Effects of noise exposure on a sessile invertebrate, the ascidian clavelina lepadiformis

Noise is now considered an emerging pollutant that can affects dif-ferent aspects of animal life. In particular, it is known that expo-sure to high frequency sounds can damage ciliated sensory cells and impair their development with consequences on animal behav-ior. Clavelina leadiformis is an ascidian belonging to the aplouso-branchia clade, common in the shallow waters of the Mediterranean Sea, such in harbors where the maritime traffic and noise pollution are particular intense. We exposed adults of C. clavelina carrying developing embryos for 24 h to a pink noise (higher intensities at 63-125 Hz), at different levels (120-180dB), in tanks using an underwater speaker. Then, we analyzed the effects on site-selection behaviors of the developed larvae by ana-lyzing the spatial distribution of juveniles attached on the bottom of the tanks. Moreover, we performed a functional, ultrastructural and immuno-histological analysis of the sensory cells of the juve-niles in order to identify alterations caused by chronic noise expo-sure. The results indicated that larvae avoided to settle near the noise source revealing that they can sense the sounds. Moreover, juveniles exposed to noise presented altered responses to sensory cells stimulation and impaired development of ciliated sensory structures as suggested by immunostaining and SEM analysis. These results suggest that studies on noise effects on invertebrate fauna deserve further considerations