Ecosystem Management, School of Environmental and Rural Science, University of New England, Armidale, NSW, 2351, Australia.
Savanna Field Station, La Democracia, Belize District, Belize; College of Science and Engineering, James Cook University, Townsville, QLD, 4811, Australia.
J Therm Biol. 2024 Apr;121:103834. doi: 10.1016/j.jtherbio.2024.103834. Epub 2024 Mar 26.
Behavioural thermoregulation by ectotherms is an important mechanism for maintaining body temperatures to optimise physiological performance. Experimental studies suggest that nocturnal basking by Krefft's river turtles (Emydura macquarii krefftii) in the tropics may allow them to avoid high water temperatures, however, this hypothesis has yet to be tested in the field. In this study, we examined the influence of environmental temperature on seasonal and diel patterns of basking in E. m. krefftii in tropical north Queensland, Australia. Wildlife cameras were used to document turtle basking events for seven consecutive days and nights for each month over a year (April 2020-March 2021). Air and water temperatures were recorded simultaneously using temperature loggers. We used a negative binomial mixed effects model to compare mean basking durations (min) occurring among four environmental temperature categories based on population thermal preference (26 °C): 1) air temperature above and water temperature below preferred temperature; 2) air temperature below and water temperature above preferred temperature; 3) air and water temperatures both above preferred temperature; and 4) air and water temperatures both below preferred temperature. Basking behaviour was influenced significantly by the relationship between air and water temperature. During the day, turtles spent significantly less time basking when both air and water temperatures were above their preferred temperatures. Conversely, at night, turtles spent significantly more time basking when water temperatures were warm and air temperatures were cool relative to their preferred temperature. This study adds to the growing body of work indicating pronounced heat avoidance as a thermoregulatory strategy among tropical reptile populations.
变温动物的行为性体温调节是维持体温以优化生理表现的重要机制。实验研究表明，热带地区的克氏龟（Emydura macquarii krefftii）在夜间进行日光浴可能使它们避免水温过高，但这一假设尚未在野外得到验证。在这项研究中，我们研究了环境温度对澳大利亚热带北昆士兰州克氏龟季节性和昼夜日光浴模式的影响。野生动物摄像机用于记录一年中七个连续昼夜的海龟日光浴事件（2020 年 4 月至 2021 年 3 月）。使用温度记录仪同时记录空气和水的温度。我们使用负二项式混合效应模型，根据种群热偏好（26°C），比较了四个环境温度类别中的平均日光浴持续时间（分钟）：1）空气温度高于和水温度低于偏好温度；2）空气温度低于和水温度高于偏好温度；3）空气和水温度均高于偏好温度；4）空气和水温度均低于偏好温度。日光浴行为受到空气和水温度之间关系的显著影响。在白天，当空气和水的温度都高于它们的偏好温度时，海龟的日光浴时间明显减少。相反，在夜间，当水温和空气温度相对其偏好温度较暖且较凉爽时，海龟的日光浴时间明显增加。这项研究增加了越来越多的工作，表明热带爬行动物种群明显避免高温是一种体温调节策略。
