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Layered Organization in the Coastal Ocean: Acoustical Data Acquisition Analyses and Synthesis

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Final rept. 1 Mar 2007-31 Jan 2009

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The research conducted with the funding made available through this grant was from an ONR Departmental Research Initiative DRI. The objective of the DRI was to better understand Layered Organization in the Coastal Ocean LOCO. The explicit goal of the DRI was To understand the properties of densely concentrated, thin layers of planktonic biota that can occur in coastal ocean environments, and the interacting physical, chemical, biological and optical processes responsible for establishment, maintenance and breakdown of layers. Our research had multiple interlinked objectives. The science objectives were twofold. The first, and most important, task involved describing the abundances and timing of changes in the spatial distribution of secondary producers zooplankton and micronekton during the LOCO field program. Several specific study sites in Monterey Bay had been selected during the LOCO groups planning meetings. Measurements at these locations were made in support of our LOCO colleagues simultaneous efforts to describe fine-scale features in the local ocean physics and to try to better understand the dynamics associated with the formation, maintenance and destruction of thin layers of phytoplankton. When present, thin phytoplankton layers are known to affect the scattering and absorption of light in the upper ocean. We had previously shown that time-depth histories for acoustic scattering layers zooplankton layers are often coherent with those observed for thin phytoplankton layers when measured at the same time and place. Grazing by zooplankton can locally modify the total phytoplankton biomass and create heterogeneity in thin phytoplankton layers. It can also change the thickness and vertical shapes of thin phytoplankton layers. Zooplankton can indirectly affect underwater visibility by changing optical absorption and scattering at different wavelengths by selectively removing particles of different sizes.

Subject Categories:

  • Biological Oceanography
  • Physical and Dynamic Oceanography
  • Acoustic Detection and Detectors

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