Measuring Behavioural Changes to Assess Anthropogenic Noise Impact in Adult Zebrafish (Danio rerio)

Underwater habitats are full of natural sounds from abiotic sources, such as wind and water flow, and biotic sources, such as chorusing fish and snapping shrimps. However, human activities elevate these ambient noise levels artificially. The so-called anthropogenic noise from traffic, industry, and recreational activities concerns an only recently recognized pollution factor underwater which is expanding in time and space [1]. The artificially high noise levels are typically of relatively low frequency and can cause many different problems such as physical damage in cases of extreme overexposure, physiological stress, and auditory masking, which are all factors that an animal is more or less passively undergoing (see Figure 1). Furthermore, anthropogenic noise may lead to spatial deterrence, behavioural interruption, and signal modifications, which are all factors that involve some sort of active response from the animal. The three passive factors are typically positively related: if one is getting worse the others are likely to follow the same pattern. An increase in any of the three passive factors also increases the probability that any of the three active factors occurs. Vice versa the opposite may be the case: the active factors have the potential to provide relief on the passive factors by reducing the level and duration of exposure.