Le Moal Alexandre, Tran Damien, Payton Laura, Pogoda Bernadette, Meyer Bettina
Institute for Chemistry and Biology of the Marine Environment, Carl von Ossietzky University of Oldenburg, 26111, Oldenburg, Germany.
Section Polar Biological Oceanography, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570, Bremerhaven, Germany.
Sci Rep. 2025 Apr 29;15(1):14952. doi: 10.1038/s41598-025-98746-x.
Marine organisms exhibit a multitude of biological rhythms synchronized with the interactions of the sun-, earth-, and moon cycles. However, the biological rhythms in bivalves remain poorly studied. This study focuses on the native European flat oyster (Ostrea edulis), an endangered species of coastal ecosystems and a key organism in restoring of biogenic reef habitats. We aim to determine whether a molecular endogenous circadian rhythm exists in O. edulis and to characterize its daily expression. To address these questions, the oysters' valve behavior, as an output of the circadian clock expression, was recorded under different light conditions and free-running regimes using non-invasive valvometry. This work demonstrates the existence of a circadian clock mechanism that generates a labile behavioral circadian oscillation under free-running conditions. In light: dark conditions, a diel rhythm appears nocturnal, synchronizable to a shift of light phase, and remains unmodified whether the oysters are fed or not. This rhythm anticipates light: dark changes, indicating its endogenous origin. Finally, when exposed to artificial light at night the daily behavior is disrupted. This study characterizes the circadian behavioral rhythm of O. edulis's as plastic and labile. This plasticity would be advantageous in terms of ecological adaptability but increases sensitivity to anthropogenic pressures such as light pollution.
海洋生物呈现出多种与太阳、地球和月球周期相互作用同步的生物节律。然而，双壳贝类的生物节律仍研究不足。本研究聚焦于欧洲本地扁蛎（Ostrea edulis），它是沿海生态系统的濒危物种，也是恢复生物礁栖息地的关键生物。我们旨在确定欧洲扁蛎是否存在分子内源性昼夜节律，并表征其每日表达情况。为解决这些问题，利用非侵入性瓣膜测量法，在不同光照条件和自由运行状态下记录了牡蛎的瓣膜行为，作为昼夜节律时钟表达的输出。这项工作证明了存在一种昼夜节律时钟机制，该机制在自由运行条件下产生不稳定的行为昼夜振荡。在光照：黑暗条件下，昼夜节律呈现夜间性，可与光相位变化同步，且无论牡蛎是否进食都保持不变。这种节律能预测光照：黑暗变化，表明其内源起源。最后，当在夜间暴露于人造光时，日常行为会受到干扰。本研究将欧洲扁蛎的昼夜行为节律表征为具有可塑性和不稳定性。这种可塑性在生态适应性方面具有优势，但会增加对诸如光污染等人为压力的敏感性。
