RAPID Proposal: Assessing changes in humpback whale stress hormone levels in response to COVID19-related decreases in ocean noise and vessel traffic

Humans influence nearly all environments and ecosystems. In marine ecosystems, sound is used by nearly all animals, but marine mammals in particular use sound to communicate, feed, navigate, and perform other critical life functions. In the oceans, sound from human activities like shipping, vessel traffic, and sonars increase stress hormone levels in whales. As well, the presence of ships and boats around whales can also increase stress. As a result of COVID19-related mandates, human use of the oceans has changed significantly. In Monterey Bay, shelter-in-place restrictions minimized recreational boating and whale watching concurrent to humpback whales returning for their feeding season. To determine the impact that changes In human activity have on stress levels in humpback whales, a unique study to compare blubber hormone levels in whales during COVID19-related human use of Monterey Bay versus a period next year when conditions return to normal is proposed. To do this, vessel numbers will be measured using AIS vessel reporting information, the ambient sound levels will be measured from continuous passive acoustic arrays, and stress hormone levels in whales from blubber biopsy samples will be collected and quantified. Comparisons will then be made between stress hormone levels in whales during periods with decreased and normal human presence to identify both how levels change and also which factors (vessel presence, ambient noise, or both) most impact whale health. This is a unique opportunity to gain critical knowledge to understand how human activities impact marine ecosystems and how these can be minimized.

Quantifying the impacts of anthropogenic activities in marine systems is difficult because it requires large-scale changes in industry and major logistic support. COVID19-related changes in human use of oceans has resulted in significant declines in recreational and commercial vessel traffic and ambient sound levels. Steroid hormones are released for myriad physiological responses, and two of these glucocorticoids, cortisol and corticosterone, have been associated with the stress in baleen whales. Combining glucocorticoid quantification with environmental factors can determine physiological responses to anthropogenic stressors. Monterey Bay is a feeding ground for humpback whales, has a real-time, calibrated, wide bandwidth passive acoustic monitoring system (Monterey Accelerated Research System: MARS, MBARI), and offers access to sample whales locally. This study will collect biopsy samples from humpback whales, both as a rapid response to current conditions and in a comparable period when activity and disturbance is more typical. Tissue samples will be evaluated for stress hormone levels and compared with concurrent noise levels and vessel activity (derived from available tracking information and passive acoustic detections of vessels) to monitor how changes in anthropogenic noise and disturbance affects whales in different conditions. The current conditions for vessel noise associated with changes in human activity related to the COVID-19 pandemic provides a unique opportunity for this comparative study. This will help to understand the magnitude of physiological stress associated with different levels of disturbance, and inform ongoing efforts to set science-based goals to strategically quiet large vessels once industrial activity returns to more typical conditions.

This award was cofunded by the Integrative Ecological Physiology and the Physiological Mechanisms and Biomechanics Programs in the Division of Integrative Organismal Systems in Directorate for Biological Science.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.