Ambient noise in standard pre-trial housing tanks.

<p>Ambient sound pressure levels (spectral density, dB/Hz re 1 µPa) from averaged power spectra (FFT analysis: spectral level units, Hann evaluation window, 50% overlap, FFT size 1024) recorded in standard stock tanks used for housing stickleback prior to studies (AS), ambient conditions in still freshwater test tanks (AT), and ambient conditions in an example freshwater lake in the UK (AL).</p

Acoustic noise increases foraging performance errors and reduces foraging efficiency.

<p>Response of foraging sticklebacks to playbacks of silence (S), brief (10 s) white noise (BN) and prolonged (300 s) white noise (PN). Bars show mean±1s.e.m. response for 24 fish during each playback of a repeated-measures experiment, with significant (**p≤0.01) and non-significant (ns p≥0.05) posthoc differences indicated (paired t-tests with Bonferroni correction). Brief noise and prolonged noise both significantly affected (A) the proportion of attacks towards non-food items, (B) the proportion of attacked food items that were not consumed, and (C) overall foraging efficiency (consumed items as proportion of all attacks on food and non-food items).</p

Acoustic noise increases startle responses but does not affect total food consumption.

<p>Response of foraging sticklebacks to playbacks of silence (S), brief (10 s) white noise (BN) and prolonged (300 s) white noise (PN). Bars show mean±1s.e.m. response for 24 fish during each playback of a repeated-measures experiment, with significant (** p≤0.01) and non-significant (ns p≥0.05) posthoc differences indicated (paired t-tests with Bonferroni correction). Brief noise and prolonged noise both significantly affected (A) the number of startle responses, but had no significant effect on (B) the total number of food items consumed.</p

Noise in the feeding areas of the experimental tank during playback and silent control conditions.

<p>Sound pressure levels (spectral density, dB/Hz re 1 µPa) from averaged power spectra (FFT analysis: spectral level units, Hann evaluation window, 50% overlap, FFT size 1024) recorded during playback of white noise in experimental test tank (NT) and during ambient silent control conditions (AT). Sound pressure levels from recordings in an example freshwater lake in the UK during recreational speedboat activity (NL) and during ambient conditions (AL).</p

Experimental test tank schematic: arrangement of fish and apparatus during and between trials.

<p>Plan view of test tank before and between trials (A) and during trials (B): focal fish (F), companion fish (C) contained in transparent plastic cylinder during trials, two areas where live <i>Daphnia</i> sp. were delivered during trials (D), speaker (S) behind opaque partition (P) during trials, mesh partitions (M) separated fish between trials. Fish in separate sections of the tank between trials with mesh partitions allowing visual, acoustic and olfactory contact.</p

Overhead view of experimental tank setup.

<p>Schematic representation of visual predatory stimulus (PS), underwater loudspeaker (LS), focal fish position for predator release (X), feeder (F), artificial plant (P), mesh separator (S) and opaque Correx dividers (D).</p

Average spectral levels of acoustic conditions in the experimental tank.

<p>Sound pressure levels of averaged power spectra (FFT spectrum level units normalised to 1 Hz bandwidth, Hann window, FFT size 1024, 50% overlap) of recordings during band-pass filtered additional-noise playbacks (0.1 to 3.0 kHz; NT) and control playbacks (AT) at two tank depths (5 cm above tank floor and 5 cm below water surface) at the location the fish had to be for the visual predatory stimulus to be released. For control playbacks, spectral levels from 30 s recordings were assessed and averaged over all playback tracks and the two tank depths; for additional-noise playbacks, spectral levels over the whole duration of single looped elements were taken, to account for power fluctuations within a recording of sound emitted by a moving ship, and averaged over all playback tracks and the two tank depths. Recordings were made with an omni-directional hydrophone with preamplifier (HTI 96-MIN; manufacturer-calibrated sensitivity −164.3 dB re 1 µPa; frequency range 2–30 000 Hz) and a solid-state recorder (Edirol R09HR, Roland Corporation), at a sampling frequency of 44.1 kHz and a sampling rate of 16 bits; recording levels calibrated against a 1 kHz reference tone of known amplitude. An example of original ship-noise (NN) and ambient-noise recording (AN) of a UK harbour are given for comparison.</p

Speed of response to a visual predatory stimulus.

<p>Minnows showed no significant effect of noise treatment on response latency (A), while sticklebacks responded significantly more quickly during additional-noise playbacks compared to control playbacks (B). Plots of Kaplan-Meier estimate from mixed model Cox proportional hazards regression, with non-responders included as right-censored maximum-latency data. N = two trials to each of 27 minnows and 35 sticklebacks.</p

Bruintjes_Data

Raw data behavioural and physiological measurement