Search

Cetacean responses to marine anthropogenic activities include changes in acoustic behavior, surface active behavior, dive behavior, direction of travel, and behavioral activity states. Behavioral effects have been observed in several field studies involving both observational and controlled exposure experiments. However, the consequences of these behavioral responses are often difficult to quantify in biological currencies. Previous work has empirically measured the energetic consequences of many of these behavioral responses that may have acute or chronic energetic consequences including our ONR-supported work on the metabolic costs of communicative sound and click production, and the metabolic costs of changes in vocal behavior in bottlenose dolphins that are consistent with vocal modification. The current investigation involves two separate but related studies that will address energetic costs of behavioral responses to anthropogenic disturbance, including acoustic effects, in odontocetes. The first study will address, in a comparative framework, metabolic costs of sound production and vocal modification across different sound types and odontocete species. The second component of the investigation will address cumulative energetic costs of behavioral responses to disturbance. These analyses will provide quantitative information that will be particularly useful to incorporate into models such as the Population Consequence of (Acoustic) Disturbance (PCAD/PCoD) as well as provide input data for environmental assessments/impact statements and other permit processes involving anthropogenic activities that have the potential to impact marine mammals.

The objective of this study was to measure oxygen consumption in two captive bottlenose dolphins to determine the metabolic cost of click production. The metabolic cost of click production was also compared to resting metabolic rates, the metabolic cost of whistles and other communicative sound, and the metabolic costs of other activities, such as performing surface active behaviors (SABs) and/or swimming. This work required over two years to complete. Work during year 1 (2012) included training dolphins to perform the necessary behaviors and measuring metabolic rates during click production and control trials. The focus of year 2 (ending in December 2013) was to increase the number of click production trials and begin analyses to quantify the metabolic cost of click production. Data analysis continued through May 2014 with subsequent post-trial calibration of the instruments and metabolic baseline., Contract no. MIPR-N0001412IP20072, N00014-1-21-0270

The objective of this study is to measure oxygen consumption in two captive bottlenose dolphins to determine the metabolic cost of click production. The metabolic cost of click production will then be compared to resting metabolic rates, the metabolic cost of whistles and other communicative sounds, and the metabolic costs of other activities, such as performing surface active behaviors (SABs) and/or swimming. This work required two years to complete. Year 1 (training dolphins to perform the necessary behaviors and measuring metabolic rates during click production and resting trials) was initiated in 2012. For the second year of this study (ending in December 2013), we aimed to increase the number of experimental trials to quantify the metabolic cost of click production in bottlenose dolphins. The metabolic cost of click production is being measured in two captive male Atlantic bottlenose dolphins (Tursiops truncatus) maintained at Dr. Terrie Williams' Mammalian Physiology Laboratory at the University of California, Santa Cruz, Long Marine Laboratory. These individuals were trained by Traci Kendall (Program Manager/Research Training Supervisor) and Beau Richter (Head Trainer) to produce clicks on command while stationed under a metabolic hood to measure oxygen consumption. The sounds of free-ranging Atlantic bottlenose dolphins have been described as clicks, whistles, buzzes, quacks, and pops (Jacobs et al., 1993). The trained sounds of the captive dolphins of the current study are representative of those found in wild, free-ranging populations., Sponsored in part by MIPR-N0001413IP20017 and MIPR-N0001412IP20072.

Animals often increase the amplitude (the Lombard effect), duration, and/or repetition rate of their acoustic signals as a strategy to help reduce the probability of masking from environmental sounds (NRC 2003). Although accumulating evidence from recent research (Scheifele et al. 2005, Holt et al. 2009, Parks et al. 2010) illustrates that several marine mammal species readily modify the parameters of their acoustic signals to compensate for masking noise, potential energetic costs of such compensation behavior are unknown. To our knowledge, there is no empirical data on the metabolic cost of sound production for any marine mammal species. Given that changes in vocal behavior in response to masking noise has been documented in several species, assessing the biological significance of these effects is paramount but also very difficult given the life histories of marine mammals. The Population Consequences of Acoustic Disturbance (PCAD) model has been proposed as a framework to address this challenging task (NRC 2005). Data on the energetic cost of dolphin vocalization from this study can be used to assess the biological significance of vocal compensation in response to sound exposure and populate transfer function 2 (transfer function between behavior change to life functions immediately affected) in the PCAD model., Contract no. MIPR-N0001410IP20067

Animals often increase the amplitude (the Lombard effect), duration, and/or repetition rate of their acoustic signals as a strategy to help reduce the probability of masking from environmental sounds (NRC 2003). Although accumulating evidence from recent research (Scheifele et al. 2005, Holt et al. 2009, Parks et al. 2010) illustrates that several marine mammal species readily modify the parameters of their acoustic signals to compensate for masking noise, potential energetic costs of such compensation behavior are unknown. To our knowledge, there is no empirical data on the metabolic cost of sound production for any marine mammal species. Given that changes in vocal behavior in response to masking noise has been documented in several species, assessing the biological significance of these effects is paramount but also very difficult given the life histories of marine mammals. The Population Consequences of Acoustic Disturbance (PCAD) model has been proposed as a framework to address this challenging task (NRC 2005). Data on the energetic cost of dolphin vocalization from this study can be used to assess the biological significance of vocal compensation in response to sound exposure and populate transfer function 2 (transfer function between behavior change to life functions immediately affected) in the PCAD model., The original document contains color images. Prepared in collaboration with the Center for Ocean Health, University of California, Santa Cruz, CA.

Animals often increase the amplitude (the Lombard effect), duration, and/or repetition rate of their acoustic signals as a strategy to help reduce the probability of masking from environmental sounds (NRC 2003). Although accumulating evidence from recent research (Scheifele et al. 2005, Holt et al. 2009, Parks et al. 2010) illustrates that several marine mammal species readily modify the parameters of their acoustic signals to compensate for masking noise, potential energetic costs of such compensation behavior are unknown. To date, the only empirical data on the metabolic cost of sound production as well as the metabolic cost of increasing the amplitude of acoustic signals for any marine mammal species has been collected by the PIs during previously ONR-supported studies. The focus of the previous work was bottlenose dolphins producing whistles and other communicative sounds (Holt et al. 2011 a, b, Noren et al. 2011). There is currently no information on energy expenditure during click production in odontocetes, and studies have demonstrated that they also readily modify these sound types in an echolocation context to compensate for masking noise. Given that changes in vocal behavior in response to masking noise has been documented in several species, assessing the biological significance of these effects is paramount but also very difficult given the life histories of marine mammals. The Population Consequences of Acoustic Disturbance (PCAD) model has been proposed as a framework to address this challenging task (NRC 2005). Data on the energetic cost of the production of clicks from this study can be used to assess the biological significance of vocal compensation in response to sound exposure and populate transfer function 2 (transfer function between behavior change to life functions immediately affected) in the PCAD model., The original document contains color images. Prepared in collaboration with the Center for Ocean Health, University of California, Santa Cruz, CA.

For the first year of this study (Phase 1), oxygen consumption was measured in two captive bottlenose dolphins during sound production of social signals and compared to resting metabolic rates (RMRs) and metabolic costs of other activities, such as performing surface active behaviors (SABs) and/or swimming. That phase of this work was completed in 2010. For the second year of this study (Phase 2, 2011), we aim to measure oxygen consumption in these individuals while they produce the same type of sounds, but at different levels and/or durations. This work is ongoing and will continue until the end of the calendar year 2011. These measurements will quantify the potential metabolic cost of vocal compensation as an anti-masking strategy in response to anthropogenic sound exposure. The metabolic cost of sound production is being measured in two captive male Atlantic bottlenose dolphins (Tursiops truncatus) maintained at Dr. Terrie Williams' Mammalian Physiology Laboratory at the University of California, Santa Cruz, Long Marine Laboratory. These individuals were trained by Traci Kendall (Program Manager/Research Training Supervisor) and Beau Richter (Head Trainer) to produce sounds on command while stationed under a metabolic hood to measure oxygen consumption. For Phase 2 of the study, the dolphins also have been trained to produce relatively higher and lower amplitude sounds of the same type on command using two different discriminative stimuli or cues (one for loud and one for quiet). The sounds of free-ranging Atlantic bottlenose dolphins have been described as clicks, whistles, buzzes, quacks, and pops (Jacobs et al. 1993). The trained sounds of the captive dolphins of the current study are representative of those found in wild, free-ranging populations., Sponsored in part by MIPR-N0001410IP20067.

Animals often increase the amplitude (the Lombard effect), duration, and/or repetition rate of their acoustic signals as a strategy to help reduce the probability of masking from environmental sounds (NRC 2003). Although accumulating evidence from recent research (Scheifele et al. 2005, Holt et al. 2009, Parks et al. 2010) illustrates that several marine mammal species readily modify the parameters of their acoustic signals to compensate for masking noise, potential energetic costs of such compensation behavior are unknown. To our knowledge, there is no empirical data on the metabolic cost of sound production for any marine mammal species. Given that changes in vocal behavior in response to masking noise has been documented in several species, assessing the biological significance of these effects is paramount but also very difficult given the life histories of marine mammals. The Population Consequences of Acoustic Disturbance (PCAD) model has been proposed as a framework to address this challenging task (NRC 2005). Data on the energetic cost of dolphin vocalization from this study can be used to assess the biological significance of vocal compensation in response to sound exposure and populate transfer function 2 (transfer function between behavior change to life functions immediately affected) in the PCAD model. For the first year of this study (Phase 1), we aim to measure oxygen consumption in two captive bottlenose dolphins during sound production at relatively low to moderate levels and compare the metabolic costs of sound production to resting metabolic rates (RMRs) and metabolic costs of other activities, such as performing surface active behaviors (SABs) and/or swimming. For the second year of this study, we propose to measure oxygen consumption in these individuals while they produce the same type of sounds but at different levels, durations, or repetition rates. These measurements will quantify the potential metabolic cost of vocal compensation.