6 Memorandum : Vibration effects on amphibians (Leiopelmatid frogs) 64524 Vibration effects_memorandum (15 June 2022)_Final Rev 0 amphibians that do not call or vocalise (e.g., leiopelmatids). Other studies looking at anuran responses to vibration, include stimulated emergence behaviour (Márquez et al., 2016), flight/ movement response (Mazerolle et al., 2015), and spontaneous or early hatching of eggs (Warkentin, 1995). Another study reported rainfall-induced vibrations in soil are the cues that trigger the emergence of arid-zone toads from underground (Márquez et al., 2016). It is not only physical behaviour that is affected by vibration, as vibration can elicit stress‐mediated effects such as increases in heart rate (Reynolds et al, 2018) and physiological changes (Felt et al., 2012). Over time, episodic or sustained vibration could potentially lead to adverse impacts on individuals. One study demonstrated morbidity and mortality in obligate aquatic African clawed toads in the laboratory in response to nearby construction vibration9 (Felt et al., 2012). Understanding how vibration influences behaviour is complicated by the interplay between characteristics of vibration, including amplitude, duration and return period (the length of time a vibration is sensed until returning to normal state), and ‘frequency’ of vibration events10 (how often vibrations occur). All characteristics need to be considered to completely understand the effects on animals. Amplitude is the characteristic that describes the severity or intensity of a vibration. Animals may respond in different ways to vibrations depending on the amplitude. In instances where the amplitude is low, animals may not respond at all but where amplitude is high (very intense) and acute or sudden, animals may react with a startle response. A startle response is a largely unconscious defensive response to sudden or threatening stimuli and typically involves abrupt cessation of ongoing movements, such as freezing or thanatosis (long-lasting freezing) or a fast jerky movement with short latency (e.g., jumping, moving away rapidly). In most instances, a startle response is short-lived, and the animal successfully recovers and continues with more controlled and decisive actions. However, where individuals are engaged in important biological behaviours (e.g., feeding, mate attraction, mating, egg brooding), startle responses, especially movement away from the engaged behaviour, may be temporarily disruptive. It could also cause stress response (energy demands) and potentially lead to long-term individual fitness effects if mating or recruitment is affected (e.g., mate desertion, abandonment of eggs, premature hatching). There is paucity of research on startle effects resulting from vibration stimuli yet Götz and Janik (2011) reported that repeated startling by anthropogenic noise sources might have severe effects on longterm behaviour and potentially and reduced individual fitness or reduced longevity of individuals. Since noise and vibration are sensed by the same organs in the body, it is plausible that similar effects could result from repeated startling in response to vibration stimulus. Alongside amplitude effects, the duration of vibration (length of time a vibration is sensed until returning to normal state) and how often vibration occurs are likely to influence animal behaviour. Intermittent vibration is thought to produce more adverse effects than continuous vibration due to its unpredictability (Carman et al., 2007). On the other hand, animals have been shown to adapt to avoid fitness-relevant 9 Jack hammer that was being used in an adjacent room approximately 10 ft away 10 Not to be confused with “frequency” i.e., the amount of time that it takes to complete one cycle from a point on one wave to the same point on the next wave. The term “Hertz” is used as a unit of measure for frequency and is the number of cycles per second.
RkJQdWJsaXNoZXIy MjE2NDg3