title: The effect of climate and environmental change on the megafaunal moa of New Zealand in the absence of humans

authors: Rawlence, Nicolas J.

subjects: ancient DNA

abstract: New Zealand offers a unique opportunity to investigate the response of extinct megafaunal ecosystems to major changes in climate and habitat prior to human settlement. Prior to this point (late 13th Century AD) New Zealand contained a diverse avian megafauna dominated by nine species of large flightless ratite moa (Dinornithiformes). We used ancient DNA approaches to generate mitochondrial DNA sequence data from 39 crested moa (Pachyornis australis) and 145 heavy-footed moa (Pachyornis elephantopus) specimens. In combination with radiocarbon dating and dietary isotope analysis we examined the effects of Late Pleistocene and Holocene climate and environmental change on the phylogeography, palaeodemographics, and eventual extinction of Pachyornis. We show that Pachyornis changed altitudinal, longitudinal and latitudinal ranges through the Late Quaternary in response to alterations in the distribution of suitable habitat. However, we found no evidence for large-scale change in population sizes during the past 40,000 radiocarbon years BP (approximately 44,000 calendar years BP), or significant changes in δ ¹³C and δ ¹⁵N isotope signatures over this time period. The results suggest that crested moa tracked habitat through time with little consequence to population size. For the more broadly distributed heavy-footed moa, changes in climate and habitat distribution may have promoted phylogeographic structuring. Overall this study suggests that the likelihood of megafaunal extinction in New Zealand was greatly reduced in the absence of humans.

text: The effect of climate and environmental change on the megafaunal moa of New Zealand in the absence of humans New Zealand offers a unique opportunity to investigate the response of extinct megafaunal ecosystems to major changes in climate and habitat prior to human settlement. Prior to this point (late 13th Century AD) New Zealand contained a diverse avian megafauna dominated by nine species of large flightless ratite moa (Dinornithiformes). We used ancient DNA approaches to generate mitochondrial DNA sequence data from 39 crested moa (Pachyornis australis) and 145 heavy-footed moa (Pachyornis elephantopus) specimens. In combination with radiocarbon dating and dietary isotope analysis we examined the effects of Late Pleistocene and Holocene climate and environmental change on the phylogeography, palaeodemographics, and eventual extinction of Pachyornis. We show that Pachyornis changed altitudinal, longitudinal and latitudinal ranges through the Late Quaternary in response to alterations in the distribution of suitable habitat. However, we found no evidence for large-scale change in population sizes during the past 40,000 radiocarbon years BP (approximately 44,000 calendar years BP), or significant changes in δ ¹³C and δ ¹⁵N isotope signatures over this time period. The results suggest that crested moa tracked habitat through time with little consequence to population size. For the more broadly distributed heavy-footed moa, changes in climate and habitat distribution may have promoted phylogeographic structuring. Overall this study suggests that the likelihood of megafaunal extinction in New Zealand was greatly reduced in the absence of humans.

year: 2012

title: Oxytocin as an appetite suppressant that reduces feeding reward

authors: Herisson, Florence

subjects: Oxytocin

abstract: In the environment in which palatable and highly caloric foods are readily available, eating behavior is oftentimes not dictated by the necessity to replenish lacking energy, but rather by the pleasure of consumption. Centrally acting oxytocin (OT) is known to promote termination of feeding to protect internal milieu by preventing excessive stomach distension, hyperosmolality and ingestion of toxins. Initial evidence suggests that another possible role for OT in mechanisms governing food intake is to reduce consumption of select palatable tastants. This thesis explores the question whether OT is as an appetite suppressant that reduces feeding reward. 
The first set of experiments addresses whether OT affects intake of (a) all carbohydrates, (b) only sweet carbohydrates or (c) sweet non-carbohydrate saccharin in mice. In those studies, generalized injection of a blood brain barrier penetrant OT receptor antagonist, L-368,899, significantly increased the intake of sweet (sucrose, glucose, fructose, polycose) and non-sweet (cornstarch) carbohydrates and promoted a trend approaching significance in saccharin consumption. Consumption of carbohydrate-enriched foods led to an increase in OT mRNA levels in the hypothalamus.
The second set of studies identifies the nucleus accumbens core (AcbC), a key component of the reward system, as a site that mediates anorexigenic effects of OT. Rats injected with OT directly in the AcbC showed a decreased intake of sucrose and saccharin solutions as well as of standard chow. This treatment did not cause taste aversion, hence the outcome was not due to sickness/malaise. The effects of AcbC OT on feeding could be observed only in animals offered a meal in a non-social environment. Once a social setting (devoid of direct antagonistic interactions between individuals) of a meal was introduced, AcbC OT failed to reduce feeding. AcbC levels of OT receptor transcript were affected by exposure to palatable food as well as by food deprivation.
The third and final set of studies shows that aberrant integrity of neuronal circuitry within the neuroendocrine and reward systems due to genetic deletion of connexin 36 (Cx36) gap junctions leads to dysregulation of the OT system’s functioning in the Cx36 KO mouse. This dysregulation is associated with hypersensitivity to aversive properties of foods, reduced interest in feeding for reward (palatable carbohydrates and saccharin) and abnormal ingestion of energy. 
Overall, the findings suggest that OT diminishes feeding for reward, particularly the intake of palatable carbohydrates and saccharin, by acting – at least in part – via the reward system. OT appears to be part of central mechanisms that cross-link homeostasis-driven and palatability-related (i.e., flavor- and macronutrient-specific) termination of consumption.

text: Oxytocin as an appetite suppressant that reduces feeding reward In the environment in which palatable and highly caloric foods are readily available, eating behavior is oftentimes not dictated by the necessity to replenish lacking energy, but rather by the pleasure of consumption. Centrally acting oxytocin (OT) is known to promote termination of feeding to protect internal milieu by preventing excessive stomach distension, hyperosmolality and ingestion of toxins. Initial evidence suggests that another possible role for OT in mechanisms governing food intake is to reduce consumption of select palatable tastants. This thesis explores the question whether OT is as an appetite suppressant that reduces feeding reward. 
The first set of experiments addresses whether OT affects intake of (a) all carbohydrates, (b) only sweet carbohydrates or (c) sweet non-carbohydrate saccharin in mice. In those studies, generalized injection of a blood brain barrier penetrant OT receptor antagonist, L-368,899, significantly increased the intake of sweet (sucrose, glucose, fructose, polycose) and non-sweet (cornstarch) carbohydrates and promoted a trend approaching significance in saccharin consumption. Consumption of carbohydrate-enriched foods led to an increase in OT mRNA levels in the hypothalamus.
The second set of studies identifies the nucleus accumbens core (AcbC), a key component of the reward system, as a site that mediates anorexigenic effects of OT. Rats injected with OT directly in the AcbC showed a decreased intake of sucrose and saccharin solutions as well as of standard chow. This treatment did not cause taste aversion, hence the outcome was not due to sickness/malaise. The effects of AcbC OT on feeding could be observed only in animals offered a meal in a non-social environment. Once a social setting (devoid of direct antagonistic interactions between individuals) of a meal was introduced, AcbC OT failed to reduce feeding. AcbC levels of OT receptor transcript were affected by exposure to palatable food as well as by food deprivation.
The third and final set of studies shows that aberrant integrity of neuronal circuitry within the neuroendocrine and reward systems due to genetic deletion of connexin 36 (Cx36) gap junctions leads to dysregulation of the OT system’s functioning in the Cx36 KO mouse. This dysregulation is associated with hypersensitivity to aversive properties of foods, reduced interest in feeding for reward (palatable carbohydrates and saccharin) and abnormal ingestion of energy. 
Overall, the findings suggest that OT diminishes feeding for reward, particularly the intake of palatable carbohydrates and saccharin, by acting – at least in part – via the reward system. OT appears to be part of central mechanisms that cross-link homeostasis-driven and palatability-related (i.e., flavor- and macronutrient-specific) termination of consumption.

year: 2016

title: Monitoring te mana o te wai: Intergrating an indigenous cultural health index with conventional biomonitoring tools for improved freshwater management

authors: Edgecombe, Shana Jade Te Iaa Tarere

subjects: Freshwater

abstract: Globally, there are universal efforts to quantify and address human impacts on ecosystems. In particular, changes in land use and river regulation have led to drastic declines in stream and river ecosystem health. These human impacts are driving the global freshwater biodiversity crisis and degrade ecosystem services provided by aquatic habitats. In Aotearoa New Zealand there is widespread concern about the state of our Nation’s freshwater ecosystems. Coupled with a renaissance in Māori culture, there has been a drive to develop indicators that help articulate cultural values, assess ecosystem health from a cultural perspective, and provide greater agency for Māori in environmental monitoring and management. In my thesis, I sought to integrate an established cultural monitoring framework with conventional biomonitoring tools for improved freshwater management. I hypothesized that using a suite of monitoring approaches would help detect the impacts of human land use on stream ecosystem health, and that cultural indicators would be consistent with conventional measures in diagnosing land use impacts. I also hypothesized that there could be discrepancies between cultural monitoring and conventional approaches, as each represent different perspectives and ways of knowing streams and rivers. 
To test my hypotheses, I selected ten stream sites across the catchment of the Kuratau River, a major tributary of Lake Taupō. Based on River Environment Classification land cover types, I used a balanced study design with five sites draining indigenous forest, and five sites draining pastoral land. I measured key stream physicochemical properties and collected water samples for determination of nutrient concentration and faecal coliform counts. I also characterised instream and riparian habitat. I collected benthic macroinvertebrate samples and sampled water for environmental DNA (eDNA) to assess different facets of biodiversity. I measured decomposition using the Cotton Strip Assay and quantified periphyton biomass using a portable fluorometer. In combination with these approaches, I also used a Cultural Health Index, an established cultural monitoring framework that assesses three components: customary significance, taonga species/mahinga kai (food gathering), and the Cultural Stream Health Measure (CSHM) to assess identified attributes for stream health.
I found that pastoral land uses lead to a decline in stream ecosystem health when compared to sites draining indigenous forest. Pastoral sites had higher specific conductivity and concentrations of total nitrogen and nitrate. Habitat variables changed, with increased sedimentation and more degraded riparian zones in pastoral streams. Decomposition rates as measured by the cotton strip assay increased in the pasture sites, which was likely a response to increased nutrient availability. There were shifts in macroinvertebrate composition, with key indicator taxa for Indigenous forest sites including pollution-sensitive mayflies and stoneflies. Total taxa, EPT (Ephemeroptera, Plecoptera, Trichoptera), and aquatic insect richness all significantly declined in pastoral sites. Increases in primary production were less pronounced, but did increase alongside abundances of grazing caddisflies and snails in the sites draining pastoral catchments. 
The Cultural Health Index indicated that sites in the Kuratau River catchment had customary and mahinga kai values. CSHM responded negatively to pastoral land uses, and the effect size it described was congruent with other responses. The CSHM was strongly correlated with an indicator of riparian habitat condition (the Riparian Condition Index) and had weak negative correlations with sedimentation and stream temperatures. The CSHM was not correlated with macroinvertebrate indices, which may have been because of the relatively few sites sampled, the narrow impact gradient in the Kuratau catchment, and the lack of temporal replication. However, cultural monitoring approaches should be seen to complement conventional environmental monitoring methods for assessing freshwater and not be expected to duplicate them. The strength of the Cultural Health Index approach comes from establishing Māori agency to assess the environment through a Te Ao Māori lens, and to support and foster inclusion for tangata whenua epistemologies in environmental monitoring and resource management. Future research should consider greater hapū involvement and further explore the mechanisms driving changes in stream health and biodiversity.

text: Monitoring te mana o te wai: Intergrating an indigenous cultural health index with conventional biomonitoring tools for improved freshwater management Globally, there are universal efforts to quantify and address human impacts on ecosystems. In particular, changes in land use and river regulation have led to drastic declines in stream and river ecosystem health. These human impacts are driving the global freshwater biodiversity crisis and degrade ecosystem services provided by aquatic habitats. In Aotearoa New Zealand there is widespread concern about the state of our Nation’s freshwater ecosystems. Coupled with a renaissance in Māori culture, there has been a drive to develop indicators that help articulate cultural values, assess ecosystem health from a cultural perspective, and provide greater agency for Māori in environmental monitoring and management. In my thesis, I sought to integrate an established cultural monitoring framework with conventional biomonitoring tools for improved freshwater management. I hypothesized that using a suite of monitoring approaches would help detect the impacts of human land use on stream ecosystem health, and that cultural indicators would be consistent with conventional measures in diagnosing land use impacts. I also hypothesized that there could be discrepancies between cultural monitoring and conventional approaches, as each represent different perspectives and ways of knowing streams and rivers. 
To test my hypotheses, I selected ten stream sites across the catchment of the Kuratau River, a major tributary of Lake Taupō. Based on River Environment Classification land cover types, I used a balanced study design with five sites draining indigenous forest, and five sites draining pastoral land. I measured key stream physicochemical properties and collected water samples for determination of nutrient concentration and faecal coliform counts. I also characterised instream and riparian habitat. I collected benthic macroinvertebrate samples and sampled water for environmental DNA (eDNA) to assess different facets of biodiversity. I measured decomposition using the Cotton Strip Assay and quantified periphyton biomass using a portable fluorometer. In combination with these approaches, I also used a Cultural Health Index, an established cultural monitoring framework that assesses three components: customary significance, taonga species/mahinga kai (food gathering), and the Cultural Stream Health Measure (CSHM) to assess identified attributes for stream health.
I found that pastoral land uses lead to a decline in stream ecosystem health when compared to sites draining indigenous forest. Pastoral sites had higher specific conductivity and concentrations of total nitrogen and nitrate. Habitat variables changed, with increased sedimentation and more degraded riparian zones in pastoral streams. Decomposition rates as measured by the cotton strip assay increased in the pasture sites, which was likely a response to increased nutrient availability. There were shifts in macroinvertebrate composition, with key indicator taxa for Indigenous forest sites including pollution-sensitive mayflies and stoneflies. Total taxa, EPT (Ephemeroptera, Plecoptera, Trichoptera), and aquatic insect richness all significantly declined in pastoral sites. Increases in primary production were less pronounced, but did increase alongside abundances of grazing caddisflies and snails in the sites draining pastoral catchments. 
The Cultural Health Index indicated that sites in the Kuratau River catchment had customary and mahinga kai values. CSHM responded negatively to pastoral land uses, and the effect size it described was congruent with other responses. The CSHM was strongly correlated with an indicator of riparian habitat condition (the Riparian Condition Index) and had weak negative correlations with sedimentation and stream temperatures. The CSHM was not correlated with macroinvertebrate indices, which may have been because of the relatively few sites sampled, the narrow impact gradient in the Kuratau catchment, and the lack of temporal replication. However, cultural monitoring approaches should be seen to complement conventional environmental monitoring methods for assessing freshwater and not be expected to duplicate them. The strength of the Cultural Health Index approach comes from establishing Māori agency to assess the environment through a Te Ao Māori lens, and to support and foster inclusion for tangata whenua epistemologies in environmental monitoring and resource management. Future research should consider greater hapū involvement and further explore the mechanisms driving changes in stream health and biodiversity.

year: 2024