In situ acoustic characteristics of the large jellyfish Nemopilema nomurai in the East China Sea

Yoon, Eun–A; Hwang, Doo–Jin; Shin, Hyeong-Ho; Gwa, Du-Seong; Cha, Cheolpyo

doi:10.3796/ksft.2012.48.3.256

Cited by 5 publications

(1 citation statement)

References 21 publications

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“…Most acous�c studies on jellies have focused on measuring TS at mul�ple narrowband frequencies commonplace for fisheries applica�ons. A broadly used method of measuring medusa TS is by analyzing in situ backscatering measurements, by detec�ng single targets (Alvarez Colombo et al, 2008;Brierley et al, 2004;Cimino et al, 2018;De Rober�s and Taylor, 2014;Kim et al, 2016b;Yoon et al, 2012) and/or by a combina�on of echo integra�on and trawls/video to obtain a rela�onship between echo intensity and numerical density (Båmstedt et al, 2003;Brierley et al, 2001). A handful of studies have obtained ex situ TS measurements in either a controlled laboratory se�ng or a semi-controlled open water enclosure (Hirose et al, 2005(Hirose et al, , 2009Kang et al, 2014;Monger et al, 1998;Mutlu, 1996;Yoon et al, 2015Yoon et al, , 2010.…”

Section: Introduc�onmentioning

confidence: 99%

Broadband acoustical scattering in coastal environments: application to gelatinous organisms

Kahn

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Broadband acoustical technology revolutionized our ability to explore, monitor, and operate in the ocean. While strides have been made in numerous physical and biological applications, there remain many standing scientific questions well suited to broadband approaches. Physics-based sound scattering models allow us to interpret and draw quantitative observations from measurements. Such models have been developed and used to assess the biomass of many types of marine organisms of ecological significance, but we lack rigorous scattering models for gelatinous organisms despite their possibly accounting for a significant proportion of global marine biomass. Additionally, acoustical techniques for characterizing microbubble populations have been established for decades, yet little is known about the spectral characteristics of dense microbubble clouds associated with estuarine tidal fronts. These bubbles facilitate air-sea gas exchange and could interfere with acoustical operations in coastal environments; however, the density and size distribution of the bubbles must be known to assess their impacts. This dissertation addresses these deficiencies in our application of broadband techniques. In Chapter 2, a sound scattering model for gelatinous organisms is developed based on the Distorted Wave Born Approximation. The 3-D model is applied to a species of scyphomedusa and verified withlaboratory measurements of broadband backscattering from live individuals. The model predicts backscattering levels and broad spectral behavior within <2 dB. In Chapter 3, a towable instrument is developed for measuring broadband excess attenuation from bubbles from which the size distribution is inferred. The instrument is tested under breaking waves in a laboratory wave tank and then used to characterize the bubble size distribution in the Connecticut River tidal ebb plume front. In Chapter 4, broadband backscattering measurements from the Connecticut River front are used to infer the associated bubble size distribution. Spatial trends in the bubble size distribution are examined within the context of frontal kinematics. An observed disparity between the bubble size distribution measured with excess attenuation and volume backscattering is hypothesized to arise from a sampling bias caused by bubbles concentrated in the upper water column.

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Section: Introduc�onmentioning

confidence: 99%

Broadband acoustical scattering in coastal environments: application to gelatinous organisms

Kahn

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Broadband backscattering from scyphozoan jellyfish

Kahn

Lavery

Govindarajan

2023

The Journal of the Acoustical Society of America

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As the ecological importance of gelatinous organisms becomes increasingly appreciated, so has the need for improved knowledge of their abundance and distribution. Acoustic backscattering measurements are routine for fisheries assessments but are not yet widely used to survey populations of gelatinous zooplankton. The use of acoustic backscattering techniques to understand the distribution and abundance of organisms requires an understanding of their target strength (TS). This study presents a framework for a sound scattering model for jellyfish based on the Distorted Wave Born Approximation that incorporates size, shape, and material properties of individual organisms. This model, with a full three-dimensional shape rendition, is applied to a common species of scyphomedusa (Chrysaora chesapeakei) and verified experimentally with broadband (52–90 and 93–161 kHz) laboratory TS measurements of live individuals. Cyclical changes in the organism's shape due to swimming kinematics were examined, as well as averages over swimming position and comparisons with scattering from simpler shapes. The model predicts overall backscattering levels and broad spectral behavior within <2 dB. Measured TS exhibits greater variability than is predicted by scaling the size of the organism in the scattering model, showing that density and sound speed vary among individuals.

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Density estimation of giant jellyfish (<i>Nemopilema nomurai</i>) using a scientific echosounder

OH,

KIM,

YOUN

et al. 2024

J. Korean Soc. Fish. Technol.

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In situ acoustic characteristics of the large jellyfish Nemopilema nomurai in the East China Sea

Cited by 5 publications

References 21 publications

Broadband acoustical scattering in coastal environments: application to gelatinous organisms

Broadband acoustical scattering in coastal environments: application to gelatinous organisms

Broadband backscattering from scyphozoan jellyfish

Density estimation of giant jellyfish (<i>Nemopilema nomurai</i>) using a scientific echosounder

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