RESUMO
The study aimed to estimate economic losses associated with heat stress in the eight dairy production regions (DPR), defined by the Dairy Chilean Consortium, using two comfort thermal indices, namely, the temperature-humidity index (THI) and the THI adjusted for solar radiation and wind speed (THIa). Hourly records from 19 weather stations (Nov - Mar 2017-2022) were collected to estimate the comfort thermal indices. The economic impact was estimated considering a critical threshold of 65 for both indices and the effect of higher values on loss in milk yield, days open, culling rate, and deaths. There were differences in the number of hours above the threshold among DPRs, independent of the thermal index used (P < 0.01). The greatest values were observed in DPRs I, II, and VIII, which concentrate most dairy cows. Average losses in milk yield were between 2.0 and 6.4 times higher when THIa was used instead of THI, which also depends on the DPR (P < 0.01). These estimations coincide with those observed empirically by producers. The lowest average economic losses per cow during the summer season (5 seasons average) occurred in DPR VI (US $ 91.5), and the highest losses were observed in DPR I (US $ 184.2) both using THIa. At the country level, economic losses fluctuate between US $ 29.0 and 108.4 million per summer season, depending on the comfort thermal index used. Finally, heat stress impacts negatively and significantly the Chilean dairy sector, which is highly dependent on the DPR.
Assuntos
Indústria de Laticínios , Transtornos de Estresse por Calor , Animais , Chile , Bovinos , Indústria de Laticínios/economia , Feminino , Transtornos de Estresse por Calor/economia , Transtornos de Estresse por Calor/veterinária , Umidade , Leite/economia , Temperatura Alta/efeitos adversos , Doenças dos Bovinos/economia , Doenças dos Bovinos/epidemiologia , Temperatura , Lactação , Estações do AnoRESUMO
The surfgrass Phyllospadix scouleri grows in highly productive meadows along the Pacific coast of North America. This region has experienced increasingly severe marine heatwaves (MHWs) in recent years. Our study evaluated the impact of consecutive MHWs, simulated in mesocosms, on essential ecophysiological features of P. scouleri. Overall, our findings show that the plants' overall physiological status has been progressively declining. Interestingly, the indicators of physiological stress in photosynthesis only showed up once the initial heat exposure stopped (i.e., during the recovery period). The warming caused increased oxidative damage and a decrease in nitrate uptake rates. However, the levels of non-structural carbohydrates and relative growth rates were not affected. Our findings emphasize the significance of incorporating recovery periods in this type of study as they expose delayed stress responses. Furthermore, experiencing consecutive intense MHWs can harm surfgrasses over time, compromising the health of their meadows and the services they offer to the ecosystem.
Assuntos
Ecossistema , Zosteraceae , Estresse Fisiológico , Fotossíntese , CarboidratosRESUMO
The global average temperature will increase by up to 5.7 °C, under high greenhouse gas emissions, consequently increasing the frequency of heatwaves, according to recent IPCC forecasts. These especially impacts ectotherms, such as insects, which are the most susceptible animals to changes in environmental temperature, affecting their physiology and reproduction. Thus, we investigated the effects of a 96-h exposure to constant temperatures (CT: 27, 30.5, 34, 39, 41, or 43 °C) and fluctuating temperatures (FT: 27/34 °C, 12/12 h) on the survival, metabolic rate, and oviposition of the female cricket Gryllus (Gryllus) assimilis (Orthoptera: Gryllidae). Mortality, body mass and water content of females and males were quantified and compared. It was found that CT27, CT34 and FT27/34 do not cause mortality in females of G. (G.) assimilis. CT30.5 (average temperature between 27 and 34), despite causing mortality of 5.0 ± 3.5%, do not differ from CT27, CT34 or FT27/34. CT39 causes a mortality of 8.3 ± 5.5%. Estimated lethal temperature for 50% of the population of females (LT50Temp) is 40 °C, and 43 °C promotes 100% mortality in 96 h. Comparing mortality between sexes, females present higher LT50Temp and thermotolerance than males. In addition, FT27/34 and CT34 do not differ in the metabolic rate, but both have higher values than CT27. CT34 strongly reduces oviposition in females, however FT27/34 does not. We suggest that CT34 reduces oviposition in females in two ways: by affecting the endocrine system related to egg production, or by causing behavioral egg retention, as a strategy to survive thermal stress. Moreover, females had a higher wet body mass and present a lower average weight loss than males. In conclusion, despite females present a higher mortality at temperatures above 39 °C, they are more thermotolerant than males. Furthermore, CT34 is detrimental to the oviposition of G. (G.) assimilis.
Assuntos
Gryllidae , Termotolerância , Masculino , Animais , Feminino , Temperatura , Gryllidae/fisiologia , Oviposição , ReproduçãoRESUMO
Abstract Increased frequency of heat waves (HWs) is one of the prominent consequences of climate change. Its impact on human health has been mostly reported in the northern hemisphere but has been poorly studied in the southern hemisphere. The aim of this study was to analyze the effects of the HWs waves occurred in the warm season 2013-14 on mortality in the center-north region of Argentina, where 22 million people live. It was carried out an observational study of ecological-type contrasting the mortality occurred during the HWs of the summer 2013-14 with the mortality in the summers 2010-11 to 2012-13, free from HWs. The mortality was analyzed according to the following variables: place of residence, age, sex and cause of death. During the HWs of the summer 2013-14, 1877 (RR=1.23, 95%CI 1.20-1.28) deaths in excess were registered. Moreover, the death risk significantly increased in 13 of the 18 provinces analyzed. The mortality rates by sex revealed heterogeneous behaviour regarding both the time and spatial scale. The death risk increased with age; it was particularly significant in four provinces for the 60-79 years group and in six provinces in people of 80 years and over. The death causes that showed significantly increments were respiratory, cardiovascular, renal diseases and diabetes.
Resumo O aumento da frequência das ondas de calor (OsC) é uma das consequências proeminentes das alterações climáticas. O seu impacto na saúde humana tem sido relatado principalmente no hemisfério norte, mas tem sido mal estudado no hemisfério sul. O objetivo deste estudo foi analisar os efeitos das OsC ocorridas no verão de 2013-14 sobre a mortalidade na região centro-norte da Argentina, onde 22 milhões de pessoas vivem. Foi realizado um estudo observacional de tipo ecológico que contrasta a mortalidade ocorrida durante as OsC do verão 2013-14 com a mortalidade nos verões 2010-11 a 2012-13. A mortalidade foi analisada de acordo com local de residência, idade, sexo e causa de morte. Durante as OsC do verão de 2013-14, registaram-se 1.877 (RR=1.23, 95%IC 1.20-1.28) mortes em excesso. O risco de morte (RM) aumentou significativamente em 13 das 18 províncias analisadas. As taxas de mortalidade por sexo revelaram um comportamento heterogêneo tanto no tempo como na escala espacial. O RM foi aumentado com a idade; este aumento foi particularmente significativo em quatro províncias para o grupo de 60-79 anos e em seis províncias em pessoas com mais de 80 anos. As causas de morte que mostraram significativamente incrementos foram: doenças respiratórias, cardiovasculares, renais e diabetes.