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Metabolic heating caused by physiological processes during the development of oviparous embryos can raise nest temperatures above those of the surrounding substrate and may be sufficient to increase embryonic growth rates, influence sex ratios of hatchlings with temperature-dependent sex determination, and increase hatching success in seasonal environments. In sea turtles with large clutch sizes, metabolic heating can raise nest temperatures by as much as 6°C. However, no studies have directly investigated metabolic heating in any species of freshwater turtle. We investigated whether metabolic heating occurs in nests of snapping turtles (Chelydra serpentina) from southeastern Michigan, United States. A temperature logger was placed in the center of 8 unaltered snapping turtle nests. A second temperature logger was placed at the same depth in the surrounding substrate 5 cm from the side of the nest chamber. Metabolic heating is more pronounced in nests with larger clutches, so we artificially increased the size of 2 additional nests using donor clutches of 11 and 21 eggs, respectively. Temperatures were recorded at 2-hr intervals until after the presumptive hatch date of all nests. We found that there was a significant increase both in mean nest temperature and accumulated heat units for natural and experimental treatment nests during the last third of incubation. Further, in nests with experimentally increased clutch sizes, mean nest temperature was significantly greater than substrate temperature throughout incubation, suggesting that large nests also exhibit a thermal inertia that results in positive heat balance throughout development, at least in the soils studied. [ABSTRACT FROM AUTHOR]

Metabolic heating has been poorly investigated in eastern Mediterranean coastline of Turkey, which host some of the most important Green Turtle (Chelonia mydas) nesting sites in the Mediterranean. We studied the effects of clutch size and embryo numbers on nest temperature and discuss the feminizing effect of metabolic heating. Two test sites were conducted in Sugözü Beaches (Turkey). Data loggers were placed in eight nests with different clutch sizes. Nest temperature was strongly correlated with embryo numbers and metabolic heating produced by embryos was calculated to be 0.019°C per late stage embryo and 0.020°C per hatchling. Metabolic heating was calculated to be 0.6°C in the middle third of the incubation period during which sex is determined. It was estimated that metabolic heating increased 10.4% of female hatchlings. The heat produced by embryos should be taken into consideration while estimating sex ratios indirectly by nest and sand temperatures. Additionally, the metabolic heating value should be known for conservation measures, such as nest relocation, dividing the nest for controlling nest temperature, especially related to climate change. [ABSTRACT FROM PUBLISHER]

O objetivo deste trabalho foi avaliar o estado fisiológico da parte aérea das plantas de morangueiro das cultivares Gariguette e Elsanta durante estocagem em câmara fria (-2ºC), de janeiro a agosto. Pelo teste biológico, a capacidade de crescimento manteve-se alta, sem evolução significativa durante a estocagem. O fluxo de calor metabólico (Q) e a intensidade respiratória (RCO2) dos tecidos da zona apical, medidos pela microcalorimetria na saída da câmara fria, não evoluíram significativamente, mas aumentaram após 48 e 72 horas de aclimatação a 20ºC. Existiu um estreito paralelismo entre os valores de Q e RCO2 e da umidade ponderal (UP) dos tecidos. A parte aérea das plantas manteve a capacidade de crescimento mesmo após oito meses de estocagem.The aim of this work was to know the physiological state of the aerial part of strawberry plants (varieties Gariguette and Elsanta) during storage in cold chamber (-2ºC) from January until August. According to the biological test (petiole test), the growth capacity was kept up without significant evolution. The flow of metabolic heating (Q) and the respiratory intensity (RCO2) of the apical zone tissues measured at the exit of the cold chamber did not change significantly. Their values measured after 48 and 72 hours of acclimatization at 20ºC were higher than at the exit of the cold chamber. The differences between the values without acclimatization and after acclimatization increased during the first weeks of storage, showing an evolution in the apex of the plant. There was a strict parallelism between the values of Q and RCO2 and of the tissues water contents (UP). The growth capacity of the aerial part of the plants seemed to keep up even after 8 months of storage.

Climate change is threatening reproduction of many ectotherms by increasing nest temperatures, potentially making it more difficult for females to locate nest sites that provide suitable incubation regimes during embryonic development. Elevated nest temperatures could increase the incidence of embryonic mortality and/or maladaptive phenotypes. We investigated whether elevated nest temperatures reduce hatching success in tropical flatback turtles (Natator depressus) nesting in the Gulf of Carpentaria, Australia. Egg incubation treatments began at 29.5°C and progressively increased in temperature throughout incubation, up to maxima of 31, 32, 33, 34 and 35°C. Elevated nest temperatures did not reduce hatching success or hatchling body size relative to control temperatures (29.5°C), but did speed up embryonic development. A combination of sudden exposure to high temperatures during the first 2 weeks of incubation (>36°C for 48 h) and prolonged warming throughout incubation (from 29.5-35°C) did not reduce hatching success. We also recorded an unusually high pivotal sex-determining temperature in this flatback turtle population relative to other sea turtle populations: an equal ratio of male and female hatchlings is produced at ~30.4°C. This adaptation may allow some flatback turtle populations to continue producing large numbers of hatchlings of both sexes under the most extreme climate change scenarios. Some tropical populations of nesting flatbacks may possess important adaptations to high-temperature incubation environments, which are not found in more southerly temperate populations. [ABSTRACT FROM AUTHOR]

While climate change is now fully recognised as a reality, its impact on biodiversity is still not completely understood. To predict its impact, proxies coherent with the studied ecosystem or species are thus required. Marine turtles are threatened worldwide (though some populations are recovering) as they are particularly sensitive to temperature throughout their entire life cycle. This is especially true at the embryo stage when temperature affects both growth rates and sex determination. Nest temperature is thus of prime importance to understand the persistence of populations in the context of climate change. We analysed the nest temperature of 21 loggerheads ( Caretta caretta ) originating from Dalyan Beach in Turkey using day-lagged generalised mixed models with autocorrelation. Surprisingly, the selected model for nest temperature includes an effect for sea surface temperature 4-times higher than for air temperature. We also detected a very significant effect of metabolic heating during development compatible with what is already known about marine turtle nests. Our new methodology allows the prediction of marine turtle nest temperatures with good precision based on a combination of air temperature measured at beach level and sea surface temperature in front of the beach. These data are available in public databases for most of the beaches worldwide. [ABSTRACT FROM AUTHOR]

This study investigated the effects of hatchery shading, nest depth, and metabolic heating on the temperature of Chelonia mydas clutches incubated in hatcheries at Ma'Daerah, Terengganu, Malaysia. Metabolic heating was found to be the most influential factor on nest temperature; the number of completely developed eggs explained nearly half of the variation in mean nest temperature. The degree of hatchery shading (70% vs. 100%) and nest depth (50 vs. 75 cm) had little influence on nest temperatures, with mean nest temperatures between 288 and 28.68C in the first third of incubation (before metabolic heating of the clutch began to have an effect). Nests at a depth of 75 cm had significantly lower daily temperature ranges than nests at a depth of 50 cm, but a maximum mean daily range of 0.58C (50 cm depth in 70% shade hatchery) resulted in calculated constant temperature equivalents (CTE) being identical to observed mean nest temperatures. The results of this study indicate that, under current climatic conditions in this area, shading between 70% and 100% and nest depths between 50 and 75 cm will incubate green turtle clutches within the optimal temperature range for development. However, this information is site-specific and could vary significantly between locations due to the complex interaction of biological, chemical, and physical factors that influence sea turtle nest temperature. [ABSTRACT FROM AUTHOR]

Abstract: Offspring sex ratio is an important demographic parameter and, given its determination by incubation temperature in sea turtles, might be a key factor for their conservation under climate warming. An appealing approach to estimate hatchling sex ratios is to measure sand temperatures at nest depth and deduce hatchling sex ratios from a beforehand-established relationship of hatchling sex ratio and sand temperature. Such estimates will only be accurate though if metabolic heat produced by the embryos is considered. Judging whether metabolic heating has a potential effect on hatchling sex ratios without actually measuring temperature within clutches would greatly facilitate monitoring protocols. We tested for a relationship between the amount of metabolic heating and the number of developed embryos as well as clutch size in the largest known loggerhead sea turtle (Caretta caretta) population of the Mediterranean on Zakynthos (Greece). Temperatures were measured within 20 nests as well as at a reference site in the sand at nest depth. Metabolic heating was detected, but only during the last third of the incubation period did nests heat up considerably (1.6°C on average) above the temperature of the surrounding sand. During the middle third of incubation, when sex is determined, the amount of metabolic heating was negligible. The amount of metabolic heating during the last third of the incubation duration was significantly correlated to the number of offspring developed to at least about 75% of incubation duration. This factor explained nearly 50% of variation in metabolic heating. Metabolic heating was also significantly correlated to clutch size. Given that clutch size within the Mediterranean is largest in Zakynthos loggerheads, we conclude that metabolic heating can be ignored in the estimate of hatchling sex ratios in Mediterranean loggerhead populations. These results thus provide the basis for a feasible monitoring of hatchling sex ratios in the loggerhead sea turtle in the Mediterranean. [Copyright &y& Elsevier]

Whether a turtle embryo develops into a male or a female depends, as with many other reptiles, on the temperature during incubation of the eggs. With sea turtles, warm temperatures produce 100% females. Therefore, global warming has the potential to drastically alter their sex ratios. Air temperatures on Antigua have increased by 0.7°C over the last 35 years. Measurements in both the sand and the clutches laid by hawksbill turtles (Eretmochelys imbricata) at Pasture Bay, Antigua, show that for important parts of the nesting season temperatures are already above the level producing 50% of each sex (pivotal level). Comparisons are made to sand temperature measurements taken on this beach in 1989 and 1990. It is estimated that fewer males were produced in 2003 than in the previous years. Recommendations are made for close monitoring of the fertility of eggs and for research on any turtles nesting at cooler times of year. [ABSTRACT FROM AUTHOR]