Preliminary study of the underwater soundscape of Cananéia, Sao Paulo, Brazil

Abstract

Studies on estuarine-coastal environments are of great importance due to the impact of various types of impacts associated with the presence and human occupation of these ecosystems. Due to the high turbidity characteristic of its waters, works that depend on visual techniques to measure species diversity are usually compromised. Sounds are of great relevance to a significant number of aquatic species, which employ them at different instances of their life history. Given the deleterious effects that unnatural sounds can have on the communication and other vital processes of these species, the study of the temporal production, propagation and distribution characteristics of all sounds that permeate the aquatic environment has become increasingly pressing. The line of research that addresses this set of characteristics is called Ecoacoustics. This proposal aims to study the composition of the underwater soundscape, i.e., the different forms of sound production, in the time domain, of the submerged region of the Cananéia-Iguape Estuarine-lagoon system. Data will be collected near Ponta da Trincheira, southern end of Ilha Comprida, Sao Paulo state, region rich in aquatic biodiversity. Two handcrafted electronic sound capture instruments will be installed on fixed fishing enclosures and will monitor the aquatic environment over a continuous 96 h period in August 2019. The acoustic data obtained will pass through spectral analysis in the R environment and will primarily result in 24-hour average spectrograms which will illustrate the acoustic patterns present in the study region. Then, they will be submitted to the alpha acoustic diversity calculation through an adaptation of the Shannon index. In the future, it is intended to investigate variations in the underwater soundscape of this region in larger scales of space and time.