title: Solo parenting in New Zealand: Who are the children?

authors: Hutton, Deborah

subjects: population

abstract: The purpose of this paper is to begin to explore some of the recent trends and attributes of sole parenting in New Zealand, but from a from a child-centered rather than a parentfocused perspective. Reports that the proportions of children living in sole parent families have significantly increased have been the source of much concern, and even ‘moral panic’, over recent quinquennia. Sole parent households made up nine per cent of all households in 1976, and were up to 19 per cent by 1991. Advocates of family values allege that the traditional family unit is breaking down, and that this will have negative consequences for society and for our children.

Previous research into the issue of sole parent families has been largely based on census information, producing snapshot-like pictures of the situation at one point in time. This paper begins to offer a more thorough look into some of the trends and processes at work by adopting the benefits of a longitudinal, retrospective survey that traces cohorts of children through their childhood. By following different cohorts through their family experiences during childhood, we can begin to build up a picture about if and how experiences of sole parenting have changed over time, and can begin to speculate about the situation for today’s children.

text: Solo parenting in New Zealand: Who are the children? The purpose of this paper is to begin to explore some of the recent trends and attributes of sole parenting in New Zealand, but from a from a child-centered rather than a parentfocused perspective. Reports that the proportions of children living in sole parent families have significantly increased have been the source of much concern, and even ‘moral panic’, over recent quinquennia. Sole parent households made up nine per cent of all households in 1976, and were up to 19 per cent by 1991. Advocates of family values allege that the traditional family unit is breaking down, and that this will have negative consequences for society and for our children.

Previous research into the issue of sole parent families has been largely based on census information, producing snapshot-like pictures of the situation at one point in time. This paper begins to offer a more thorough look into some of the trends and processes at work by adopting the benefits of a longitudinal, retrospective survey that traces cohorts of children through their childhood. By following different cohorts through their family experiences during childhood, we can begin to build up a picture about if and how experiences of sole parenting have changed over time, and can begin to speculate about the situation for today’s children.

year: 2001-08

title: Pilot scale pyrolysis - determination of critical moisture content for sustainable organic waste pyrolysis

authors: Sichone, Kavwa

abstract: Economic feasibility of large scale organic waste pyrolysis was investigated for Inghams Enterprise (Waitoa) chicken dissolved air flotation sludge (DAF) and activated sludge (biosolids) from the Hamilton municipal waste water treatment plant. Processing data was obtained from pilot plant trials using the Lakeland Steel (Rotorua) continuous auger pyrolysis plant using feedstock at 15, 30, 45 and ~80% moisture contents. Economics were calculated based on estimated capital and operating costs of a large scale facility, revenue from selling char, savings from landfill diversion (including transportation and gate costs), energy savings by recycling syngas product and using waste heat for drying feedstock.
For DAF, 15% moisture content gave yields of 21% syngas, 27% char, and 52% oil (dry weight basis). 15% moisture content gave the best processing conditions based on handling properties and degree of autogenesis. The DAF case does not give a payback period due to low scale of operations.
For biosolids, 15% moisture content feedstock gave yields of 46% syngas, 31% char, and 21% oil (wet weight). Difficulties were found with plant blockages at 45% and 80% moisture contents. 15% moisture content gave the best processing conditions and the best economic performance with a payback time of 4.6 years for a facility that could process 11,000 tonnes per year.

text: Pilot scale pyrolysis - determination of critical moisture content for sustainable organic waste pyrolysis Economic feasibility of large scale organic waste pyrolysis was investigated for Inghams Enterprise (Waitoa) chicken dissolved air flotation sludge (DAF) and activated sludge (biosolids) from the Hamilton municipal waste water treatment plant. Processing data was obtained from pilot plant trials using the Lakeland Steel (Rotorua) continuous auger pyrolysis plant using feedstock at 15, 30, 45 and ~80% moisture contents. Economics were calculated based on estimated capital and operating costs of a large scale facility, revenue from selling char, savings from landfill diversion (including transportation and gate costs), energy savings by recycling syngas product and using waste heat for drying feedstock.
For DAF, 15% moisture content gave yields of 21% syngas, 27% char, and 52% oil (dry weight basis). 15% moisture content gave the best processing conditions based on handling properties and degree of autogenesis. The DAF case does not give a payback period due to low scale of operations.
For biosolids, 15% moisture content feedstock gave yields of 46% syngas, 31% char, and 21% oil (wet weight). Difficulties were found with plant blockages at 45% and 80% moisture contents. 15% moisture content gave the best processing conditions and the best economic performance with a payback time of 4.6 years for a facility that could process 11,000 tonnes per year.

year: 2012

title: Studies on the health and bacterial symbionts of  toheroa (Paphies ventricosa)

authors: Bennion, Matthew Joseph

subjects: Shellfish health

abstract: Disease outbreaks in marine species can have devastating consequences for host populations, host-associated species assemblages, ecosystem functioning, and for human users of these marine resources. At present, the risk factors associated with disease outbreaks, such as warming and pollution, are increasing. Given the increasing risk of disease outbreaks and the role that parasites play in marine ecosystems, there is a vital need to gain knowledge of marine diseases for species conservation, and the monitoring, management, and forecasting of disease. The field of marine disease ecology is growing, but many facets of our understanding remain in their infancy. Faced with a lack of baseline health data, efforts to combat disease outbreak in the ocean are impeded, even though the future of food security hinges on an ability to source food from the ocean. With a shift towards aquaculture, in particular bivalve aquaculture, knowledge of ambient health of wild and farmed species will dictate both yield, and our ability to protect wild stocks. 
Disease outbreak poses added risk to species that are already in peril. The toheroa (Paphies ventricosa) is a threatened surf clam endemic to Aotearoa (New Zealand). Once bountiful, overharvesting and population collapse put an end to the large-scale fisheries of the early and mid-1900s. The protections enacted on toheroa populations should have ensured their recovery, but recovery has not occurred. Disease has been suggested as one possible explanation. However, without knowledge of disease dynamics in toheroa populations, restorative efforts risk failure, or worse, inflicting further damage. Intracellular microcolonies of bacteria (IMCs) have been linked to numerous shellfish mass mortality events (MMEs) in Aotearoa in recent years, and were first detected in toheroa in 2017. This discovery raised questions regarding the role IMCs might be playing in preventing the recovery of toheroa populations. 
To address this uncertainty, this thesis set out to investigate what pathogens and parasites are present in toheroa, and determine what effect they might be having on toheroa health. A histopathology survey was conducted to gather fundamental baseline health information on toheroa populations across their entire distribution. IMCs were found to be the only potential pathogens of note. Histology data coupled with Bayesian models indicated that the probability of higher IMC intensity was associated with decreased toheroa condition. Using PCR, DNA sequencing, and in situ hybridisation, IMCs were characterised as bacteria in the genus Endozoicomonas. In many marine organisms, Endozoicomonas spp. are cosmopolitan members of associated-bacterial communities, often fulfilling biogeochemical cycling functions in host tissues. In toheroa populations, Endozoicomonas spp. abundance was found to be seasonal, but site specificity indicated habitat characteristics (specifically, the presence of freshwater outflows) might be a significant driver of their abundance. The bacterial community of toheroa was subsequently investigated using 16S rRNA gene sequencing, and candidates common to other coastal bivalve molluscs were found to be dominant, including Spirochaetaceae, Mycoplasmataceae, and Endozoicomonadaceae (in order of relative dominance). Freshwater outflows appeared to be such a significant driver of microbiome taxonomic dissimilarity, that specimens collected from sites 1240 km apart hosted more similar bacterial communities than specimens from sites with and without streams on the same beach and within the same region. The key indicator taxa driving microbiome dissimilarity were found to be Endozoicomonas spp. and sulfate-reducing bacteria in the phylum Desulfobacterota. 
Gas bubbles were also observed on the shells of toheroa at the same time that IMCs were first detected. At that stage, temperature and total dissolved gaseous pressure was thought to contribute to their manifestation. To gain a better understanding of this phenomenon, a spatio-temporal survey was conducted which revealed an association of high gas bubble intensity with the austral-autumn/winter and freshwater outflows. A new hypothesis is therefore presented that links gas bubbles to sulfate-reducing bacteria and hydrogen sulfide (H₂S), a by-product of anaerobic digestion. Given the apparent influence of freshwater on toheroa intrinsic health, the capacity for streams to deliver pollutants to toheroa beds was assessed. Results gained from inductively coupled plasma-mass spectrometry (ICP-MS) suggest that despite the modified nature of adjacent land, streams do not deliver significant loads of bioavailable trace metals to toheroa beds in the intertidal zone. Instead, nutrition in the form of large phytoplankton blooms in autumn/winter is thought to be the primary source of bioavailable trace metals for toheroa.
No observations of significant pathogenesis, associated with Endozoicomonas species, were made throughout this research. Furthermore, during the timeframe of this research (apart from intermittent mortality events reported), there is no evidence of an ongoing disease epidemic in toheroa populations. While not providing evidence for the factor preventing the recovery of toheroa, this research does have implications for the ongoing conservation and management of toheroa. It seems reasonable to assume that infectious disease is not a major factor contributing to the limited recovery of toheroa throughout Aotearoa. Instead, associations made between freshwater outflows, nutrition, and detritus indicate that habitat requirements provided by freshwater streams are having significant effects on toheroa health, survival, and homeostasis. Furthermore, evidence presented suggests that the Endozoicomonas spp. present in toheroa and other Aotearoa shellfish are likely to be an important endosymbiont. In the future, studies on remaining toheroa populations should prioritise nutritional health. Namely, what role symbionts play in toheroa nutrition, and how niche requirements shape symbiont community composition and function in toheroa tissues. Answers to these questions could profoundly increase the success of toheroa restoration and conservation efforts.

text: Studies on the health and bacterial symbionts of  toheroa (Paphies ventricosa) Disease outbreaks in marine species can have devastating consequences for host populations, host-associated species assemblages, ecosystem functioning, and for human users of these marine resources. At present, the risk factors associated with disease outbreaks, such as warming and pollution, are increasing. Given the increasing risk of disease outbreaks and the role that parasites play in marine ecosystems, there is a vital need to gain knowledge of marine diseases for species conservation, and the monitoring, management, and forecasting of disease. The field of marine disease ecology is growing, but many facets of our understanding remain in their infancy. Faced with a lack of baseline health data, efforts to combat disease outbreak in the ocean are impeded, even though the future of food security hinges on an ability to source food from the ocean. With a shift towards aquaculture, in particular bivalve aquaculture, knowledge of ambient health of wild and farmed species will dictate both yield, and our ability to protect wild stocks. 
Disease outbreak poses added risk to species that are already in peril. The toheroa (Paphies ventricosa) is a threatened surf clam endemic to Aotearoa (New Zealand). Once bountiful, overharvesting and population collapse put an end to the large-scale fisheries of the early and mid-1900s. The protections enacted on toheroa populations should have ensured their recovery, but recovery has not occurred. Disease has been suggested as one possible explanation. However, without knowledge of disease dynamics in toheroa populations, restorative efforts risk failure, or worse, inflicting further damage. Intracellular microcolonies of bacteria (IMCs) have been linked to numerous shellfish mass mortality events (MMEs) in Aotearoa in recent years, and were first detected in toheroa in 2017. This discovery raised questions regarding the role IMCs might be playing in preventing the recovery of toheroa populations. 
To address this uncertainty, this thesis set out to investigate what pathogens and parasites are present in toheroa, and determine what effect they might be having on toheroa health. A histopathology survey was conducted to gather fundamental baseline health information on toheroa populations across their entire distribution. IMCs were found to be the only potential pathogens of note. Histology data coupled with Bayesian models indicated that the probability of higher IMC intensity was associated with decreased toheroa condition. Using PCR, DNA sequencing, and in situ hybridisation, IMCs were characterised as bacteria in the genus Endozoicomonas. In many marine organisms, Endozoicomonas spp. are cosmopolitan members of associated-bacterial communities, often fulfilling biogeochemical cycling functions in host tissues. In toheroa populations, Endozoicomonas spp. abundance was found to be seasonal, but site specificity indicated habitat characteristics (specifically, the presence of freshwater outflows) might be a significant driver of their abundance. The bacterial community of toheroa was subsequently investigated using 16S rRNA gene sequencing, and candidates common to other coastal bivalve molluscs were found to be dominant, including Spirochaetaceae, Mycoplasmataceae, and Endozoicomonadaceae (in order of relative dominance). Freshwater outflows appeared to be such a significant driver of microbiome taxonomic dissimilarity, that specimens collected from sites 1240 km apart hosted more similar bacterial communities than specimens from sites with and without streams on the same beach and within the same region. The key indicator taxa driving microbiome dissimilarity were found to be Endozoicomonas spp. and sulfate-reducing bacteria in the phylum Desulfobacterota. 
Gas bubbles were also observed on the shells of toheroa at the same time that IMCs were first detected. At that stage, temperature and total dissolved gaseous pressure was thought to contribute to their manifestation. To gain a better understanding of this phenomenon, a spatio-temporal survey was conducted which revealed an association of high gas bubble intensity with the austral-autumn/winter and freshwater outflows. A new hypothesis is therefore presented that links gas bubbles to sulfate-reducing bacteria and hydrogen sulfide (H₂S), a by-product of anaerobic digestion. Given the apparent influence of freshwater on toheroa intrinsic health, the capacity for streams to deliver pollutants to toheroa beds was assessed. Results gained from inductively coupled plasma-mass spectrometry (ICP-MS) suggest that despite the modified nature of adjacent land, streams do not deliver significant loads of bioavailable trace metals to toheroa beds in the intertidal zone. Instead, nutrition in the form of large phytoplankton blooms in autumn/winter is thought to be the primary source of bioavailable trace metals for toheroa.
No observations of significant pathogenesis, associated with Endozoicomonas species, were made throughout this research. Furthermore, during the timeframe of this research (apart from intermittent mortality events reported), there is no evidence of an ongoing disease epidemic in toheroa populations. While not providing evidence for the factor preventing the recovery of toheroa, this research does have implications for the ongoing conservation and management of toheroa. It seems reasonable to assume that infectious disease is not a major factor contributing to the limited recovery of toheroa throughout Aotearoa. Instead, associations made between freshwater outflows, nutrition, and detritus indicate that habitat requirements provided by freshwater streams are having significant effects on toheroa health, survival, and homeostasis. Furthermore, evidence presented suggests that the Endozoicomonas spp. present in toheroa and other Aotearoa shellfish are likely to be an important endosymbiont. In the future, studies on remaining toheroa populations should prioritise nutritional health. Namely, what role symbionts play in toheroa nutrition, and how niche requirements shape symbiont community composition and function in toheroa tissues. Answers to these questions could profoundly increase the success of toheroa restoration and conservation efforts.

year: 2021