title: Resilience of microbial mats in Antarctic ponds to climate-relevant environmental disturbance

authors: Mills, Francesca

subjects: Antarctica

abstract: Continental Antarctica is a cold desert, where the hydrologic system is dependent on melting of snow and ice. In a warming climate it is projected that there will be a significant change in precipitation, evaporation, cloud formation, all affecting the ice-water dynamic. Hydrology is considered vulnerable to climatic change. Hydrological change cascades through the environment affecting Antarctic ponds which are important centres for inland microbial biodiversity. An understanding of community vulnerability to anticipated change can be developed through assessing organism and functional resilience to climate-related and other forms of disturbance. The aim of this study is to identify the effects of disturbance on microbial communities, specifically cyanobacterial mats, with a particular focus on changes that may occur resultant to anthropogenic climate change.

This study undertook three experiments, which identified impacts of disturbance on three key cyanobacterial mat functions – nitrogen fixation, photosynthesis/respiration, and recovery after a physical disturbance. Sampling was undertaken in the McMurdo Ice Shelf (MIS) meltwater ponds in late January 2019. The design for the nitrogen fixation experiment used a natural gradient of conductivity across five ponds (Fresh, Casten, P70, Brack and Salt) in a space-for-time approach that compared microbial composition and nitrogen fixation rates. The light disturbance study completed in New and P70 ponds tested mat ability to retain photosynthesis and respiration under a pulsed disturbance – covering microbial mats with shade cloth for 12 months. In this study the light-photosynthesis response and mat composition were analysed when shaded and not shaded (control plots). The third experiment examined short-term response to physical disturbance by observing the recovery of mat structure and community composition for 2 years was also completed in New and P70 ponds.

It was identified that there was no significant change in acetylene reduction (as a proxy for nitrogen fixation) over the salinity range. Acetylene reduction ranged between 22.4 ± 3.4 µMol/m²/h in Brack Pond (conductivity = 10.5 mS/cm) and 49.6 ± 17.1 µMol/m²/h in Casten Pond (conductivity = 2.3 mS/cm). The acetylene reduction difference was statistically significant between Brack Pond and Casten Pond (F = 0.006 (Bonferroni Correction significance of F ≤ 0.01)). Microbial mat composition changed across the conductivity gradient, but significant proportions of different N-fixing and mat-forming genera were evident along the salt gradient, suggesting functional resilience through species turnover.

It was also identified that when receiving a 95-96% decrease in ambient light photosynthetic bacteria were able to maintain photosynthesis and respiration at similar rates within the microbial mats. However, in shaded plots the maximum net oxygen production occurred at an average irradiance between 350 – 450 µMol photons m-²s-¹ and was inhibited at higher levels. In control plots the maximum net oxygen production was ≥900 µMol photons m-²s-¹. In control samples net photosynthesis exceeds zero (photosynthesis exceeds respiration) at ~275 µMol photons m-²s-¹, in shaded samples this occurred at ~100 µMol photons m-²s-¹. Rapid shifts in the appearance of mats under, and after shading led to the conclusion that the acclimation may be based on vertical migration of cyanobacteria within the mats, which showed no significant changes in relative abundance of taxa.

After physical removal of microbial mat, communities were shown to reform to similar relative abundances as control samples within two years of the disturbance, within this experiment a successional change in species abundance was observed. 

This research highlights the resilience of microbial mat populations on the MIS to the types of change that are anticipated to accompany climate change. It supports conclusions previously identified that cyanobacterial mats are functionally resilient to short-term and long-term disturbances. Ongoing research will improve the knowledge on the resilience of other functions required in these environments.

text: Resilience of microbial mats in Antarctic ponds to climate-relevant environmental disturbance Continental Antarctica is a cold desert, where the hydrologic system is dependent on melting of snow and ice. In a warming climate it is projected that there will be a significant change in precipitation, evaporation, cloud formation, all affecting the ice-water dynamic. Hydrology is considered vulnerable to climatic change. Hydrological change cascades through the environment affecting Antarctic ponds which are important centres for inland microbial biodiversity. An understanding of community vulnerability to anticipated change can be developed through assessing organism and functional resilience to climate-related and other forms of disturbance. The aim of this study is to identify the effects of disturbance on microbial communities, specifically cyanobacterial mats, with a particular focus on changes that may occur resultant to anthropogenic climate change.

This study undertook three experiments, which identified impacts of disturbance on three key cyanobacterial mat functions – nitrogen fixation, photosynthesis/respiration, and recovery after a physical disturbance. Sampling was undertaken in the McMurdo Ice Shelf (MIS) meltwater ponds in late January 2019. The design for the nitrogen fixation experiment used a natural gradient of conductivity across five ponds (Fresh, Casten, P70, Brack and Salt) in a space-for-time approach that compared microbial composition and nitrogen fixation rates. The light disturbance study completed in New and P70 ponds tested mat ability to retain photosynthesis and respiration under a pulsed disturbance – covering microbial mats with shade cloth for 12 months. In this study the light-photosynthesis response and mat composition were analysed when shaded and not shaded (control plots). The third experiment examined short-term response to physical disturbance by observing the recovery of mat structure and community composition for 2 years was also completed in New and P70 ponds.

It was identified that there was no significant change in acetylene reduction (as a proxy for nitrogen fixation) over the salinity range. Acetylene reduction ranged between 22.4 ± 3.4 µMol/m²/h in Brack Pond (conductivity = 10.5 mS/cm) and 49.6 ± 17.1 µMol/m²/h in Casten Pond (conductivity = 2.3 mS/cm). The acetylene reduction difference was statistically significant between Brack Pond and Casten Pond (F = 0.006 (Bonferroni Correction significance of F ≤ 0.01)). Microbial mat composition changed across the conductivity gradient, but significant proportions of different N-fixing and mat-forming genera were evident along the salt gradient, suggesting functional resilience through species turnover.

It was also identified that when receiving a 95-96% decrease in ambient light photosynthetic bacteria were able to maintain photosynthesis and respiration at similar rates within the microbial mats. However, in shaded plots the maximum net oxygen production occurred at an average irradiance between 350 – 450 µMol photons m-²s-¹ and was inhibited at higher levels. In control plots the maximum net oxygen production was ≥900 µMol photons m-²s-¹. In control samples net photosynthesis exceeds zero (photosynthesis exceeds respiration) at ~275 µMol photons m-²s-¹, in shaded samples this occurred at ~100 µMol photons m-²s-¹. Rapid shifts in the appearance of mats under, and after shading led to the conclusion that the acclimation may be based on vertical migration of cyanobacteria within the mats, which showed no significant changes in relative abundance of taxa.

After physical removal of microbial mat, communities were shown to reform to similar relative abundances as control samples within two years of the disturbance, within this experiment a successional change in species abundance was observed. 

This research highlights the resilience of microbial mat populations on the MIS to the types of change that are anticipated to accompany climate change. It supports conclusions previously identified that cyanobacterial mats are functionally resilient to short-term and long-term disturbances. Ongoing research will improve the knowledge on the resilience of other functions required in these environments.

year: 2021

title: A changing dialogue within health communication in New Zealand: a case study of the Waikato screening mammography programme

authors: Brunton, Margaret Ann

abstract: As part of changes in the health sector in New Zealand over the past decade, government has provided a number of community-based health interventions. The purpose of such interventions is to provide information and resources that will empower “well” individuals to participate in proactively managing their health, thereby contributing towards both cost and mortality savings.

In 1991, government introduced population-based screening mammography pilot programmes into two communities: one in Otago and Southland, the other in the greater Waikato region. As a community-based health intervention, the breast screening programme communicates with eligible women to encourage them to participate in screening mammograms every two years. The purpose is early detection and treatment of malignant tumours. However, to achieve mortality and cost savings the programme must attain a 70% participation rate of eligible women. The purpose of this research was to examine the ways in which the breast screening programme in the greater Waikato region communicates with women to encourage them both to participate in the programme and also return regularly. In turn, the ways in which a random sample of women responded to that communication were also examined.

To investigate the process, a triangulated approach to data collection and analysis was undertaken. First, a questionnaire survey was sent to a random sample of 1,085 women, stratified by age and ethnicity; 611 (58%) usable responses were returned. Following initial analysis of the questionnaire data, five focus groups were held with 41 women, and 3 individual interviews undertaken to further explore the outcomes from the questionnaire. Nineteen interviews were also held with staff in the breast screening programme to identify the influences on the ways in which they communicate with eligible women who undergo the process of mammography.

The resulting data were analysed and interpreted using a combined quantitative and qualitative approach. Fisher’s exact tests in 2x2 tables and chi-squared tests for independence in contingency tables were used to establish general trends in the data. Qualitative analysis was undertaken using interpretive thematic analysis (Owen, 1984) with a critical turn and reference to Ricoeur (1981).

The findings from this research emphasise the importance of effective communication in the process of screening mammography, to encourage both initial and ongoing participation. There were a number of discrepancies identified between the perception of staff and participants about the communication processes from the breast screening programme. The use of a random sample stratified by ethnicity further identified a number of statistically significant differences among ethnic groups in their responses to communication from the programme. The analysis identifies the divergent communication that women receive from staff in the breast screening programme.

The importance of communication in enhancing both the invitation and physical process for women participating in the population-based breast screening programme is highlighted in this research. Although the programme is provided as a community intervention there appears to be little consultation with participants. Accordingly, the diverse cultural needs of ethnic minority groups are not always recognised in the programme’s practice. A willingness to both recognise and incorporate the varied needs of women undergoing screening mammography would serve to not only enhance the process for participants but also assist the programme to attain the desired 70% participation rate of the eligible population.

text: A changing dialogue within health communication in New Zealand: a case study of the Waikato screening mammography programme As part of changes in the health sector in New Zealand over the past decade, government has provided a number of community-based health interventions. The purpose of such interventions is to provide information and resources that will empower “well” individuals to participate in proactively managing their health, thereby contributing towards both cost and mortality savings.

In 1991, government introduced population-based screening mammography pilot programmes into two communities: one in Otago and Southland, the other in the greater Waikato region. As a community-based health intervention, the breast screening programme communicates with eligible women to encourage them to participate in screening mammograms every two years. The purpose is early detection and treatment of malignant tumours. However, to achieve mortality and cost savings the programme must attain a 70% participation rate of eligible women. The purpose of this research was to examine the ways in which the breast screening programme in the greater Waikato region communicates with women to encourage them both to participate in the programme and also return regularly. In turn, the ways in which a random sample of women responded to that communication were also examined.

To investigate the process, a triangulated approach to data collection and analysis was undertaken. First, a questionnaire survey was sent to a random sample of 1,085 women, stratified by age and ethnicity; 611 (58%) usable responses were returned. Following initial analysis of the questionnaire data, five focus groups were held with 41 women, and 3 individual interviews undertaken to further explore the outcomes from the questionnaire. Nineteen interviews were also held with staff in the breast screening programme to identify the influences on the ways in which they communicate with eligible women who undergo the process of mammography.

The resulting data were analysed and interpreted using a combined quantitative and qualitative approach. Fisher’s exact tests in 2x2 tables and chi-squared tests for independence in contingency tables were used to establish general trends in the data. Qualitative analysis was undertaken using interpretive thematic analysis (Owen, 1984) with a critical turn and reference to Ricoeur (1981).

The findings from this research emphasise the importance of effective communication in the process of screening mammography, to encourage both initial and ongoing participation. There were a number of discrepancies identified between the perception of staff and participants about the communication processes from the breast screening programme. The use of a random sample stratified by ethnicity further identified a number of statistically significant differences among ethnic groups in their responses to communication from the programme. The analysis identifies the divergent communication that women receive from staff in the breast screening programme.

The importance of communication in enhancing both the invitation and physical process for women participating in the population-based breast screening programme is highlighted in this research. Although the programme is provided as a community intervention there appears to be little consultation with participants. Accordingly, the diverse cultural needs of ethnic minority groups are not always recognised in the programme’s practice. A willingness to both recognise and incorporate the varied needs of women undergoing screening mammography would serve to not only enhance the process for participants but also assist the programme to attain the desired 70% participation rate of the eligible population.

year: 2000

title: Family structure and change in early childhood and the wellbeing of tamariki Maori

authors: Kukutai, Tahu

subjects: family structure

abstract: Internationally there is growing evidence that family structure, and changes in structure, have an impact on children’s health and wellbeing and the intergenerational transmission of inequity. The effects, however, vary by socio-economic context and ethnicity. Using longitudinal data from Growing Up in New Zealand (n = 1349), we examine family structure and change for tamariki Māori during early childhood, and the potential impacts on their development and wellbeing. We find that a stable two-parent family is the primary experience for tamariki Māori, and sole parenthood is transitory. Diverse family trajectories appear to be linked to poorer cognitive and socio-emotional outcomes but are not the main driver. More important are maternal factors, notably age and education, and material hardship. Importantly, higher levels of cultural connectedness among tamariki Māori, which are associated with diverse family forms, seem to promote socio-emotional development. Our study provides further incentive for policy and programmes that centre equity and support access to the determinants of health for tamariki Māori.

text: Family structure and change in early childhood and the wellbeing of tamariki Maori Internationally there is growing evidence that family structure, and changes in structure, have an impact on children’s health and wellbeing and the intergenerational transmission of inequity. The effects, however, vary by socio-economic context and ethnicity. Using longitudinal data from Growing Up in New Zealand (n = 1349), we examine family structure and change for tamariki Māori during early childhood, and the potential impacts on their development and wellbeing. We find that a stable two-parent family is the primary experience for tamariki Māori, and sole parenthood is transitory. Diverse family trajectories appear to be linked to poorer cognitive and socio-emotional outcomes but are not the main driver. More important are maternal factors, notably age and education, and material hardship. Importantly, higher levels of cultural connectedness among tamariki Māori, which are associated with diverse family forms, seem to promote socio-emotional development. Our study provides further incentive for policy and programmes that centre equity and support access to the determinants of health for tamariki Māori.

year: 2020