Firth Britney L, Drake D Andrew R, Power Michael
Department of Biology, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.
Great Lakes Laboratory for Fisheries and Aquatic Sciences, Fisheries and Oceans Canada, Burlington, Ontario L7S 1A1, Canada.
Conserv Physiol. 2021 Aug 3;9(1):coab057. doi: 10.1093/conphys/coab057. eCollection 2021.
Anthropogenic stressors are predicted to increase water temperature, which can influence physiological, individual, and population processes in fishes. We assessed the critical thermal maximum (CT) of eastern sand darter (), a small benthic fish listed as threatened under the in Canada. Field trials were conducted stream side June-November 2019 in the Grand River, Ontario, to encompass a range of ambient water temperatures (7-25°C) for which agitation temperature (T) and CT were determined. Additional measures were taken in the comparatively more turbid Thames River to test the effect of turbidity on both measures. In the Grand, T and CT ranged from 23°C to 33°C and 27°C to 37°C, respectively, and both significantly increased with ambient water temperature, with a high acclimation response ratio (0.49). The thermal safety margin (difference between ambient temperatures and CT) was smallest in July and August (~11°C) indicating that eastern sand darter lives closer to its physiological limit in summer. The between-river comparison indicated that turbidity had no significant influence on T and CT. Comparison of CT with in-river temperatures suggested that mean stream temperature 24 hours before the trial was most important for determining CT. Fish mass, temperature variance and maximum temperature in the 24-hour period prior to the CT trial were also shown to have some effect on determining CT. Overall, study results better define the sensitivity of eastern sand darter to temperature changes across the growing season and provide information to assess the availability of suitable thermal habitat for conservation purposes.
预计人为压力源会使水温升高，这可能会影响鱼类的生理、个体和种群过程。我们评估了东部沙镖鲈（Etheostoma strigatum）的临界热最大值（CT），它是一种小型底栖鱼类，在加拿大被列为受威胁物种。2019年6月至11月在安大略省格兰德河的溪边进行了实地试验，以涵盖一系列环境水温（7 - 25°C），并确定了激惹温度（T）和临界热最大值（CT）。在相对更浑浊的泰晤士河还采取了额外措施，以测试浑浊度对这两个指标的影响。在格兰德河，激惹温度（T）和临界热最大值（CT）分别在23°C至33°C和27°C至37°C范围内，且两者均随环境水温显著升高，具有较高的驯化反应率（0.49）。热安全边际（环境温度与临界热最大值之间的差值）在7月和8月最小（约11°C），这表明东部沙镖鲈在夏季的生存接近其生理极限。河流间的比较表明，浑浊度对激惹温度（T）和临界热最大值（CT）没有显著影响。将临界热最大值（CT）与河内温度进行比较表明，试验前24小时的平均溪流温度对确定临界热最大值最为重要。还表明，在临界热最大值试验前24小时内的鱼体质量、温度变化和最高温度对确定临界热最大值也有一定影响。总体而言，研究结果更好地界定了东部沙镖鲈在整个生长季节对温度变化的敏感性，并提供了信息以评估用于保护目的的适宜热栖息地的可用性。
