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Images, UC QuakeStudies

A photograph of Sharon McIver and Barnaby Bennett at the public launch of Agropolis, during FESTA 2013. Agropolis is an urban farm on the corner of High Street and Tuam Street. Organic waste from inner-city hospitality businesses is composted and used to grow food.

Images, UC QuakeStudies

A photograph of people at Agropolis just before the public launch event, which was part of FESTA 2013. Agropolis is an urban farm on the corner of High Street and Tuam Street. Organic waste from inner-city hospitality businesses is composted and used to grow food.

Research papers, University of Canterbury Library

Environmental stress and disturbance can affect the structure and functioning of marine ecosystems by altering their physical, chemical and biological features. In estuaries, benthic invertebrate communities play important roles in structuring sediments, influencing primary production and biogeochemical flux, and occupying key food web positions. Stress and disturbance can reduce species diversity, richness and abundance, with ecological theory predicting that biodiversity will be at its lowest soon after a disturbance with assemblages dominated by opportunistic species. The Avon-Heathcote Estuary in Christchurch New Zealand has provided a novel opportunity to examine the effects of stress, in the form of eutrophication, and disturbance, in the form of cataclysmic earthquake events, on the structure and functioning of an estuarine ecosystem. For more than 50 years, large quantities (up to 500,000m3/day) of treated wastewater were released into this estuary but in March 2010 this was diverted to an ocean outfall, thereby reducing the nutrient loading by around 90% to the estuary. This study was therefore initially focussed on the reversal of eutrophication and consequent effects on food web structure in the estuary as it responded to lower nutrients. In 2011, however, Christchurch was struck with a series of large earthquakes that greatly changed the estuary. Massive amounts of liquefied sediments, covering up to 65% of the estuary floor, were forced up from deep below the estuary, the estuary was tilted by up to a 50cm rise on one side and a corresponding drop on the other, and large quantities of raw sewage from broken wastewater infrastructure entered the estuary for up to nine months. This study was therefore a test of the potentially synergistic effects of nutrient reduction and earthquake disturbance on invertebrate communities, associated habitats and food web dynamics. Because there was considerable site-to-site heterogeneity in the estuary, the sites in this study were selected to represent a eutrophication gradient from relatively “clean” (where the influence of tidal flows was high) to highly impacted (near the historical discharge site). The study was structured around these sites, with components before the wastewater diversion, after the diversion but before the earthquakes, and after the earthquakes. The eutrophication gradient was reflected in the composition and isotopic chemistry of primary producer and invertebrate communities and the characteristics of sediments across the sample sites. Sites closest to the former wastewater discharge pipe were the most eutrophic and had cohesive organic -rich, fine sediments and relatively depauperate communities dominated by the opportunistic taxa Capitellidae. The less-impacted sites had coarser, sandier sediments with fewer pollutants and far less organic matter than at the eutrophic sites, relatively high diversity and lower abundances of micro- and macro-algae. Sewage-derived nitrogen had became incorporated into the estuarine food web at the eutrophic sites, starting at the base of the food chain with benthic microalgae (BMA), which were found to use mostly sediment-derived nitrogen. Stable isotopic analysis showed that δ13C and δ15N values of most food sources and consumers varied spatially, temporally and in relation to the diversion of wastewater, whereas the earthquakes did not appear to affect the overall estuarine food web structure. This was seen particularly at the most eutrophic site, where isotopic signatures became more similar to the cleaner sites over two-and-a-half years after the diversion. New sediments (liquefaction) produced by the earthquakes were found to be coarser, have lower concentrations of heavy metals and less organic matter than old (existing) sediments. They also had fewer macroinvertebrate inhabitants initially after the earthquakes but most areas recovered to pre-earthquake abundance and diversity within two years. Field experiments showed that there were higher amounts of primary production and lower amounts of nutrient efflux from new sediments at the eutrophic sites after the earthquakes. Primary production was highest in new sediments due to the increased photosynthetic efficiency of BMA resulting from the increased permeability of new sediments allowing increased light penetration, enhanced vertical migration of BMA and the enhanced transport of oxygen and nutrients. The reduced efflux of NH4-N in new sediments indicated that the capping of a large portion of eutrophic old sediments with new sediments had reduced the release of legacy nutrients (originating from the historical discharge) from the sediments to the overlying water. Laboratory experiments using an array of species and old and new sediments showed that invertebrates altered levels of primary production and nutrient flux but effects varied among species. The mud snail Amphibola crenata and mud crab Austrohelice crassa were found to reduce primary production and BMA biomass through the consumption of BMA (both species) and its burial from bioturbation and the construction of burrows (Austrohelice). In contrast, the cockle Austrovenus stutchburyi did not significantly affect primary production and BMA biomass. These results show that changes in the structure of invertebrate communities resulting from disturbances can also have consequences for the functioning of the system. The major conclusions of this study were that the wastewater diversion had a major effect on food web dynamics and that the large quantities of clean and unpolluted new sediments introduced to the estuary during the earthquakes altered the recovery trajectory of the estuary, accelerating it at least throughout the duration of this study. This was largely through the ‘capping’ effect of the new liquefied, coarser-grained sediments as they dissipated across the estuary and covered much of the old organic-rich eutrophic sediments. For all aspects of this study, the largest changes occurred at the most eutrophic sites; however, the surrounding habitats were important as they provided the context for recovery of the estuary, particularly because of the very strong influence of sediments, their biogeochemistry, microalgal and macroalgal dynamics. There have been few studies documenting system level responses to eutrophication amelioration and to the best on my knowledge there are no other published studies examining the impacts of large earthquakes on benthic communities in an estuarine ecosystem. This research gives valuable insight and advancements in the scientific understanding of the effects that eutrophication recovery and large-scale disturbances can have on the ecology of a soft-sediment ecosystem.

Images, UC QuakeStudies

A photograph of Sharon McIver and Barnaby Bennett at the public launch of Agropolis, which was part of FESTA 2013. Agropolis is an urban farm on the corner of High Street and Tuam Street. Organic waste from inner-city hospitality businesses is composted and used to grow food.

Images, UC QuakeStudies

A photograph of the beginnings of a shed at Agropolis. Agropolis is an urban farm on the corner of High Street and Tuam Street. Organic waste from inner-city hospitality businesses is composted and used to grow food. Agropolis was the venue for several events throughout FESTA 2013.

Images, UC QuakeStudies

A photograph of the beginnings of a shed at Agropolis. Agropolis is an urban farm on the corner of High Street and Tuam Street. Organic waste from inner-city hospitality businesses is composted and used to grow food. Agropolis was the venue for several events throughout FESTA 2013.

Images, UC QuakeStudies

A photograph of plants in a raised garden bed at the public launch event for Agropolis, which was part of FESTA 2013. Agropolis is an urban farm on the corner of High Street and Tuam Street. Organic waste from inner-city hospitality businesses is composted and used to grow food.

Images, UC QuakeStudies

A photograph of a woman with soil in her hands, before the opening of Agropolis, an urban farm on the corner of High Street and Tuam Street. Organic waste from inner-city hospitality businesses is composted and used to grow food. Agropolis was the venue for several events throughout FESTA 2013.

Images, UC QuakeStudies

A photograph of a City Care truck delivering mulch to Agropolis before the public launch event. The launch was part of FESTA 2013. Agropolis is an urban farm on the corner of High Street and Tuam Street. Organic waste from inner-city hospitality businesses is composted and used to grow food.

Images, UC QuakeStudies

A photograph of people jumping in a pile of soil that has been placed on a white sheet, as part of the launch event of Agropolis during FESTA 2013. Agropolis is an urban farm on the corner of High Street and Tuam Street. Organic waste from inner-city hospitality businesses is composted and used to grow food.

Images, UC QuakeStudies

A photograph of people jumping in a pile of soil that has been placed on a white sheet, as part of the launch event of Agropolis during FESTA 2013. Agropolis is an urban farm on the corner of High Street and Tuam Street. Organic waste from inner-city hospitality businesses is composted and used to grow food.

Images, UC QuakeStudies

A photograph of people jumping in a pile of soil that has been placed on a white sheet, as part of the launch event of Agropolis during FESTA 2013. Agropolis is an urban farm on the corner of High Street and Tuam Street. Organic waste from inner-city hospitality businesses is composted and used to grow food.

Images, UC QuakeStudies

A photograph of people jumping in a pile of soil that has been placed on a white sheet, as part of the launch event of Agropolis during FESTA 2013. Agropolis is an urban farm on the corner of High Street and Tuam Street. Organic waste from inner-city hospitality businesses is composted and used to grow food.

Videos, UC QuakeStudies

A video about C1 Espresso's pneumatic tube food delivery system. The video includes an interview with café owner Sam Crofskey about his decision to install the pneumatic tubes. It also includes an interview with chef Richie Ward, who demonstrates how the tubes work. Mini burgers will be stacked inside tubes and then placed in the pneumatic system. The tube will then be sent through the café at 140 km/h to appear at people's tables.

Audio, Radio New Zealand

DENIS O'ROURKE to the Minister for Canterbury Earthquake Recovery: Is he satisfied with progress on all aspects of the Canterbury earthquake recovery? JACINDA ARDERN to the Minister of Police: Does she have confidence in the Police investigation of alleged sexual violation against young women and underage girls in West Auckland? PAUL GOLDSMITH to the Minister of Finance: What progress has the National-led Government made in building a more productive and competitive economy capable of supporting more jobs and higher incomes for New Zealanders? METIRIA TUREI to the Minister of Police: When was she first advised that Police had received a complaint from a girl who alleged she had been raped by members of a group calling themselves the Roast Busters? Hon DAVID PARKER to the Minister for Communications and Information Technology: Will the Government enforce its broadband contract with Chorus? CLAUDETTE HAUITI to the Minister for the Environment: What announcements has the Government made in relation to the national policy statement for freshwater? PHIL TWYFORD to the Minister of Housing: What reports has he received on the effect of loan-to-value restrictions on the housing market? Hon PHIL HEATLEY to the Minister for Social Development: What reports has she received about the number of people receiving benefits? CAROL BEAUMONT to the Minister for Tertiary Education, Skills and Employment: How does women's participation rate of 1 percent in building and construction industry training assist with the Christchurch rebuild? Dr CAM CALDER to the Minister of Education: What recent announcements has she made to strengthen the status of the teaching profession? EUGENIE SAGE to the Associate Minister of Health: Does she agree with the Canterbury Medical Officer of Health that increasing nitrate levels in Canterbury groundwater are a health risk, particularly for pregnant women and babies; if not, why not? HONE HARAWIRA to the Minister of Finance: What is his budget plan, if any, to immediately address growing poverty in New Zealand, which has got so bad that charitable organisations have today said they are expecting an influx of more than 40,000 struggling families for Christmas dinner because they can't afford to put food on the table?

Audio, Radio New Zealand

GRANT ROBERTSON to the Minister for Tertiary Education, Skills and Employment: Does he stand by his statement that the Household Labour Force Survey is "the standard internationally recognised measure of employment and unemployment"? PAUL GOLDSMITH to the Minister of Finance: What recent reports has he received on the economy? Dr KENNEDY GRAHAM to the Minister for Climate Change Issues: Does he stand by the answer given by the Minister of Finance to the question "Does he accept that human-induced climate change is real?" that "It may well be…"? Hon DAVID PARKER to the Minister of Finance: Given that unemployment is rising, exports are down, and house price inflation in Auckland and Canterbury is in double-digits, does he agree that after 5 years as Finance Minister he has failed to rebalance and diversify the economy; if not, why not? JOHN HAYES to the Minister of Trade: What efforts is the Government making to deal with the market effects of the possible contamination of some Fonterra diary exports? Hon SHANE JONES to the Minister for Economic Development: What action has he taken to ensure high value jobs are retained in Otago, Waikato, Northland, East Coast and Manawatu? KEVIN HAGUE to the Minister of Health: Exactly how many of the 21 recommendations to the Minister in the 2010 Public Health Advisory Committee Report The Best Start in Life: Achieving effective action on child health and wellbeing has he implemented? JACQUI DEAN to the Minister for Food Safety: What update can she provide the public on the safety of infant formula? Hon DAMIEN O'CONNOR to the Minister for Primary Industries: Does he stand by all his statements? NICKY WAGNER to the Minister for Building and Construction: What reports has he received following the Government's announcement of a new earthquake-prone building policy? RICHARD PROSSER to the Minister for Primary Industries: What reports, if any, has he received regarding the regeneration of fish stocks in the Snapper 1 fishery? Dr DAVID CLARK to the Minister for Economic Development: Does he agree with Dunedin Mayor Dave Cull that "Central government needs to understand we can't have a … two-speed economy where Christchurch and Auckland are ripping ahead and the rest of the regions are withering"; if not, why not?

Research papers, University of Canterbury Library

The Avon-Heathcote Estuary is of significant value to Christchurch due to its high productivity, biotic diversity, proximity to the city, and its cultural, recreational and aesthetic qualities. Nonetheless, it has been subjected to decades of degradation from sewage wastewater discharges and encroaching urban development. The result was a eutrophied estuary, high in nitrogen, affected by large blooms of nuisance macroalgae and covered by degraded sediments. In March 2010, treated wastewater was diverted from the estuary to a site 3 km offshore. This quickly reduced water nitrogen by 90% within the estuary and, within months, there was reduced production of macroalgae. However, a series of earthquakes beginning in September 2010 brought massive changes: tilting of the estuary, changes in channels and water flow, and a huge influx of liquefied sediments that covered up to 65% of the estuary floor. Water nitrogen increased due to damage to sewage infrastructure and the diversion pipeline being turned off. Together, these drastically altered the estuarine ecosystem. My study involves three laboratory and five in situ experiments that investigate the base of the food chain and responses of benthic microalgae to earthquake-driven sediment and nutrient changes. It was predicted that the new sediments would be coarser and less contaminated with organic matter and nutrients than the old sediments, would have decreased microalgal biomass, and would prevent invertebrate grazing and bioturbation activities. It was believed that microalgal biomass would become similar across new and old sediments types as the unstable new sediments were resuspended and distributed over the old sediments. Contact cores of the sediment were taken at three sites, across a eutrophication gradient, monthly from September 2011 to March 2012. Extracted chlorophyll a pigments showed that microalgal biomass was generally lower on new liquefied sediments compared to old sediments, although there was considerable site to site variation, with the highly eutrophic sites being the most affected by the emergence of the new sediments. Grazer experiments showed that invertebrates had both positive and negative site-specific effects on microalgal biomass depending on their identity. At one site, new sediments facilitated grazing by Amphibola crenata, whereas at another site, new sediments did not alter the direct and indirect effects of invertebrates (Nicon aestuariensis, Macropthalmus hirtipes, and A. crenata) on microalgae. From nutrient addition experiments it was clear that benthic microalgae were able to use nutrients from within both old and new sediments equally. This implied that microalgae were reducing legacy nutrients in both sediments, and that they are an important buffer against eutrophication. Therefore, in tandem with the wastewater diversion, they could underpin much of the recovery of the estuary. Overall, the new sediments were less favourable for benthic microalgal growth and recolonisation, but were less contaminated than old sediments at highly eutrophic sites. Because the new sediments were less contaminated than the old sediments, they could help return the estuary to a noneutrophic state. However, if the new sediments, which are less favourable for microalgal growth, disperse over the old sediments at highly eutrophic sites, they could become contaminated and interfere with estuarine recovery. Therefore, recovery of microalgal communities and the estuary was expected to be generally long, but variable and site-specific, with the least eutrophic sites recovering quickly, and the most eutrophic sites taking years to return to a pre-earthquake and non-eutrophied state. changes in channels and water flow, and a huge influx of liquefied sediments that covered up to 65% of the estuary floor. Water nitrogen increased due to damage to sewage infrastructure and the diversion pipeline being turned off. Together, these drastically altered the estuarine ecosystem. My study involves three laboratory and five in situ experiments that investigate the base of the food chain and responses of benthic microalgae to earthquake-driven sedimen tand nutrient changes. It was predicted that the new sediments would be coarser and less contaminated with organic matter and nutrients than the old sediments, would have decreased microalgal biomass, and would prevent invertebrate grazing and bioturbation activities. It was believed that microalgal biomass would become similar across new and old sediments types as the unstable new sediments were resuspended and distributed over the old sediments. Contact cores of the sediment were taken at three sites, across a eutrophication gradient, monthly from September 2011 to March 2012. Extracted chlorophyll a pigments showed that microalgal biomass was generally lower on new liquefied sediments compared to old sediments, although there was considerable site to site variation, with the highly eutrophic sites being the most affected by the emergence of the new sediments. Grazer experiments showed that invertebrates had both positive and negative site-specific effects on microalgal biomass depending on their identity. At one site, new sediments facilitated grazing by Amphibola crenata, whereas at another site, new sediments did not alter the direct and indirect effects of invertebrates (Nicon aestuariensis, Macropthalmus hirtipes, and A. crenata) on microalgae. From nutrient addition experiments it was clear that benthic microalgae were able to use nutrients from within both old and new sediments equally. This implied that microalgae were reducing legacy nutrients in both sediments, and that they are

Research Papers, Lincoln University

Mitigating the cascade of environmental damage caused by the movement of excess reactive nitrogen (N) from land to sea is currently limited by difficulties in precisely and accurately measuring N fluxes due to variable rates of attenuation (denitrification) during transport. This thesis develops the use of the natural abundance isotopic composition of nitrate (δ15N and δ18O of NO₃-) to integrate the spatialtemporal variability inherent to denitrification, creating an empirical framework for evaluating attenuation during land to water NO₃- transfers. This technique is based on the knowledge that denitrifiers kinetically discriminate against 'heavy' forms of both N and oxygen (O), creating a parallel enrichment in isotopes of both species as the reaction progresses. This discrimination can be quantitatively related to NO₃- attenuation by isotopic enrichment factors (εdenit). However, while these principles are understood, use of NO₃- isotopes to quantify denitrification fluxes in non-marine environments has been limited by, 1) poor understanding of εdenit variability, and, 2) difficulty in distinguishing the extent of mixing of isotopically distinct sources from the imprint of denitrification. Through a combination of critical literature analysis, mathematical modelling, mesocosm to field scale experiments, and empirical studies on two river systems over distance and time, these short comings are parametrised and a template for future NO₃- isotope based attenuation measurements outlined. Published εdenit values (n = 169) are collated in the literature analysis presented in Chapter 2. By evaluating these values in the context of known controllers on the denitrification process, it is found that the magnitude of εdenit, for both δ15N and δ18O, is controlled by, 1) biology, 2) mode of transport through the denitrifying zone (diffusion v. advection), and, 3) nitrification (spatial-temporal distance between nitrification and denitrification). Based on the outcomes of this synthesis, the impact of the three factors identified as controlling εdenit are quantified in the context of freshwater systems by combining simple mathematical modelling and lab incubation studies (comparison of natural variation in biological versus physical expression). Biologically-defined εdenit, measured in sediments collected from four sites along a temperate stream and from three tropical submerged paddy fields, varied from -3‰ to -28‰ depending on the site’s antecedent carbon content. Following diffusive transport to aerobic surface water, εdenit was found to become more homogeneous, but also lower, with the strength of the effect controlled primarily by diffusive distance and the rate of denitrification in the sediments. I conclude that, given the variability in fractionation dynamics at all levels, applying a range of εdenit from -2‰ to -10‰ provides more accurate measurements of attenuation than attempting to establish a site-specific value. Applying this understanding of denitrification's fractionation dynamics, four field studies were conducted to measure denitrification/ NO₃- attenuation across diverse terrestrial → freshwater systems. The development of NO₃- isotopic signatures (i.e., the impact of nitrification, biological N fixation, and ammonia volatilisation on the isotopic 'imprint' of denitrification) were evaluated within two key agricultural regions: New Zealand grazed pastures (Chapter 4) and Philippine lowland submerged rice production (Chapter 5). By measuring the isotopic composition of soil ammonium, NO₃- and volatilised ammonia following the bovine urine deposition, it was determined that the isotopic composition of NO₃ - leached from grazed pastures is defined by the balance between nitrification and denitrification, not ammonia volatilisation. Consequently, NO₃- created within pasture systems was predicted to range from +10‰ (δ15N)and -0.9‰ (δ18O) for non-fertilised fields (N limited) to -3‰ (δ15N) and +2‰ (δ18O) for grazed fertilised fields (N saturated). Denitrification was also the dominant determinant of NO₃- signatures in the Philippine rice paddy. Using a site-specific εdenit for the paddy, N inputs versus attenuation were able to be calculated, revealing that >50% of available N in the top 10 cm of soil was denitrified during land preparation, and >80% of available N by two weeks post-transplanting. Intriguingly, this denitrification was driven by rapid NO₃- production via nitrification of newly mineralised N during land preparation activities. Building on the relevant range of εdenit established in Chapters 2 and 3, as well as the soil-zone confirmation that denitrification was the primary determinant of NO₃- isotopic composition, two long-term longitudinal river studies were conducted to assess attenuation during transport. In Chapter 6, impact and recovery dynamics in an urban stream were assessed over six months along a longitudinal impact gradient using measurements of NO₃- dual isotopes, biological populations, and stream chemistry. Within 10 days of the catastrophic Christchurch earthquake, dissolved oxygen in the lowest reaches was <1 mg l⁻¹, in-stream denitrification accelerated (attenuating 40-80% of sewage N), microbial biofilm communities changed, and several benthic invertebrate taxa disappeared. To test the strength of this method for tackling the diffuse, chronic N loading of streams in agricultural regions, two years of longitudinal measurements of NO₃- isotopes were collected. Attenuation was negatively correlated with NO₃- concentration, and was highly dependent on rainfall: 93% of calculated attenuation (20 kg NO₃--N ha⁻¹ y⁻¹) occurred within 48 h of rainfall. The results of these studies demonstrate the power of intense measurements of NO₃- stable isotope for distinguishing temporal and spatial trends in NO₃ - loss pathways, and potentially allow for improved catchment-scale management of agricultural intensification. Overall this work now provides a more cohesive understanding for expanding the use of NO₃- isotopes measurements to generate accurate understandings of the controls on N losses. This information is becoming increasingly important to predict ecosystem response to future changes, such the increasing agricultural intensity needed to meet global food demand, which is occurring synergistically with unpredictable global climate change.