scholarly journals Spatial and temporal variability in Phormidium mats and associated anatoxin-a and homoanatoxin-a in two New Zealand rivers

2011 ◽  
Vol 64 (1) ◽  
pp. 69-79 ◽  
Author(s):  
MW Heath ◽  
SA Wood ◽  
KG Ryan
Keyword(s):  
New Zealand ◽  
Temporal Variability ◽  
Spatial And Temporal Variability

scholarly journals Variability in glacier albedo and links to annual mass balance for the gardens of Eden and Allah, Southern Alps, New Zealand

2020 ◽  
Vol 14 (10) ◽  
pp. 3425-3448
Author(s):  
Angus J. Dowson ◽  
Pascal Sirguey ◽  
Nicolas J. Cullen
Keyword(s):  
New Zealand ◽  
Mass Balance ◽  
Temporal Variability ◽  
Conservation Status ◽  
Regional Climate ◽  
Southern Alps ◽  
Spatial And Temporal Variability ◽  
Climate Signal ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
High Consistency

Abstract. The gardens of Eden and Allah (GoEA) are two of New Zealand's largest ice fields. However, their remote location and protected conservation status have limited access and complicated monitoring and research efforts. To improve our understanding of the spatial and temporal changes in mass balance of these unique ice fields, observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors are used to monitor annual minimum glacier-wide albedo (α¯yrmin) over the period 2000–2018. The α¯yrmin for 12 individual glaciers ranges between 0.42 and 0.70 and can occur as early as mid-January and as late as the end of April. The evolution of the timing of α¯yrmin indicates a shift to later in the summer over the 19-year period on 10 of the 12 glaciers. However, there is only a weak relationship between the delay in timing and the magnitude of α¯yrmin, which implies that albedo is not necessarily lower if it is delayed. The largest negative departures in α¯yrmin (lower-than-average albedo) are consistent with high snowline altitudes (SLAs) relative to the long-term average as determined from the End of Summer Snowline (EOSS) survey, which has been the benchmark for monitoring glaciers in the Southern Alps for over 40 years. While the record of α¯yrmin for Vertebrae Col 25, an index glacier of the EOSS survey and one of the GoEA glaciers, explains less than half of the variability observed in the corresponding EOSS SLA (R2=0.43, p=0.003), the relationship is stronger when compared to other GoEA glaciers. Angel Glacier has the strongest relationship with EOSS observations at Vertebrae Col 25, accounting for 69 % of its variance (p<0.001). A key advantage in using the α¯yrmin approach is that it enables variability in the response of individual glaciers to be explored, revealing that topographic setting plays a key role in addition to the regional climate signal. The observed variability in individual glacier response at the scale of the GoEA contrasts with the high consistency of responses found by the EOSS record across the Southern Alps and challenges the suggestion that New Zealand glaciers behave as a unified climatic unit. MODIS imagery acquired from the Terra and Aqua platforms also provides insights about the spatial and temporal variability in clouds. The frequency of clouds in pixels west of the Main Divide is as high as 90 % during summer months and reaches a minimum of 35 % in some locations in winter. These complex cloud interactions deserve further attention as they are likely a contributing factor in controlling the spatial and temporal variability in glacier response observed in the GoEA.

Spatial and temporal variability in sediment deposition and seabed character on the Waipaoa River margin, New Zealand

2014 ◽  
Vol 86 ◽  
pp. 85-102 ◽  
Author(s):  
J.P. Walsh ◽  
D.R. Corbett ◽  
J.M. Kiker ◽  
A.R. Orpin ◽  
R.P. Hale ◽  
...  
Keyword(s):  
New Zealand ◽  
Temporal Variability ◽  
Sediment Deposition ◽  
Spatial And Temporal Variability

Evaluating Stocking Rate Impacts in Rangelands: Animals Don't Practice What We Preach.

1996 ◽  
Vol 18 (2) ◽  
pp. 216 ◽  
Author(s):  
AJ Ash ◽  
DMS Smith
Keyword(s):  
New Zealand ◽  
Temporal Variability ◽  
Simulation Models ◽  
Animal Production ◽  
Policy Framework ◽  
Government Printing ◽  
Spatial And Temporal Variability ◽  
United States Department ◽  
Stocking Rate ◽  
The Impact

paper session 29: Molecular biology - forage quality. In: Proc. XVII International Grassland Congress, pp. 1105-6. Keeling and Mundy Ltd., Palmerston North, New Zealand. United States Department of Agriculture. (1980). Report and recommendations on organic farming. U.S. Government Printing Office, Washington, DC. VanTassel, L. W., Heitschmidt, R.K. and Conner, J.R. (1987). Modeling variation in range calf growth under conditions of environmental uncertainty. J. Range. Manage. 40: 310-4. Walker, B.H. (1993). Stability in rangelands: ecology and economics. In: Proc. XW International Grassland Congress, pp. 1885-90. Keeling and Mundy Ltd., Palmerston North, New Zealand. Walker, J.W. (1994). Multispecies grazing: the ecological advantage. Sheep Res. J. Special Issue: 52-64. Walker, A.B., Frizelle, J.A. and Morris, S.D. (1994). The New Zealand policy framework for sustainable agriculture and some implications for animal production research. Proc. N. Z. Soc. Anim Prod. 54: 369-72. Walker, J.W., Heitschmidt, R.K., DeMoraes, E.A., Kothmann, M.M. and Dowhower, S.L. (1989). Quality and botanical composition of cattle diets under rotational and continuous grazing treatments. J. Range Manage . 42: 239-42. Whitson, R.E., Heitschmidt, R.K., Kothmann, M.M. and Lundgren, G.K. (1982). The impact of grazing systems on the magnitude and stability of ranch income in the Rolling Plains of Texas. J. Range Manage .35: 526-32. Wight, J.R. and Hanson, C.L. (1993). Simulation models as decision aids for management of rangeland ecosystems. In: Proc. XVII International Grassland Congress, pp. 770-1. Keeling and Mundy Ltd., Palmerston North, New Zealand. Wilson, A.D., Harrington, G.N. and Beale, I.F. (1984). Grazing management. In: Management of Australia's rangelands (Eds G.N. Harrington, A.D. Wilson and M.D. Young) pp. 129-40. Commonwealth Scientific and Industrial Research Organization, Australia. Wood, W.R. and Thiessen, T.D. (Eds) (1985). Early fur trade on the Northern Plains: the narratives of John Macdonnell, David Thompson, Francois-Antoine Laraocque and Charles McKenzie. University of Oklahoma Press, Norman, Oklahoma. Manuscript received 4 April 1996, accepted 30 July 1996. Rangel. J. 18(2) 1996, 216-43 EVALUATING STOCKING RATE IMPACTS IN RANGELANDS: ANIMALS DON'T PRACTICE WHAT WE PREACH A.J. Ash1 and D.M. Stafford Smith2 'CSIRO Division of Tropical Crops and Pastures, PMB, Aitkenvale, Qld 4814 2CSIR0 Division of Wildlife and Ecology, PO Box 2111, Alice Springs, NT 0871 Abstract Stocking rate is the most important management variable affecting productivity and stability in rangelands. In this paper we examine the relevance of stocking rate research to the complex and highly variable ecosystems that make up most rangeland enterprises. We review a number of stocking rate experiments that have been conducted in both rangelands and more intensively grazed, improved pastures and demonstrate a fundamental difference in the nature of the stocking rate - animal production relationship between the two environments. Animal production in rangelands is less sensitive to increases in utilisation rate than in improved pastures, at least in the short to medium time frame of most experiments. These differences can largely be explained by factors relating to the much greater spatial and temporal variability of rangelands such as: inter-annual and seasonal fluctuations in vegetation composition and quality; long-term vegetation changes; and spatial and temporal patterns of diet selection in complex vegetation. Together, these factors limit the application of linear stocking rate models to complex rangeland environments for prediction of animal production responses. We suggest that dynamic simulation models, which incorporate the spatial and temporal variability of rangelands, may be the best way of developing simple but useful management principles for setting stocking rates that are more appropriate than simplified regression relationships.

scholarly journals Spatial and Temporal Variability in the Development and Potential Toxicity of Phormidium Biofilms in the Tarn River, France

Toxins ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 418 ◽  
Author(s):  
Isidora Echenique-Subiabre ◽  
Maxime Tenon ◽  
Jean-François Humbert ◽  
Catherine Quiblier
Keyword(s):  
Risk Assessment ◽  
New Zealand ◽  
Environmental Conditions ◽  
Temporal Variability ◽  
Temporal Variations ◽  
Spatiotemporal Variability ◽  
Spatial And Temporal Variability ◽  
Summer Period ◽  
Potential Toxicity ◽  
Biofilm Development

Proliferation of Phormidium biofilms in rivers is becoming a worldwide sanitation problem for humans and animals, due to the ability of these bacteria to produce anatoxins. To better understand the environmental conditions that favor the development of Phormidium biofilms and the production of anatoxins, we monitored the formation of these biofilms and their toxins for two years in the Tarn River, biofilms from which are known to have caused the deaths of multiple dogs. As previously observed in New Zealand, Phormidium biofilm development occurred in riffle areas. The coverage of these biofilms at the bottom of the river exhibited strong spatial and temporal variations, but was positively correlated with water temperature and depth. Anatoxin-a was detected in less than 50% of the biofilms. The concentrations of these toxins in the biofilms exhibited high spatiotemporal variability, with the highest concentrations being recorded at the end of the summer period at the upstream sampling sites. These findings suggest that the maturity of the biofilms, combined with the local environmental conditions, have an impact on the production of anatoxin, making risk assessment for these benthic proliferations challenging.

Sign in / Sign up

Export Citation Format

Share Document