ASA 124th Meeting New Orleans 1992 October

4pAB8. Behavioral study of zooplankton response to high-frequency acoustics.

Kilian B. Sullivan-Silva

Michael J. Forbes

Naval Undersea Warfare Ctr., Code 8213, Newport, RI 02841-5047

An experimental investigation of behavioral patterns and responses of zooplankton was performed in Narragansett Bay, RI by the Naval Undersea Warfare Center Division, Newport, with scientists from Woods Hole Oceanographic Institution (WHOI). Normal swim behaviors of zooplankton (unstimulated) were compared to behaviors of zooplankton subjected to high-frequency acoustic pulses (stimulated). Of particular interest was the effect of acoustics on the jump or ``burst'' behavior of the zooplankton. The zooplankton were videotaped with the WHOI Video Plankton Recorder (VPR), resulting in approximately 30 h of video data from each of the VPR's four cameras. The cameras were concentrically focused on the ensonified volume of water, with fields of view ranging from 6.3 to 0.5 cm. The dominant species observed was the copepod Acartia tonsa, ranging in size from approximately 0.2 to 1.5 cm. Data analyzed yield an average particle density of 117 000/m[sup 3], and overall burst rates per particle of 0.62 bursts/s with acoustics and 0.80 bursts/s with no acoustic stimulation. However, real-time observations and a statistical data assessment reflect no quantitative difference in swim behaviors due to the acoustic stimulation.