Abstract
Anthropogenic noise impacts behaviour and physiology in many species, but responses could change with repeat exposures. As repeat exposures can vary in regularity, identifying regimes with less impact is important for regulation. We use a 16-day split-brood experiment to compare effects of regular and random acoustic noise (playbacks of recordings of ships), relative to ambient-noise controls, on behaviour, growth and development of larval Atlantic cod (Gadus morhua). Short-term noise caused startle responses in newly hatched fish, irrespective of rearing noise. Two days of both regular and random noise regimes reduced growth, while regular noise led to faster yolk sac use. After 16 days, growth in all three sound treatments converged, although fish exposed to regular noise had lower body width–length ratios. Larvae with lower body width–length ratios were easier to catch in a predator-avoidance experiment. Our results demonstrate that the timing of acoustic disturbances can impact survival-related measures during development. Much current work focuses on sound levels, but future studies should consider the role of noise regularity and its importance for noise management and mitigation measures.
Highlights
Some anthropogenic noise, such as that arising from traffic, resource extraction and construction, is recognized as pollution both in air and underwater [1,2]
Yolk sacs decreased in size between days 1 and 2 by 0.128 + 0.022, but fish reared with regular additional noise had yolk sacs at day 2 that were smaller than those in the control
Two days of additional noise of both regular and random regimes reduced growth, while regular noise led to faster yolk sac use
Summary
Some anthropogenic (man-made) noise, such as that arising from traffic, resource extraction and construction, is recognized as pollution both in air and underwater [1,2]. From individual behaviour and physiology up to community structure, a wide variety of species are affected by noise [3,4]. Repeated and/or chronic exposure could alter how terrestrial and aquatic animals respond to noise as a consequence of changes across time and cumulative effects [7,8,9]. Recent evidence using brief (30 min) exposures indicates that different temporal patterns of noise may impact animals in different ways [10], but long-term studies of how different noise patterns or ‘regimes’ may affect animals differently are needed for more effective regulation of this global pollutant. Shifts in tolerance may be dependent on the intensity, duration and interval time of stressors (reviewed in [11]). Regularity of noise does not affect cognitive impairment in rats [13], but stress responses in fish can be influenced by regularity in other contexts; for example, regular
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