Rosalind M. Rolland

Evidence that ship noise increases stress in right whales

Baleen whales (Mysticeti) communicate using low-frequency acoustic signals. These long-wavelength sounds can be detected over hundreds of kilometres, potentially allowing contact over large distances. Low-frequency noise from large ships (20–200 Hz) overlaps acoustic signals used by baleen whales, and increased levels of underwater noise have been documented in areas with high shipping traffic. Reported responses of whales to increased noise include: habitat displacement, behavioural changes and alterations in the intensity, frequency and intervals of calls. However, it has been unclear whether exposure to noise results in physiological responses that may lead to significant consequences for individuals or populations. Here, we show that reduced ship traffic in the Bay of Fundy, Canada, following the events of 11 September 2001, resulted in a 6 dB decrease in underwater noise with a significant reduction below 150 Hz. This noise reduction was associated with decreased baseline levels of stress-related faecal hormone metabolites (glucocorticoids) in North Atlantic right whales (Eubalaena glacialis). This is the first evidence that exposure to low-frequency ship noise may be associated with chronic stress in whales, and has implications for all baleen whales in heavy ship traffic areas, and for recovery of this endangered right whale population.

Overcoming the challenges of studying conservation physiology in large whales: a review of available methods

A description and comparison of the four major methods available for studying conservation physiology of large whales, namely analysis of faecal, respiratory vapour, and skin/blubber biopsy samples, and photographs.

Baleen hormones: a novel tool for retrospective assessment of stress and reproduction in bowhead whales (Balaena mysticetus)

Baleen samples from sixteen bowhead whales contained measurable cortisol and progesterone, and both hormones demonstrated significant correlations with sex, age class and reproductive state. Analysis of hormones in baleen shows promise as a novel tool for retrospective analysis of stress and reproductive physiology of large mysticete whales.

Using hierarchical bayes to understand movement, health, and survival in the endangered north atlantic right whale.

Body condition is an indicator of health, and it plays a key role in many vital processes for mammalian species. While evidence of individual body condition can be obtained, these observations provide just brief glimpses into the health state of the animal. An analytical framework is needed for understanding how health of animals changes over space and time.Through knowledge of individual health we can better understand the status of populations. This is particularly important in endangered species, where the consequences of disruption of critical biological functions can push groups of animals rapidly toward extinction. Here we built a state-space model that provides estimates of movement, health, and survival. We assimilated 30+ years of photographic evidence of body condition and three additional visual health parameters in individual North Atlantic right whales, together with survey data, to infer the true health status as it changes over space and time. We also included the effect of reproductive status and entanglement status on health. At the population level, we estimated differential movement patterns in males and females. At the individual level, we estimated the likely animal locations each month. We estimated the relationship between observed and latent health status. Observations of body condition, skin condition, cyamid infestation on the blowholes, and rake marks all provided measures of the true underlying health. The resulting time series of individual health highlight both normal variations in health status and how anthropogenic stressors can affect the health and, ultimately, the survival of individuals. This modeling approach provides information for monitoring of health in right whales, as well as a framework for integrating observational data at the level of individuals up through the health status of the population. This framework can be broadly applied to a variety of systems – terrestrial and marine – where sporadic observations of individuals exist.

Adrenal responses of large whales: Integrating fecal aldosterone as a complementary biomarker to glucocorticoids

Until now, physiological stress assessment of large whales has predominantly focused on adrenal glucocorticoid (GC) measures. Elevated GC concentrations in feces (fGC) are known to reflect stressful disturbances, such as fishing gear entanglement and human-generated underwater noise, in North Atlantic right whales (Eubalaena glacialis). However, there can be considerable variation in GC production as a function of sex and life history stage, which may confound the interpretation of fGC levels. Additionally, GC antibodies used in immunoassays can cross-react with other fecal metabolites (i.e., non-target steroids), potentially influencing fGC data. Here, aldosterone concentrations (fALD; aldosterone and related metabolites) were measured in fecal samples from right whales (total n=315 samples), including samples from identified individuals of known life history (n=82 individual whales), to evaluate its utility as a complementary biomarker to fGC for identifying adrenal activation. Concentrations of fALD were positively correlated with fGCs in right whales (r=0.59, P<0.001), suggesting concurrent secretion of these hormones by the adrenal gland. However, fALD levels were less influenced by concentrations of reproductive steroids in feces, minimizing the potential confounder of assay cross-reactivity in samples with highly skewed hormone ratios. Across different life history states for right whales, fALD concentrations showed similar patterns to those reported for fGC, with higher levels in pregnant females (35.9±7.6ng/g) followed by reproductively mature males (9.5±0.9ng/g) (P<0.05), providing further evidence of elevated adrenal activation in these groups of whales. The addition of fALD measurement as a biomarker of adrenal activation may help distinguish between intrinsic and external causes of stress hormone elevations in large whales, as well as other free-living wildlife species, providing a more comprehensive approach for associating adrenal activation with specific natural and anthropogenic stressors.

Longitudinal progesterone profiles in baleen from female North Atlantic right whales (Eubalaena glacialis) match known calving history

We compared known calving events to longitudinal baleen progesterone profiles from baleen plates of two stranded adult female North Atlantic right whales. Reproductive history of the previous ten years was recorded accurately in baleen, with pronounced elevations in progesterone in regions of baleen grown during known pregnancies.

Get the most out of blow hormones: validation of sampling materials, field storage and extraction techniques for whale respiratory vapour samples

Respiratory vapor (blow) of cetaceans may contain vital physiologic data, yet fundamental methodological issues remain to be addressed for this nascent technique. We validated sample field storage; hormone extraction methods; and assay interference from sampling materials in order to ensure that reliable hormone data is obtained from whale blow.

Endocrine responses to diverse stressors of capture, entanglement and stranding in leatherback turtles (Dermochelys coriacea)

Limited data on stress physiology exist for leatherback turtles. Examination of 32 leatherback turtles showed that individuals exposed to entanglement, stranding, or entrapment in a weir net had elevated corticosterone and thyroxine compared to healthy controls.

Conservation Physiology of an Uncatchable Animal: The North Atlantic Right Whale (Eubalaena glacialis).

The North Atlantic right whale, Eubalaena glacialis (NARW), a critically endangered species that has been under intensive study for nearly four decades, provides an excellent case study for applying modern methods of conservation physiology to large whales. By combining long-term sighting histories of known individuals with physiological data from newer techniques (e.g., body condition estimated from photographs; endocrine status derived from fecal samples), physiological state and levels of stress can be estimated despite the lack of any method for nonlethal capture of large whales. Since traditional techniques for validating blood assays cannot be used in large whales, assays of fecal hormones have been validated using information on age, sex, and reproductive state derived from an extensive NARW photo-identification catalog. Using this approach, fecal glucocorticoids have been found to vary dramatically with reproductive state. It is therefore essential that glucocorticoid data be interpreted in conjunction with reproductive data. A case study correlating glucocorticoids with chronic noise is presented as an example. Keys to a successful research program for this uncatchable species have included: consistent population monitoring over decades, data-sharing across institutions, an extensive photo-identification catalog that documents individual histories, and consistent efforts at noninvasive collection of samples over years. Future research will require flexibility to adjust to changing distributions of populations.

Quantifying hormones in exhaled breath for physiological assessment of large whales at sea

Exhaled breath analysis is a non-invasive assessment tool that has shown promise in human diagnostics, and could greatly benefit research, management, and conservation of large whales. However, hormone assessment of whale respiratory vapor (blow) has been challenged by variable water content and unknown total volume of collected samples. To advance this technique, we investigated urea (a compound present in narrow range in circulation) as a normalizing factor to correct for blow sample concentration. Normalized progesterone, testosterone, and cortisol concentrations of 100 blow samples from 46 photo-identified North Atlantic right whales (Eubalaena glacialis) were more biologically relevant compared to absolute estimates, varying by sex, age class, or individual. Progesterone was elevated in adult females compared with other cohorts and highest in one independently confirmed pregnant female. For both sexes, testosterone was two-fold higher in reproductively mature whales but studied adult females showed the widest variation. Cortisol was present in relatively low concentrations in blow and demonstrated variation between individual whales, suggesting potential for studies of individual differences in adrenal activity. Incorporation of methodologies that normalize sample concentration are essential for blow hormone analysis of free-swimming whales, and measurement of urea could be used to optimize non-invasive physiological assessment of whales.