Chronobiology and the design of marine biology experiments

Marine habitats are shaped by several geophysical cycles ranging from a few hours (tidal and solar cycles) to a year (seasons). These cycles have favoured the selection of endogenous biological clocks. Such a clock is a molecular time-keeping mechanism that consists of a set of core clock genes whose expression oscillates. The clocks produce biological rhythms and influence virtually all metabolic, physiological, and behavioural functions in organisms. This work highlights the importance to take chronobiology into account in experimental marine biology to avoid faulty results, misinterpretation of results, and/or to strengthen observations and conclusion. A literature survey, based on 150 articles, was conducted and showed that, despite the pervasive imprint of biological rhythms in marine species, environmental cycles such as the 24 h-light/dark cycle and the seasonality are rarely considered in experimental designs. This work emphasizes that better integrating the temporal organization and regulation of marine species within the marine biology community is essential for obtaining representative results.