Suffering in receivers: Negative effects of noise persist regardless of experience in female anurans. (24th May 2018)

• Record Type: Journal Article
• Authors: Senzaki, Masayuki; Kadoya, Taku; Francis, Clinton D.; Ishiyama, Nobuo; Nakamura, Futoshi
• Editors: Angelier, Frédéric
• Is Part Of: Functional ecology. Volume 32:Number 8(2018)
• Page Start: 2054
• Page End: 2064
• Publication Date: 2018-05-24
• Subjects: aversion -- behavioural plasticity -- distraction -- experience -- masking -- noise pollution -- signal receivers; Ecology -- Periodicals; 574.505
• DOI: 10.1111/1365-2435.13130
• Languages: English
• ISSNs: 0269-8463

Abstract

Abstract: Anthropogenic noise is widespread, and growing evidence suggests that it can negatively affect animals through many different mechanisms including masking of cues and signals, distraction, and aversion to noise. Acoustic masking has received the most attention from researchers and recent evidence suggests that masking effects can be mitigated by alteration of signal frequencies or amplitudes by signalers. Additionally, alteration can be a learned response via prior experience with noise exposure. However, it remains unclear whether distraction or aversive effects due to noise can be mitigated by prior experience with noise, especially among signal receivers. Here, we addressed this gap by separating mechanisms of noise disturbances on female phonotaxis towards male advertisement calls in anurans. To do this, we experimentally examined phonotaxis of gravid females that differ in their prior experience with noise under three acoustic manipulations: spectrally overlapping and non‐overlapping noise that either mask or do not mask male advertisement calls respectively, plus a silent control. We confirm two experience‐dependent responses of noisy‐site individuals relative to quiet‐site individuals: faster initiation of phonotaxis under non‐overlapping noise and a stronger aversive response against overlapping noise. However, we showed that, for both noisy‐ versus quiet‐site individuals, both overlapping and non‐overlapping noise treatments resulted in delayed initiation and disorientation of phonotaxis relative to silent control treatments. Our study provides the first evidence to demonstrate that, although prior experience appears to mitigate the negative effects of distraction or aversion to noise, prior experience falls short of fully compensating for disrupted orientation through phonotaxis. Additionally, although most studies have emphasized masking of biologically relevant cues and signals as the most prominent mechanism by which noise negatively affects wild organisms, we show that non‐overlapping noise, which cannot cause signal and cue masking, can have negative consequences via distraction or aversive responses. This finding suggests that noise impacts could extend well beyond contexts involving acoustic cue detection and discrimination and deserves increased attention by researchers. A plain language summary is available for this article. Abstract : Plain Language Summary Foreign Language Abstract: abs現在、人為的騒音が世界中に蔓延しており、動物の行動への騒音の影響が懸念されている。音響マスキング(騒音と動物の音声信号の周波数の重複)は、騒音の悪影響の根底にある主要なメカニズムの一つである。これまで、信号発信者は信号の周波数や音量を変えることで音響マスキングの影響を小さくできること、この能力は騒音への暴露経験を経て獲得されることが解明されてきた。一方で、騒音による注意力散漫や騒音への嫌悪もまた、動物の行動を変えるメカニズムである。しかしながら、動物、とりわけ信号受信者が、騒音への暴露経験を通して、騒音による注意力散漫や嫌悪の影響を小さくできるのかどうかはわかっていない。そこで我々は、騒音への暴露経験が異なる雌のカエル類の音走性行動(雄の声に向かう行動)に対して、騒音がどのように影響するのかを実験的に調べた。具体的には、3つの音声状況下(雄の声と周波数が重複する騒音[マスキング騒音]、重複しない騒音[非マスキング騒音]、無騒音)で、騒音への暴露経験を持つ個体(騒音サイト個体)と持たない個体(静穏サイト個体)の音走性行動を比較した。その結果、静穏サイトの個体と比べて騒音サイトの個体は、非マスキング騒音下で音走性行動をより早く開始し、マスキング騒音に対して明確な忌避行動を示した。しかしながら、無騒音下と比べて二つの騒音下では、いずれのサイトの個体も音走性行動の開始が遅く、雄の声への指向性が失われていた。これらの結果は、雌のカエル類が騒音に対して被る注意力散漫や嫌悪といった影響は、騒音への暴露経験により緩和されるが完全に消えるわけではないことを示す。本研究によって、動物への騒音の影響は音響マスキングの観点からだけでなく、注意力散漫や嫌悪の影響からも注視されるべきことが明らかになった。