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article: harbor porpoise response to ACME

Subject: article: harbor porpoise response to ACME
From: Dave Mellinger <>
Date: Mon, 13 Dec 2004 18:00:28 -0800
contact [EMAIL PROTECTED] for a copy:
 Kastelein, R., W. Verboom, M. Muijsers, N. Jennings, and S. van der Heul. 
 The influence of acoustic emissions for underwater data transmission on the 
 behaviour of harbour porpoises (Phocoena phocoena) in a floating pen. Marine 
 Environmental Research 59:287-307.
 To prevent grounding of ships and collisions between ships in shallow
 coastal waters, an underwater data collection and communication
 network is currently under development: Acoustic Communication network
 for Monitoring of underwater Environment in coastal areas
 (ACME). Marine mammals might be affected by ACME sounds since they use
 sounds of similar frequencies (around 12 kHz) for communication,
 orientation, and prey location. If marine mammals tend to avoid the
 vicinity of the transmitters, they may be kept away from ecologically
 important areas by ACME sounds. One marine mammal species that may be
 affected in the North Sea is the harbour porpoise. Therefore, as part
 of an environmental impact assessment program, two captive harbour
 porpoises were subjected to four sounds, three of which may be used in
 the underwater acoustic data communication network. The effect of each
 sound was judged by comparing the animals' positions and respiration
 rates during a test period with those during a baseline period. Each
 of the four sounds could be made a deterrent by increasing the
 amplitude of the sound. The porpoises reacted by swimming away from
 the sounds and by slightly, but significantly, increasing their
 respiration rate. From the sound pressure level distribution in the
 pen, and the distribution of the animals during test sessions,
 discomfort sound level thresholds were determined for each sound. In
 combination with information on sound propagation in the areas where
 the communication system may be deployed, the extent of the
 'discomfort zone' can be estimated for several source levels
 (SLs). The discomfort zone is defined as the area around a sound
 source that harbour porpoises are expected to avoid. Based on these
 results, SLs can be selected that have an acceptable effect on harbour
 porpoises in particular areas. The discomfort zone of a communication
 sound depends on the selected sound, the selected SL, and the
 propagation characteristics of the area in which the sound system is
 operational. In shallow, winding coastal water courses, with
 sandbanks, etc., the type of habitat in which the ACME sounds will be
 produced, propagation loss cannot be accurately estimated by using a
 simple propagation model, but should be measured on site. The SL of
 the communication system should be adapted to each area (taking into
 account bounding conditions created by narrow channels, sound
 propagation variability due to environmental factors, and the
 importance of an area to the affected species). The discomfort zone
 should not prevent harbour porpoises from spending sufficient time in
 ecologically important areas (for instance feeding areas), or routes
 towards these areas.

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