scholarly journals Characteristics and Long-Term Trends of Heat Stress for South Africa

2021 ◽  
Vol 13 (23) ◽  
pp. 13249
Author(s):  
Katlego P. Ncongwane ◽  
Joel O. Botai ◽  
Venkataraman Sivakumar ◽  
Christina M. Botai ◽  
Abiodun M. Adeola
Keyword(s):  
South Africa ◽  
Heat Stress ◽  
Heat Exposure ◽  
Stress Conditions ◽  
Apparent Temperature ◽  
Trend Test ◽  
Significance Level ◽  
Long Term Trends ◽  
Geographical Locations

Increasing air temperature coupled with high humidity due to ongoing climate change across most parts of South Africa is likely to induce and intensify heat exposure, particularly in densely populated areas. The adverse health implications, including heatstroke, are expected to be common and more severe during extreme heat and heat wave events. The present study was carried out to examine heat stress conditions and long-term trends in South Africa. The study aimed to identify geographical locations exposed to elevated heat stress based on over two decades of hourly ground-based data. Selected heat stress indicators were calculated based on Steadman’s apparent temperature (AT in °C). The trends in AT were assessed based on the non-parametric Mann–Kendall (MK) trend test at 5% significance level. Positive trends were detected in 88% of the selected weather stations except in Welkom-FS, Ficksburg-FS, Langebaanweg-WC, Lambertsbaai Nortier-WC, Skukuza-MP, and Thabazimbi-LP. Approximately 47% of the detected positive trends are statistically significant at 5% significant level. Overall, high climatological annual median (ATmed) values (>32 °C) were observed at 42 stations, most of which are in low altitude regions, predominately along the coastlines. The hottest towns with ATmed values in the danger category (i.e., 39–50 °C) were found to be Patensie-EC (41 °C), Pietermaritzburg-KZN (39 °C), Pongola-KZN (39 °C), Knysna-WC (39 °C), Hoedspruit-LP (39 °C), Skukuza-MP (45 °C), and Komatidraai-MP (44 °C). The results provide insight into heat stress characteristics and pinpoint geographical locations vulnerable to heat stress conditions at the community level in South Africa. Such information can be useful in monitoring hotspots of heat stress and contribute to the development of local heat–health adaptation plans.

scholarly journals A Review of Factors to Consider for Permanent Cordon Establishment and Maintenance

Agronomy ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1811
Author(s):  
Patrick O’Brien ◽  
Roberta De Bei ◽  
Mark Sosnowski ◽  
Cassandra Collins
Keyword(s):  
Climate Change ◽  
Heat Stress ◽  
Vascular System ◽  
Vascular Diseases ◽  
Stress Conditions ◽  
Normal Flow ◽  
Training Techniques ◽  
Long Term Consequences ◽  
Over Time

Decisions made during the establishment and reworking of permanent cordon arms may have long-term consequences on vineyard health and longevity. This review aims to summarise several of the important considerations that must be taken into account during cordon establishment and maintenance. Commonly practiced cordon training techniques such as wrapping developing arms tightly around the cordon wire may result in a constriction of the vascular system, becoming worse over time and disrupting the normal flow of water and nutrients. Studies have shown that other factors of cordon decline such as the onset of vascular diseases may be influenced by pre-existing stress conditions. Such conditions could be further exacerbated by water and heat stress events, an important consideration as these scenarios become more common under the influence of climate change. Vineyard sustainability may be improved by adopting cordon training techniques which promote long-term vitality and avoid a reduction in vine defence response and the costly, premature reworking of vines.

Long-term trends in the competitive shore fishery along the KwaZulu-Natal coast, South Africa

2007 ◽  
Vol 42 (2) ◽  
pp. 216-236 ◽  
Author(s):  
P. Pradervand ◽  
B. Q. Mann ◽  
M. F. Bellis
Keyword(s):  
South Africa ◽  
Kwazulu Natal ◽  
Long Term Trends

scholarly journals Shift of symbiont communities in Acropora tenuis juveniles under heat stress

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e4055 ◽  
Author(s):  
Makiko Yorifuji ◽  
Saki Harii ◽  
Ryota Nakamura ◽  
Masayuki Fudo
Keyword(s):  
Heat Stress ◽  
Survival Rates ◽  
Thermal Conditions ◽  
Experimental Period ◽  
Ocean Warming ◽  
Stress Conditions ◽  
Algal Symbiont ◽  
Term Change ◽  
Acropora Tenuis

Ocean warming is a major threat to coral reefs, leading to an increasing frequency and amplitude of coral bleaching events, where the coral and its algal symbiont associations breakdown. Long-term change and resilience of a symbiont community in coral juveniles is thought to be one of the most important aspects for determining thermal tolerance of the coral holobionts; however, despite its importance, they are not well documented in both under elevated temperature and even under natural condition. Here we investigated changes in symbiont communities in juveniles of the coral Acropora tenuis under controlled heat stress conditions (30 °C, 31/32 °C) and natural variations in seawater temperatures (19–30 °C) for up to four months. Compared with the ambient temperature conditions, coral survival rates were higher when exposed to 30 °C, but survival rates decreased when exposed to 31/32 °C. Symbiodinium types A3, C1, and D1-4 were detected in the juveniles under all thermal conditions; however, in higher water temperatures (31/32 °C), both the prevalence of D1-4 Symbiodinium and the number of juveniles harboring only this type of symbiont increased after two to four months later. In contrast, colonies at lower temperatures (30 °C and ambient) harbored multiple clades of symbionts over the same experimental period. These results highlight the flexibility of the coral–Symbiodinium symbiosis for juvenile A. tenuis under variable thermal conditions. In particular, the benefit of the preferential association with type D1-4 can be considered as a response when under heat-stress conditions, and that could help corals to cope with ocean warming.

Long-term trends of heat stress and energy use implications in subtropical climates

2010 ◽  
Vol 87 (2) ◽  
pp. 608-612 ◽  
Author(s):  
Joseph C. Lam ◽  
Kevin K.W. Wan ◽  
S.L. Wong ◽  
Tony N.T. Lam
Keyword(s):  
Heat Stress ◽  
Energy Use ◽  
Long Term Trends

Long-term changes in the discharge regime in Finland

2010 ◽  
Vol 41 (3-4) ◽  
pp. 253-268 ◽  
Author(s):  
Johanna Korhonen ◽  
Esko Kuusisto
Keyword(s):  
Time Series ◽  
Peak Flow ◽  
Trend Test ◽  
Regulated Rivers ◽  
Annual Peak ◽  
Discharge Regime ◽  
Long Term Trends ◽  
Individual Time Series ◽  
Selection Of

This paper presents characteristics of the discharge regime, long-term trends and variability in Finland. A selection of long-term discharge records including both unregulated and regulated rivers and lake outlets were analysed up to the year 2004. In addition to individual time series, monthly and annual discharges from the territory of Finland were calculated for the period 1912–2004. The observed drought and flood periods are also discussed, as well as the connection between discharge regime and climate. Moreover, the periodicity of the time series is examined for a couple of sites. The Mann–Kendall trend test was applied to assess changes in annual, monthly and seasonal mean discharges, maximum and minimum flows and, in addition, the date of the annual peak flow. The trend analysis revealed no changes in mean annual flow in general, but the seasonal distribution of streamflow has changed. Winter and spring mean monthly discharges have increased at most of the observation sites. The spring peak has moved to an earlier date at over one-third of the sites. However, the magnitudes of spring high flow have not changed. Autumn flow did not show trends in general. Minimum flows have increased at about half of the unregulated sites.

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