possibilities for the repoliticisation of participatory discourse within social geography, through a more considered engagement with participatory action research, Indigenous research practices and audiovisual media such as video. I offer cautionary insights into the ‘power-full’ effects of these ways of working.

year: 2012