Thermal related variations of seasonal and daily spawning periodicity in Barbus barbus

In 1993, nocturnal spawning activities were observed in the diurnal spawning cyprinid Barbus barbus . This behaviour is interpreted as a response to exceptionally high daily thermal amplitudes, regarded as the sign of an unpredictable environment.     

Seasonal variations in daily rhythms of activity in athletic horses

Circadian rhythms reflect extensive programming of biological activity that meets and exploits the challenges and opportunities offered by the periodic nature of the environment. In the present investigation, we recorded the total activity of athletic horses kept at four different times of the year (vernal equinox, summer solstice, autumn equinox and winter solstice), to evaluate the presence of seasonal variations of daily activity rhythms. Athletic Thoroughbred horses were kept in individual boxes with paddock. Digitally integrated measure of total activity of each mare was continuously recorded by actigraphy-based data loggers. Horse total activities were not evenly distributed over the day, but they were mainly diurnal during the year. Daily activity rhythms showed clear seasonal variations, with the highest daily amount of activity during the vernal equinox and the lowest during the winter solstice. Interestingly, the amount of activity during either photophase or scotophase changed significantly throughout the year. Circadian analysis of horse activities showed that the acrophase, the estimated time at which the peak of the rhythm occurs, did not change during the year, it always occurred in the middle of the photoperiod. Analysing the time structure of long-term and continuously measured activity and feeding could be a useful method to critically evaluate athletic horse management systems in which spontaneous locomotor activity and feeding are severely limited. Circadian rhythms are present in several elements of sensory motor and psychomotor functions and these would be taken into consideration to plan the training schedules and competitions in athletic horses.     

龟类野外活动节律的研究进展

龟类野外活动具有时间尺度上的差异性和周期性,温度、湿度、光照、天气、年龄和性别差异等各种因子对龟的野外活动有着不同程度的影响.从日活动、季节活动两个不同时间尺度对龟类野外活动节律的研究成果做了系统总结,将休眠作为一种特殊的季节活动进行了小结,并对影响龟类野外活动节律的相关因子进行了分析和探讨.     

Different behavior of body temperature and total locomotor activity daily rhythms during light/dark cycle in stabled Oryctolagus cuniculus

In order to investigate the potential causal link between the rhythm of activity and body temperature, we simultaneously recorded rectal temperature and total locomotor activity in five clinically healthy female rabbits (blue Vienna breed), 12 week old and mean body weight 2.7 ± 0.3. Animals were housed in individual cages (90?×?50?×?35 cm) under natural 12/12 light/dark cycle. Total locomotor activity was monitored for 15 days by an activity data logger. On day 1, 5, 10, and 15 rectal temperature was recorded every 2 h for a 24-h period. Application of single cosinor method showed a nocturnal daily rhythm of rectal temperature with a range of oscillation of about 1 °C, acrophase after dusk and low robustness value. The daily rhythm of locomotor activity showed its acrophase in the middle of the scotophase and a high robustness value. This information improves the knowledge available on the circadian biology of rabbits useful in the evaluation of physiology of this species.     

Seasonal cues act through the circadian clock and pigment-dispersing factor to control EYES ABSENT and downstream physiological changes

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河南内乡宝天曼国家级自然保护区豹猫及其潜在猎物之间日活动节律的季节性

日活动节律是动物应对食物可利用性、天敌捕食风险和环境条件等变化的适应性特征。阐明捕食者与猎物之间的日活动节律以及相关影响因素, 对于理解不同物种的生存策略、指导保护对策至关重要。然而, 由于采样方法的限制和人类干扰下的快速环境变化, 人们对许多野生动物日活动节律的了解并不全面, 甚至与实际情况存在偏差。以往认为夜行性的豹猫(Prionailurus bengalensis)被发现有一定程度的日间活动, 并增加晨昏活动, 这说明有必要深入调查豹猫等野生动物的昼夜节律为何存在这些变化。本研究在河南内乡宝天曼国家级自然保护区通过红外相机技术对豹猫及其潜在猎物进行调查, 基于核密度函数比较分析了豹猫与其潜在猎物在冷、暖季节的日活动节律。2016年全年设置了55个红外相机位点, 累计14,972个相机工作日, 获得豹猫及其潜在猎物的独立有效照片1,343张。结果显示, 该保护区内豹猫、蒙古兔(Lepus tolai)和鼠类以夜间活动为主, 其中豹猫有明显的晨昏活动高峰, 而赤腹松鼠(Callosciurus erythraeus)、岩松鼠(Sciurotamias davidianus)、红腹锦鸡(Chrysolophus pictus)和勺鸡(Pucrasia macrolopha)均在昼间活动。活动重叠度分析结果显示, 豹猫与夜行性的蒙古兔和鼠类在冷季和暖季均有较高重叠度(Δ ≥ 0.50), 但与其他猎物之间的重叠度均相对较低(Δ ≤ 0.40)。本研究显示豹猫及其猎物的昼夜节律既有保守性, 也具有一定的季节可塑性, 可能受到季节性猎物分布和环境变化的影响。因此, 需要加强调查研究来充分认识不同物种日活动节律的季节性变化规律及其驱动因素。     

Tenebrionid beetles in the shortgrass prairie: daily and seasonal patterns of activity and temperature

ABSTRACT. 1. Patterns of daily and seasonal activity for seven species of tenebrionid beetles, genus Eleodes , were investigated in the shortgrass prairie of northeastern Colorado. The relationship between time of activity, body temperatures, and rates of water loss of the beetles was examined in the field and in laboratory experiments.
2. Common species were active from April until the end of October; however, asynchronous peaks of abundance occurred.
3. Beetles were diurnally active with peaks of daily activity occurring 2–4 h after sunrise and before sunset. Less than a 2 h shift in mean time of activity occurred between seasons.
4. Within species, body temperatures measured in the field closely corresponded to temperatures selected in an experimental thermal gradient; hence, species seemed to prefer particular body temperatures and were most active during times when those temperatures could be achieved. Body temperatures measured in the field approximated ambient temperatures measured in the vicinity of the beetle.
5. Significant differences among several species were found for times of daily activity and corresponding body temperatures.
6. Ability to resist water loss by evaporation was not correlated with daily or seasonal activity patterns.     

Seasonal variation in enzyme activities and temperature sensitivities in Arctic tundra soils

Arctic soils contain large amounts of organic matter due to very slow rates of detritus decomposition. The first step in decomposition results from the activity of extracellular enzymes produced by soil microbes. We hypothesized that potential enzyme activities are low relative to the large stocks of organic matter in Arctic tundra soils, and that enzyme activity is low at in situ temperatures. We measured the potential activity of six hydrolytic enzymes at 4 and 20 °C on four sampling dates in tussock, intertussock, shrub organic, and shrub mineral soils at Toolik Lake, Alaska. Potential activities of N‐acetyl glucosaminidase, β‐glucosidase, and peptidase tended to be greatest at the end of winter, suggesting that microbes produced enzymes while soils were frozen. In general, enzyme activities did not increase during the Arctic summer, suggesting that enzyme production is N‐limited during the period when temperatures would otherwise drive higher enzyme activity in situ. We also detected seasonal variations in the temperature sensitivity (Q₁₀) of soil enzymes. In general, soil enzyme pools were more sensitive to temperature at the end of the winter than during the summer. We modeled potential in situβ‐glucosidase activities for tussock and shrub organic soils based on measured enzyme activities, temperature sensitivities, and daily soil temperature data. Modeled in situ enzyme activity in tussock soils increased briefly during the spring, then declined through the summer. In shrub soils, modeled enzyme activities increased through the spring thaw into early August, and then declined through the late summer and into winter. Overall, temperature is the strongest factor driving low in situ enzyme activities in the Arctic. However, enzyme activity was low during the summer, possibly due to N‐limitation of enzyme production, which would constrain enzyme activity during the brief period when temperatures would otherwise drive higher rates of decomposition.     

Seasonal variation in basal and plastic cold tolerance: Adaptation is influenced by both long‐ and short‐term phenotypic plasticity

Understanding how thermal selection affects phenotypic distributions across different time scales will allow us to predict the effect of climate change on the fitness of ectotherms. We tested how seasonal temperature variation affects basal levels of cold tolerance and two types of phenotypic plasticity in Drosophila melanogaster. Developmental acclimation occurs as developmental stages of an organism are exposed to seasonal changes in temperature and its effect is irreversible, while reversible short‐term acclimation occurs daily in response to diurnal changes in temperature. We collected wild flies from a temperate population across seasons and measured two cold tolerance metrics (chill‐coma recovery and cold stress survival) and their responses to developmental and short‐term acclimation. Chill‐coma recovery responded to seasonal shifts in temperature, and phenotypic plasticity following both short‐term and developmental acclimation improved cold tolerance. This improvement indicated that both types of plasticity are adaptive, and that plasticity can compensate for genetic variation in basal cold tolerance during warmer parts of the season when flies tend to be less cold tolerant. We also observed a significantly stronger trade‐off between basal cold tolerance and short‐term acclimation during warmer months. For the longer‐term developmental acclimation, a trade‐off persisted regardless of season. A relationship between the two types of plasticity may provide additional insight into why some measures of thermal tolerance are more sensitive to seasonal variation than others.     

Effect of temperature on circadian rhythm controlling the crepuscular activity of the burying beetle Nicrophorus quadripunctatus Kraatz (Coleoptera: Silphidae)

Locomotor activity rhythm was examined at various temperatures under a 16 h light : 8 h dark photoperiod (LD 16:8) or LD 12:12 using adults of the burying beetle Nicrophorus quadripunctatus. At 20°C, the locomotor activity of the beetles showed a bimodal daily pattern with two peaks around lights on and lights off under both photoperiods. This bimodal activity rhythm persisted under constant darkness; therefore, the activity of adult N. quadripunctatus is controlled by a circadian clock. Adults showed a bimodal activity pattern for temperatures ranging from 15 to 25°C. The evening peak of the daily activity was earlier at lower temperatures. These findings suggest that in the field, N. quadripunctatus shows crepuscular activity, and is active earlier in the afternoon in cooler seasons. In this species, therefore, temperature appears to play an important role in the determination of daily activity patterns.     

Diazepam affects both level and amplitude of rat locomotor activity rhythm but has no effect on core body temperature

The present study investigates the effects of a chronic administration of diazepam, a benzodiazepine widely used as an anxiolytic, on locomotor activity and body core temperature rhythms in male Wistar rats housed under 12∶12 light∶dark (LD) cycle conditions. Diazepam was administered subcutaneously for 3 wks in a dosage of 3 mg/kg body weight/day, 1 h before the onset of darkness. Diazepam increased the level of locomotor activity from the first day until the end of treatment, and also increased the amplitude of the activity circadian rhythm, but only on the third wk of treatment. Diazepam exerted no effects on the length of the period and did not affect the phase of the locomotor activity rhythm. The body temperature rhythm of rats was affected neither by short‐term (a single injection) nor by long‐term (every day for 3 wks) diazepam treatment. Diazepam lacked effect on body core temperature even on the first day of administration, thereby ruling out the possibility of drug tolerance development. The fact that diazepam affects locomotor activity, but not core body temperature, suggests that different mechanisms mediate the actions of diazepam on locomotor activity and on core body temperature.     

Diazepam affects both level and amplitude of rat locomotor activity rhythm but has no effect on core body temperature

The present study investigates the effects of a chronic administration of diazepam, a benzodiazepine widely used as an anxiolytic, on locomotor activity and body core temperature rhythms in male Wistar rats housed under 12:12 light:dark (LD) cycle conditions. Diazepam was administered subcutaneously for 3 wks in a dosage of 3 mg/kg body weight/day, 1 h before the onset of darkness. Diazepam increased the level of locomotor activity from the first day until the end of treatment, and also increased the amplitude of the activity circadian rhythm, but only on the third wk of treatment. Diazepam exerted no effects on the length of the period and did not affect the phase of the locomotor activity rhythm. The body temperature rhythm of rats was affected neither by short-term (a single injection) nor by long-term (every day for 3 wks) diazepam treatment. Diazepam lacked effect on body core temperature even on the first day of administration, thereby ruling out the possibility of drug tolerance development. The fact that diazepam affects locomotor activity, but not core body temperature, suggests that different mechanisms mediate the actions of diazepam on locomotor activity and on core body temperature.     

广州地区红火蚁工蚁的巢外活动及有翅蚁的婚飞规律

为了阐明红火蚁Solenopsis invicta Buren的发生危害规律,为制定红火蚁的监测与防治措施提供科学依据,本研究调查了广州地区（113°45′E,22°43′N）红火蚁工蚁巢外活动日节律和季节性变化,以及有翅蚁的婚飞活动。结果表明,工蚁巢外活动日节律随季节或月份的不同而存在着明显差异：其中12-2月份的日活动节律为单峰型,即在中午温度较高时数量较大,而在5-10月份的日活动节律为双峰型,即在上午或下午工蚁数量较大,其余月份的活动为不明显的双峰型。工蚁巢外活动数量和时间随季节的不同而有显著差异。其中以6月和10月份的日活动数量最多,而在1月和2月份的活动数量最少,时间最短,其余月份活动数量居中。工蚁在阵雨前后的活动数量明显多于晴天,但处于降雨时刻的巢外工蚁数量极少。蚁巢受侵扰后出巢工蚁数量在30 s内最大,之后便随时间的延长而逐渐减少,该种现象可以用房室函数进行描述。另外,工蚁的巢外数量会随侵扰强度的加大而增加。在试验区内全年都可见到红火蚁婚飞,但婚飞活动主要集中在3-5月份,每日婚飞活动主要发生在下午,并主要发生在雨前或雨后。上述结果对于了解我国红火蚁的发生危害规律和提升其监控技术水平有较大参考价值。     

An acoustic telemetry study of seabream (Sparus aurata L.): first results on activity rhythm,effects of environmental variables and space utilization

The movements of seabream (Sparus aurata L) were recorded in two earthen ponds (250 m² and 400 m²) by tracking fish tagged with miniature acoustic transmitters. Five seabreams, 500 g in weight, were tracked for periods of four or five days. Fish positions were recorded continuously using an acoustic telemetry system. Each of the five tagged seabreams were tracked individually. Two fishes were released schooled with numerous other individuals, two others were released in isolation and one was grouped with three other individuals.The schooled seabreams were more active in general and, in the large school they were diurnal; isolated fishes however, were more active at night. Temperature influences significantly and progressively the fish activity. Activity decreases at night and increases during daylight. Oxygen saturation also influences swimming activity with a general positive relationship.The horizontal distribution of this species was not uniform. Its resting area was generally located around some particular landmarks such as inlet or outlet pipes in the ponds. No feverish feeding competition was observed between individuals of the same school. The feeding area was cleaned rapidly, in less than 10 minutes, without subsequent returns from the resting area to the feeding area.

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Résumé Les déplacements de la daurade (Sparus aurata L.) ont été enregistrés dans deux bassins en terre (250 m² et 400 m²) en suivant des poissons marqués avec des émetteurs acoustiques miniaturisés. Cinq daurades d'un poids individuel de 500 g furent suivies durant des périodes de 4 ou 5 jours. Les positions des poissons ont été enregistrées en continu avec un systéme de télémétrie acoustique. Chacun des cinq poissons marqués fut suivi individuellement. Deux poissons furent regroupés avec de nombreux autres individus, deux autres furent laissés seuls et le dernier fut mis avec trois autres individus.Les daurades groupées étaient en général plus actives et, en grand banc, étaient diurnes; les poissons isolés étaient toutefois plus actifs durant la nuit. La température influence significativement et progressivement l'activité des poissons. L'activité décroît durant la nuit et augmente pendant le jour. Le pourcentage de saturation en oxygéne agit aussi, de façon positive, sur l'activité de nage.La distribution horizontale de cette espéce n'est pas uniforme. Son aire de repos est généralement localisée dans quelques zones particuliéres comme les arrivées et les sorties d'eau. Aucune compétition alimentaire fébrile n'a été observée entre les individus d'un même banc. L'aire de nourrissage est rapidement nettoyée, en moins de 10 minutes, sans retours ultérieurs depuis la zone de repos jusqu' à la zone de nourrissage.

     

Circadian and seasonal rhythms in the behavior of spinner dolphins (Stenella longirostris)

The present study investigated both circadian and seasonal fluctuations in the daytime activities of the spinner dolphin, Stenella longirostris , from the Fernando de Noronha Archipelago in Brazil. The number of dolphins, and aerial, and reproductive activities were documented. The observations were carried out from January 1997 to December 2001. Temporal series and rhythmic characteristics (mesor, rhythmic percentage, and acrophase) were obtained by COSINOR analysis and later compared. The dolphins entered the bay in the morning, displayed aerial and reproductive activities during daytime, and left the bay in late afternoon to the open ocean. This study indicated that the rainy season affected the three behaviors investigated decreasing the rhythms parameter and advancing the beginning of these activities. The number of individuals was higher during the dry season and the animals stayed longer inside the bay. During the dry season, there was a bimodal expression of aerial activity, expressing a longer use of the temporal niche than in the rainy season. The phases with high frequencies of aerial activity seemed associated with those showing high reproductive activity, both with peak frequencies at about 0800. The results represent an important contribution to the advancement of chronobiological studies, and to the biology of cetaceans, considering that the existence of circadian and seasonal rhythms was proven in the behavior of spinner dolphins in an area of the SW Atlantic. Moreover, it allows restricting periods of the day for the activities of tourism as a form of minimizing the impacts of the boats on the dolphins.     

Comparison of rectal and vaginal temperature daily rhythm in dogs (Canis familiaris) under different photoperiod

To investigate the daily rhythm of rectal and vaginal temperature, we used six mongrel dogs with a mean body weight of 15±3 kg, aged between 2 and 3 years old. Rectal and vaginal temperatures were recorded every 3 h over 48-h period during three different lighting regimes: natural light/dark (L/D) cycle (sunrise 06:25, sunset 17:05), constant light (L/L) and constant darkness (D/D). A daily rhythm of rectal temperature was observed in both days of monitoring in all experimental conditions. Vaginal temperature showed a daily rhythmicity in L/D and D/D cycle. During the L/L cycle, daily rhythm was disrupted. Rhythmic parameters (MESOR, amplitude, acrophase and robustness) did not change between the different photoperiod and the site of temperature collection. In conclusion, the monitoring of vaginal temperature can be considered a valid alternative to the monitoring of body temperature as well as rectal temperature under natural lighting conditions in canine medicine.     

Acoustic emission monitoring of the effect of temperature on activity rhythms of the subterranean termite Reticulitermes speratus

Daily activity rhythms are widespread characteristics among many organisms and are usually related to one or more physical environmental variables, such as light and temperature. Even organisms that are not obviously exposed to wide fluctuations in environmental variables, such as troglodytic and endogeic species, exhibit some daily activity patterns. Termites inhabit underground areas or tree trunks where little or no fluctuation in light occurs. In the present study, the activity rhythms of field colonies of the subterranean termite Reticulitermes speratus Kolbe (Blattodea: Termitidae) are examined, during all four seasons, by monitoring their acoustic emissions using a newly‐modified method. Nest temperature affects termite activity significantly during all four seasons. By contrast, no significant effect of time is observed during the different seasons, with the exception of autumn. Activity and nest temperature are negatively correlated in summer and autumn, although thay are are positively correlated during winter and spring. The greatest activity occurs at 23–25 °C. The experimental observations suggest that the activity of R. speratus termite colonies is affected mainly by ambient temperature, in a manner that is based on optimum temperature.     

Effects of different photoperiods on the reproduction of the barbel, Barbus barbus (L.), reared at constant temperature

The role of photoperiod as an environmental factor controlling reproduction, particularly the duration and ending of the breeding season, in the barbel was investigated by tank experiments. The experiments used a population of barbel matured in captivity which were stripped of eggs at frequent intervals: 10–15 'spawnings'for each female were obtained at 15-day intervals.
A decreasing photoperiod (16·5 light: 7·5 dark→8L: 16D), for an annual cycle contracted to 6 months duration, inhibited the spawning of both female and male fish. This allowed two periods of reproduction (February-May and September-November) within one year. Under natural or constant (10L: 14D) photoperiod conditions, spawning came to an end spontaneously. The rate (accelerated, slow or natural) of daylength increase did not affect the onset of spawning.     

同步遥测分析大鼠棕色脂肪产热与体温昼夜节律变化的时间关系

目的：同步遥测棕色脂肪组织（BAT）产热与体核温度昼夜律变化的时间曲线,分析二者昼夜节律变化的时间关系。方法：实验用成年雄性SD大鼠,在22℃环境温度下,明暗时间各12h,昼光时间为06：00h-18：00h,同步无线遥测体核温度（TC）、BAT温度（T队T）、腋窝温度（Tax）和动物活动的昼夜节律变化。结果：①在昼光中,TBAT较TC低0．67％,而在暗光中二者则相似。大鼠从昼光进入暗光时,TBAT升高的速率较TC升高速率快,开始上升的时间较TC提前8min;而从暗光进入昼光时,TBAT开始下降的时间则较TC提前4min。②Tax的昼夜节律幅度与TC相似,但无论动物在明光期或暗光期中,Tax均低于同步测量的TC。③从昼光期转入暗光期时,动物的行为活动出现增加反应先于TBAT和TC开始上升的时间。结论：实验结果证明,在暗光期中大鼠TC升高与BAT产热增加有关,说明BAT昼夜节律性产热的变化在维持体温昼夜生理节律中有重要的作用。