Applicability of the gape monitor to study flat oyster (Ostrea edulis) feeding behaviour

innovative techniques are needed to assess oyster performance in flat oyster reef restoration projects. a valve gape monitor, a device that continuously measures opening and closing of live bivalves, can potentially be used as an effective method to determine survival and behaviour of the european flat oyster ostrea edulis. the method has been successfully used in combination with a number of bivalve species to investigate valve gape activity in response to environmental factors.in this study, eight o. edulis were equipped with valve gape sensors in order to relate gape to environmental conditions such as food availability. valve gape activity was monitored under controlled laboratory conditions, with and without food, in a concrete basin in the oosterschelde and in the field (voordelta, dutch north sea). under controlled laboratory conditions, oysters clearly responded to changes in food availability. starved oysters closed their valves significantly longer than oysters that received food, and the relative gape width in fed oysters were larger. in the concrete basin (oosterschelde), a positive correlation between valve opening and chlorophyll-a was found. additionally, valve gape activity and tidal movement appeared to be linked. when exposed to a full tidal cycle (voordelta), a negative correlation between valve opening and chlorophyll-a was found. however, there was no correlation between valve gape and current velocity. in autumn, longer periods of inactivity were seen, but when valves opened, the valve gape was larger. these data indicate that valve gape can provide valuable information on behaviour (gape frequency and gape width), but also show that it is not necessarily a good proxy for feeding rate. nevertheless, these results show that the gape monitor can be used to determine the natural behaviour of flat oysters under field conditions, and that gape opening provides information on behaviour and the stress response of bivalves to environmental conditions.

在平坦的牡蛎礁修复项目中，评估牡蛎性能亟需创新技术。一种阀门开度监测器，该设备可连续测量活双壳类生物的开合情况，有望成为确定欧洲平坦牡蛎（Ostrea edulis）存活状况和行为的有效方法。该方法已成功与多种双壳类物种结合使用，以研究在环境因素影响下阀门开度活动的响应。在本研究中，将八只O. edulis装备上阀门开度传感器，以将开度与食物可用性等环境条件相关联。在受控的实验室条件下，以及在含有和不含有食物的混凝土池（Oosterschelde）和野外（Voordelta，荷兰北海）中，对阀门开度活动进行了监测。在受控的实验室条件下，牡蛎明显对食物可用性的变化作出反应。饥饿的牡蛎关闭其壳瓣的时间显著长于接受食物的牡蛎，而接受食物的牡蛎的相对开度宽度更大。在混凝土池中（Oosterschelde），发现阀门开启与叶绿素a之间存在正相关关系。此外，阀门开度活动与潮汐运动似乎存在联系。在经历完整潮汐周期（Voordelta）时，发现阀门开启与叶绿素a之间存在负相关关系。然而，阀门开度与流速之间没有相关性。在秋季，观察到较长的非活动期，但阀门开启时，开度更大。这些数据表明，阀门开度可以提供关于行为（开度频率和开度宽度）的宝贵信息，但同时也表明，它并不一定是摄食率的良好替代指标。尽管如此，这些结果表明，开度监测器可用于确定平坦牡蛎在野外条件下的自然行为，并且开度开启提供了关于双壳类生物对环境条件的行为和压力反应的信息。