How animals partition activity throughout the day is influenced by processes that affect supply and obtainability of resources. However, as resource supply and usability are often entrained by the same diurnal pattern, it has been difficult to disentangle their relative importance. Given the strong influence that tide has on the distribution and accessibility of resources, intertidal systems present opportunities to examine questions surrounding the drivers of activity patterns. Here, we used multisensory biologgers to study the activity patterns of a coastal marine predator, sicklefin lemon sharks ( Negaprion acutidens ), in a tidally driven environment. Hidden Markov models were used to identify relatively high and low locomotory activity states, which were used as proxies for behavioural–activity states and to examine the factors underpinning variation in activity patterns. Although tide governs the spatial distributions of this species and showed some effect on sharks’ activity, diurnal light patterns were the predominant factor influencing behavioural-activity patterns, with the probability of high activity peaking overnight. Temperature and body size also had minor negative influences on the probability of animals being in the high-activity state. Interestingly, sharks were least likely to be in a high-activity state during high tide, a time of presumed high resource supply, contradicting the common assumption that this species forages during high tide. We suggest that despite the importance of the accessibility of resources, functional constraints, such as sensory (e.g., visual) and mechanical (e.g., swimming) performance ultimately underpin the activity patterns of intertidal marine predators through their influence on foraging success.

中文翻译：

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评估控制沿海海洋顶级捕食者活动模式的约束

动物在一天中如何划分活动受到影响资源供应和可获得性的过程的影响。然而，由于资源供应和可用性通常受到相同的昼夜模式的影响，因此很难区分它们的相对重要性。鉴于潮汐对资源的分布和可及性的强烈影响，潮间带系统提供了研究围绕活动模式驱动因素的问题的机会。在这里，我们使用多感官生物记录器来研究沿海海洋捕食者镰鳍柠檬鲨 (Negaprion acutidens) 在潮汐驱动的环境中的活动模式。隐马尔可夫模型用于识别相对高和低的运动活动状态，它们被用作行为活动状态的代理，并检查支持活动模式变化的因素。尽管潮汐控制着该物种的空间分布并对鲨鱼的活动产生了一些影响，但昼夜光模式是影响行为活动模式的主要因素，高活动性的可能性在一夜之间达到峰值。温度和体型对动物处于高活动状态的概率也有轻微的负面影响。有趣的是，鲨鱼在涨潮期间最不可能处于高活动状态，这是一个假定资源供应充足的时期，这与该物种在涨潮期间觅食的普遍假设相矛盾。我们建议，尽管资源的可及性很重要，但功能限制，例如感官（例如，