Clough T.J.,Lincoln University at Christchurch |
Buckthought L.E.,Lincoln University at Christchurch |
Casciotti K.L.,Woods Hole Oceanographic Institution |
Kelliher F.M.,Lincoln University at Christchurch |
And 2 more authors.
Journal of Environmental Quality | Year: 2011
Recently the Intergovernmental Panel on Climate Change (IPCC) emission factor EF5-r was revised downward to a value of 0.0025 kg N2O-N per kg NO3--N leached. It was not reduced further due to the continued uncertainty surrounding the dynamics of N2O in river systems. There have been few studies where river system N2O yields and fluxes have been measured. In this study, we examined the relationship between NO3--N and N2O-N fluxes at 10 sites along a braided river system (84 km) over a 397-d period. Isotopic analysis of NO3--N river water samples and the potential agricultural nitrogen (N) sources demonstrated that the NO3--N came from agricultural or sewage sources. Percent saturation of N2O varied with site and date (average, 114%) and correlated with river NO3--N concentrations. Modeled N2O fluxes (16-30 μg m-2 h-1) from five sites were strongly related to river NO3--N concentrations (r2 = 0.86). The modeled N2O-N fluxes ranged from 39 to 81% of the IPCC-derived emissions based on the NO3--N load in the river over 397 d and do not support further lowering of the EF5-r. Further in situ river studies are required to verify the N2O-N fluxes and the calculated gas transfer velocity values for these braided river systems. © 2011 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.
Lagrue C.,University of Burgundy |
Kelly D.W.,Environment Canterbury |
Hicks A.,University of Otago |
Poulin R.,University of Otago
Journal of Fish Biology | Year: 2011
Parasite infection patterns were compared with the occurrence of their intermediate hosts in the diet of nine sympatric fish species in a New Zealand lake. Stomach contents and infection levels of three gastrointestinal helminth species were examined from the entire fish community. The results highlighted some links between fish host diet and the flow of trophically transmitted helminths. Stomach contents indicated that all but one fish species were exposed to these helminths through their diet. Host feeding behaviour best explained infection patterns of the trematode Coitocaecum parvum among the fish community. Infection levels of the nematode Hedruris spinigera and the acanthocephalan Acanthocephalus galaxii, however, were not correlated with host diets. Host specificity is thus likely to modulate parasite infection patterns. The data indicate that host diet and host-parasite compatibility both contribute to the distribution of helminths in the fish community. Furthermore, the relative influence of encounter (trophic interactions between prey and predator hosts) and compatibility (host suitability) filters on infection levels appeared to vary between host-parasite species associations. Therefore, understanding parasite infection patterns and their potential impacts on fish communities requires determining the relative roles of encounter and compatibility filters within and across all potential host-parasite associations. © 2011 The Authors. Journal of Fish Biology © 2011 The Fisheries Society of the British Isles.
Schallenberg M.,University of Otago |
Larned S.T.,NIWA - National Institute of Water and Atmospheric Research |
Hayward S.,Environment Canterbury |
Arbuckle C.,Environment Southland
Estuarine, Coastal and Shelf Science | Year: 2010
Intermittently closed and open lakes and lagoons (ICOLLs) are shallow barrier lakes which are intermittently connected to the sea and experience saline intrusions. Many ICOLLs are mechanically opened to prevent flooding of surrounding agricultural and urban land and to flush water of poor quality. In this study, the effects of modified opening regimes (frequency and duration of barrier openings and closures) on water quality and phytoplankton in two New Zealand ICOLLs were investigated over a number of opening/closure cycles. Water quality in Lake Ellesmere (Te Waihora) responded weakly to both opening and closing events, indicating that sea-ICOLL exchange did not markedly improve water quality. Conversely, water quality in Waituna Lagoon responded rapidly to barrier openings; water level decreased to near sea level within days of opening and subsequent seawater exchange resulted in rapid decreases in nitrate and chlorophyll a concentrations. The closure of Waituna Lagoon resulted in rapid rise in water level and a pulse of nitrate and phosphorus in the water column and phytoplankton chlorophyll a concentrations increased with increasing closed-period duration. Based on data on the underwater light climate and nutrient dynamics, phytoplankton in Lake Ellesmere was probably light-limited, whereas phytoplankton in Waituna Lagoon was rarely light-limited, and appeared to be predominately P-limited. The marked differences in responses of Lake Ellesmere and Waituna Lagoon to barrier openings and closures reflected differences in ICOLL water levels and morphological characteristics, which dictated the degree of tidal flushing when the barriers were open. The inter-ICOLL differences observed in this study indicate that unless the effects of ICOLL openings/closures on phytoplankton and nutrient dynamics are understood, changes to ICOLL opening regimes may have unintended consequences for the water quality and ecology of these systems. © 2009 Elsevier Ltd. All rights reserved.
Somervell E.R.,NIWA - National Institute of Water and Atmospheric Research |
Aberkane T.,Environment Canterbury
Open Atmospheric Science Journal | Year: 2015
The New Zealand region of Canterbury has experienced over three years of frequent seismic activity, centred under or near the main city of Christchurch. Larger earthquakes and aftershocks have triggered liquefaction in certain parts of the city, depositing significant amounts of fine silt on the surface, which is a new source of dust emissions. Historically, concerns about air quality in Christchurch have been dominated by emissions from wood burning in winter for domestic heating. High emissions, along with frequent temperature inversions lead to regular exceedances of the national standard for PM10 of 50 μg m-3 for a twenty-four hour average concentration. The health effects of PM10 are widely acknowledged, and regulatory drives to improve ambient air quality are succeeding in recent years. During 2011, ratios of PM2.5 to PM10 suggested that some periods of elevated concentrations were due to the liquefaction from the earthquakes and that the silt may represent a novel air quality issue to be managed. In addition, the earthquakes have damaged thousands of residences, causing changes in domestic heating practices as many chimneys are destroyed or currently in need of repair. This will affect emissions in upcoming winters and thus, the health burden may alter if a permanent step change in wood burning emissions is observed. However, the increased dust levels from liquefaction introduce a potentially compounding factor to any estimates of exposure. Thus, as a result of the earthquakes, air quality in Christchurch is rapidly changing with unknown effects on exposure and ultimately, the health of the Christchurch population. © Somervell and Aberkane; Licensee Bentham Open.
News Article | November 13, 2016
The quake struck southern Xinjiang in western China at a relatively shallow depth of 12 kilometres (seven miles), the USGS said (AFP Photo/Olivier Morin) WELLINGTON (Reuters) - A powerful earthquake rocked New Zealand on Monday killing at least two people, damaging roads and buildings, and prompting a tsunami warning that sent thousands fleeing to higher ground. Emergency response teams were flying by helicopter to the region at the epicenter of the 7.8 magnitude quake, some 91 km (57 miles) northeast of Christchurch in the South Island, amid reports of injuries and collapsed buildings. Hundreds of aftershocks, the strongest measuring 6.1 magnitude, continued to shake the country well into mid-morning, after the initial quake struck minutes after midnight. Powerlines and telecommunications were down, and daylight revealed sizeable cracks in roads and damage to infrastructure. "It was the most significant shock I can remember in Wellington," Prime Minister John Key told reporters at a dawn news conference from the parliament's underground bunker in the capital city. "There will be quite major costs around roads and infrastructure." The first tremor struck just 23 km (14 miles) deep, jolting many from their sleep and raising memories of the 6.3 magnitude Christchurch quake in 2011, which killed 185 people. New Zealand's Geonet measured Monday's quake at magnitude 7.5, while the U.S. Geological Survey put it at 7.8. But a tsunami warning that led to mass evacuations was downgraded after large swells hit Wellington, in the North Island, and Christchurch, the South Island's largest city. New Zealand lies in the seismically active "Ring of Fire", a 40,000 km arc of volcanoes and oceanic trenches that partly encircles the Pacific Ocean. Around 90 percent of the world's earthquakes occur within this region. Stock exchange operator NZX Ltd said financial markets would be open as usual, although many offices in the capital were closed. The NZX said its Wellington staff were working remotely. A flurry of listed property companies, including Investore Property and Argosy Property , issued notices to the NZX saying they were engaging structural engineers to examine buildings for any damage. Initial inspections showed limited impact. The New Zealand dollar fell as low as $0.7086 after the quake, from around $0.7125 before it struck, but recovered to $0.7110. The 2011 earthquake was not all bad news for the local currency, as it sparked a building boom and resulted in a huge net inflow of insurance payments. Key was meeting national emergency officials later on Monday morning and postponed a trip to Argentina, where he had planned to hold a series of trade meetings ahead of the Asia-Pacific Economic Cooperation (APEC) leaders' summit in Peru later in the week. "The situation is still unfolding and we don't yet know the full extent of the damage," Key said. "I believe it is better that I remain in New Zealand in the coming days to offer my assistance and support." Key said he hoped to travel to the tourist town of Kaikoura, which appeared to have borne the brunt of the quake, later on Monday. St. John Ambulance said it was sending helicopters carrying medical and rescue personnel to Kaikoura, where at least one of the casualties was found in a collapsed house. The South Island town, a popular destination for whale watching, was completely cut off and officials said there were reports of a collapsed building. Kevin Heays, of Environment Canterbury in Kaikoura, told Radio New Zealand there had been a lot of damage to roads. "There are a lot of poles down," he said. "I'd say we will be without power for a long, long time. I understand that the roads north and south are out so we are pretty well isolated." Local television reported that water to the town had also been cut off. A Reuters photographer about 60 km from the town reported damage to roads, bridges and railway lines. In Wellington residents caused gridlock on the roads to Mount Victoria, a hill with a lookout over the low-lying coastal city. Around 100 people, including children sleeping on floors and benches, were camped out in the distinctive parliament "Beehive" building. "I never thought I would go to a parliament in my pyjamas," said German tourist Agatha Blasinski, 35, who had been sleeping in a Wellington backpackers' hostel when the quake struck.
Urbina M.A.,University of Canterbury |
Meredith A.S.,Environment Canterbury |
Glover C.N.,University of Canterbury |
Forster M.E.,University of Canterbury
Journal of Fish Biology | Year: 2014
The Canterbury mudfish Neochanna burrowsius was found to be a pseudo-aestivating galaxiid with a low metabolic rate and significant cutaneous oxygen uptake (c. 43%) in both air and water. Another galaxiid, inanga Galaxias maculatus, had a higher metabolic rate in both media but the proportion of oxygen uptake met by cutaneous respiration rose significantly from 38 to 63% when the fish were exposed to air. Besides its important role in oxygen uptake, the skin of both species also contributed significantly to excretion of carbon dioxide in air, indicating the critical role of the integument as a respiratory tissue. In air, G. maculatus may increase cutaneous gas exchange to meet metabolic demands owing to the reduced utility of the gills, but as emersed G. maculatus were only able to maintain metabolic rates at c. 67% of that measured in water, this strategy probably only permits short-term survival. By contrast, the low and unchanging metabolic rate in water and air in N. burrowsius is a feature that may facilitate tolerance of long periods of emersion in the desiccating environments they inhabit. © 2014 The Fisheries Society of the British Isles.
Pairman D.,Landcare Research |
Belliss S.E.,Landcare Research |
Cuff J.,Environment Canterbury |
McNeill S.J.,Landcare Research
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2011
Identification of irrigated farm land is critical to a variety of environmental models. For this work, it is needed to model the impacts of irrigation on groundwater quality and flow rates. As the ground cover appearance for many land uses is quite dynamic, we take a multi-temporal remote sensing approach and classify each location as likely irrigated if it appears irrigated at any stage. Our model also uses a landform analysis to determine where irrigation is feasible. Either the presence of visible infrastructure or NDVI values higher than expected from rainfall data are then used as evidence for irrigated land. Paddocks identified by fieldwork as irrigated were 75.6% correctly classified, rising to 88.9% for a pasture subset. Cropping fields have proved more difficult as their NDVI also depends on their growth stage and the specific crop type. © 2011 IEEE.
Scott A.J.,Environment Canterbury |
Scarrott C.,University of Canterbury
Atmospheric Environment | Year: 2011
Elevated wintertime particulate concentrations in the New Zealand cities of Christchurch and Timaru are mostly attributed to the burning of wood and coal for residential heating. A carrot-and-stick approach was adopted for managing air quality in Christchurch, where strict intervention measures were introduced together with a residential heater replacement programme to encourage householders to change to cleaner forms of heating. A similar approach was only recently implemented for Timaru. This paper presents the results of a partial accountability analysis, where the impact of these measures on the target source, PM10 emissions, and PM10 concentrations are quantified. A statistical model was developed to estimate trends in the concentrations, which were tested for significance after accounting for meteorological effects, and to estimate the probability of meeting air quality targets. Results for Christchurch and Timaru are compared to illustrate the impacts of differing levels of intervention on air quality. In Christchurch, approximately 34,000 (76%) open fires and old solid fuel burners were replaced with cleaner heating technology from 2002 to 2009, and total open fires and solid fuel burner numbers decreased by 45%. Over the same time period, estimated PM10 emissions reduced by 71% and PM10 concentrations by 52% (maxima), 36% (winter mean), 26% (winter median) and 41% (meteorology-adjusted winter means). In Timaru, just 3000 (50%) open fires and old solid fuel burners were replaced from 2001 to 2008, with total open fire and solid fuel burner numbers reduced by 24%. PM10 emissions declined by 32%, with low reductions in the PM10 concentrations (maxima decreased by 7%, winter means by 11% and winter medians by 3%). These findings, supported by the results of the meteorology corrected trend analysis for Christchurch, strongly indicate that the combination of stringent intervention measures and financial incentives has led to substantial air quality improvements in the city. The lesser impact of more lenient rules and the late introduction of an incentives programme are obvious on air quality in Timaru. Trends established for the two cities were extrapolated under various scenarios to determine the likelihood of meeting air quality targets. In Christchurch the probability of compliance is low and is essentially impossible for Timaru if recent trends continue. © 2010 Elsevier Ltd.
North H.,Landcare Research |
Pairman D.,Landcare Research |
Belliss S.E.,Landcare Research |
Cuff J.,Environment Canterbury
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2012
Use of temporal signatures to classify the complex land use patterns in Canterbury New Zealand is investigated. Two datasets of detailed field histories spanning 5-7 years are used to develop a rule set for classifying from satellite imagery (SPOT/Landsat). While many individual crops proved inseparable, a broader set of land use classes such as 'winter forage' or 'summer arable crop' were defined that could be separated with accuracies between 71% and 96% (averaging 82% over 8 classifications). These broader land use classes will be used in a second stage of the project to guide and constrain classifications incorporating spectral information from the crop's peak NDVI phase. © 2012 IEEE.
Poulin R.,University of Otago |
Closs G.P.,University of Otago |
Lill A.W.T.,University of Otago |
Hicks A.S.,University of Otago |
And 2 more authors.
Oecologia | Year: 2012
Parasite avoidance is increasingly considered to be a potential driving factor in animal migrations. In many marine and freshwater benthic fish, migration into a pelagic environment by developing larvae is a common life history trait that could reduce exposure to parasites during a critical window of developmental susceptibility. We tested this hypothesis on congeneric fish (family Galaxiidae, genus Galaxias) belonging to a closely related species complex sampled from coastal streams in southeastern New Zealand. Migratory Galaxias have larvae that migrate to pelagic marine environments, whereas the larvae of non-migratory species rear close to adult habitats with no pelagic larval phase. Both migratory and non-migratory fish are hosts to two species of skin-penetrating trematodes that cause spinal malformations and high mortality in young fish. Using generalized linear models within an Akaike information criterion and model averaging framework, we compared infection levels between migratory and non-migratory fish while taking into account body size and several other local factors likely to influence infection levels. For one trematode species, we found a significant effect of migration: for any given body length, migratory fish harboured fewer parasites than non-migratory fish. Also, no parasites of any kind were found in juvenile migratory fish sampled in spring shortly after their return to stream habitats. Our results demonstrate that migration spares juvenile fish from the debilitating parasites to which they would be exposed in adult stream habitats. Therefore, either the historical adoption of a migratory strategy in some Galaxias was an adaptation against parasitism, or it evolved for other reasons and now provides protection from infection as a coincidental side-effect. © 2012 Springer-Verlag.