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.

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diel循环缺氧是否会改变贝类对夏末严重缺氧事件的敏感性。在本研究中，沿富营养化梯度的5个位置使海湾扇贝（Argopecten irradians）适应了50天，其中扇贝很少，偶尔和经常遇到缺氧条件。在实验室实验中，然后将扇贝暴露于24小时缺氧事件中，并在初始氧气下降期间，长期缺氧期间以及恢复常氧后一小时内，用无创红外传感器记录心跳率。无论适应环境如何，在缺氧期间，扇贝都会持续增加心跳率，但是在适应过程中经常遇到缺氧的扇贝，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受到接触史的影响，接触史可能会对扇贝的生态生理和动态沿海环境的适应力产生重要影响。