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Effects of underwater noise on behavioral performances of the ascidian Botryllus schlosseri

    82° Congresso Unione Zoologica Italiana. 19-23 September, Palermo, Italy. Abstract. P. 134

    Sabbadın G., De Lısa E., La Torre F., Balların L., Anselmı C., Zambon G., Bısceglıe A., Asnaghı E., Mannı L.

    In this study, we analyzed the effects of noise generated by maritime traffic (low-frequency noise) on the colonial ascidian Botryllus schlosseri. Mechanoreceptors potentially able to respond to water particle vibrations are both epidermal neurons of the siphons, and receptors on oral tentacles, called coronal cells, homologues of vertebrate hair cells of inner ear and lateral line organ.

    To assess the noise effects, we exposed colonies to a continuous and discontinuous noise, and used two behavioral tests allowing detecting sensory cell efficiency in responding to mechanical stimulation: the siphon stimulation test, which involves the oral siphon epidermal neurons, and the tentacle stimulation test, which specifically monitors the coronal cells.

    The oral siphon sensory cells induce the oral siphon contraction, whereas the coronal cells evoke the atrial siphon closure. Both tests were performed before and after noise stimulation in triplicates and heartbeats were counted to assess potential effects of noise on animal physiology. The results show that the tested continuous stimulation has negative effects at both the behavioral and physiological levels, decreasing animal sensitivity and heartbeat frequency; vice versa, colonies can adapt to discontinuous stimulation.