Heart rate variability as a neurophysiological biomarker of stress and welfare in olive flounder (Paralichthys olivaceus) under varying stocking densities
不同放养密度下比目鱼压力和福利的神经生理学生物标志物:心率变异性
Abstract
This study sought to evaluate the physiological stress responses of olive flounder (Paralichthys olivaceus) to varying stocking densities by analyzing heart rate and heart rate variability (HRV). All experiments were conducted in flow-through tanks under both normal- and high-density conditions. Bio-loggers were implanted in the fish to continuously monitor their heart rates and HRV over a 25-day period. The collected data were processed using the Mercury software, using only high-quality heart rate data. To evaluate HRV, the coefficient of variation (CV) was calculated, offering a standardized measure of heart rate variability. The fish in the high-density environments exhibited significantly higher heart rates and lower HRVs than those in normal-density environments. Elevated plasma cortisol levels in the high-density group (p < 0.05) further validated the stress responses indicated by heart rate and HRV. These findings suggest that high-density conditions induce significant stress in olive flounder, potentially reducing physiological adaptability and autonomic nervous system balance due to sympathetic dominance. This underscores the importance of density management in aquaculture to enhance fish welfare and highlights HRV analysis as a reliable, non-invasive tool for stress assessment.
摘要
本研究旨在通过分析心率和心率变异性（HRV）来评估橄榄鲆（Paralichthys olivaceus）在不同养殖密度下的生理应激反应。所有实验均在流水养殖箱中进行，分别设置正常密度与高密度条件。实验鱼体内植入生物记录器，持续监测25天的心率与HRV数据。数据采用Mercury软件处理，仅使用高质量心率数据。为评估HRV，计算变异系数（CV）作为标准化的心率变异性指标。高密度环境中的鱼类心率显著高于正常密度环境中的鱼类，而心率变异性则显著降低。高密度组的血浆皮质醇水平升高（p < 0.05），进一步证实了心率和心率变异性所反映的压力反应。这些结果表明，高密度条件会诱导橄榄鲆显著应激，可能导致因交感神经优势而降低生理适应性和自主神经系统平衡。这凸显了水产养殖中密度管理的重要性，以提升鱼类福利，并强调心率变异性分析作为可靠、无创的压力评估工具的价值。
