Acoustic ecology of Guiana dolphin (Sotalia guianensis) in Sepetiba bay and Ilha Grande bay
bioacoustic; soundscape ecology; vocal stability; anthropic impact
Acoustic repertoires can change in temporal and spatial scale. It can change influenced by creation of new alliances, by soudscape changes or by geographic variation. In this way the goal of this study is to evaluate spatial and
temporal changes in the acoustic repertoire of Guiana dolphin (Sotalia guianensis). This study uses a database of acoustic recordings in Sepetiba Bay between 1998 and 2002, new recordings made from 2015 to 2018 in Sepetiba
Bay and in 2017 and 2018 in Ilha Grande Bay. In order to understand temporal variations, will be compared changes in signature whistles over time. Also in the temporal scale, will be measured the soundscape and the average values of frequency, duration and emission rate. Spatially, will be compared frequency contours between populations of Sepetiba bay and Ilha Grande bay. Preliminarily, the temporal comparison Guiana dolphin repertoire indicated 27
signatures in the past, but still inconclusive in the present. However, changes was observed in the frequency, duration and emission rate averages (Past: high frequency = 13.31 kHz, minimum frequency = 10.52 kHz, duration = 0.79 s and emission rate = 0.27 whistles/min/animal; Present: high frequency = 16.64 kHz, minimum frequency = 9.68 kHz, duration = 0.17 s and emission rate = 0.004 whistle/min/animal). A total of 37 frequency contours were identified, of which 17 were shared among populations. The spatial comparison indicated 31 contours in Ilha Grande population, of which 14 were exclusive, and 23 contours in Sepetiba, being six exclusive. Temporal changes point to changes in the acoustic soundscape. It was probably caused by increase in anthropic noise, tending to communication at higher frequencies to avoid the masking effect. Spatial changes indicate that despite geographic variations, these populations remain connected