Marine wildlife are exposed to a rising tide of human impacts including shipping traffic, fishing gear entanglement, underwater noise, offshore energy development and climate change. These factors can increase levels of chronic stress, which can have profound effects on immune system function, health, reproduction and survival.
Our scientists develop and apply innovative techniques to measure hormones to understand stress physiology and evaluate the impacts of different stressors on key species and populations. Our laboratory pioneered the first stress assessments of free-swimming whales using immunoassay of stress-related hormone metabolites in fecal samples. Building on this seminal work, our research expanded to measuring hormones in respiratory vapor (“blow”) and baleen. Hormones in whale blow reflect the short-term physiological state of the whale and baleen provides a unique retrospective record of stress responses over a decade or more.
Building on our expertise, we have diversified our techniques to investigate stress in other species, including Florida manatees, seals, and sea turtles. Many studies have shown that chronic stress responses in wildlife (also humans and domestic animals) resulting from long-term disturbance of various types leads to debilitating effects on the cardiovascular system, increased disease susceptibility, decreased reproductive success and body growth, and slowed development. This can ultimately can impact survival.
Research by our scientists found that North Atlantic right whales exposed to chronic underwater noise have elevated levels of stress hormones with potential long-term consequences for health, reproduction and survival.
- Develop innovative, non-invasive approaches to evaluate stress in marine wildlife;
- Validate new assays for measuring stress-associated hormones in marine wildlife, using a variety of sample types including plasma, feces, baleen and respiratory vapor;
- Assess how chronic stress affects health, reproduction and survival in marine wildlife; and
- Identify the major causes of human-induced stress in the marine environment.
Monitoring North Atlantic right whale health and stress to assess threats from human activities
North Atlantic right whales are called “urban whales” because they are exposed to numerous threats from human activities along their coastal range from Florida to Canada. Anthropogenic mortalities, low reproductive rates and declining health are impeding recovery of this critically endangered species. Our research program develops innovative approaches to evaluate health and understand the impacts of human activities on right whales. Our visual health assessment method (using photographs of each whale) enables us to follow trends in health of individual whales and across the population over decades, and evaluate the health impacts in response to stressors in their environment. Our program has accumulated two decades of physiologic data on living right whales–including a panel of reproductive, metabolic and stress hormone assays–that provides a window into reproduction, health and levels of stress experienced by whales in response to different factors.
Investigating bowhead whale stress responses to Arctic development and climate change
The Arctic is experiencing rapid environmental changes coupled with the effects of increasing human activity associated with resource extraction, and expanded shipping traffic and fishing effort. Assessment of stress responses in bowhead whales, using hormone concentrations in different biological matrices, is a useful tool for understanding and monitoring the impacts of ecological changes (such as reductions in sea ice), and the effects of increasing human-activities. We started collaborating with the North Slope Borough Department of Wildlife Management in 2000 to monitor fecal reproductive and stress hormones in western Arctic bowheads. More recently, we have been measuring hormones deposited along the growth layers of baleen plates. This provides both short (fecal) and long-term (baleen) approaches to stress monitoring.
Measuring hormones in whale "blow" to study physiological responses to human activities in near real-time
A major challenge for studying large whales is that sample types conventionally used for health analyses are logistically challenging to collect from free-swimming cetaceans. But whales breathe at the surface with huge tidal volume, and the exhaled clouds of respiratory vapor or “blow”” contain measurable hormone biomarkers. Our scientists have pioneered a novel technique for collecting and measuring reproductive and stress hormones in the blow of North Atlantic right whales. The long-term records of the North Atlantic Right Whale Catalog and sightings database have provided detailed life history information to validate this method. This tool may allow us to measure in near real-time, whale responses to a variety of human activities, and to determine those that are most detrimental.
Assessing health and human impacts on Florida manatees
As a coastal species living near humans, Florida manatees are vulnerable to increasing anthropogenic and environmental pressures that are often recognized too late to prevent or contain large die-offs –and challenging to investigate after death. Since 2012, more than 150 manatees have died in the polluted Indian River Lagoon during “unusual mortality events”. Understanding these mortalities is critical because mass die-offs serve as indicators of serious ocean health problems, and provide key information about how environmental changes are impacting manatees and ecosystems. Our program is developing a tool to measure stress and metabolic hormones, as vital biomarkers, in fecal samples. This will provide critical data to actively monitor the health of manatees in the wild–and enhance the opportunity for earlier intervention.
Developing biomarkers of chronic stress in sea turtles
The number of sea turtles that wash ashore deeply chilled and unable to swim (hypothermic or “cold-stunned”) along Cape Cod beaches in late Fall has risen markedly in recent years, reaching 700 turtles in 2014. Given the numbers of stranded turtles in need of critical care–including endangered Kemp’s Ridley sea turtles–it is important to understand the physiological responses of these imperiled turtles to better inform clinical and management practices. Our sea turtle rehabilitation efforts provide an unparalleled opportunity to explore new biomarkers to evaluate and understand chronic stress in sea turtles. Results of this work can be used to improve rehabilitation efforts in stranded turtles and provide the tools to investigate stressors from environmental and anthropogenic causes in wild sea turtles.
Investigating reproduction and stress physiology in the northern fur seal
In recent decades, the largest breeding colony of northern fur seals has faced drastic, unexplained declines, necessitating the development of new tools to assess fur seal health and reproduction. Our program is developing non-invasive fecal biomarkers to investigate primary threats to fur seals, and to examine the impact of various stressors on health and reproduction. This project involves partnerships with other institutions across the U.S. to study the physiology of aquarium-housed, stranded, and wild populations of northern fur seals. These data will advance our knowledge of species physiology, help inform management decisions regarding threats, and can be applied to monitor changes in reproductive and health patterns for vulnerable populations of northern fur seals.