Abstract
Simple SummaryTo date there is not much information regard the role that sounds may play in the life of elasmobranchs. This gains particular importance if we consider the current understanding about noise pollution at sea. In fact, in the past few years, the effects of anthropogenic noise on marine fauna have received increasing attentions considering the plethora of repercussions deriving from the expansion of this type of pollution. Here, we exposed small-spotted catshark specimens kept in an aquarium, to different acoustic conditions to analyse the possible changes in swimming behaviour. Four different acoustic conditions consisted of biological sounds and anthropogenic noises. Moreover, the amplitude levels were differentiated among them, to analyse the effects caused by different signal-to-noise ratios. The results highlighted both a tendency of the animals to increase the overall time spent swimming and to avoid the noisiest section of the aquarium when subjected to higher amplitude levels of noise.Despite the growing interest in human-made noise effects on marine wildlife, few studies have investigated the potential role of underwater noise on elasmobranch species. In this study, twelve specimens of small-spotted catshark (Scyliorhinus canicula) were exposed to biological and anthropogenic sounds in order to assess their behavioural changes in response to prey acoustic stimuli and to different amplitude levels of shipping noise. The sharks, individually held in aquariums, were exposed to four experimental acoustic conditions characterized by different spectral (Hz) components and amplitude (dB re 1 µPa) levels. The swimming behaviour and spatial distribution of sharks were observed. The results highlighted significant differences in swimming time and in the spatial use of the aquarium among the experimental conditions. When the amplitude levels of biological sources were higher than those of anthropogenic sources, the sharks’ swimming behaviour was concentrated in the bottom sections of the aquarium; when the amplitude levels of anthropogenic sources were higher than biological ones, the specimens increased the time spent swimming. Moreover, their spatial distribution highlighted a tendency to occupy the least noisy sections of the aquarium. In conclusion, this study highlighted that anthropogenic noise is able to affect behaviour of catshark specimens and the impact depends on acoustic amplitude levels.
Highlights
To understand a species’ key bioecological activities in aquatic environments, as in terrestrial environments, it is important to examine the role of hearing
The aim of the present study was to analyse the potential effects caused by the presence of anthropogenic noise on behavioural responses of S. canicula specimens subjected to different acoustic experimental conditions
The study was conducted at the Centro Studi Squali, Aquarium, Massa Marittima (SW Tuscany, Italy), where twenty-two small-spotted catsharks were relocated to one indoor rectangular glass aquarium (2.5 m in length, 1 m in width, and 1.5 m in height) for a month-long acclimation period, after being captured between Elba Island and the Sardinia by trawling activity
Summary
To understand a species’ key bioecological activities in aquatic environments, as in terrestrial environments, it is important to examine the role of hearing. Noise pollution can drive acoustic interference compromising the ability to effectively perceive acoustic information between aquatic organisms [17]. This phenomenon can affect the acoustic relations between species and their environment, interfering with ecological strategies [18,19,20,21]. In this regard, it must be noted that non-vocal species, may take advantage of the sounds produced by other species to gather useful information. Myrberg et al [22], when studying the behavioural response of free-ranging sharks to low frequency pulsed sounds, hypothesised that these species monitor the sounds of struggling fish in order to locate and capture their prey
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