Laboratory Methods for Determining Temperature Preference

1977 ◽  
Vol 34 (5) ◽  
pp. 749-752 ◽  
Author(s):  
Robert W. McCauley

Different types of temperature-gradient devices used in the laboratory to determine temperature preferences of fish are classified and reviewed. The type of device used seems to have less effect on experimental results than do other variables such as age, size, season, physiological state, or social interactions. Key words: preferred temperature, thermal gradients, thermoregulation, behavioral, gradient devices, laboratory techniques

1978 ◽  
Vol 35 (11) ◽  
pp. 1430-1433 ◽  
Author(s):  
Wen-Hwa Kwain ◽  
Robert W. McCauley

During their first 12 mo of life rainbow trout, Salmo gairdneri, preferred progressively cooler temperatures as they grew older; 19 °C was selected during the 1st mo and the selected temperature declined by intervals of 0.5 °C for each of the following months up to the 3rd mo. Fish swam higher in temperature gradients exposed to overhead illumination than in those in total darkness. This trend was reversed during the following 9 mo. These findings demonstrate the important role that age plays in the temperature preference of this species and the influence that overhead light may have on the distribution of fish in vertical gradients. Key words: preferred temperature, age, Salmo gairdneri, light gradients


1980 ◽  
Vol 58 (4) ◽  
pp. 586-588 ◽  
Author(s):  
Peter H. Johansen ◽  
Jennifer A. Cross

In a horizontal temperature gradient, male guppies prefer a significantly lower temperature (24.5 °C) than females (28.2 °C) or juveniles (28.1 °C). Treatment of juveniles and females with testosterone lowers their preferred temperature to that of males. The reduction in the preferred temperature of testosterone-treated juveniles can occur without the development of male secondary sexual characters. Estrogen treatment of juveniles is without effect, as is treatment of males with estrogen or testosterone. It is postulated that testosterone acts at the level of the hypothalamic thermoregulatory centre.


1969 ◽  
Vol 101 (11) ◽  
pp. 1214-1218
Author(s):  
V. A. Dyck

AbstractNymphs and adults of Melanoplus sanguinipes (Fabricius) were placed, one stage at a time, into a temperature choice chamber. Their behavior was observed while a temperature gradient was established and then allowed to collapse. The grasshoppers aggregated and remained quiescent at a temperature of about 38 °C. An implication of this preferred temperature regarding behavior in the field is discussed.


1991 ◽  
Vol 81 (3) ◽  
pp. 273-276 ◽  
Author(s):  
Claudio R. Lazzari

AbstractThe thermal preference of adults of the reduviid bug Triatoma infestans (Klug) was investigated along a temperature gradient by means of video recording. The preferred temperature varied with a daily rhythm, reaching the highest value at the onset and the lowest at the end of the dark phase. The daily range of preferred temperatures depended on the starvation level. After feeding it was about 28–29°C, and after 12 days of starvation 25–26°C. The number of eggs laid showed a bimodal pattern, with maxima at 29°C and 26°C. Along a gradient of relative humidity, the bugs were always found around 40% r.h.


2019 ◽  
Author(s):  
Natalie Pilakouta ◽  
Shaun S. Killen ◽  
Bjarni K. Kristjánsson ◽  
Skúli Skúlason ◽  
Jan Lindström ◽  
...  

ABSTRACTGiven the threat of climate change to biodiversity, a growing number of studies are investigating the potential for organisms to adapt to rising temperatures through changes in their physiology, morphology, and behaviour. Earlier work has predicted that evolutionary adaptation to climate change will be accompanied by a shift in temperature preferences, but empirical evidence for this is limited. Here, we test whether exposure to a warm environment over multiple generations has led to the evolution of higher preferred temperatures in the wild. We have taken advantage of a ‘natural experiment’ in Iceland, where freshwater populations of threespine sticklebacks (Gasterosteus aculeatus) are found in waters warmed by geothermal activity year-round (warm habitats), adjacent to populations in ambient-temperature lakes (cold habitats). We hypothesised that sticklebacks from warm habitats would prefer higher water temperatures than those from cold habitats, but we found no support for this hypothesis. Fish from both warm and cold habitats had an average preferred temperature of 13°C, which is considerably lower than the temperatures experienced by fish in warm habitats for most of the year. Our results therefore challenge the assumption that temperature preferences in ectotherms will readily evolve as a response to climate change. Furthermore, the fact that warm-habitat fish are able to persist at relatively high temperatures despite a lower temperature preference suggests that preferred temperature may be a poor indicator of a population’s evolutionary potential and capacity to adapt to a novel thermal environment.


2020 ◽  
Vol 45 (4) ◽  
pp. 319-332
Author(s):  
Xiaoyu Chen ◽  
Ruquan Liang ◽  
Yong Wang ◽  
Ziqi Xia ◽  
Lichun Wu ◽  
...  

AbstractThe effect of the temperature gradient on the Soret coefficient in n-pentane/n-decane (n-C5/n-C10) mixtures was investigated using non-equilibrium molecular dynamics (NEMD) with the heat exchange (eHEX) algorithm. n-Pentane/n-decane mixtures with three different compositions (0.25, 0.5, and 0.75 mole fractions, respectively) and the TraPPE-UA force field were used in computing the Soret coefficient ({S_{T}}) at 300 K and 1 atm. Added/removed heat quantities (ΔQ) of 0.002, 0.004, 0.006, 0.008, and 0.01 kcal/mol were employed in eHEX processes in order to study the effect of different thermal gradients on the Soret coefficient. Moreover, a phenomenological description was applied to discuss the mechanism of this effect. Present results show that the Soret coefficient values firstly fluctuate violently and then become increasingly stable with increasing ΔQ (especially in the mixture with a mole fraction of 0.75), which means that ΔQ has a smaller effect on the Soret coefficient when the temperature gradient is higher than a certain thermal gradient. Thus, a high temperature gradient is recommended for calculating the Soret coefficient under the conditions that a linear response and constant phase are ensured in the system. In addition, the simulated Soret coefficient obtained at the highest ΔQ within three different compositions is in great agreement with experimental data.


Author(s):  
S Ganesh ◽  
M Mishra

Abstract Thermal systems have traditionally been modeled via Euclideanized space by analytical continuation of time to an imaginary time. We extend the concept to static thermal gradients by recasting the temperature variation as a variation in the Euclidean metric. We apply this prescription to determine the Quark anti-Quark potential in a system with thermal gradient. A naturally occurring QCD medium with thermal gradients is a Quark Gluon Plasma (QGP). However, the QGP evolves in time. Hence, we use a quasi-stationary approximation, which is applicable only if the rate of time evolution is slow. Hence the application of our proposal to a Quark anti-Quark potential in QGP can be seen as a step towards a more exact theory which would incorporate time varying thermal gradients. The effect of a static temperature gradient on the Quark anti-Quark potential is analyzed using a gravity dual model. A non-uniform black string metric is developed, by perturbing the Schwarzchild metric, which allows to incorporate the temperature gradient in the dual AdS space. Finally, an expression for the Quark anti-Quark potential, in the presence of a static temperature gradient, is derived.


1982 ◽  
Vol 39 (4) ◽  
pp. 548-553 ◽  
Author(s):  
Dilip Mathur ◽  
Robert M. Schutsky ◽  
Edmund J. Purdy Jr.

Acute temperature selection and avoidance responses of the crayfish, Orconectes obscurus, acclimated at field collection temperatures of 1.5–26.0 °C and determined in a spatial thermal gradient, were similar to those noted for fishes. Acclimation temperature was positively correlated with the acute preferred and avoided temperatures; both were several degrees higher than the acclimation temperature. A large proportion of the total variance in these data was unexplained. Most variable responses occurred at low acclimation temperatures. The estimated final preferred temperature ranged from 29.8 to 33.9 °C depending upon the method of calculation. Methods of estimating final preferenda from acute tests are considered arbitrary due to statistical problems and the associated high variability. Statistical problems were also noted in the determination of avoidance temperatures of crayfish due to nonindependence of observations on the same organism. No differences were noted (P < 0.05) between the preferred or avoided temperatures when the direction of field temperatures was rising or falling. A statistical comparison of the new and published data on this species revealed general similarities, particularly over an acclimation temperature range of 18.0–30.0 °C. The analysis minimizes the importance of site-specific studies on this species using the current acute testing methods.Key words: crayfish, temperature preference, avoidance, populational variation, statistics, experimental and statistical problems


2021 ◽  
Vol 7 (9) ◽  
pp. 709
Author(s):  
Eva Breyer ◽  
Markus Böhm ◽  
Magdalena Reitbauer ◽  
Chie Amano ◽  
Marilena Heitger ◽  
...  

Natural autofluorescence is a widespread phenomenon observed in different types of tissues and organisms. Depending on the origin of the autofluorescence, its intensity can provide insights on the physiological state of an organism. Fungal autofluorescence has been reported in terrestrial and human-derived fungal samples. Yet, despite the recently reported ubiquitous presence and importance of marine fungi in the ocean, the autofluorescence of pelagic fungi has never been examined. Here, we investigated the existence and intensity of autofluorescence in five different pelagic fungal isolates. Preliminary experiments of fungal autofluorescence at different growth stages and nutrient conditions were conducted, reflecting contrasting physiological states of the fungi. In addition, we analysed the effect of natural autofluorescence on co-staining with DAPI. We found that all the marine pelagic fungi that were studied exhibited autofluorescence. The intensity of fungal autofluorescence changed depending on the species and the excitation wavelength used. Furthermore, fungal autofluorescence varied depending on the growth stage and on the concentration of available nutrients. Collectively, our results indicate that marine fungi can be auto-fluorescent, although its intensity depends on the species and growth condition. Hence, oceanic fungal autofluorescence should be considered in future studies when fungal samples are stained with fluorescent probes (i.e., fluorescence in situ hybridization) since this could lead to misinterpretation of results.


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