Discriminação acústica entre Sotalia guianensis (van Bénéden, 1864) e duas espécies simpátricas de delfinídeos no Oceano Atlântico Sul Ocidental

Abstract

The present study aimed to acoustically discriminate three dolphin species – Sotalia guianensis, Steno bredanensis, and Tursiops truncatus – based on the acoustic parameters of echolocation clicks. Passive Acoustic Monitoring has proven to be a viable tool for estimating cetacean abundance; however, the identification of species-specific acoustic properties remains necessary. Here, echolocation signals were collected using PAMGuard and subsequently processed with the PAMpal package in R, from which the following parameters were extracted: peak, minimum, maximum, and centroid frequencies at 3 dB and 10 dB, in addition to bandwidth at 3 dB and 10 dB. In total, 1,128 clicks were analyzed: 653 from S. guianensis, 260 from S. bredanensis, and 215 from T. truncatus. Principal Component Analysis (PCA) indicated an overlap of acoustic parameters among species, particularly between S. guianensis and S. bredanensis, whereas T. truncatus exhibited less overlap. The Kruskal–Wallis statistical test revealed that bandwidth at 10 dB was not significant for acoustic discrimination among species. Subsequently, Dunn-Bonferroni post-hoc test showed that bandwidth at 3 dB, minimum frequencies at 3 dB and 10 dB, and maximum frequency at 3 dB were the most effective parameters for distinguishing the three species. Peak frequency, although relevant, was not discriminatory between S. guianensis and S. bredanensis. The results indicate potential for the development of species-specific acoustic classification models for S. guianensis.