Data from: Individual variation in whole animal hypoxia tolerance is associated with cardiac hypoxia tolerance in a marine teleost

Hypoxia is a pervasive problem in coastal environments and is predicted to have enduring impacts on aquatic ecosystems. Intraspecific variation in hypoxia tolerance is well documented in fish; however the factors underlying this variation remain unknown. Here, we investigate the role of the heart in individual hypoxia tolerance of the European sea bass (Dicentrarchus labrax). We found individual whole-animal hypoxia tolerance is a stable trait in sea bass for more than 18 months (duration of study). We next examined in vitro cardiac performance and found myocardial muscle from hypoxia-tolerant individuals generated greater force, with higher rates of contraction and relaxation, than hypoxic-sensitive individuals during hypoxic exposure. Thus whole animal hypoxia tolerance is associated with cardiac hypoxia tolerance. As the occurrence of aquatic hypoxia is expected to increase in marine ecosystems, our experimental data suggests that cardiac performance may influence fish survival and distribution.

低氧（hypoxia）是近岸海域普遍存在的环境问题，且预计会对水生生态系统造成持久影响。鱼类对低氧的种内耐受差异已有广泛研究记载，但该差异的潜在调控机制仍不明晰。本研究以欧洲海鲈（Dicentrarchus labrax）为实验对象，探究心脏在个体低氧耐受能力中的作用。研究发现，在本研究周期（18个月以上）内，欧洲海鲈的个体整体低氧耐受能力是一种稳定的性状。随后我们开展了离体（in vitro）心脏功能检测，结果显示：在低氧暴露条件下，低氧耐受个体的心肌所产生的收缩力更强，收缩与舒张速率也显著高于低氧敏感个体。由此可见，个体整体低氧耐受能力与心脏的低氧耐受能力密切相关。鉴于海洋生态系统中水生低氧事件的发生频率预计将持续上升，本实验数据表明心脏功能可能会影响鱼类的存活与种群分布。