Acoustic Technology -- Executive Summary

## Executive Summary

Changes in global climate, whether from anthropogenic or natural causes, will produce changes in the ocean environment. One of the primary objectives of GLOBEC is to assess the ultimate predictability of the response of life in the sea to changes in ocean physics. Understanding the mechanisms and processes that relate an animal's ability to survive and reproduce to the ocean's dynamic environment are essential to the success of GLOBEC. Understanding these complex interactions will require the advancement of technology on a variety of fronts. Ready access to conventional oceanographic technology, as well as the development of new instrumentation and methodology, is required to achieve GLOBEC's objectives.

The GLOBEC science community is interdisciplinary. It includes a diverse group of technologists who develop instrumentation that biological oceanographers, physical oceanographers, and mathematical modelers will use in the design and interpretation of experiments. This integration of technologists and scientists provides the means for effectively studying and understanding the structure and dynamics of marine ecosystems. Establishment of a coherent approach for use in addressing GLOBEC science issues, especially to quantify the physical environment and the relation of ocean physics to the animals that live in the sea, is a continuing concern in GLOBEC.

To facilitate achieving the goals of GLOBEC, a coherent approach to GLOBEC related studies is advised. To enhance communication and cooperation between scientists, the GLOBEC Steering Committee is sponsoring a series of focused, interdisciplinary workshops that address the role of advanced technology in the GLOBEC program. In this context, over 50 biological and physical oceanographers, fisheries scientists, mathematical modelers, physicists, and engineers met at NOAA/NMFS and WHOI in Woods Hole, MA in April 1991 to discuss the existing capabilities and potential developments in acoustical and optical technology, methodology, and instrumentation for measuring spatial and temporal distributions and assessing the behavior of animals in the sea.

The group identified a variety of acoustical and optical instruments and techniques that can be used in pursuit of GLOBEC's science objectives. It was determined that the integration of acoustical and optical technology would be highly beneficial and that the technologies were both complementary and synergistic in their potential utility. Synoptic sampling of both the biological and physical characteristics of the water column was stressed. Sensors which operate on quasi-continuous spatial and temporal scales were viewed as essential if GLOBEC is to link small scale process measurements to population parameters. The importance of quickly establishing a definition of data archiving and retrieval protocols for GLOBEC was recognized. Several methods for enhancing an individual investigator's access to complex acoustical and optical instruments were examined. Similarities were identified in the acoustical technologies used to examine zooplankton, micronekton, macroplankton, and fish, but it was recognized that system parameters (e.g., operating frequencies, beamwidths, signal and data processing algorithms) are often so different that alternate implementations of the same basic technologies may be necessary to examine different elements of the food web. An emphasis on the acquisition, integrated processing, and display of multifrequency acoustic data was a recurring theme in working groups dealing with different trophic levels. Specific requirements for new research regarding the synthesis and display of multifrequency data sets were identified. Calls for new research also included the advancement of theory and supporting measurements in describing scattering from individual organisms and the development and validation of methods for quantitative fusion of multisensor data.