Characterization of sound scattering layers in the Bay of Biscay using broadband acoustics, nets and video

Type Article
Date 2019-10
Language English
Author(s) Blanluet Arthur1, Doray MathieuORCID1, Berger LaurentORCID2, Romagnan Jean-Baptiste1, Le Bouffant Naig1, Lehuta SigridORCID1, Petitgas Pierre1
Affiliation(s) 1 : Unité Écologie et Modèles pour l’Halieutique, Ifremer, Nantes, France
2 : Service Acoustique Sous-marine et Traitement de l’Information, Ifremer, Brest, France
Source Plos One (1932-6203) (Public Library of Science (PLoS)), 2019-10 , Vol. 14 , N. 10 , P. e0223618 (19p.)
DOI 10.1371/journal.pone.0223618
WOS© Times Cited 4
Abstract

Sound scattering layers (SSLs) are observed over a broad range of spatio-temporal scales and geographical areas. SSLs represent a large biomass, likely involved in the biological carbon pump and the structure of marine trophic webs. Yet, the taxonomic composition remains largely unknown for many SSLs. To investigate the challenges of SSL sampling, we performed a survey in a small study area in the Northern Bay of Biscay (France) by combining broadband and narrowband acoustics, net sampling, imagery and video recordings. In order to identify organisms contributing to the observed SSLs, we compared measured frequency spectra to forward predicted spectra derived from biological data. Furthermore, to assess the confidence in SSL characterization, we evaluated uncertainties in modeling, acoustical and biological samplings. Here, we demonstrate for the first time that SSL backscattering intensity in the Bay of Biscay can be dominated in springtime by resonant gas bearing organisms below 100 kHz, namely siphonophores and juvenile fishes and by pteropods at higher frequencies. Thus, we demonstrate the importance of broadband acoustics combined to nets, imagery and video to characterize resonant backscatterers and mixed mesozooplankton assemblages.

Full Text
File Pages Size Access
Publisher's official version 19 3 MB Open access
S1 Appendix. Echosounder calibrations. 2 35 KB Open access
S2 Appendix. Gaseous target backscattering model. 2 131 KB Open access
S1 Fig. Noise spectrum. 1 MB Open access
S2 Fig. Images of main scatterers. 686 KB Open access
S3 Fig. Hydrological context. 375 KB Open access
S1 Table. Description of used mesozooplankton and micronekton nets. 1 56 KB Open access
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