ABSTRACT Coastal hypoxia can negatively impact shellfish, but it is unclear if exposure to intensifying diel-cycling hypoxia alters shellfish susceptibility to severe hypoxic events in late summer. In this study, bay scallops (Argopecten irradians) were acclimatized for 50 days at 5 sites along a eutrophication gradient, where scallops rarely, occasionally and frequently encountered hypoxic conditions. In a laboratory experiment, scallops were then exposed to a 24-h hypoxic event and heartbeat rates were recorded with non-invasive infrared sensors during the initial oxygen decline, during extended hypoxia, and for one hour after re-establishment of normoxia. Irrespective of acclimatization site, scallops sustained increased heartbeat rates during hypoxia, but cardiac responses were less pronounced in scallops that frequently encountered hypoxia during acclimatization. This study suggests that cardiac responses to changes in dissolved oxygen concentrations can be affected by exposure history, which may have important ramifications for scallop ecophysiology and resilience in dynamic coastal environments.

中文翻译：

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海湾扇贝 Argopecten irradians 沿富营养化梯度的适应：模拟缺氧事件期间心跳率测量的见解

摘要 沿海缺氧会对贝类产生负面影响，但尚不清楚暴露于加剧的日循环缺氧是否会改变贝类在夏末对严重缺氧事件的易感性。在这项研究中，海湾扇贝 (Argopecten irradians) 在沿富营养化梯度的 5 个地点适应了 50 天，扇贝很少、偶尔和经常遇到缺氧条件。在实验室实验中，扇贝随后暴露于 24 小时缺氧事件中，并在初始氧气下降期间、长期缺氧期间以及重新建立正常氧后一小时内使用非侵入性红外传感器记录心跳率。不考虑适应地点，扇贝在缺氧期间持续增加心跳率，但在适应过程中经常遇到缺氧的扇贝中，心脏反应不太明显。这项研究表明，心脏对溶解氧浓度变化的反应可能会受到暴露历史的影响，这可能对动态沿海环境中的扇贝生态生理学和恢复力产生重要影响。