Finding patterns within the noise: Modelling baleen whale response to multiple stressors through replicate physiological sampling of gray whales
Abstract
The physiological response of whales to stressors is dependent on multiple internal and external factors. Without understanding the effects of each stressor individually, accounting for the type, magnitude and duration of stressors, as well as the effects of internal factors such as body condition and reproductive state, the whales response to multiple stressors, cumula, cannot be assessed. These limitations are particularly challenging because there is rarely sufficient sample size or repeated sampling of individuals to robustly describe patterns within this noisy and complex data. To quantify and model baleen whale physiological response to different stressors we propose to use the well-studied Pacific Coast Feeding Group (PCFG) sub-population of Eastern North Pacific gray whales (Eschrichtius robustus) as a case study. While not a threatened, endangered or at risk species (TES), the PCFG gray whales have considerable study advantages (multiple stressors, reliable repeated sampling of known individuals, high fecal sample collection rate, tractable regulatory environment) that enable us to leverage existing knowledge and collect sufficient data to fit robust models of the effects of multiple types of stressors on baleen whales. Additionally, this population is expected to experience a unique disturbance during 2020-2022 due to construction of a renewable energy facility ("PacWave"), providing a rare opp collection on the whales baseline exposure to noise, we will be able to quantify soundscape contributions from natural and anthropogenic sound sources (e.g., PacWave construction, vessel traffic, dredging operations) to describe gray whale exposure to acoustic stressors. We will use fecal hormone analyses (glucocorticoids, reproductive steroids, and thyroid hormones), drone-based measures of behavior and body condition (photogrammetry), along with data on demography and behavior, to determine how multiple types of stressors may affect individual allostasis. These data will also be characterized by environmental conditions (as a proxy of prey availability) and temporal period (season and year). We will model these data to describe relationships between an individuals exposure to stressors and their physiological stress, and how this connects to an individuals health and vital rates. We will then integrate over the individuals in the population, accounting for the duration and intensity of the disturbances, to determine how different types of stressors may impact population dynamics. As a result, our project will provide information on the physiological impacts of various acoustic sources on baleen whales, and how best to evaluate potential disturbance, helping to support the Navys efforts to evaluate the consequences of their at-sea activities. Our specific objectives are to (1) distinguish between relevant and non-relevant stressors to a baleen whale, (2) quantify temporal thresholds and recovery rates of whales to stressors, (3) improve predictions of how multiple types of stressors will impact different demographic groups, (4) describe the population consequences of individual exposure to different stressors, (5) describe how relevant stressors interact to cause different physiological responses in individual baleen whales, and (6) inform the development of the population consequences of multiple stressors (PCoMS) framework through both the assessment of the efficacy of novel data collection, and by collaborating with Department of Defense (DoD) Strategic Environmental Research and Development Program (SERDP) research teams to scale changes in individuals physiological health due to exposure to m
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 31, 2020
- Source ID
- N000142012760
Entities
People
- Leigh G Torres
Organizations
- Office of Naval Research
- Oregon State University
- United States Navy