Repeated exposure to noise increases tolerance in a coral reef fish

This is the author accepted manuscript. The final version is freely available from the publisher via the DOI in this record.Some anthropogenic noise is now considered pollution, with evidence building that noise from human activities such as transportation, construction and exploration can impact behaviour and physiology in a broad range of taxa. However, relatively little research has considered the effects of repeated or chronic noise; extended exposures may result in habituation or sensitisation, and thus changes in response. We conducted a field-based experiment at Moorea Island to investigate how repeated exposure to playback of motorboat noise affected a coral reef fish (Dascyllus trimaculatus). We found that juvenile D. trimaculatus increased hiding behaviour during motorboat noise after two days of repeated exposure, but no longer did so after one and two weeks of exposure. We also found that naïve individuals responded to playback of motorboat noise with elevated ventilation rates, but that this response was diminished after one and two weeks of repeated exposure. We found no strong evidence that baseline blood cortisol levels, growth or body condition were affected by three weeks of repeated motorboat-noise playback. Our study reveals the importance of considering how tolerance levels may change over time, rather than simply extrapolating from results of short-term studies, if we are to make decisions about regulation and mitigation.Open Access funded by Engineering and Physical Sciences Research Council, under a Creative Commons licenseFunding was provided to: Sophie Nedelec by a studentship from EPSRC, Subacoustech and an Eiffel grant – Egide program – from Campus France; Suzanne Mills and David Lecchini by the Agence National de Recherche, ANR-11-JSV7-012-01 Live and Let Die and Partnership University Fund of the French American Cultural Exchange (Ocean Bridges Program, http://facecouncil.org/puf/); Stephen Simpson by a NERC Fellowship (NE/J500616/2); and Andrew Radford by a Defra grant (ME5207)