Effects of sonar and other manmade ocean noises on marine mammals have traditionally been defined either as injury or disruption of behavior. The earliest concern was that elevated noise could reduce the range of communication by masking faint signals. Few studies have documented this effect, according to Peter Tyack (ptyack@whoi.edu) of the Woods Hole Oceanographic Institute, but recent work emphasizes the various mechanisms animals use to compensate for elevated noise.
Tyack will present initial results from a study on behavioral responses of beaked whales and other whales to sonar and other sounds. The study was conducted at the Atlantic Undersea Test and Evaluation Center (AUTEC) range near Andros Island in the Bahamas, where beaked whales can regularly be detected using passive acoustic monitoring of their echolocation clicks. The tagged beaked whale responded to both sonar and killer whale sounds by premature cessation of clicking during foraging dives, and an unusually slow and long ascent. [Papers 1aID1 and 1pAB3]
Several other scientists who conduct research on the effects of noise and other human activities on marine mammals are also presenting papers at the Paris meeting. James Finneran (james.finneran@navy.mil) of the U.S. Navy Marine Mammal Program will report on recent data for temporary threshold shifts (TTS) -- an increase in threshold for species such as bottlenose dolphins and belugas that persists after a noise has ended [Paper 1pAB7]. TTS depends on the exposure frequency of the noise, as well as sound pressure, duration, and temporal pattern, according to studies comparing hearing thresholds before and after subjects are exposed to intense sounds. Carmen Bazua (bazua@seridor.unam.mx) of the University of Mexico (UNAM) will report on her studies of the effect of ves
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| Contact: Jason Bardi jbardi@aip.org 301-209-3091 American Institute of Physics Source:Eurekalert |