Cape Eleuthera Institute, Eleuthera, The Bahamas.
Department of Biological Sciences, Florida International University, Miami, FL, USA.
J Fish Biol. 2023 Aug;103(2):336-346. doi: 10.1111/jfb.15448. Epub 2023 May 31.
Near-future climate change projections predict an increase in sea surface temperature that is expected to have significant and rapid effects on marine ectotherms, potentially affecting a number of critical life processes. Some habitats also undergo more thermal variability than others, and the inhabitants therefore must be more tolerant to acute periods of extreme temperatures. Mitigation of these outcomes may occur through acclimation, plasticity or adaptation, although the rate and extent of a species' ability to adjust to warmer temperatures is largely unknown, specifically as it pertains to effects on various performance metrics in fishes that inhabit multiple habitats throughout ontogenetic stages. Here, the thermal tolerance and aerobic performance of schoolmaster snapper (Lutjanus apodus Walbaum, 1792) collected from two different habitats were experimentally assessed under different warming scenarios (temperature treatments = 30, 33, 35, 36°C) to assess vulnerability to an imminently changing thermal habitat. Larger subadult and adult fish collected from a 12 m deep coral reef exhibited a lower critical thermal maximum (CT ) compared to smaller juvenile fish collected from a 1 m deep mangrove creek. However, the CT of the creek-sampled fish was only 2°C above the maximum water temperature measured in the habitat from which they were collected, compared to a CT that was 8°C higher in the reef-sampled fish, resulting in a wider thermal safety margin at the reef site. A generalized linear model showed a marginally significant effect of temperature treatment on resting metabolic rate (RMR), but there were no effects of any of the tested factors on maximum metabolic rate or absolute aerobic scope. Post hoc tests revealed that RMR was significantly higher for creek-collected fish at the 36°C treatment and significantly higher for reef-collected fish at 35°C. Swimming performance [measured by critical swimming speed] was significantly lower at the highest temperature treatment for creek-collected fish and trended down with each successive increase in temperature treatment for reef-collected fish. These results show that metabolic rate and swimming performance responses to thermal challenges are somewhat consistent across collection habitats, and this species may be susceptible to unique types of thermal risk depending on its habitat. We show the importance of intraspecific studies that couple habitat profiles and performance metrics to better understand possible outcomes under thermal stress.
未来的气候变化预测表明，海面温度将上升，这预计会对海洋变温动物产生重大且快速的影响，可能会影响到许多关键的生命过程。一些栖息地比其他栖息地经历更多的热波动，因此，这些栖息地的生物必须对急性的极端温度更耐受。这些结果可以通过适应、可塑性或适应性来缓解，尽管一个物种适应温暖温度的速度和程度在很大程度上是未知的，特别是因为它涉及到栖息在不同生境中的鱼类的各种性能指标的影响。在这里，从两个不同栖息地采集的石斑鱼（Lutjanus apodus Walbaum，1792）的热耐受性和有氧性能在不同的变暖情景（温度处理=30、33、35、36°C）下进行了实验评估，以评估它们对即将发生的热栖息地变化的脆弱性。从 12 米深的珊瑚礁中采集的较大亚成体和成年鱼的临界热最大值（CT）低于从 1 米深的红树林溪中采集的较小幼鱼。然而，与从采集鱼的栖息地测量到的最高水温相比，溪流采集的鱼的 CT 仅高 2°C，而在珊瑚礁采集的鱼的 CT 高 8°C，从而在珊瑚礁地点有更宽的热安全裕度。广义线性模型显示温度处理对静息代谢率（RMR）有一定程度的显著影响，但任何测试因素对最大代谢率或绝对有氧范围都没有影响。事后检验表明，在 36°C 处理下，溪流采集的鱼的 RMR 显著较高，在 35°C 处理下，珊瑚礁采集的鱼的 RMR 显著较高。在最高温度处理下，溪流采集的鱼的游泳性能[通过临界游泳速度测量]显著较低，而珊瑚礁采集的鱼的游泳性能随着温度处理的连续升高而呈下降趋势。这些结果表明，对热挑战的代谢率和游泳性能的反应在一定程度上在采集栖息地之间是一致的，并且这种物种可能容易受到特定类型的热风险的影响，具体取决于其栖息地。我们展示了结合栖息地概况和性能指标进行种内研究的重要性，以更好地了解热应激下可能出现的结果。
