Chronic low-intensity noise exposure affects the hearing thresholds of juvenile snapper

Abstract

A growing body of evidence suggests that larval fish use sound as an orientation cue to remotely locate suitable settlement habitats. Several theoretical models have used hearing thresholds to estimate the distance at which fish larvae can detect reefs. However, researchers have often measured hearing thresholds from fish raised in aquaculture environments, or held them in closed-system tanks once caught, where equipment can significantly increase the noise levels in the tanks. The possibility arises that exposure to such noise negatively affects the hearing ability of the fish held there, such that distances predicted from these studies may be underestimated. The objective of this study was to compare the hearing ability of wild versus aquacultured snapper Pagrus auratus using auditory evoked potentials. Juvenile snapper from aquaculture tanks had significantly higher hearing thresholds at 100, 200 and 400 Hz than wild snapper. A controlled noise-exposure experiment, where snapper were ex posed for 2 wk to low-intensity noise at 120 dB re 1 µPa, confirmed these results. When plotted using an extended reef-based model, the distance at which aquaculture-raised snapper are predicted to detect a particular reef was half of that found for their wild counterparts. Clearly, the acoustic history of experimental subjects is an important consideration when using hearing thresholds to make ecological estimations, such as the distance at which larvae could detect reefs.

The effect of motorboat sound on Australian snapper Pagrus auratus inside and outside a marine reserve

“…A previous study showed that fish exposed to ecotourism tend to have higher cortisol levels than fish that are protected from sound (Oliveira, Canário, & Bshary, 1999), which suggests these fish are stressed. Snapper (Caiger, Montgomery, & Radford, 2012) show a similar hearing ability to rainbow trout (Wysocki, Davidson, Smith, & Frankel, 2007), with greatest sensitivity to low‐frequency sounds (<400 Hz). Rainbow trout showed no effect of hearing loss after being exposed to sounds up to 150 dB re 1 μPa, therefore the exposure level of motorboat sound (125 dB re 1 μPa) in the present study is significantly less and unlikely to have caused any significant hearing damage to the protected fish.…”

Shipping alters the movement and behavior of Arctic cod (Boreogadus saida), a keystone fish in Arctic marine ecosystems

“…Evidence is also available that fish exposed to constant noise, such as that in aquaculture facilities, exhibit significantly higher hearing thresholds, and are acclimated to it (Caiger et al. ). In the Arctic, vessels only visit in the summer months and are not constantly present in one area.…”

“…Bluefin tuna (Thunnus thynnus) was reported to acclimate to short (10-15 s) repeating loud noise, but not to long stimuli noise (10-15 m) of the same source (associated with wind farms), or to the regular boat noise associated with feeding time (P erez-Arjona et al 2014). Evidence is also available that fish exposed to constant noise, such as that in aquaculture facilities, exhibit significantly higher hearing thresholds, and are acclimated to it (Caiger et al 2012). In the Arctic, vessels only visit in the summer months and are not constantly present in one area.…”

Contributions of the Leigh Marine Laboratory to marine science, 1962–2012: sensory neuroethology

“…This same AEP technique has been used to begin to characterise the development of hearing over the larval life history period, initially using hāpuku (Polyprion oxygeneios), a species with an extended larval duration (Caiger et al 2013). It has also been used to show that background noise can detrimentally affect hearing thresholds (Caiger et al 2012), so care needs to taken to provide appropriate quite conditions for housing fish for later experimental evaluation of hearing thresholds.…”