Integrative bioacoustics discrimination of eight delphinid species in the western South Atlantic Ocean

PLoS One. 2019 Jun 6;14(6):e0217977. doi: 10.1371/journal.pone.0217977. eCollection 2019.

Abstract

This study presents an integrative bioacoustics approach to discriminate eight species of odontocetes found on the outer continental shelf and slope of the western South Atlantic Ocean. Spinner, Atlantic spotted, rough-toothed, Risso's, bottlenose, short-beaked common dolphins, killer and long-finned pilot whales were visually confirmed during recordings with a 3-element omnidirectional hydrophone array. Spectral and time parameters of whistles and echolocation clicks were used in a discriminant function analysis and a classification tree model. As a first step, whistles and clicks were analysed separately; a further analysis consisted of both vocalisations jointly classified. All species showed species-specific properties in their vocalisations. Whistles had greater misclassification rates when compared to clicks. The correct classification was enhanced by the joint step, given the 5.8% error in the discriminant function analysis and a misclassification rate of 18.8% in the tree model. In addition, Receiver Operating Characteristic curves resulting from the tree algorithm analysis exhibited better model efficiency for all species in the joint classification. These findings on acoustical discrimination of such abundant and cosmopolitan species contribute to delphinid classification systems.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acoustics*
  • Algorithms
  • Animals
  • Atlantic Ocean
  • Discriminant Analysis
  • Dolphins / physiology*
  • Geography
  • Multivariate Analysis
  • ROC Curve
  • Sound Spectrography
  • Species Specificity
  • Time Factors
  • Vocalization, Animal / physiology*

Grants and funding

This work had the logistical support of Instituto Aqualie and Auset, along with financial support from Chevron Brasil Upstream Frade Ltda and CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior) scholarship. We also want to thank Universidade Federal de Juiz de Fora for financial support in publishing this work. The funders had no role in this study design, data collection and analysis, decision to publish, or preparation of the manuscript.