Environmental and Life Sciences Graduate Program, Trent University, Peterborough, ON, K9J 5G7, Canada.
Ontario Ministry of Natural Resources and Forestry, Aquatic Research and Monitoring Section, Codrington Fisheries Research Facility, Codrington, ON, K0K 1R0, Canada.
J Therm Biol. 2023 Feb;112:103482. doi: 10.1016/j.jtherbio.2023.103482. Epub 2023 Jan 14.
Critical thermal maximum (CT) is widely used for measuring thermal tolerance but the strong effect of acclimation on CT is a likely source of variation within and among studies/species that makes comparisons more difficult. There have been surprisingly few studies focused on quantifying how quickly acclimation occurs or that combine temperature and duration effects. We studied the effects of absolute temperature difference and duration of acclimation on CT of brook trout (Salvelinus fontinalis), a well-studied species in the thermal biology literature, under laboratory conditions to determine how each of the two factors and their combined effects influence critical thermal maximum. Using an ecologically-relevant range of temperatures and testing CT multiple times between one and 30 days, we found that both temperature and duration of acclimation had strong effects on CT. As predicted, fish that were exposed to warmer temperatures longer had increased CT, but full acclimation (i.e., a plateau in CT) did not occur by day 30. Therefore, our study provides useful context for thermal biologists by demonstrating that the CT of fish can continue to acclimate to a new temperature for at least 30 days. We recommend that this be considered in future studies measuring thermal tolerance that intend to have their organisms fully acclimated to a given temperature. Our results also support using detailed thermal acclimation information to reduce uncertainty caused by local or seasonal acclimation effects and to improve the use of CT data for fundamental research and conservation planning.
临界热最大值 (CT) 被广泛用于测量耐热性，但驯化对 CT 的强烈影响可能是导致研究/物种内部和之间变异的一个来源，这使得比较更加困难。令人惊讶的是，很少有研究集中于量化驯化发生的速度，或者将温度和持续时间的影响结合起来。我们在实验室条件下研究了驯化的绝对温度差异和持续时间对溪红点鲑 (Salvelinus fontinalis) CT 的影响，溪红点鲑是热生物学文献中研究较多的物种，以确定这两个因素及其组合效应对临界热最大值的影响。我们使用了生态相关的温度范围，并在 1 至 30 天之间多次测试 CT，发现驯化的温度和持续时间都对 CT 有很强的影响。正如预测的那样，暴露在更高温度下更长时间的鱼类 CT 会增加，但到第 30 天仍未完全驯化（即 CT 达到稳定）。因此，我们的研究通过表明鱼类的 CT 可以继续适应新温度至少 30 天，为热生物学家提供了有用的背景信息。我们建议在未来旨在使生物完全适应特定温度的测量耐热性的研究中考虑这一点。我们的结果还支持使用详细的热驯化信息来减少由局部或季节性驯化效应引起的不确定性，并提高 CT 数据在基础研究和保护规划中的使用。
