Cull F, Suski C D, Shultz A, Danylchuk A J, O'Connor C M, Murchie K J, Cooke S J
Fish Ecology and Conservation Physiology Laboratory, Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6.
Department of Natural Resources and Environmental Sciences, University of Illinois, Champaign, IL 61801, USA.
J Therm Biol. 2015 Jan;47:63-74. doi: 10.1016/j.jtherbio.2014.11.003. Epub 2014 Nov 7.
Anthropogenic climate change is altering temperature regimes for coastal marine fishes. However, given that temperature changes will not occur in isolation of other stressors, it is necessary to explore the potential consequences of stress on the thermal tolerances and preferences of tropical marine fish in order to understand the thresholds for survival, and predict the associated coastal ecological consequences. In this study, we used exogenous cortisol injections to investigate the effects of a thermal challenge on checkered puffers (Sphoeroides testudineus) as a secondary stressor. There were no significant differences between control and cortisol-treated fish 48h following cortisol treatment for swimming ability (using a chase to exhaustion protocol), blood glucose concentrations or standard metabolic rate. In the lab, control and cortisol-treated puffers were exposed to ambient (29.1±1.5°C), ambient +5°C (heat shock) and ambient -5°C (cold shock) for 4h and to evaluate the consequences of abrupt temperature change on puff performance and blood physiology. Following cold shock, control fish exhibited increases in cortisol levels and weak 'puff' performance. Conversely, fish dosed with cortisol exhibited consistently high cortisol levels independent of thermal treatment, although there was a trend for an attenuated cortisol response in the cortisol-treated fish to the cold shock treatment. A 20-day complementary field study conducted in the puffer's natural habitat, a tidal creek in Eleuthera, The Bahamas, revealed that cortisol-injected fish selected significantly cooler temperatures, measured using accumulated thermal units, when compared to controls. These results, and particularly the discrepancies between consequences documented in the laboratory and the ecological trends observed in the field, highlight the need to establish the link between laboratory and field data to successfully develop management policies and conservation initiatives with regards to anthropogenic climate change.
人为气候变化正在改变沿海海洋鱼类的温度状况。然而，鉴于温度变化不会孤立于其他压力源而发生，有必要探究压力对热带海洋鱼类热耐受性和偏好的潜在影响，以便了解生存阈值，并预测相关的沿海生态后果。在本研究中，我们使用外源皮质醇注射来研究热挑战作为次要压力源对花斑河鲀（Sphoeroides testudineus）的影响。在皮质醇处理48小时后，对照鱼和经皮质醇处理的鱼在游泳能力（采用追逐至疲惫方案）、血糖浓度或标准代谢率方面没有显著差异。在实验室中，将对照鱼和经皮质醇处理的河鲀暴露于环境温度（29.1±1.5°C）、环境温度+5°C（热休克）和环境温度-5°C（冷休克）下4小时，以评估温度突然变化对河鲀表现和血液生理学的影响。冷休克后，对照鱼的皮质醇水平升高，“吹气”表现较弱。相反，注射皮质醇的鱼无论热处理如何，皮质醇水平始终较高，尽管经皮质醇处理的鱼对冷休克处理的皮质醇反应有减弱的趋势。在巴哈马群岛伊柳塞拉的一条潮汐小溪（花斑河鲀的自然栖息地）进行的一项为期20天的补充野外研究表明，与对照鱼相比，注射皮质醇的鱼选择的温度明显更低（使用累积热量单位测量）。这些结果，尤其是实验室记录的结果与野外观察到的生态趋势之间的差异，凸显了建立实验室数据与野外数据之间联系的必要性，以便成功制定应对人为气候变化的管理政策和保护措施。
