Hopkins Marine Station, Department of Biology, Stanford University, Pacific Grove, CA 93950, USA
Hopkins Marine Station, Department of Biology, Stanford University, Pacific Grove, CA 93950, USA.
J Exp Biol. 2019 Sep 3;222(Pt 17):jeb203166. doi: 10.1242/jeb.203166.
Intertidal communities of wave-swept rocky shores have served as a powerful model system for experiments in ecology, and mussels (the dominant competitor for space in the mid-intertidal zone) play a central role in determining community structure in this physically stressful habitat. Consequently, the ability to account for mussels' physiological responses to thermal stress affects ecologists' capacity to predict the impacts of a warming climate on this ecosystem. Here, we examined the effect of heating rate on cardiac thermal tolerance in the ribbed mussel, , comparing populations from high and low sites in the intertidal zone where emersion duration leads to different mean daily heating rates. Two temperature-related cardiac variables were examined: (1) the critical temperature () at which heart rate (HR) precipitously declines, and (2) flatline temperature (FLT) where HR reaches zero. Mussels were heated in air at slow, moderate and fast rates, and HR was measured via an infrared sensor affixed to the shell. Faster heating rates significantly increased in high- but not low-zone mussels, and was higher in high- versus low-zone mussels, especially at the fastest heating rate. By contrast, FLT did not differ between zones, and was minimally affected by heating rate. As heating rate significantly impacted high- but not low-zone mussels' cardiac thermal tolerance, realistic zone-specific heating rates must be used in laboratory tests if those tests are to provide accurate information for ecological models attempting to predict the effects of increasing temperature on intertidal communities.
潮间带受波浪冲击的岩石海岸群落一直是生态学实验的有力模式系统，而贻贝（潮间带中部区域的主要竞争空间者）在确定该物理压力生境中的群落结构方面发挥着核心作用。因此，能够解释贻贝对热应激的生理反应能力会影响生态学家预测气候变暖对该生态系统影响的能力。在这里，我们研究了升温率对肋贻贝 心脏热耐受性的影响，比较了来自潮间带高、低区的种群，因为暴露时间导致不同的日平均升温率。我们研究了两个与温度相关的心脏变量：（1）心率（HR）急剧下降时的临界温度（ ），以及（2）心率降为零时的平板温度（FLT）。贻贝在空气中以缓慢、中等和快速的速率加热，并用贴在贝壳上的红外传感器测量 HR。更快的升温率显著增加了高区贻贝的 ，而高区贻贝的 高于低区贻贝，尤其是在最快的升温率下。相比之下，FLT 在不同区域之间没有差异，并且受升温率的影响最小。由于升温率显著影响了高区贻贝的心脏热耐受性，但如果这些测试要为试图预测温度升高对潮间带群落影响的生态模型提供准确信息，则必须在实验室测试中使用现实的特定区域升温率。
