David B.O.,Environment Waikato |
Hamer M.P.,Environment Waikato |
Collier K.J.,Environment Waikato |
Collier K.J.,University of Waikato |
And 5 more authors.
New Zealand Journal of Marine and Freshwater Research | Year: 2010
The New Zealand fish fauna contains species that are affected not only by river system connectivity, but also by catchment and local-scale changes in landcover, water quality and habitat quality. Consequently, native fish have potential as multi-scale bioindicators of human pressure on stream ecosystems, yet no standardised, repeatable and scientifically defensible methods currently exist for effectively quantifying their abundance or diversity in New Zealand stream reaches. Here we report on the testing of a back-pack electrofishing method, modified from that used by the United States Environmental Protection Agency, on a wide variety of wadeable stream reaches throughout New Zealand. Seventy-three first- to third-order stream reaches were fished with a single pass over 150-345m length. Time taken to sample a reach using single-pass electrofishing ranged from 1-8 h. Species accumulation curves indicated that, irrespective of location, continuous sampling of 150 stream metres is required to accurately describe reach-scale fish species richness using this approach. Additional species detection beyond 150m was rare (<10%) with a single additional species detected at only two out of the 17 reaches sampled beyond this distance. Apositive relationship was also evident between species detection and area fished, although stream length rather than area appeared to be the better predictor. The method tested provides a standardised and repeatable approach for regional and/or national reporting on the state of New Zealand's freshwater fish communities and trends in richness and abundance over time.
Douglas G.B.,Agresearch Ltd. |
McIvor I.R.,Plant and Food Research |
Manderson A.K.,Agresearch Ltd. |
Koolaard J.P.,Agresearch Ltd. |
And 3 more authors.
Land Degradation and Development | Year: 2013
Shallow landslides occur globally on soil-mantled hilly and mountainous terrain. In New Zealand, they are a nation-wide problem, particularly on pastoral hill country grazed by livestock. On these landscapes, trees are planted at low densities, often <70 stems per hectare (sph), to reduce landslide occurrence, but there has been limited quantification of their effectiveness in this role. This study determined the reduction in landslide occurrence at 65 sites planted with spaced trees (53×Populus, 6×Salix, 6×Eucalyptus) following rainstorm events. Sites had a mean slope angle of 27 degrees and soils were predominantly silt or sand-loams. Tree density across all sites was 32-65sph, height was 8-43m, canopy radius was 1-10m and trunk diameter was 18-99cm. Trees reduced landslide occurrence by 95 per cent compared to paired pasture control sites (0·4 per cent vs. 7·9 per cent scar area, respectively), and scars occurred on fewer sites with trees than pasture (10 vs. 45). For the 10 tree sites with scars, their area was <3·5 per cent, except at one site where it was 11·3 per cent. There were no significant differences between species in their effectiveness in reducing landslide occurrence. Analyses were partially successful in discriminating between sites with and without shallow landslides and identified some attributes with potentially useful discriminatory power. Aspect, mean slope angle and tree density did not feature significantly in the analyses because they were homogeneous across site groups. The study verified the large benefit from wide-spaced tree planting on sites susceptible to shallow landslides. © 2011 John Wiley & Sons, Ltd.
Kim N.D.,Massey University |
Taylor M.D.,Waikato Regional Council |
Drewry J.J.,Greater Wellington Regional Council
Environmental Earth Sciences | Year: 2016
Application of phosphate (P) fertilizers to farmland is projected to be causing worldwide accumulation of fluorine (F) in agricultural soils and associated ecosystems, but wide-scale field data have been lacking. We report results of sampling across two large regions of New Zealand involving soils of 298 native and farmed properties. This has enabled the first wide-scale retrospective estimates of anthropogenic F enrichment in pastoral and horticultural soils. Results validate earlier projections: F accumulation in farmed soils has been comparatively rapid (mean increase 2.1 % per year) and widespread. Over 50 years, average total F concentrations in surface soils have doubled from ~220 to 440 mg/kg. Thresholds protective against chronic fluorosis in grazing animals are being substantively passed, indicating that land may be rendered unsuitable for pastoral production in the mid-term future: when sampled 44 % of dairy farm soil samples exceeded 500 mg/kg total F, and 10 % exceeded 650 mg/kg. Potential for F toxicity to plants and wildlife appear to be significant and marginal, respectively, at current soil F concentrations. Relationships between F and other elements suggest P fertilizers are also a source of several elements geochemically linked to F, and that anthropogenic F modifies soil aluminium (Al) chemistry, potentially opening a broad-scale Al exposure pathway to pollinating insects. Findings signal a need for systematic examination of the range of possible affects that may be linked to increasing soil F, which include various types of ecotoxicity, altered Al chemistry, reduced P availability, and potential for increased dietary intakes of F, Al and aluminofluoride (AlFx) species over time. © 2015, Springer-Verlag Berlin Heidelberg.
McConchie J.,Opus International Consultants Ltd |
Webby G.,Opus International Consultants Ltd |
Morrow F.,Opus International Consultants Ltd |
Maas F.,Opus International Consultants Ltd |
Cox J.,Greater Wellington Regional Council
Journal of Hydrology New Zealand | Year: 2011
A sediment budget for the Hutt River was developed to assess the volume of sediment that needs to be removed to maintain hydraulic efficiency of the channel, and the potential environmental effects of sediment extraction along the river and at its mouth. The transport of both suspended sediment and bedload was calculated using the characteristics of the available sediment and flow records from Taita Gorge. There are no significant inputs of either sediment or water downstream of this location. The volume of suspended load was estimated using a sediment rating curve. Bedload transport was estimated using a range of theoretical equations relating sediment transport to flow and channel parameters, and the characteristics of the material forming the river bed and banks. The sediment transport models were validated using the cumulative change in sediment volume determined from repeated cross-section surveys, and the volume of sediment extracted from the river. Analysis of the sediment budget indicates that the average annual sediment transport, including suspended and bedload, downstream of Taita Gorge is approximately 104,000 m 3/year. The calculated average sediment transport rate compares favourably to that derived from the analysis of channel cross-sections and sediment extraction records (approximately 88,000 m 3/year). The difference is from material deposited downstream of the analysed cross-sections (and beyond the river mouth) which was not quantified, and also from errors in the cross-section data analysis and the records of sediment extraction volumes. Only 8% of the material transported downstream is bedload; the remaining 82% is suspended sediment. These estimates are consistent with other New Zealand data. The total volume of suspended sediment and bedload transported exceeds that removed for flood protection works, and extracted at the river mouth. The excess sediment contributes to aggradation of the river bed and harbour floor. Sediment transport varies considerably over time and is controlled largely by the number, magnitude, and duration of floods. The annual rate of sediment transport since 1987 has ranged from 75,000 to 139,000 m 3. Lower than average rates since 2004 reflect the lack of significant floods over this period. The calibrated sediment budget for the lower Hutt River is valuable for guiding river management and flood mitigation works, and assessing the potential environmental effects of human activities such as sediment extraction at the river mouth. © New Zealand Hydrological Society (2011).
PubMed | CSIC - Doñana Biological Station and Greater Wellington Regional Council
Type: Journal Article | Journal: Royal Society open science | Year: 2016
Declines in pollinator abundance and diversity are not only a conservation issue, but also a threat to crop pollination. Maintained infrastructure corridors, such as those containing electricity transmission lines, are potentially important wild pollinator habitat. However, there is a lack of evidence comparing the abundance and diversity of wild pollinators in transmission corridors with other important pollinator habitats. We compared the diversity of a key pollinator group, bumblebees (
McColl S.T.,Massey University |
McCabe M.,Greater Wellington Regional Council
Landslides and Engineered Slopes. Experience, Theory and Practice | Year: 2016
The size and abundance of active, soft-rock landslides in New Zealand results in extensive, but seldom quantified, damage to productive land. This study draws on case-studies of New Zealand farms affected by large, slow-moving landslides in Tertiary-aged strata, to explore the causes of movement, financial costs, and the current management strategies. While most of the landslides are initiated by stream incision and vary in speed depending on seasonal changes in groundwater, some of these landslides are initiated by as yet unidentified processes. The financial costs are severe and tend to be disproportionate to the area that the landslides occupy, significantly increasing the average per-hectare operating costs. The farmers receive little guidance on management, and in some cases their actions may worsen, rather than reduce movement. Effective management strategies may involve slowing movement, minimizing damage, or retirement of the land, but the scale of the problem renders complete arrest unfeasible. © 2016 Associazione Geotecnica Italiana, Rome, Italy.
Heath M.,Greater Wellington Regional Council |
Wood S.A.,Cawthron Institute |
Wood S.A.,University of Waikato |
Young R.G.,Cawthron Institute |
Ryan K.G.,Victoria University of Wellington
FEMS Microbiology Ecology | Year: 2016
Benthic proliferations of the cyanobacteria Phormidium can cover many kilometres of riverbed. Phormidium can produce neurotoxic anatoxins and ingestion of benthic mats has resulted in numerous animal poisonings in the last decade. Despite this, there is a poor understanding of the environmental factors regulating growth and anatoxin production. In this study, the effects of nitrogen and phosphorus on the growth of two Phormidium strains (anatoxin-producing and non-anatoxin-producing) were examined in batch monocultures. Cell concentrations were significantly reduced under reduced nitrogen (ca. < 0.100 mM) and phosphorus conditions (ca. < 0.003 mM). Cell concentrations and maximum growth rates were higher for the non-anatoxin-producing strain in all treatments, suggesting there may be an energetic cost to toxin production. Cellular anatoxin concentrations were lowest (169 fg cell-1) under the high-nitrogen and high-phosphorus treatment. This supports the growth-differentiation balance hypothesis that suggests actively dividing and expanding cells are less likely to produce secondary-metabolites. Anatoxin quota was highest (> 407 fg cell-1) in the reduced phosphorus treatments, possibly suggesting that it is produced as a stress response to growth limiting conditions. In all treatments there was a 4-5-fold increase in anatoxin quota in the lag growth phase, possibly indicating it may provide a physiological benefit during initial substrate colonization. © FEMS 2016.
Olson D.,Victoria University of Wellington |
Kennedy D.M.,Greater Wellington Regional Council |
Dawe I.,Aurecon |
Calder M.,Victoria University of Wellington
Earth Surface Processes and Landforms | Year: 2012
Uplift of the shoreline in tectonically-active areas can have a profound influence on geomorphology changing the entire process dynamics of the coast as the landforms are removed from the influence of the sea. Over decadal timescales it is possible for the landforms to return to their pre-earthquake condition and this paper examines the re-establishment of mixed sand and gravel beaches on the coast of Wellington, New Zealand, subsequent to an uplift event in 1855. Over 60 topographic profiles were surveyed, seven sets of aerial photographs from a 67year period were mapped and sediment size analyses conducted in order to quantify the nature of beach change following uplift, and associated relative sea level fall. These data were supported by surveys using ground penetrating radar. It is found that uplift raised the gravel beaches out of the swash zone thereby removing them from the littoral zone. Intertidal rocky reefs which occur between each embayment were also uplifted during the same event and completely interrupted the longshore transport system. Continued input of gravel material to the littoral zone allowed beaches to re-establish sequentially along the coast as each embayment was infilled with sediment. This reconnection of the embayments with the longshore drift system is associated with the beach planform being initially drift dominated during infill but then switching to swash alignment once the embayment becomes infilled. This has resulted in shoreline accretion of over 100m in some places, at rates of up to 4m/yr, covering shore protection works built in the past few decades. The ability of the shore to adjust back to its pre-uplift condition appears to be a function of the accommodation space created during uplift and the rate of sediment supply. © 2012 John Wiley & Sons, Ltd.
Ancelet T.,Institute of Geological & Nuclear Sciences |
Ancelet T.,Victoria University of Wellington |
Davy P.K.,Institute of Geological & Nuclear Sciences |
Mitchell T.,Greater Wellington Regional Council |
And 3 more authors.
Environmental Science and Technology | Year: 2012
Particulate matter (PM) sources at two different sites in a rural town in New Zealand were investigated on an hourly time-scale. Streaker samplers were used to collect hourly, size-segregated PM10-2.5 and PM2.5 samples that were analyzed for elemental content using ion beam analysis techniques. Black carbon concentrations were determined using light reflection and PM10 concentrations were recorded using colocated continuous PM monitors. PM10 concentrations at both sites displayed a diurnal pattern, with hourly PM10 concentration maxima in the evening (7 pm-midnight) and in the morning (7-9 am). One of the monitoring sites experienced consistently higher average PM10 concentrations during every hour and analysis indicated that katabatic flows across the urban area contributed to the increased concentrations observed. Source apportionment using positive matrix factorization on the hourly data revealed four primary PM 10 sources for each site: biomass burning, motor vehicles, marine aerosol and crustal matter. Biomass burning was the most dominant source at both sites and was responsible for both the evening and morning PM10 concentration peaks. The use of elemental speciation combined with PM 10 concentrations for source apportionment on an hourly time-scale has never been reported and provides unique and useful information on PM sources for air quality management. © 2012 American Chemical Society.
PubMed | Victoria University of Wellington, Greater Wellington Regional Council and Cawthron Institute
Type: Journal Article | Journal: FEMS microbiology ecology | Year: 2016
Benthic proliferations of the cyanobacteria Phormidium can cover many kilometres of riverbed. Phormidium can produce neurotoxic anatoxins and ingestion of benthic mats has resulted in numerous animal poisonings in the last decade. Despite this, there is a poor understanding of the environmental factors regulating growth and anatoxin production. In this study, the effects of nitrogen and phosphorus on the growth of two Phormidium strains (anatoxin-producing and non-anatoxin-producing) were examined in batch monocultures. Cell concentrations were significantly reduced under reduced nitrogen (ca. <0.100 mM) and phosphorus conditions (ca. <0.003 mM). Cell concentrations and maximum growth rates were higher for the non-anatoxin-producing strain in all treatments, suggesting there may be an energetic cost to toxin production. Cellular anatoxin concentrations were lowest (169 fg cell(-1)) under the high-nitrogen and high-phosphorus treatment. This supports the growth-differentiation balance hypothesis that suggests actively dividing and expanding cells are less likely to produce secondary-metabolites. Anatoxin quota was highest (>407 fg cell(-1)) in the reduced phosphorus treatments, possibly suggesting that it is produced as a stress response to growth limiting conditions. In all treatments there was a 4-5-fold increase in anatoxin quota in the lag growth phase, possibly indicating it may provide a physiological benefit during initial substrate colonization.