Approaches to Understanding the Cumulative Effects of Stressors on Marine Mammals (2017) / Chapter Skim
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2 Estimating Exposure and Effects of Sound on Wildlife
2 Estimating Exposure and Effects of Sound on Wildlife
Pages 17-32
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From page 17... ...
. tive effects of anthropogenic stressors, including sound, on There is a diverse array of anthropogenic sound sources, marine mammals, recent terrestrial studies have evaluated which vary in time, frequency, and intensity.
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The stronger response Anthropogenic sounds can also distract animals (Chan of killer whales (Orcinus orca) than that of sperm whales et al., 2010)
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colonies such that received levels The costs in reduction of habitat are obvious for species at the center of colonies were approximately 52 dbA Leq that avoid noisy areas entirely or that decline in abundance (re 20 μPa; Shannon et al., 2014) .1 In response to exposure, with noise exposure, but there also may be costs for those prairie dogs significantly reduced aboveground activity, and individuals that remain in noisy areas.
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The animals are more likely to react behaviorally to short, intense sounds, MARINE STUDIES This section provides a selection of studies showing the 2 Defined in the Marine Mammal Protection Act as "harass, hunt, cap anatomical, physiological, and behavioral responses of marine ture, or kill, or attempt to harass, hunt, capture, or kill" (16 U.S.C. § 1362; mammals to different intensities of sound.
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The Navy has adopted more conservative sources, it is more effective as a physical measure than as a criteria for behavioral response thresholds for beaked whales predictor of aggregate impact on marine mammals. Predict- (all-or-nothing threshold of 140 dBRMS)
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(2014) for killer whales showing onset of avoidance behavior in a controlled exposure experiment that used a scaled mid-frequency sonar source as the stimulus (see Box Figure 1a)
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Thus, any effort to include measures of uncertainty, such as confidence intervals for estimates of predicted take, as required under the Marine Mammal Protection Act, would be more consistent with the state of our knowledge than providing a single number for takes. Calculations of take are very sensitive to the shape of the dose–response function at low levels of dose, because this corresponds to larger distances, where relatively more animals are exposed.
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It is recognized that the curves are based on marine mammal hearing groups. The HF cetaceans have the small numbers of animals, and only a few species are sur- lowest estimated PTS threshold, 173 dBSEL for nonimpulse rogates for each entire hearing group.
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to suggest limits on the ranges at which sound could injure marine mammals, evidence began to accumulate that lethal Dose–Response Relationships strandings of a poorly known group of whales called beaked whales coincided with naval sonar exercises. Frantzis (1998)
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For example, tagged Cuvier's beaked whales responded to the simulated sonar at received levels as low as 89 dB re 1 µPa but did not respond to sonar from an active naval ship farther away with a received level up to 106 dB. Within the U.S.
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at 5 km at received levels of 155 dBRMS (Thompson et al., for captive harbor porpoises and long-finned pilot whales, 2013a)
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Some harbor porpoises and Cuvier's U.S. naval test and training ranges in Southern California, beaked whales respond at levels well below the 120 and 140 the Bahamas, and Hawaii (Falcone et al., 2009; McCarthy dBRMS response thresholds currently used for these species.
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. All birds and mammals tested have of impulsive sounds that marine mammals experience come from seismic activity associated with oil and gas exploration; 8A band-pass filter allows a range of frequencies to pass with minimum pile driving associated with construction of bridges, docks, attenuation and strongly attenuates frequencies outside that band.
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Avoidance responses have more commonly been reported for baleen whales. Avoidance responses to airgun sounds at received levels of 160-170 dBP-P re 1 μPa have been reported Acoustic Deterrent Devices for migrating gray whales (Malme et al., 1983)
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This level is high enough that few sources of noise would be likely to mask the clicks, so it is unlikely that Sharks and killer whales are some of the primary predaelevated noise would make the shad less likely to escape. tors of marine mammals.
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(2012a) report on a group sary to establish the probabilistic relationships between of killer whales exposed to a playback of mid-frequency exposure to sound, contextual factors, and severity of sonar sounds.
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