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The past six years have been marked by some of the most dramatic climatic events observed in the Antarctic region in recent history, commencing with the 2017 sea-ice extreme low. The Humpback Whale Sentinel Programme is a circum-polar biomonitoring program for long term surveillance of the Antarctic sea-ice ecosystem. It has previously signalled the extreme La Niña event of 2010/11, and it was therefore of interest to assess the capacity of existing biomonitoring measures under the program to detect the impacts of 2017 anomalous climatic events. Six ecophysiological markers of population adiposity, diet, and fecundity were targeted, as well as calf and juvenile mortality via stranding records. All indicators, with the exception of bulk stable isotope dietary tracers, indicated a negative trend in 2017, whilst C and N bulk stable isotopes appeared to indicate a lag phase resulting from the anomalous year. The collation of multiple biochemical, chemical, and observational lines of evidence via a single biomonitoring platform provides comprehensive information for evidence-led policy in the Antarctic and Southern Ocean region.

Ryan, C. (2020). Lipid content of whale blubber cannot be measured using biopsies. J. Exp. Biol. 223, jeb227710. [doi:10.1242/jeb.227710][1] [1]: https://doi.org/10.1242/jeb.227710

An animal's body condition provides valuable information for ecophysiological studies, and is an important measure of fitness in population monitoring and conservation. While both the external body shape of an animal, as well as its internal tissues (i.e. fat content) can be used as measures of body condition, the relationship between the two is not always linear. We compared the morphological body condition (external metric obtained through aerial photogrammetry) of migrating humpback whales (Megaptera novaeangliae) with their outer blubber lipid concentration (internal metric obtained through blubber biopsy sampling) off south-west Australia early and late in the breeding season (spanning ∼4.5 months). The external body condition index of juvenile and adult humpback whales decreased with 26.9 (from 18.8 to −8.1%) and 12.0 percentage points (from 8.6 to −3.4%) between the early and late phase, respectively. In contrast, we found no intra-seasonal change in blubber lipid concentration, and no difference between reproductive classes (juveniles, adults and lactating females), however the small sample size prevented us from effectively testing these effects. Importantly however, in the 33 animals for which paired metrics were obtained, we found no correlation between the morphometric body condition index and the blubber lipid concentration of individual whales. The lack of a linear relationship suggest that changes in outer blubber lipid concentration do not reflect external changes in body shape, thus limiting the utility of outer blubber lipid reserves for individual body condition evaluation. The wider spectrum of change in body morphometry captured with aerial photogrammetry, supports the use of body morphometry as a reliable and well tested method.

The behavioural context provides opportunities for studying the use and characteristics of acoustic signals. We analysed the context-specific use of acoustic signals in a population of Atlantic spotted dolphins around the Canary archipelago. We calculated the whistle diversity, the mean value of whistle stereotypy and the repetition rate of both tonal and burst-pulsed sounds. Eleven parameters of frequency, signal duration and modulation were measured from each whistle. Results showed that whistle diversity and whistle and chirp repetition rates were negatively correlated with group size, but only whistle diversity and the mean number of stereotypy were related to behavioural activity. Whistles were more complexly modulated during high behavioural activity than when engaged in moderate movements. Furthermore, during socialising and feeding, the highest mean value of stereotypy was displayed, and the parameters of non-stereotyped whistles had lower variability. Our results suggest the use of a complex comm...

Southern hemisphere humpback whales (Megaptera novaeangliae) rely on summer prey abundance of Antarctic krill (Euphausia superba) to fuel one of the longest‐known mammalian migrations on the planet. It is hypothesized that this species, already adapted to endure metabolic extremes, will be one of the first Antarctic consumers to show measurable physiological change in response to fluctuating prey availability in a changing climate; and as such, a powerful sentinel candidate for the Antarctic sea‐ice ecosystem. Here, we targeted the sentinel parameters of humpback whale adiposity and diet, using novel, as well as established, chemical and biochemical markers, and assembled a time trend spanning 8 years. We show the synchronous, inter‐annual oscillation of two measures of humpback whale adiposity with Southern Ocean environmental variables and climate indices. Furthermore, bulk stable isotope signatures provide clear indication of dietary compensation strategies, or a lower trophic level isotopic change, following years indicated as leaner years for the whales. The observed synchronicity of humpback whale adiposity and dietary markers, with climate patterns in the Southern Ocean, lends strength to the role of humpback whales as powerful Antarctic sea‐ice ecosystem sentinels. The work carries significant potential to reform current ecosystem surveillance in the Antarctic region. This is the peer reviewed version of an article, which has been published in final form at [http://dx.doi.org/10.1111/gcb.14035]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.

Background Ethanol (EtOH) intake correlates with increased risk-taking, and sex differences exist in both EtOH use and risk-taking in humans and rats. However, the interaction of sex and gonadal hormones to affect risk-taking under the influence of EtOH has not been determined. This was the focus of the current study. Methods Adult Long-Evans rats (n = 18 males and females) were gonadectomized and received hormone replacement at physiologic levels or blank implants (n = 7-9/group). Risk-taking was assessed with probability discounting, requiring rats to choose between a small/certain reward and a large/uncertain reward delivered with decreasing probability throughout each daily session. Before testing, rats received saline or EtOH (0.5 or 1.0 g/kg) ip. Results In males, EtOH increased preference for the large/uncertain reward lever (F2,28 = 10.462, p 0.05). At baseline, ORCHX+T males showed a greater preference for the large/uncertain reward lever then ORCHX males (F1,14 = 13.805, p Conclusions These results show that EtOH, sex, and hormones interact to influence decision making. EtOH increases risk taking in males, but not in females. However, EtOH selectively decreases choice latency in females, and decreases loss sensitivity in both sexes. These findings are relevant to understanding human behavior, particularly in adolescents who experience increased hormone levels and often drink EtOH and engage in risky behavior.

Southern hemisphere humpback whales have evolved energetically demanding capital breeding and migratory life-history behaviours. It has been hypothesised that not all individuals of a population participate in the seasonal migration each year, or only undertake partial migrations. Given the cost of migration and reproduction, we explored the possibility that specifically, not all mature females participate in the seasonal migration every year, or significantly delay or shorten their migration, in response to poor feeding conditions. That is, females must attain a minimum threshold of accumulated energy reserves to commit to a reproductive event that likely occurs as a product of mating during migration. With a 1:1 male to female birth ratio, yet a male bias observed along the main migratory corridor; this study utilised inter-annual migratory cohort sex ratios to explore their potential to serve as measures of population fecundity, as a function of ecosystem health. The sex ratios of randomly biopsied adult humpback whales, sampled at a defined location and set time-points along the main migratory corridor from 2008 to 2016 were investigated. Northward migration sex ratios in 2009, 2014 and 2016 revealed a lower male bias suggesting good female participation in the migration and therefore apparent optimal provisioning during the two preceding summers. By contrast, the 2011 southward migration, revealed the highest male bias recorded of 5.75:1. Southward migration sex ratios were found to oscillate closely with measures of population adiposity, a sentinel parameter employed for long-term surveillance of the Antarctic sea-ice ecosystems under the Southern Ocean Observing System-endorsed Humpback Whale Sentinel Program. Anomalously poor humpback whale body condition recorded in 2011 was attributed to poor Antarctic feeding conditions during the extreme La Niña event of 2010/11. These findings lend support for the application of migratory cohort sex ratios, standardised by time and location, as a measure of relative inter-annual population fecundity. This work therefore contributes a new non-lethal tool for the study of population health, as a function of ecosystem productivity, and facilitates the inclusion of fecundity as a sentinel parameter into long-term Antarctic ecosystem surveillance under the Humpback Whale Sentinel Program.

© 2017 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd. The ability to accurately evaluate the energetic health of wildlife is of critical importance, particularly under conditions of environmental change. Despite the relevance of this issue, currently there are no reliable, standardized, nonlethal measures to assess the energetic reserves of large, free-roaming marine mammals such as baleen whales. This study investigated the potential of adipocyte area analysis and further, a standardized adipocyte index (AI), to yield reliable information regarding humpback whale (Megaptera novaeangliae) adiposity. Adipocyte area and AI, as ascertained by image analysis, showed a direct correlation with each other but only a weak correlation with the commonly used, but error prone, blubber lipid-percent measure. The relative power of the three respective measures was further evaluated by comparing humpback whale cohorts at different stages of migration and fasting. Adipocyte area, AI, and blubber lipid-percent were assessed by binary logistic regression revealing that adipocyte area had the greatest probability to predict the migration cohort with a high level of redundancy attributed to the AI given their strong linear relationship (r = −.784). When only AI and lipid-percent were assessed, the performance of both predictor variables was significant but the power of AI far exceeded lipid-percent. The sensitivity of adipocyte metrics and the rapid, nonlethal, and inexpensive nature of the methodology and AI calculation validate the inclusion of the AI in long-term monitoring of humpback whale population health, and further raises its potential for broader wildlife applications.

The ability to accurately evaluate the energetic health of wildlife is of critical importance, particularly under conditions of environmental change. Despite the relevance of this issue, currently there are no reliable, standardized, nonlethal measures to assess the energetic reserves of large, free‐roaming marine mammals such as baleen whales. This study investigated the potential of adipocyte area analysis and further, a standardized adipocyte index (AI), to yield reliable information regarding humpback whale (Megaptera novaeangliae) adiposity. Adipocyte area and AI, as ascertained by image analysis, showed a direct correlation with each other but only a weak correlation with the commonly used, but error prone, blubber lipid‐percent measure. The relative power of the three respective measures was further evaluated by comparing humpback whale cohorts at different stages of migration and fasting. Adipocyte area, AI, and blubber lipid‐percent were assessed by binary logistic regression revealing that adipocyte area had the greatest probability to predict the migration cohort with a high level of redundancy attributed to the AI given their strong linear relationship (r = −.784). When only AI and lipid‐percent were assessed, the performance of both predictor variables was significant but the power of AI far exceeded lipid‐percent. The sensitivity of adipocyte metrics and the rapid, nonlethal, and inexpensive nature of the methodology and AI calculation validate the inclusion of the AI in long‐term monitoring of humpback whale population health, and further raises its potential for broader wildlife applications.