Effects of boat noise on fish fast-start escape response depend on engine type

Mark I Mccormick,Eric P Fakan,Sophie L Nedelec,Bridie J M Allan

doi:10.1038/s41598-019-43099-5

Abstract

Vessel noise represents a relatively recent but rapidly increasing form of pollution, which affects the many organisms that use sound to inform their behavioural decisions. Recent research shows that anthropogenic noise can lead to reduced responsiveness to risk and higher mortality. The current laboratory experiment determined whether the playback of noise from motorboats powered by two- or four-stroke outboard engines affected the kinematics of the fast-start response in a juvenile coral reef fish, and the time scale over which the effects may occur. Results show that the two engine types produce slightly different sound spectra, which influence fish differently. Playback of 2-stroke engines had the greatest effect on activity, but only for a brief period (45 s). While noise from 4-stroke outboard engines affected fast-start kinematics, they had half the impact of noise from 2-stroke engines. Two-stroke engine noise affected routine swimming more than 4-stroke engines, while 4-stroke noise had a greater effect on the speed at which fish responded to a startle. Evidence suggests that the source of the noise pollution will have a major influence on the way marine organisms will respond, and this gives managers an important tool whereby they may reduce the effects of noise pollution on protected communities.

Highlights

Vessel noise is recognised as an important source of pollution that is ubiquitous in aquatic environments within populated areas around the world[1,2]
Few studies have examined the effect of noise from different engine types on fish behaviour, and this is the first study to examine the effect of noise with differing acoustic characteristics on routine behaviour and escape response kinematics
Our study shows that the playback of boat noise had a marked influence on the routine swimming, latency to respond and escape kinematics of a common juvenile damselfish

Summary

Introduction

Vessel noise is recognised as an important source of pollution that is ubiquitous in aquatic environments within populated areas around the world[1,2]. Anthropogenically-produced marine noise has been found to have significant effects on the distribution, behaviour, reproduction and survival of marine invertebrates and fishes[7,8] These organisms often use sound as an important source of information and have well-developed ways of producing and hearing sound[9,10]. One of the most disruptive effects that anthropogenic noise can have on fishes is through its effect on their ability to assess risk and make choices concerning anti-predator behaviour (e.g.17,18). This is the case at the end of the larval phase when reef fishes, like other demersal marine organisms, are vulnerable to predation. McCormick et al.[22] found that latency to respond, measured in the same way as the present study, was one of five key predictors of survival, the others being aspects of behaviour and space use in the field

Objectives

Methods

Results

Conclusion