Probing the fine structure of ocean sound‐scattering layers with ROVERSE technology

• Published in: Limnology and Oceanography
• Main Authors: Greene, Charles H., Wiebe, Peter H., Miyamoto, Robert T., Burczynski, Janusz
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1991
• Subjects: Aquatic Science; Oceanography; Arctic; Arctic Ocean; North Atlantic; Zooplankton
• Online Access: http://dx.doi.org/10.4319/lo.1991.36.1.0193; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.4319%2Flo.1991.36.1.0193; https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1991.36.1.0193

A 420‐kHz, dual‐beam SONAR system, deployed on a remotely operated vehicle (ROV), was used to examine the fine structure of sound‐scattering layers (SSLs) in Puget Sound and the Arctic Ocean. The Puget Sound SSL, initially detected with a shipboard, 200‐kHz SONAR system, was correlated with a high biomass of sound scatterers in the size range of macrozooplankton and micronekton. Its vertical position appeared unrelated to profiles of temperature, salinity, or chlorophyll fluorescence. The Arctic Ocean SSL was composed of similar‐sized sound scatterers, although its volume backscattering intensity was 10–100 times lower than that observed for the Puget Sound SSL. The vertical position of the Arctic SSL was closely associated with the thermocline separating Arctic Water from North Atlantic Water. The fine‐scale, horizontal variability of water‐column volume backscattering was examined at both study sites. The highest variability observed was associated with the Puget Sound SSL where the mean intensity of volume backscattering was also the highest. These findings are consistent with the common observation that, whatever methods are used to measure zooplankton and micronekton abundance, sampling variance nearly always increases with the mean.