A hydrogeologic model, groundwater chemistry and stable isotopic analysis were used to establish recharge resources and outflows so a water balance could be developed for the Cromwell Terrace Aquifer (CTA) in Central Otago, New Zealand. Increased popularity of the Central Otago region for viticulture, orcharding and tourism, has resulted in an increased demand for water. Groundwater is a viable option to meet this demand for water. The CTA is a single unconfined aquifer contained within a thin veneer of permeable Quaternary glacial outwash gravels that range in thickness between 10 and 50m. These gravels rest unconformably on less permeable folded Tertiary sediments. The buried surface of the Tertiary sediments is irregular and provides the main hydrogeologic control in the CTA. Buried topographic highs in the Tertiary sediments impede groundwater flow, while the buried paleochannels at the southern end of the Cromwell Flat allow groundwater to flow unrestricted. The saturated thickness of the aquifer varies between 10 and 30 m. The direction of groundwater flow is in south easterly and south westerly directions toward both Lake Dunstan and the Kawarau Arm respectively. This indicates that recharge is from the Pisa Range. Annual fluctuations in groundwater levels show that there is a seasonal effect on the groundwater table. Annual fluctuations in groundwater level are in the range of 0.4 – 0.5 m, with lowest levels in winter and highest groundwater levels in late summer. The higher groundwater levels in summer correlate with when higher rainfall occurs, but could also be due to artificial recharge from irrigation during summer, and/or seepage from the Ripponvale Irrigation Scheme canals and storage ponds. Groundwater chemical analysis showed the dominant facies to be calcium bicarbonate waters. The source of the calcium bicarbonate is considered to be calcite in the Otago Schist, with concentrations of calcium bicarbonate being higher closer to the bedrock schist of the Pisa Range. Concentrations decreased toward Lake Dunstan, where calcium bicarbonate concentrations were lowest. The trend of calcium bicarbonate concentrations decreasing toward Lake Dunstan produces a similar pattern to the direction of groundwater flow. This would suggest that calcium bicarbonate concentrations are being diluted by rainwater infiltrating into the aquifer. However stable isotopic analysis showed that lake water infiltrates into the aquifer around the lake margin, and would also dilute calcium bicarbonate concentrations. Stable isotopic analysis found that groundwater was more depleted in both δ¹⁸O and δ²H than water from Lake Dunstan. The average δ¹⁸O for groundwater was -9.5‰, whereas the average δ¹⁸O for samples from Lake Dunstan was -8.1‰. The average δ¹⁸O value of Pisa Range snow, Pisa Range streams and Cromwell Flat precipitation gave values of -9.2‰ +/- 1.4‰, which is very similar to groundwater. This suggests recharge to the CTA is from a combination of snow melt and surface stream flow from the Pisa Range, and some direct rainfall infiltration on the Cromwell Flat. A water balance was calculated for the CTA groundwater system using the information from this study, and from a limited Otago Regional Council (O.R.C.) database. The main inputs to the CTA were found to be recharge precipitation and subsurface flows from the Pisa Range. The main outputs were identified as surface evaporation and discharge from the CTA to Lake Dunstan. The water balance showed that the total flow of water through the CTA is 93 Million cubic metres per year (Mm³/yr). At present the CTA has limited groundwater allocation measures in place. Using the information from the water balance, a volume of groundwater that could be abstracted sustainably was estimated. This volume was estimated using the O.R.C. method of allocating 50% of the mean annual precipitation that recharges the aquifer for groundwater abstraction. The total mean annual precipitation for the Cromwell Flat and Pisa Range is 20 Mm³/yr. Using the 50% of mean annual precipitation method, 10 Mm³/yr can be allocated for groundwater abstraction. The total volume of groundwater currently abstracted is 3 Mm³/yr, leaving 7 Mm³/yr of unallocated groundwater. Due to the small land area, types of land use, low population density of Cromwell Flat and availability of surface water (i.e. Lake Dunstan), it is unlikely that the total volume of 10 Mm³/yr will be fully allocated.

This thesis is a micro-study of intermarriage at the small Kāi Tahu community of Maitapapa from 1830 to 1940. Maitapapa is located on the northern bank of the Taieri River, 25 kilometres south of Dunedin, in Otago. It was at Moturata Island, located at the mouth of the Taieri River, that a whaling station was established in 1839. The establishment of this station initiated changes to the economy and settlement patterns, and saw the beginning of intermarriage between 'full-blood' women and Pākehā men. From 1848, Otago was colonized by British settlers and in the process ushered in a new phase of intermarriage where single white men married the 'half-caste' and 'quarter-caste' daughters of whalers. In short, in the early years of settlement intermarriage was a gendered 'contact zone' from which a mixed descent population developed at Taieri. The thesis traces the history of the mixed descent families and the Maitpapapa community throughout the nineteenth century until the kāika physically disintegrated in the 1920s. It argues that the creation of a largely 'quarter-caste' population at Maitapapa by 1891 illustrates the high rate of intermarriage at this settlement in contrast to other Kāi Tahu kāika in the South Island. While the population was 'quarter-caste' in 'blood', the families articulated an identity that was both Kāi Tahu and mixed descent. From 1916, the community underwent both physical and cultural disintegration. This disintegration was rapid and complete by 1926. The thesis demonstrates that while land alienation, poverty, poor health and a subsistence economy characterized the lives of the mixed descent families at Maitapapa in the nineteenth century, it was a long history of intermarriage begun in the 1830s and continued throughout the nineteenth century which was the decisive factor in wholesale migrations post World War One. Education, dress and physical appearance alongside social achievements assisted in the integration of persons of mixed descent into mainstream society. While Kāi Tahu initially welcomed intermarriage as a way of integrating newcomers of a different culture such as whalers into a community, the sustained pattern of intermarriage at Maitapapa brought with it social and cultural change in the form of outward migration and eventual cultural loss by 1940.

The vegetation communities that existed in the semi-arid intermontane basins and gorges of Central Otago prior to human settlement ~750 years B.P. are poorly understood. This is because of a lack of fossil evidence and complex restructuring by anthropogenic factors, especially increased fire frequency, and more recently mammalian grazing. There is also little information regarding the effect of the lost fauna on maintaining and structuring presettlement communities, both in Central Otago and throughout the eastern South Island dryland zone. This study aims to provide a clearer understanding of the functioning of pre-settlement ecosystems in dryland Central Otago, particularly the role of the largest vertebrate herbivores, the moa (Aves: Dinornithiformes), and to explore the implications of the extinct fauna for land conservation management across New Zealand. Late Pleistocene and Holocene vegetation communities of the Central Otago lowlands were reconstructed from plant macrofossils, including seeds, leaves, and wood, excavated from rockshelter, cave, and swamp deposits throughout the region. The macrofossils represent three main vegetation types: late Pleistocene to mid (late?) Holocene basin floor wetland herb associations, Olearia-shrublands surrounding these wetlands, and mid to late Holocene open scrubland and woodland in gorges and on low altitude slopes, dominated by filiramulate Olearia, Coprosma, and Corokia, with abundant lianes (Muehlenbeckia spp. and Rubus spp.) and understorey herbs. Many native tree and shrub species that are presently widespread in the Central Otago lowlands were rare or absent prior to anthropogenic fires (e.g. Discaria toumatou, Kunzea ericoides, Leptospermum scoparium). Other tree and shrub species once present are now extinct in the region (e.g. Coprosma obconica, Plagianthus regius, Pseudopanax ferox). The loss of these indigenous woody vegetation communities was a major factor contributing to the extirpation of many small bird species, and undoubtedly also reptile and invertebrate species, from the region. Plant macrofossils from rockshelters included remains of bird nests, identifiable by desiccated feathers and eggshell amongst them. These macrofossils include the first described plant remains from the nests of moa, which were constructed from a shallow bed of twigs of locally available shrubs and lianes. Many of the twigs are 25-30 mm in length and show evidence of having been clipped by moa bills. Desiccated coprolites, mostly of moa, but also specimens attributed to Finsch�s duck (Chenonetta finschi) and red-crowned parakeet (Cyanoramphus novaezelandiae), were recovered from rockshelter excavations. Moa species associated with a sample of coprolites were identified using ancient DNA analysis, and plant macrofossils from these were examined, together with previously unexamined moa gizzard content samples excavated from mires in the eastern South Island dryland zone. The results indicate that, in addition to previously reported browsing, upland moa (Megalapteryx didinus) and heavy-footed moa (Pachyornis elephantopus) also functioned as grazers, and seeds in their coprolites are dominantly of low shrubs and ground-cover herbs. Of particular interest was the higher than expected frequency of seeds from the currently rare and threatened 'spring annual' herbs; Ceratocephala pungens and Myosurus minimus subsp. novae-zelandiae (Ranunculaceae), suggesting further research on potential ecological relationships between moa and these plants would be worthwhile. The results of this study have provided a baseline for future conservation and restoration projects in the Central Otago lowlands.

Studies were conducted to broadly describe and understand the sediment benthos of a shallow-water coastal area (Aramoana Beach - Heyward Point - Blueskin Bay) near the entrance to Otago Harbour, a system largely representative for southeastern New Zealand. Benthic assemblages were examined in relation to gradients of wave exposure and disturbance, sediment type and bathymetry, and dredge-spoil disposal. Sediment and macrofaunal surveys in autumn and spring 2003 found little change in sediment texture gradients from historical studies and a lack of vertical stratification. Macrobenthic samples from spring produced significantly higher abundances of three numerically dominant phyla (Arthropoda, Annelida, and Mollusca) and higher taxon richness compared to autumn. Within water depths of 6-30 m, abundance, richness, and diversity increased with depth. Multivariate analyses identified similar assemblages among deeper sites, despite sediment textural differences, whereas distinct assemblages were found in the shallow portions of the three areas. Meiofaunal abundance patterns did not reflect those of macrofauna, possibly indicating greater vertical penetration of sediments in these hydrodynamic environments. Several new kinorhynch taxa were found. In a field manipulation, part of the Aramoana dredge-spoil dumpground was protected from spoil disposal for an extended period followed by experimental dumping of sandy and muddy spoil. Macrofaunal samples were collected before dumping and at nine sites < 119 d after disposal. Water velocities at the sediment-water interface were compared to a local sediment disturbance model. Dumpground samples were depauperate in individuals and taxa compared to an area protected from dumping for > 180 d. A drop in abundance and a dissimilar community coincided with muddy spoil, but fine sediments were dispersed within 26 d and macrofaunal assemblages recovered to the pre-existing state. Sandy spoil, while not altering native sediment textures, had a more prolonged impact due to transplantation of macrofauna from the dredged area that persisted for < 41 d after disposal. Side-scan sonar mapping indicated that the disposal footprint model used approximated the extent of sandy spoil impacts well, while local conditions spread muddy sediments beyond the initial impact site. A novel sediment profile imaging device was constructed that has many advantages over existing devices for spoil mound studies and habitat mapping: it is smaller, can be manually deployed from small boats, is cheaper, and can be modified to work in almost any soft sediment. Studies of one dominant taxon, the gastropod Zethalia zelandica, showed it was better able to survive sand burial than mud burial, did not vary in overall activity through a range of 5-14� C, and contributed a large proportion of biomass of its community. The spoil disposal strategy used does not appear as environmentally neutral as originally thought. Only muds are effectively dispersed whereas coarser sediments accumulate, affecting physical and biological benthic processes of a wider area. Two mitigation strategies were evaluated using a heuristic model. Reducing the disposal area and spreading mud disposal events over a longer time span may be an effective interim strategy. Overall, the studies will help guide management of the area.

Quartz and pyrite samples from Pliocene-recent, sub-economic orogenic gold mineralisation in the Southern Alps and Mesozoic economic deposits in the Otago Schist Belt have been analysed for noble gases and halogens. Palaeo-hydrothermal fluids preserved in fluid inclusions were released by crushing and analysed by mass spectrometry. Helium isotope measurements confirm the absence of a mantle-derived fluid component in gold-bearing veins from the Southern Alps and at the large gold deposit at Macraes in Otago. A possible minor mantle helium component is observed in veins within 10km of the Alpine Fault that do not contain gold. Halogen ratios support the absence of mantle-derived fluid and support the presence of a crustal fluid derived from sediments, indicated by high I/Cl ratios. Mixing trends between 40Ar/36Ar and Cl/36Ar indicate mixing between a meteoric-derived fluid or air and crust-derived fluid in all sample types. A correlation between 40Ar/36Ar and 132Xe/36Ar shows that xenon is also sourced from the crustal fluid. Despite a strong crustal-radiogenic Ar signal in some samples, measured neon isotope ratios are atmosphere like. Noble gas elemental ratios show strongly fractionated 20Ne/36Ar away from air-saturated water and air values in deeper formed veins, suggesting air contamination is not dominant. Evidence for the presence of a significant trapped vapour phase is provided by calculated noble gas concentrations in water. Formation of this vapour phase using a two-stage model of de-gassing of meteoric water, and subsequent partial re-dissolution by a Rayleigh fractionation process could account for fractionated 20Ne/36Ar and atmospheric neon isotope ratios. In the Southern Alps, three main types of mineralisation can be identified by noble gas and halogen properties. Deep forming veins contain the most gold and are characterised by 20Ne/36Ar greater than air, 132Xe/36Ar ratios up to 75 times the air value, indicating metamorphic and meteoric fluid components. Some deep ankeritic type veins that display evidence of a CO2-rich component fluid show the highest 20Ne/36Ar ratios. Shallow, late veins have 20Ne/36Ar between air-saturated water and air values, and lower xenon and iodine contents. These veins formed from a boiling rock-exchanged meteoric fluid with a minor metamorphic fluid component and contain less gold. The characteristics of the Nenthorn deposit in Otago are similar to those of the shallow Alpine veins. The economically significant Macraes deposit possibly formed from a meteoric component and a strong metamorphic fluid component derived from the original sediments. This is indicated by the highest levels of excess xenon (relative to air) determined in this study. There is some potential for xenon to be used to fingerprint gold bearing fluids sourced from similar metasedimentary piles in orogenic belts.

Agriculture is key to New Zealand�s economy with land-use conversions in response to market forces occurring regularly. Recently, high-intensity dairy farming has replaced low-density livestock farming, often degrading surrounding waterways. Of particular concern is that dairy cattle can be a source of the parasite Giardia, which in humans is a common cause of gastrointestinal infection. Thus, this thesis evaluated whether dairy farm conversions posed significant consequences for public health. First I examined the prevalence of Giardia in calves in a rapidly intensifying dairying region of New Zealand. A total of 1190 faecal samples were collected from calves one to seven weeks old during two spring calving seasons and screened by direct immunofluorescent microscopy. Giardia cysts were detected in 31% of samples. To evaluate the potential risk that this environmental source of Giardia posed to the human population, molecular genotyping was used to compare forty Giardia strains isolated from calves with thirty isolates from humans collected in the same region and period. Sequencing the β-giardin gene, Giardia duodenalis assemblages A and B were identified from both hosts, with genotype comparisons revealing substantial overlap of identical genotypes for both assemblages, implying zoonotic transmission. Environmental agencies routinely promote the planting of streamside edges to decrease nonpoint pollution from dairy farms entering waterways. However, current methods for tracking pathogens across farmland and into waterways via surface runoff are limited and typically have been developed using artificially created landscapes. Furthermore, no studies have investigated how Giardia moves across the landscape in farm surface runoff. I developed a field-based tracking method specific for Giardia and used this technique to compare the ability of recently planted vegetation strips with bare soil strips cleared of vegetation at decreasing pathogen concentrations; a typical scenario when planting barriers to reduce waterway contamination. A spike containing a bromide tracer and inactivated Giardia cysts was applied in drip-irrigated surface runoff, with one-minute samples collected from the bottom of the plot. A significant treatment effect was identified for Giardia, with 26% fewer detected in runoff from the planted strip, highlighting the immediate benefit of vegetation planting in removing pathogens. Next I evaluated the effects of four riparian treatments on Giardia runoff: exotic pasture grass and weeds growing in the absence of cattle grazing due to fencing, in comparison to monocultural plantings of three New Zealand native grassland species. Runoff experiments were performed after planting, both prior to and following the main summer growing season. Bromide recovery was high from all four treatments (54 - 99%), with no significant treatment effects. By comparison, Giardia recovery was low (1 - 13%). Prior to summer, two native species reduced Giardia in runoff more than the pasture grass/weed treatment which was almost vegetation-free at this time. After summer, Giardia recoveries were uniformly lower in all treatments. These results demonstrate that after one growing season, fencing waterways produces riparian buffers, via the growth of exotic pasture plants released from grazing, that decrease pathogen concentrations in surface runoff to concentrations indistinguishable from native plantings. Given infectious organisms are known to be in the environment, it is important to assess the risk these pose to human populations. Findings from this research can be used to improve currently available risk-assessment models for Giardia transmission from infected dairy animals via water to humans.

This thesis set out to examine the soils, plants, lichens, invertebrates and common skinks along a gradient of habitat modification. This gradient was represented by ten study sites, of varying management histories, in a mid altitude tall tussock (Chionochloa spp.) grassland in eastern Central Otago. One extreme of the gradient was represented by intact tall tussock plants with a high density of inter tussock vegetation. The other extreme was represented by intensively managed exotic pasture. Native plants, invertebrates and reptiles were present along the entire gradient of modification and there was a clear threshold in the diversity of native plants along the gradient. This threshold was reached after the management practice of ploughing was applied to a site. Sites that had not been ploughed were found to be similar in their native plant diversity, and all unploughed sites had significantly higher native plant diversity than unploughed sites. There was considerable variation in the abundance of individual plant and Coleoptera species along the modification gradient. The most intensively modified sites had the lowest plant diversity, the lowest abundance and diversity of Orthoptera, as well as the lowest abundance of common skinks. Sites with low levels of modification contained a higher abundance of common skinks, and, native forbs, lichens and bryophytes than the more intensively modified sites. With regard to individual plant and Coleoptera species recorded, there were generally not clear thresholds for their presence and absence along the modification gradient. Rather, there was a gradual turnover for most species along the gradient such that the plant and Coleoptera community at opposing ends of the gradient had less species in common sites of similar modification levels. A high proportion of the Coleoptera species observed were present in all sites, suggesting that disturbance has selected for an adaptive generalist life trait, and that the species remaining comprise the resilient portion of the Coleoptera fauna. The relationship between Coleoptera communities and the gradient of modification was scale dependent, with the strongest relationship being observed at the largest scale measured. The hypothesis that faunal diversity and abundance would be best predicted by the structural diversity of the vegetation rather than by plant species diversity was tested. Structural diversity was strongly correlated (p < 0.01) with Coleoptera diversity, and Coleoptera abundance whereas plant species diversity was not. However, plant species diversity was a stronger correlate of common skink abundance than plant structural diversity. The structural diversity of the vegetation has the potential to be measured remotely and could be a correlate for faunal diversity and abundance when undertaking landscape scale studies. This thesis demonstrates that native biota exists within the agricultural environment of the mid-altitude tall tussock (Chionochloa rigida) grasslands of eastern Central Otago despite intensive modification in some areas. The findings suggest that it is possible to integrate the objectives of agriculture and the conservation of some faunal groups especially for the more resilient species. However, this study also indicates that relatively unmodified sites are valuable reservoirs of biodiversity in the mid altitude zone and it is recommended that the limited number of lightly modified sites that remain in the mid altitude zone be conserved.

Tuatara (Sphenodon spp.) were once widespread over both the North and the South Islands of New Zealand approximately 1000 years ago but are now restricted to offshore islands due to introduced predators and habitat destruction. The survival of tuatara is now threatened by climate change because of isolation on islands that prevent them from migrating to cooler regions, and by their limited capacity to adapt due to their long life span and low genetic diversity. The thermal suitability of cooler regions for future translocations could be the key for tuatara conservation. The overall aim of the study was to determine the effect of cool temperature on the physiology, behaviour and egg incubation of Cook Strait tuatara (Sphenodon punctatus). As well answering specific questions about tuatara and their adaptation to cool temperature this study aimed at answering general questions about the behavioural and evolutionary ecology of reptiles. I first compared the preferred body temperature, feeding responses and tolerance to cold temperature of tuatara (Sphenodon punctatus) with three lizard species that inhabit the Otago region of southern New Zealand: Hoplodactylus maculatus, Naultinus gemmeus and Oligosoma maccanni. As well as testing the co-adaptation hypothesis between preferred body temperature and physiological performance of reptiles, I wanted to determine whether tuatara (which are planned to be reintroduced from a warmer site to the Otago region) have similar responses to cool temperature as do Otago lizard species. I found that tuatara show responses to cold temperatures similar to those of lizards from southern New Zealand, suggesting that if tuatara are translocated outside of their geographical range, they are likely to survive. I then tested if tuatara were capable of modifying their thermoregulatory behaviour if translocated to a cooler region. To do so, I conducted a laboratory experiment in which tuatara were provided with three thermal treatments corresponding to the thermal environments they would experience in their current habitat and the proposed reintroduction site. Contrary to the prediction of the cost-benefit model of thermoregulation, tuatara became active thermoregulators when the thermal quality of the habitat decreased. The results suggest that the model is less applicable to cold-adapted species and that if translocated to cooler regions, tuatara will be able to adjust their thermoregulatory behaviour to their thermal environment. Tuatara are temperature-dependent sex determination (TSD) reptiles and their translocation to cooler regions could have an dramatic impact on the sex ratio of new populations. To determine if potentially lower incubation temperature would be a limiting factor for the reintroduction of tuatara, I translocated eggs to the proposed reintroduction site. Some tuatara embryos developed at the site (and later hatched in the laboratory), but incubation lasted longer than in natural nests and all hatchlings were female. This trend observed in biased sex ratio might change in the context of climate change as an increase of soil temperature by 3�C would allow the production of males at the proposed site. The present study demonstrates that the translocation of tuatara further south, outside of their current geographical range, is possible and recommended. Tuatara show similar responses to cool temperatures compared with lizards that live in southern New Zealand, they can also adjust their thermoregulatory behaviour if translocated to cooler habitats, and tuatara embryos could potentially develop successfully in cooler regions. The greatest chance for the future survival of tuatara and TSD species in general, lies in translocation to other locations that are thermally suitable.

Tuatara (Sphenodon spp.) were once widespread over both the North and the South Islands of New Zealand approximately 1000 years ago but are now restricted to offshore islands due to introduced predators and habitat destruction. The survival of tuatara is now threatened by climate change because of isolation on islands that prevent them from migrating to cooler regions, and by their limited capacity to adapt due to their long life span and low genetic diversity. The thermal suitability of cooler regions for future translocations could be the key for tuatara conservation. The overall aim of the study was to determine the effect of cool temperature on the physiology, behaviour and egg incubation of Cook Strait tuatara (Sphenodon punctatus). As well answering specific questions about tuatara and their adaptation to cool temperature this study aimed at answering general questions about the behavioural and evolutionary ecology of reptiles. I first compared the preferred body temperature, feeding responses and tolerance to cold temperature of tuatara (Sphenodon punctatus) with three lizard species that inhabit the Otago region of southern New Zealand: Hoplodactylus maculatus, Naultinus gemmeus and Oligosoma maccanni. As well as testing the co-adaptation hypothesis between preferred body temperature and physiological performance of reptiles, I wanted to determine whether tuatara (which are planned to be reintroduced from a warmer site to the Otago region) have similar responses to cool temperature as do Otago lizard species. I found that tuatara show responses to cold temperatures similar to those of lizards from southern New Zealand, suggesting that if tuatara are translocated outside of their geographical range, they are likely to survive. I then tested if tuatara were capable of modifying their thermoregulatory behaviour if translocated to a cooler region. To do so, I conducted a laboratory experiment in which tuatara were provided with three thermal treatments corresponding to the thermal environments they would experience in their current habitat and the proposed reintroduction site. Contrary to the prediction of the cost-benefit model of thermoregulation, tuatara became active thermoregulators when the thermal quality of the habitat decreased. The results suggest that the model is less applicable to cold-adapted species and that if translocated to cooler regions, tuatara will be able to adjust their thermoregulatory behaviour to their thermal environment. Tuatara are temperature-dependent sex determination (TSD) reptiles and their translocation to cooler regions could have an dramatic impact on the sex ratio of new populations. To determine if potentially lower incubation temperature would be a limiting factor for the reintroduction of tuatara, I translocated eggs to the proposed reintroduction site. Some tuatara embryos developed at the site (and later hatched in the laboratory), but incubation lasted longer than in natural nests and all hatchlings were female. This trend observed in biased sex ratio might change in the context of climate change as an increase of soil temperature by 3�C would allow the production of males at the proposed site. The present study demonstrates that the translocation of tuatara further south, outside of their current geographical range, is possible and recommended. Tuatara show similar responses to cool temperatures compared with lizards that live in southern New Zealand, they can also adjust their thermoregulatory behaviour if translocated to cooler habitats, and tuatara embryos could potentially develop successfully in cooler regions. The greatest chance for the future survival of tuatara and TSD species in general, lies in translocation to other locations that are thermally suitable.

Agriculture is key to New Zealand�s economy with land-use conversions in response to market forces occurring regularly. Recently, high-intensity dairy farming has replaced low-density livestock farming, often degrading surrounding waterways. Of particular concern is that dairy cattle can be a source of the parasite Giardia, which in humans is a common cause of gastrointestinal infection. Thus, this thesis evaluated whether dairy farm conversions posed significant consequences for public health. First I examined the prevalence of Giardia in calves in a rapidly intensifying dairying region of New Zealand. A total of 1190 faecal samples were collected from calves one to seven weeks old during two spring calving seasons and screened by direct immunofluorescent microscopy. Giardia cysts were detected in 31% of samples. To evaluate the potential risk that this environmental source of Giardia posed to the human population, molecular genotyping was used to compare forty Giardia strains isolated from calves with thirty isolates from humans collected in the same region and period. Sequencing the β-giardin gene, Giardia duodenalis assemblages A and B were identified from both hosts, with genotype comparisons revealing substantial overlap of identical genotypes for both assemblages, implying zoonotic transmission. Environmental agencies routinely promote the planting of streamside edges to decrease nonpoint pollution from dairy farms entering waterways. However, current methods for tracking pathogens across farmland and into waterways via surface runoff are limited and typically have been developed using artificially created landscapes. Furthermore, no studies have investigated how Giardia moves across the landscape in farm surface runoff. I developed a field-based tracking method specific for Giardia and used this technique to compare the ability of recently planted vegetation strips with bare soil strips cleared of vegetation at decreasing pathogen concentrations; a typical scenario when planting barriers to reduce waterway contamination. A spike containing a bromide tracer and inactivated Giardia cysts was applied in drip-irrigated surface runoff, with one-minute samples collected from the bottom of the plot. A significant treatment effect was identified for Giardia, with 26% fewer detected in runoff from the planted strip, highlighting the immediate benefit of vegetation planting in removing pathogens. Next I evaluated the effects of four riparian treatments on Giardia runoff: exotic pasture grass and weeds growing in the absence of cattle grazing due to fencing, in comparison to monocultural plantings of three New Zealand native grassland species. Runoff experiments were performed after planting, both prior to and following the main summer growing season. Bromide recovery was high from all four treatments (54 - 99%), with no significant treatment effects. By comparison, Giardia recovery was low (1 - 13%). Prior to summer, two native species reduced Giardia in runoff more than the pasture grass/weed treatment which was almost vegetation-free at this time. After summer, Giardia recoveries were uniformly lower in all treatments. These results demonstrate that after one growing season, fencing waterways produces riparian buffers, via the growth of exotic pasture plants released from grazing, that decrease pathogen concentrations in surface runoff to concentrations indistinguishable from native plantings. Given infectious organisms are known to be in the environment, it is important to assess the risk these pose to human populations. Findings from this research can be used to improve currently available risk-assessment models for Giardia transmission from infected dairy animals via water to humans.