ASA 128th Meeting - Austin, Texas - 1994 Nov 28 .. Dec 02

4pAB5. Zooplankton population density assessment and acoustics.

D. V. Holliday

Tracor Appl. Sci. Anal. and Appl. Res. Div., 9150 Chesapeake Dr., San Diego, CA 92123

There are a variety of acoustical methods which can be used as tools in basic and applied research in biological oceanography, estuarine ecology, and in limnology. The mode of application of these tools is often as important and interesting as are the sensor characteristics. Two such sensor systems, the TAPS and the BITS, are being used to sense and describe temporal and spatial distributions of small zooplankton in situ. These sensors operate as active sonars at discrete, multiple frequencies from hundreds of kilohertz to several megahertz. Acoustical design parameters and the mode of deployment for several of these systems will be presented. TAPS operates in either a profiling mode or in a cast mode. BITS estimates zooplankton abundance at discrete depths from a mooring and telemeters the data to shore. Data from both will be used to illustrate their application in both marine and estuarine ecosystems science. Illustrations of the acoustical data each of these systems produces will be illustrated, along with several ancillary abiotic measurements and derived estimates of the size structure and biomass of the underlying population of zooplankton that causes the scattering. [Work supported by ONR Oceanic Biology, NSF Biological Oceanography, and Tracor.]