Type
Text
Type
Thesis
Advisor
Warren, Joseph D. | Patrick H. Ressler | Stephan B -- Munch.
Date
2010-08-01
Keywords
Biology, Oceanography -- Applied Mathematics | acoustics, Bering Sea, modeling, target strength, zooplankton
Department
Department of Marine and Atmospheric Science
Language
en_US
Source
This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree.
Identifier
http://hdl.handle.net/11401/72672
Publisher
The Graduate School, Stony Brook University: Stony Brook, NY.
Format
application/pdf
Abstract
Acoustic assessment of Bering Sea euphausiids and their predators can provide useful data for ecosystem studies if the acoustic scattering characteristics of these animals are known. The amount of acoustic energy that is scattered by different marine zooplankton taxa is strongly affected by the contrast of the animal's density (g) and sound speed (h) with the surrounding seawater. Density and sound speed contrast were measured in the Bering Sea during the summer of 2008 for several different zooplankton and nekton taxa including: euphausiids (Thysanoessa inermis, Thysanoessa raschii, and Thysanoessa spinifera), copepods, amphipods, chaetognaths, gastropods, fish larvae, jellyfish, and squid. Density contrast values varied between different taxa as well as between individual animals within the same species. Sound speed contrast was measured for monospecific groups of animals and differences were found among taxa. The range, mean, and standard deviation of g and h for all euphausiid species were: g = 1.001-1.041; 1.018 ñ 0.009 and h = 0.990-1.017; 1.006 ñ 0.008. Changes in the relationship between euphausiid material properties and animal length, seawater temperature, seawater density, and geographic location were also evaluated. Results suggest that environmental conditions at different sample locations led to significant differences in animal density and material properties.Acoustic surveys monitor euphausiid populations in the Bering Sea because of their importance as prey walleye pollock. Various scattering models exist to convert acoustic survey data to numerical density estimates of euphausiids, but a target strength (TS) model specific to Bering Sea euphausiids did not exist. This study parameterized a distorted wave Borne approximation model using measured lengths and material properties (density contrast, g, and sound speed contrast, h) from live euphausiids. All model parameters (length, g, h, shape, orientation) were evaluated for their effect on TS estimates.
Recommended Citation
Smith, Joy Nicole, "Physical Characteristics of Bering Sea Zooplankton and Their Use to Parameterize an Acoustic Scattering Model for Euphausiids" (2010). Stony Brook Theses and Dissertations Collection, 2006-2020 (closed to submissions). 1875.
https://commons.library.stonybrook.edu/stony-brook-theses-and-dissertations-collection/1875