Section of Terrestrial Ecology, Department of Ecoscience, Aarhus University, Aarhus, Denmark.
Section of Terrestrial Ecology, Department of Ecoscience, Aarhus University, Aarhus, Denmark.
J Therm Biol. 2024 Aug;124:103950. doi: 10.1016/j.jtherbio.2024.103950. Epub 2024 Aug 20.
Behavioural thermoregulation (thermotaxis) is essential for soil invertebrates to evade thermal extremes in terrestrial environments. Extensive and continuous use of copper (Cu) based products has led to elevated Cu concentration in soils across the globe and in some areas reaching concentrations that are hazardous to soil invertebrates. We hypothesised that environmental stressors, for example, exposure to heavy metals may compromise the adaptive behavioural thermoregulation of organisms, but very little is known of such interactions. In this study, we chose Cu as a model toxicant and investigated the potential effect of Cu-contaminated soils on the behavioural thermoregulation of springtails (Folsomia candida). We measured the distribution of springtails when placed on a temperature gradient ranging from 6 to 46 °C and estimated their thermal preference as an indicator of behavioural thermoregulation. Results showed that within 60 min of being introduced to the thermal gradient, the distribution of springtails was unimodal with slight skewness towards high temperature. Springtails exhibited a consistent preferred temperature range of approximately 21-23 °C across all Cu exposure levels and time points. However, Cu contamination increased the frequency of springtails recorded along the gradient where temperature was above 30 °C. We interpreted this observation as Cu-exposed animals having an elevated risk of entering heat coma and not being able to evade noxious temperatures. We conclude that Cu contamination does not alter the thermal preference of F. candida but compromises their ability to tolerate extreme high temperature. Incorporating behavioural responses into ecotoxicological assessments provides ecologically relevant insights into the impacts of chemical pollution on soil ecosystems.
行为体温调节（热趋性）对于土壤无脊椎动物在陆地环境中逃避极端温度至关重要。广泛和持续使用含铜（Cu）的产品导致全球土壤中 Cu 浓度升高，在某些地区达到对土壤无脊椎动物有害的浓度。我们假设，环境胁迫因素，例如暴露于重金属可能会损害生物体适应性的行为体温调节，但对此类相互作用知之甚少。在这项研究中，我们选择 Cu 作为模型毒物，并研究了受 Cu 污染的土壤对跳虫（Folsomia candida）行为体温调节的潜在影响。我们测量了跳虫在 6 到 46°C 的温度梯度上的分布，并将其热偏好作为行为体温调节的指标进行了估计。结果表明，在引入到热梯度 60 分钟内，跳虫的分布呈单峰型，略微偏向高温。跳虫在所有 Cu 暴露水平和时间点上都表现出约 21-23°C 的一致偏好温度范围。然而，Cu 污染增加了记录在温度高于 30°C 的梯度上的跳虫的频率。我们将这种观察解释为暴露于 Cu 的动物进入热昏迷的风险增加，并且无法逃避有害温度。我们得出结论，Cu 污染不会改变 F. candida 的热偏好，但会损害它们耐受极端高温的能力。将行为反应纳入生态毒理学评估中，为化学污染对土壤生态系统的影响提供了具有生态相关性的见解。
