Impacts of an anxiolytic drug on fish behaviour and habitat use in a natural landscape

Pharmaceutical contaminants reaching natural aquatic ecosystems can affect fish behaviour, modifying activity patterns, foraging behaviour, and antipredator responses. While laboratory-based studies can offer key insights, assessing the ecological relevance of these findings requires field-based approaches. Therefore, we examined the effects of oxazepam, a widely prescribed anxiolytic drug, on the behaviour of a cyprinid fish (the common roach, Rutilus rutilus) in the wild, combining slow-release exposure implants with continuous tracking via acoustic telemetry. To add ecological realism, we created a landscape of fear with an uneven distribution of resources (macrophytes) and exposure to predators (pike, Esox lucius), additionally testing the effects of the drug on roach habitat selection and predator-prey interactions. Fish exposed to the drug showed an increased swimming activity and speed, but exhibited a more constrained spatial distribution in the pond, favoring areas with higher refuge availability. Both exposed and unexposed fish modified their habitat use in the presence of predators. Exposed fish appeared to get closer to the predators when these were caged, but not when predators were free-roaming. Our findings highlight the importance of considering ecological context to understand how pharmaceuticals affect fish behaviour, which is crucial for assessing risks at population and ecosystem levels.

Our study had two experimental treatments: oxazepam exposure (control fish and oxazepam-exposed fish) and the landscape of fear predation treatment I. No predators, II. Caged predators, and III. Free-roaming predators, these stages are called conditions throughout. We separated the data into three data sets, one per week, representing the different stages of the predation treatment. Here we provide the data and code used for the analysis of fish positions to extract movement parameters and statistical analysis. There are six folders with the datasets and respective R scripts: data filtering, swimming activity, behavioral states, Habitat selection, Home range, and predator-prey interactions.

进入自然水生生态系统的药物污染物可影响鱼类行为，改变其活动模式、觅食行为以及反捕食响应。尽管基于实验室的研究可提供关键见解，但要评估这些发现的生态相关性，需采用野外研究方法。因此，我们在野外环境中探究了奥沙西泮(oxazepam)——一种临床广泛开具的抗焦虑药物——对鲤科鱼类普通欧鳊（Rutilus rutilus）行为的影响，结合了缓释暴露植入剂与声学遥测(acoustic telemetry)连续追踪技术。为增强研究的生态真实性，我们构建了“恐惧景观”：资源（大型水生植物）分布不均，且存在捕食者白斑狗鱼（Esox lucius）暴露风险，同时还探究了该药物对欧鳊栖息地选择以及捕食者-猎物相互作用的影响。
暴露于奥沙西泮的鱼类游泳活动量与游速均有所提升，但在池塘中的空间分布更为受限，更偏好避难所可获得性更高的区域。无论是否暴露于药物，鱼类在捕食者存在时均会改变其栖息地利用模式。当捕食者被笼养时，暴露于药物的鱼类会更接近捕食者，但当捕食者为自由活动时则无此现象。本研究结果凸显了考虑生态背景的重要性，这有助于理解药物如何影响鱼类行为，而这对评估种群与生态系统层面的风险至关重要。
本研究设置两类实验处理：一是奥沙西泮暴露处理（分为对照组鱼与奥沙西泮暴露组鱼），二是恐惧景观捕食处理，包含三个阶段：I. 无捕食者、II. 笼养捕食者、III. 自由活动捕食者，后续将这些阶段统称为“处理条件”。我们将数据按每周划分为三个数据集，分别对应捕食处理的不同阶段。本数据集附带用于鱼类位置分析、运动参数提取与统计分析的代码与原始数据。本次共享的数据集与对应R脚本共分为6个文件夹，分别为：数据过滤、游泳活动、行为状态、栖息地选择、家域范围以及捕食者-猎物相互作用。