School of Biological Sciences, Washington State University, Pullman, WA 99164, USA.
J Exp Biol. 2024 Sep 1;227(17). doi: 10.1242/jeb.248040. Epub 2024 Sep 6.
In natural environments, two or more abiotic parameters often vary simultaneously, and interactions between co-varying parameters frequently result in unpredictable, non-additive biological responses. To better understand the mechanisms and consequences of interactions between multiple stressors, it is important to study their effects on not only fitness (survival and reproduction) but also performance and intermediary physiological processes. The splash-pool copepod Tigriopus californicus tolerates extremely variable abiotic conditions and exhibits a non-additive, antagonistic interaction resulting in higher survival when simultaneously exposed to high salinity and acute heat stress. Here, we investigated the response of T. californicus in activity and oxygen consumption under simultaneous manipulation of salinity and temperature to identify whether this interaction also arises in these sublethal measures of performance. Oxygen consumption and activity rates decreased with increasing assay salinity. Oxygen consumption also sharply increased in response to acute transfer to lower salinities, an effect that was absent upon transfer to higher salinities. Elevated temperature led to reduced rates of activity overall, resulting in no discernible impact of increased temperature on routine metabolic rates. This suggests that swimming activity has a non-negligible effect on the metabolic rates of copepods and must be accounted for in metabolic studies. Temperature also interacted with assay salinity to affect activity, and with acclimation salinity to affect routine metabolic rates upon acute salinity transfer, implying that the sublethal impacts of these co-varying factors are also not predictable from experiments that study them in isolation.
在自然环境中，两个或更多的非生物参数通常同时发生变化，而共同变化的参数之间的相互作用经常导致不可预测的、非加性的生物反应。为了更好地理解多种胁迫因素之间的相互作用的机制和后果，研究它们对适应性（生存和繁殖）以及表现和中间生理过程的影响是很重要的。飞溅池桡足类加利福尼亚 T. californicus 能耐受极其多变的非生物条件，并表现出非加性的拮抗相互作用，当同时暴露于高盐度和急性热胁迫时，生存能力更高。在这里，我们研究了 T. californicus 在盐度和温度同时操纵下的活动和耗氧率的反应，以确定这种相互作用是否也出现在这些亚致死性能的测量中。耗氧率和活动率随着测定盐度的增加而降低。氧消耗也急剧增加，以响应急性转移到低盐度，而没有转移到高盐度。高温导致活动率整体降低，导致高温对常规代谢率没有明显影响。这表明游泳活动对桡足类的代谢率有不可忽视的影响，在代谢研究中必须加以考虑。温度也与测定盐度相互作用影响活动，与适应盐度相互作用影响急性盐度转移时的常规代谢率，这意味着这些共同变化因素的亚致死影响也不能从单独研究它们的实验中预测。
