Mapping Delphinid Occurrence using a Passive ...

Mapping Delphinid Occurrence using a Passive Acoustic Monitoring System towed by an Unmanned Surface Vehicle on the Southeast Coast of Brazil Lis Bittencourt; William Soares-Filho; Isabela Maria Seabra de Lima; Sudhir Pai; José Lailson-Brito Junior; Leonardo M. Barreira; Alexandre de Freitas Azevedo; Luiz Alexandre A. Guerra Rio Acoustics 2017 – Rio de Janeiro

Introduction Delphinids => diverse acoustic repertoire Pulsed sounds

Whistles (tonal sounds)

Burst pulses

Echolocation clicks

Introduction  Ecological importance of sound => monitoring animals through passive acoustics;  Autonomous acoustic recorders => habitat use and seasonal variation in the marine environment (Lammers et al., 2013; Ward et al., 2011; Baumann-Pickering et al., 2016);  Acoustic data collected using of unmanned vehicles => large areas in diferente time scales;  Present study focused on assessing delphinid acoustic presence in offshore waters of the Southeast Coast of Brazil using an autonomous recorder embedded in an unmanned surface vehicle.

What is a Wave Glider? It is an unmanned surface vehicle with the following characteristics:  Wave energy thrust

 Two componentes: surface and subsea  Longterm endurance (months)  Maximum speed: 2 m/s

 Full-time telemetry

How does the Wave Glider work?

Inside the tow-body there is a TC4014-5 Reson/Teledyne hydrophone (-180 dB re 1V/µPa, 15 Hz-480 kHz) connected to a SAIL Decimus® digital acquisition and processing system (sampling rate of 50 kHz in 16 bits, with 26 dB gain).

Passive Acoustic Monitoring from 6-15th February 2016 in the Santos Basin > 24 one-hour recording files per day

Material and methods – analyses Detection and analysis in Raven 1.4 (512-point Hann window, 50% overlap) Detector 1 – 8 to 22 kHz (frequency range) and 60 to 900 ms (duration)

Detector 2 – 2 to 7 kHz (frequency range) and 60 to 900 ms (duration)

Detector 3 – 15 to 24 kHz (frequency range) and 5 to 10 ms (duration)

Detector 2 Detector 1

Detector 3

Material and methods – analyses

 Detections were considered a part of the same event when they occured in intervals of less than 1 hour from each other;  Detection events were quantified and mapped temporal and spatial distribution in the area.

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Results and discussion

Results and discussion 25% of the sampling period (54 hours) presented detections

Results and discussion

Results and discussion  Detections occured on all recording days: an evidence that delphinids are acoustically active in the area;  The amount of positive detections in an event does not reflect the real number of delphinid sounds;  Separate events do not necessarily represent different groups;  The use of different detectors was useful to reflect the presence of marine fauna and acoustic activity variations in the region.

Large diversity of whistles indicates more than one species!

Conclusion and future recomendations  The use of Wave Glider for PAM at the Southwestern Atlantic Ocean is unprecedented and demonstrated high potential;  Higher sample rate may be important for recording species that produce sounds in higher frequency;  The use of detectors on frequencies below 1 kHz can be useful for evidence of whales and fish presence;

 This study shows that delphinid species use a significant portion of the sampled area located on the Southeast Coast of Brazil.

Acknowledgements This study resulted from a partnership of PETROBRAS, WesternGeco/LROG, and BRAZILIAN NAVY under the PETROBRAS Research & Development Project PT-128.01.12041 – “Novas tecnologias e inovações em sensores e coletas meteooceanográficas”.

Authors thank the Faculty of Oceanography (FAOC/UERJ) and the Brazilian Navy Research Institute (IPqM) for logistic support for acoustic analysis. Also, we would like to thank the Rio Acoustics 2017 organizing committee for the opportunity.

Questions are welcome!

Thank you! Isabela Maria Seabra de Lima Laboratório de Mamíferos Aquáticos e Bioindicadores Faculdade de Oceanografia UERJ