Physiological Consequences of Flight Responses in Diving Mammals: Critical metrics for assessing the impacts of novel environmental stimuli on cetaceans and other marine living species
Abstract
During the past two decades, oceanic noise including Navy sonar has remained one of the most controversial and debated stressors aff""ecting marine mammal populations. Although it has been linked to numerous mass stranding events involving deep-diving cetaceans, ide"ntifying the actual cause of injury has been difficult. This is due to the fact that scientists are just beginning to understand how" marine mammals respond to anthropogenic disturbances. Specifically, we do not know how the suite of conflicting biological response"s associated with escaping noise interacts in marine mammals to result in tissue injury or death. Only after determining the physiol"ogical consequences of, 1) diving deep and fast, 2) performing escape maneuvers, and 3) surviving disrupted metabolic control during" submerged flight will we be able to make the link between abnormal behaviors by marine mammals and harm by aversive oceanic noise." To address this, the main purpose of the pr""oposed study is to determine the physiological consequences of escape responses in cetaceans, and to develop the key metrics for acc"urately predicting short- and long-term energetic impacts of anthropogenic noise on diving mammals. Our approach considers that anth"ropogenic disturbances that harm marine mammals are associated with extreme, conflicting physiological responses (high speed and ele"vated stroke frequencies coupled to bradycardia and metabolic suppression) that occur with submerged escape. We focus on cetaceans d"ue to the sensitivity of this group to oceanic noise, their vulnerability to developing decompression syndromes, the lack of biologi""cal information regarding anthropogenic threats, and concern over the number of cetacean strandings attributed to Navy sonar. Usign" a lab-to-field protocol with trained and wild odontocete cetaceans ranging in body mass from 50 kg porpoises to 3500 kg killer whal"es, we will test the central hypothesis, that the unique biological adaptations that normally enable cetaceans to safely complete a" dive are overridden during escape responses and pose a risk to metabolic and cardiovascular homeostasis. Four specific aims are pro"posed, 1) determine energetic costs and physiological risks of evasive manuevers by dolphins and whales, 2) build allometric regress""ions for predicting gait-specific stroking costs for small and large cetaceans, 3) assess the physiological effects of metabolic dia""pause in diving cetaceans particularly for maintaining heart-brain integration, and 4) apply energetic/physiological metrics to pred"ict the cost of escape in free-ranging cetaceans exposed to anthropogenic noise. Custom heart rate-accelerometer instruments and blood flow monitors combined with open-flow respirometry will be used to determine the capacity for submerged escape by cetacea"ns. We will develop a suite of metrics (peformance costs, evidence of cardiovascular anomalies, relative risk to neural function, at"ypical behaviors) to define acute and chronic impacts due to oceanic noise. By combining data for small and large cetaceans from thi"s proposal and our previous work, we will complete an allometric analysis that will allow investigators to translate behavioral and"" accelerometer data collected previously or in the future into energetic impacts for animals responding to noise. Thus, results from"" this project will be directly applicable to all cetaceans, will represent the most comprehensive energetic analysis for free-rangin""g cetaceans, will represent the most comprehensive energetic analysis for free-ranging cetaceans to date, and will provide critical"" data for population threat models. Importantly, the project will accomplish the overall objective of improving the protection of ma"rine mammals during Naval operations by enabling Navy person
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Sep 01, 2017
- Source ID
- N000141712737
Entities
People
- Terrie M. Williams
Organizations
- Office of Naval Research
- United States Navy
- University of California, Santa Cruz