Behavioral and Physiological Response Studies (BPRS) with Social Delphinid Cetaceans Using Operational and Simulated Military Mid-Frequency Active Sonar
Abstract
Delphinid cetaceans are generally abundant off the U.S. coast, with smaller social species including common, bottlenose, and Risso s dolphins being among the most commonly seen marine mammals in many areas. Consequently, these protected species comprise a disproportionately large percentage of the total numbers of animals predicted to be affected by large-scale human acoustic disturbances, including Navy active sonar training and testing. To this point, these predictions of impact have been based on assumptions about many aspects of baseline movement and social behavior and how they change as a function of disturbance. Major progress has been made in research on other species with use of tag sensors to monitor behavior and behavioral change, but most of these are either challenging or inappropriate to apply to small, fast delphinids that occur in large groups and whose social response is strongly mediated by group dynamics. Our research team has successfully demonstrated the application of completely novel multi-disciplinary methods to measure baseline behavior and behavioral and physiological responses to noise in small delphinid cetaceans. This approach relies on an integration of: broad-scale visual monitoring of group movement and behavior using theodolites and high-power binoculars; fine-scale measurements of spacing, speed, and directionality using photogrammetry from unmanned aerial systems (UAS); strategic deployments of drifting passive acoustic recorders; and strategic biopsy tissue samples. We applied these methods within controlled exposure experiments (CEEs) using no-noise controls and known noise exposure conditions using an experimental sound source. Our recent ONR-funded pilot effort demonstrated that these approaches can be successfully applied to challenging species and integrated to provide direct, previously unavailable data on behavior and behavioral response at the broad and fine scales needed to greatly improve predictions of response probability. The pilot project was rightly intended to prove the concept and provide direction on the field viability of these methods and conditions favorable to research success. It clearly did so, with specific lessons-learned regarding methodology, species-typical contexts, and environmental factors considered in detail. Further, it provided extensive baseline data on movement and social behavior for these species as well as considerable novel data on behavioral responses to Navy mid-frequency active sonar (MFAS) using an experimental sound source simulating signals commonly used in training operations. Here, we propose to apply these proven methods to: (1) test behavioral and physiological responses to operational MFAS sources for common dolphins in defined contexts: and (2) expand sample sizes for simulated MFAS sources from the pilot effort for four different cetacean species (long- and short-beaked common dolphins, bottlenose dolphins, and Risso s dolphins). This will result in a robust sample size (comparable CEEs to published tag-based studies in other species) for multiple species using the experimental source, as well as sufficient samples (>10 CEEs over four field periods) for common dolphins with operational MFAS sources to evaluate response probabilities to these sources and any contextual differences from the simulated source, which will inform how results in other species may appropriately be extrapolated. We will coordinate directly with operationally Navy helicopter-dipping MFAS sources (AN/AQS-22) in part recognizing logistical challenges of coordinating directly with Navy source vessels using other MFAS sources and given the greater contextual similarity of these sources with the experimental simulated MFAS source. These results will be published and directly integrated into Navy regulatory compliance processes for species that comprise the majority of predicted takes in all training areas where the Navy operates.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 20, 2019
- Source ID
- N000141912572
Entities
People
- Brandon L. Southall
Organizations
- Office of Naval Research
- Southall Environmental Associates (United States)
- United States Navy