Quantifying Loss of Acoustic Communication Space for Right Whales in and around a U.S. National Marine Sanctuary

• Main Authors: Hatch, Leila T, Clark, Christopher W, Van Parijs, Sofie M, Frankel, Adam S, Ponirakis, Dimitri W
• Other Authors: NOAAS STELLWAGEN BANK NATIONAL MARINE SANCTUARY SCITUATE MA
• Format: Text
• Language: English
• Published: 2012
• Subjects: Acoustics; Radio Communications; *ACOUSTIC SIGNATURES; *COMMUNICATION AND RADIO SYSTEMS; *SUBMARINE NOISE; *UNDERWATER SOUND; AMBIENT NOISE; ANIMALS; BUOYS; DOSAGE; IDENTIFICATION SYSTEMS; INTEGRATED SYSTEMS; MEASUREMENT; MERCHANT VESSELS; MOUNTS; NOISE(SOUND); NORTH ATLANTIC OCEAN; OCEANOGRAPHIC EQUIPMENT; PEAK VALUES; POPULATION; RECORDING SYSTEMS; RESPONSE(BIOLOGY); SELF OPERATION; SIGNAL TO NOISE RATIO; WHALES; WIND VELOCITY; AREA MARINA PROTEGIDA; ESPECIES EN PELIGRO; PLANIFICACI ON ESPACIAL MARINA; RUIDO SUBMARINO; Eubalaena glacialis; North Atlantic
• Online Access: http://www.dtic.mil/docs/citations/ADA563664; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA563664

The effects of chronic exposure to increasing levels of human-induced underwater noise on marine animal populations reliant on sound for communication are poorly understood. We sought to further develop methods of quantifying the effects of communication masking associated with human-induced sound on contact-calling North Atlantic right whales (Eubalaena glacialis) in an ecologically relevant area (∼10,000 km2) and time period (peak feeding time). We used an array of temporary, bottom-mounted, autonomous acoustic recorders in the Stellwagen Bank National Marine Sanctuary to monitor ambient noise levels, measure levels of sound associated with vessels, and detect and locate calling whales. We related wind speed, as recorded by regional oceanographic buoys, to ambient noise levels. We used vessel-tracking data from the Automatic Identification System to quantify acoustic signatures of large commercial vessels. On the basis of these integrated sound fields, median signal excess (the difference between the signal-to-noise ratio and the assumed recognition differential) for contact-calling right whales was negative (−1 dB) under current ambient noise levels and was further reduced (−2 dB) by the addition of noise from ships. Compared with potential communication space available under historically lower noise conditions, calling right whales may have lost, on average, 63?67% of their communication space. One or more of the 89 calling whales in the study area was exposed to noise levels ≥120 dB re 1 μPa by ships for 20% of the month, and a maximum of 11 whales were exposed to noise at or above this level during a single 10-min period. These results highlight the limitations of exposure-threshold (i.e., dose-response) metrics for assessing chronic anthropogenic noise effects on communication opportunities. Our methods can be used to integrate chronic and wide-ranging noise effects in emerging ocean-planning forums that seek to improve management Pub. in Conservation Biology, p1-12, 14 AUG 2012,Government or Federal Purpose Rights License. The original document contains color images.