Anthropogenic noise has been shown to affect marine animals in various ways, this may have fitness consequences at individual and population level. This thesis aims to increase insight into the... Show moreAnthropogenic noise has been shown to affect marine animals in various ways, this may have fitness consequences at individual and population level. This thesis aims to increase insight into the quantification of sound-induced behavioural responses that are relevant to fitness, and into factors that modulate the responses. I addressed both knowledge gaps using captive and field studies on marine animals from multiple trophic levels. For the quantification of behavioural responses relevant to fitness, I examined the changes in time budgets of Atlantic cod in a net pen and basin in response to sound (chapter 2 and 3). To increase insight into factors that modulate sound impact, I examined the effect of various acoustic characteristics of sound stimuli and the environment on European seabass (chapter 4), the interaction between foraging shore crabs and common shrimps during noise (chapter 6), the cross-sensory interference by noise in foraging crabs (chapter 7), and habituation to repeated sound exposures by blue mussels (chapter 8). Future studies are needed to be able to link changes in time budgets to changes in energy budgets, and consequently to fitness. Additionally, studies into the factors that modulate the effects of sound are needed to fully understand the impact of sound. Show less
Fish live in a world that is not silent. In fact, fish hear low frequency sounds and may need them for navigation, predator-prey interactions and mate attraction. Due to their dependence on sounds... Show moreFish live in a world that is not silent. In fact, fish hear low frequency sounds and may need them for navigation, predator-prey interactions and mate attraction. Due to their dependence on sounds, fish may be particularly sensitive to changes in their acoustic world. Since the 1900s, the acoustic world of fish has been altered by a new prominent sound source: human activities. These activities generate a cacophony of high-intensity sounds. At close range, they may cause tissue damage and temporary hearing loss. At further distances, more moderate sounds may cause auditory masking, behavioural changes and reduced efficacy in foraging and avoiding predators. Assessing the severity of behavioural impacts of sounds is not straightforward and are often problematic.This thesis used European seabass to study behavioural effects of man-made sounds of different temporal structures. It also compared the effects of tank-based experiments with open-water experiments. Finally, this thesis studied the habituation of fish to sound exposure and how sound effects are influenced by various environmental factors. Show less
