[MARMAM] New paper: Description and classification of echolocation clicks of Indian Ocean humpback (Sousa plumbea) and Indo-Pacific bottlenose (Tursiops aduncus) dolphins from Menai Bay, Zanzibar, East Africa. (Liangliang Yang)

Liangliang YANG yllxmu at gmail.com
Sat Mar 14 07:48:29 PDT 2020

Dear Marmam readers,

On behalf of my co-authors, I am very pleased to announce the publication
of our paper.

Yang L, Sharpe M, Temple AJ, Jiddawi N, Xu X, Berggren P (2020) Description
and classification of echolocation clicks of Indian Ocean humpback (*Sousa
plumbea*) and Indo-Pacific bottlenose (*Tursiops aduncus*) dolphins from
Menai Bay, Zanzibar, East Africa. PLoS ONE 15(3): e0230319.

*Abstract*: Passive acoustic monitoring (PAM) is a powerful method to study
the occurrence, movement and behavior of echolocating odontocetes (toothed
whales) in the wild. However, in areas occupied by more than one species,
echolocation clicks need to be classified into species. The present study
investigated whether the echolocation clicks produced by small, at-risk,
resident sympatric populations of Indian Ocean humpback dolphin (*Sousa
plumbea*) and Indo-Pacific bottlenose dolphin (*Tursiops aduncus*) in Menai
Bay, Zanzibar, East Africa, could be classified to allow species specific
monitoring. Underwater sounds of *S. plumbea* and *T. aduncus* groups were
recorded using a SoundTrap 202HF in January and June-August 2015. Eight
acoustic parameters, i.e. -10 dB duration, peak, centroid, lower -3 and
lower -10 dB frequencies, and -3 dB, -10 dB and root-mean-squared
bandwidth, were used to describe and compare the two species’ echolocation
clicks. Statistical analyses showed that *S. plumbea* clicks had
significantly higher peak, centroid, lower -3 and lower -10 dB frequencies
compared to *T. aduncus, *whereas duration and bandwidth parameters were
similar for the two species. Random Forest (RF) classifiers were applied to
determine parameters that could be used to classify the two species from
echolocation clicks and achieved 28.6% and 90.2% correct species
classification rates for *S. plumbea* and *T. aduncus*, respectively. Both
species were classified at a higher rate than expected at random, however
the identified classifiers would only be useful for *T. aduncus*
monitoring. The
frequency and bandwidth parameters provided most power for species
classification. Further study is necessary to identify useful classifiers
for* S. plumbea*. This study represents a first step in acoustic description
and classification of *S. plumbea* and *T. aduncus *in the western Indian
Ocean region, with potential application for future acoustic monitoring of
species-specific temporal and spatial occurrence in these sympatric species.

The paper is open access and freely available to read or download at:


If you have any questions, please do not hesitate to email me at
yllxmu at gmail.com

All the best,



Dr. Liangliang Yang

Postdoc Research Associate

Marine Megafauna Lab

School of Natural and Environmental Sciences

Newcastle University, UK
Email:  yllxmu at gmail.com   Phone: +44 (0)1912085091
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