title: The effects of common carp on zooplankton communities using morphological and molecular techniques

authors: Woods, Steve

abstract: Understanding the factors causing a decline of water quality is important to ecologists, but particularly challenging given the complexity of natural systems. New Zealand’s freshwater ecosystems are under threat from increased eutrophication, and in the Waikato region this is intensified with the presence of common carp (Cyprinus carpio). The overall aim of this thesis was to capture the environmental and biological changes of a natural pond environment when carp were introduced at a high density, and to develop and test a DNA based approach of assessing zooplankton communities for quick and easy monitoring of lakes.  

The ecological aspect of this thesis explored how carp influenced the physical and chemical variables, as well as the biological communities of a shallow lake environment. Suspended sediments and nitrogen increased in the presence of carp. The zooplankton communities changed through time and were associated with small suspended sediments, but there was no observed influence on the zooplankton community driven by carp. This study illustrates how a new introduction of carp may have little impact on an already degraded system, such as those commonly seen in the Waikato region. 

The genetic component of this thesis aimed to determine the suitability of the 28S nuclear gene region as an ecological tool used in the routine monitoring of lakes. A reference library was created with 336 zooplankton individuals, including 60 rotifer, nine cladoceran, and seven copepod taxa. Sequence success was high (79%) and support for identification was generally high at the species level.  These findings showed that the 28S region could be used to sample entire zooplankton communities taken from natural environments. 

Next generation sequencing was used to sequence the entire zooplankton communities and test the effectiveness of 28S to capture the abundant and less abundant taxa, and ultimately determine its use as a tool for ecologists. Samples were identified and counted prior to sequencing to validate the results. High and moderate abundant zooplankton taxa successfully generated sequences and were correctly identified but primer biases were apparent with the low abundant taxa. There was no evidence to support that metabarcoding can provide an estimation of abundance, as the number of sequences generated was correlated with body size. However, metabarcoding appears to be able to determine the trophic state of lake ecosystems based on the composition of the rotifer community. 

Overall findings show how adding additional stressors to an already degraded lake may not result in the predicted outcome. This shows that the work needed to restore or remediate the system is not as simple as removing the one stressor predicted to be causing the majority of issues (e.g. carp), but reducing all stressors that are associated with the degradation of the lake (e.g. nutrients, sediments). This thesis also shows the benefits of including DNA based techniques in ecological monitoring.

text: The effects of common carp on zooplankton communities using morphological and molecular techniques Understanding the factors causing a decline of water quality is important to ecologists, but particularly challenging given the complexity of natural systems. New Zealand’s freshwater ecosystems are under threat from increased eutrophication, and in the Waikato region this is intensified with the presence of common carp (Cyprinus carpio). The overall aim of this thesis was to capture the environmental and biological changes of a natural pond environment when carp were introduced at a high density, and to develop and test a DNA based approach of assessing zooplankton communities for quick and easy monitoring of lakes.  

The ecological aspect of this thesis explored how carp influenced the physical and chemical variables, as well as the biological communities of a shallow lake environment. Suspended sediments and nitrogen increased in the presence of carp. The zooplankton communities changed through time and were associated with small suspended sediments, but there was no observed influence on the zooplankton community driven by carp. This study illustrates how a new introduction of carp may have little impact on an already degraded system, such as those commonly seen in the Waikato region. 

The genetic component of this thesis aimed to determine the suitability of the 28S nuclear gene region as an ecological tool used in the routine monitoring of lakes. A reference library was created with 336 zooplankton individuals, including 60 rotifer, nine cladoceran, and seven copepod taxa. Sequence success was high (79%) and support for identification was generally high at the species level.  These findings showed that the 28S region could be used to sample entire zooplankton communities taken from natural environments. 

Next generation sequencing was used to sequence the entire zooplankton communities and test the effectiveness of 28S to capture the abundant and less abundant taxa, and ultimately determine its use as a tool for ecologists. Samples were identified and counted prior to sequencing to validate the results. High and moderate abundant zooplankton taxa successfully generated sequences and were correctly identified but primer biases were apparent with the low abundant taxa. There was no evidence to support that metabarcoding can provide an estimation of abundance, as the number of sequences generated was correlated with body size. However, metabarcoding appears to be able to determine the trophic state of lake ecosystems based on the composition of the rotifer community. 

Overall findings show how adding additional stressors to an already degraded lake may not result in the predicted outcome. This shows that the work needed to restore or remediate the system is not as simple as removing the one stressor predicted to be causing the majority of issues (e.g. carp), but reducing all stressors that are associated with the degradation of the lake (e.g. nutrients, sediments). This thesis also shows the benefits of including DNA based techniques in ecological monitoring.

year: 2018

title: Modelling attribute non-attendance in choice experiments for rural landscape valuation

authors: Scarpa, Riccardo

subjects: attribute non-attendance

abstract: Non-market effects of agriculture are often estimated using discrete choice models from stated preference surveys. In this context we propose two ways of modelling attribute non-attendance. The first involves constraining coefficients to zero in a latent class framework, whereas the second is based on stochastic attribute selection and grounded in Bayesian estimation. Their implications are explored in the context of a stated preference survey designed to value landscapes in Ireland. Taking account of attribute non-attendance with these data improves fit and tends to involve two attributes one of which is likely to be cost, thereby leading to substantive changes in derived welfare estimates.

text: Modelling attribute non-attendance in choice experiments for rural landscape valuation Non-market effects of agriculture are often estimated using discrete choice models from stated preference surveys. In this context we propose two ways of modelling attribute non-attendance. The first involves constraining coefficients to zero in a latent class framework, whereas the second is based on stochastic attribute selection and grounded in Bayesian estimation. Their implications are explored in the context of a stated preference survey designed to value landscapes in Ireland. Taking account of attribute non-attendance with these data improves fit and tends to involve two attributes one of which is likely to be cost, thereby leading to substantive changes in derived welfare estimates.

year: 2009

title: Young Māori mothers and bed-sharing with their pēpi/baby: A case study focusing on the relevance and influence of three varying health promotion resources

authors: Haereroa, Nikki M.

subjects: Māori

abstract: Māori Sudden Unexpected Death in Infancy (SUDI) rates are significantly higher than non-Māori. Bed-sharing is considered to be one of the major modifiable risk factors associated with SUDI rates (Mitchell et al., 1992), although there is strong opposition that suggests bed-sharing can act as a preventative measure against SUDI (McKenna & McDade, 2005). As a result of quantitative research and statistical data, many health promotion messages now focus on discouraging the practice of bed-sharing, whether it be through policy implementation throughout hospitals or through to health promotion guidelines. Although there is a high incidence of Māori SUDI rates, there has been little emphasis on Māori perspectives and insights into the practice. Of the few qualitative studies that focus on infant sleep practices, a significant finding is the high prevalence of Māori who bed-share regularly (Tipene-Leach et al., 2010). This paper will investigate the motivations and rationale of bed-sharing amongst young urban Māori mothers to gain a deeper understanding and appreciation into the lived realities of this group. The lack of consultation with a group that has been classed by New Zealand Government bodies, the Health Quality and Safety Commission and Child and Youth Mortality Review Committee Group, as ‘most at risk’ of experiencing a SUDI, maybe a contributing factor to the high Māori SUDI rates. This has brought about the question of whether current health resources are relevant and/or influence young Māori mothers. Using a Te Whare Tapa Wha framework within a Kaupapa Māori Research methodology, this paper provides a unique and much-needed perspective into the lives of young Māori mothers. The purpose of this research overall is: if health resources and messages are not relevant to a community and they have little or no influence over infant care practices, then do health professionals and researchers need to rethink current strategies and working models to ensure we focus on the real, lived needs of our community?

text: Young Māori mothers and bed-sharing with their pēpi/baby: A case study focusing on the relevance and influence of three varying health promotion resources Māori Sudden Unexpected Death in Infancy (SUDI) rates are significantly higher than non-Māori. Bed-sharing is considered to be one of the major modifiable risk factors associated with SUDI rates (Mitchell et al., 1992), although there is strong opposition that suggests bed-sharing can act as a preventative measure against SUDI (McKenna & McDade, 2005). As a result of quantitative research and statistical data, many health promotion messages now focus on discouraging the practice of bed-sharing, whether it be through policy implementation throughout hospitals or through to health promotion guidelines. Although there is a high incidence of Māori SUDI rates, there has been little emphasis on Māori perspectives and insights into the practice. Of the few qualitative studies that focus on infant sleep practices, a significant finding is the high prevalence of Māori who bed-share regularly (Tipene-Leach et al., 2010). This paper will investigate the motivations and rationale of bed-sharing amongst young urban Māori mothers to gain a deeper understanding and appreciation into the lived realities of this group. The lack of consultation with a group that has been classed by New Zealand Government bodies, the Health Quality and Safety Commission and Child and Youth Mortality Review Committee Group, as ‘most at risk’ of experiencing a SUDI, maybe a contributing factor to the high Māori SUDI rates. This has brought about the question of whether current health resources are relevant and/or influence young Māori mothers. Using a Te Whare Tapa Wha framework within a Kaupapa Māori Research methodology, this paper provides a unique and much-needed perspective into the lives of young Māori mothers. The purpose of this research overall is: if health resources and messages are not relevant to a community and they have little or no influence over infant care practices, then do health professionals and researchers need to rethink current strategies and working models to ensure we focus on the real, lived needs of our community?

year: 2015