Size-dependent physiological responses of shore crabs to single and repeated playback of ship noise

Anthropogenic noise has fundamentally changed the acoustics of terrestrial and aquatic environments, and there is growing empirical evidence that even a single noise exposure can impact behaviour in a variety of vertebrate organisms. Here we use controlled experiments to investigate how the physiology of a marine invertebrate, the shore crab (Carcinus maenas), is affected by both single and repeated exposure to ship-noise playback. Crabs experiencing ship-noise playback consumed more oxygen, indicating a higher metabolic rate and potentially greater stress, than those exposed to ambient-noise playback. The response to single ship-noise playback was size-dependent, with heavier crabs showing a stronger response than lighter individuals. Repeated exposure to ambient-noise playback led to increased oxygen consumption (likely due to handling stress), whereas repeated exposure to ship-noise playback produced no change in physiological response; explanations include the possibility that crabs...