The noise egg: a cheap and simple device to produce low‐frequency underwater noise for laboratory and field experiments

Abstract

Summary1. Studying the effect of anthropogenic noise on animal behaviour and physiology is a field of growing scientific and management interest. Anthropogenic noise is internationally seen as major environmental concern, but knowledge of the response of animals to noise and its ecological and evolutionary consequences is disparate. Even though fish and invertebrates form the majority of aquatic taxa, the effects of noise on these taxa are largely understudied. Especially the consequences of noise for short-range communication and behavioural interactions are yet unknown. While experimental studies on this subject are thus greatly needed, the expense of the equipment can be a main factor limiting data generation. Speakers that produce low-frequency sounds under water are currently either too large or too expensive to allow for sufficient replication in many research set-ups. 2. Here, we describe a device that can produce a low-frequency sound, which can be used as an experimental source of noise both in aquaria and in the field. The device is completely self-contained and costs around 10 euros per 'noise egg'. 3. The sound created consists of frequency bands (harmonics), which has the advantage that broadband and pulsed sounds, such as sounds produced by vocal fish, are easily detected in a spectrogram. Because the sound from the egg attenuates quickly, it can be used in aquaria and in the field to target certain study species or individuals without affecting a large part of the surrounding area. 4. We have developed the device to study the effects of noise on communication and behaviour in small aquatic animals; however, it could be used for other purposes, such as testing the propagation of certain frequencies in shallow-water habitats. 5. We hope the described method will facilitate the generation of experimental data on the effect of noise on behaviour and communication in aquatic animals in a wide variety of study systems and study areas.

Decreased feeding rates of the copepod Acartia tonsa when exposed to playback harbor traffic noise

“…Our results are inconsistent with a feeding experiment by Tremblay et al (2019) in which A. tonsa was exposed to a noise egg, a waterproof device that produces low-frequency sound (de Jong et al, 2017). Nevertheless, they found a physiological response correlated with oxidative stress (Tremblay et al, 2019).…”

Effects of low-frequency noise and temperature on copepod and amphipod performance

“…Identical glass bottles of 5 L were placed at 18°C (n = 4), 21°C, (n = 4) and 24°C (n = 4) for a total of 12. Added low-frequency noise treatments (n = 2 at each temperature) consisted of a vibration motor source of approximately 110 Hz contained in a waterproof egg standardized for small experimental units, similar to the device used in recent publications [11,12]. Waterproof eggs without motor were used as control (n = 2 at each temperature).…”

Noise Affects Multimodal Communication During Courtship in a Marine Fish

“…removal and photography of the eggs in the nest. The "noise egg, " consisting of an electromotor in a waterproof container, was used to generate a constant low frequency multi-tone with a fundamental frequency around 100 Hz and several strong harmonics (de Jong et al, 2017(de Jong et al, , 2018 The background noise level in the control treatment was 100 ± 1 dB re 1 µPa (N = 16) compared to 125 ± 6 dB re 1 µPa (N = 20) in the added noise treatments [see (de Jong et al, 2018) for details]. Particle acceleration, measured with an accelerometer (see Klein et al, 2013;de Jong et al, 2018), was elevated on average by 20 dB at 200 Hz (i.e., around the main frequency of courtship drums; Amorim et al, 2013) compared to ambient recordings in the male nest.…”