A year of conservation physiology: from gloom to hope…

A year of conservation physiology: from gloom to hope…

By: Kim Birnie-Gauvin

At the start of 2020, few people had heard of COVID-19, and fewer still could imagine the world would be facing its most recent global pandemic. As the virus continued to spread, human activity slowed to reduce transmission, making way for the so-called Anthropause. This period presented a unique opportunity to not only understand how humans had affected the environment and its inhabitants, but to also give it some time to recover from previous anthropogenic impacts (e.g. lower carbon emissions).

In the meantime, the scientific community was working hard to understand the conditions that enabled disease development, and the role of human–wildlife interactions in this context. In their recent perspective paper, Cooke et al. (2021) argue that this is an opportunity for conservation physiologists to interact with medicine and human health experts to reduce the probability of future pandemics.¹ The conservation physiology toolbox is particularly well suited to understand the effects of the pandemic in two ways: 1) retroactively, by investigating different components of wildlife ecology before, during, and after the pandemic; and 2) proactively, by determining the factors that led to the pandemic, to prevent future viral waves. As is the case for many other disciplines, the conservation physiology community has been deeply affected by COVID-19 through interruptions in research, training, and networking. But while this last year has been challenging, it has also given rise to new, creative, and exciting science that continues to play an important role in informing some of the most pressing conservation issues. Below are just a few examples of this science.

History meets physiology

As the climate continues to warm, the thickness, coverage, and duration of Arctic sea ice continues to decline, with important consequences for species that rely on sea ice for life history events. For example, walruses passively float on sea ice to different feeding locations, but receding sea ice has forced them to use coastal land haulouts, resulting in them feeding in less productive waters or going on energetically costly foraging trips. For this species, understanding how reproductive and stress-related hormones respond to changes in sea ice could be particularly helpful to deduce the extent to which sea ice loss is affecting them, as well as to determine their resilience to it. However, studying modern populations is not ideal, because sea ice has receded extensively in the last two decades. But, there is a solution.

Charapata et al. (2021) addressed this concern by extracting hormones from Pacific walrus bones collected over three millennia.² Concentrations of cortisol (a stress hormone) and progesterone, testosterone, and oestradiol (reproductive hormones) were analysed in walrus bones covering a period of approximately 3651 years to track changes in reproductive activity and stress. While cortisol profiles did not change between archaeological and modern samples, reproductive hormones were much lower in modern samples than in archaeological samples, when the population was rapidly increasing, presumably even at carrying capacity. Progesterone in females and testosterone in males were significantly correlated to ice cover for the years 1880–2016. This study provides a method for conservation physiologists to monitor long-term changes in the physiology of animals using museum collections, and is valuable for management and conservation, particularly because little is known about how populations fared prior to the Anthropocene.

Tracking human–wildlife interactions

Wildlife conservation and management in a human-dominated world requires a deep understanding of how humans are affecting the physiology and ecology of animals. In many instances, human activities can be stressful for wildlife, though the extent of this stressor is rarely well described. Let’s say you take your family and dog out for a hike and encounter a deer; the deer gets spooked and runs off, but do we know just how stressful that encounter was for the deer? In some contexts, like during the hunting season, these encounters are common. In some cases, hunters will even use baying dogs, but the effects of this hunting method on stress are poorly described.

Recent advances in technology, like biologging, allow scientists to gain detailed information from free-ranging animals, and provides the perfect tool for tracking the effects of human–wildlife interactions. In their study, Græsli et al. (2020) evaluated the effects of hunting with baying dogs on adult female moose equipped with temperature loggers, heart rate loggers, and GPS collars with accelerometers.³ Their findings suggest that the presence of a dog within 240 m for more than 10 minutes caused the moose’s maximum body temperature and mean heart rate to increase for the day of the encounter. In addition, the moose travelled longer and at a higher speed on the day of the encounter, and rested longer the following day. This means that body condition and reproduction rates may be affected if hunting disturbances are frequent. Such unique experimental studies provide us with important knowledge on the extent to which human activities affect wildlife.

Conservation physiology: lightning round

So much fascinating research has happened in the last year—here are a few noteworthy findings.

·       Good news! Heart rate and locomotor behaviour of Caribbean spiny lobster are not affected by light pollution.⁴

·       Bad news. Migrating brown trout and Arctic char might be in serious trouble; cardiac impairment occurred at only 2°C above river temperature, causing serious concerns given current climate predictions.⁵

·       Narwhals recover relatively fast from handling, but handling time appears to have some significant and longer-time impacts on behaviour and activity levels.⁶

·       Turns out that using species’ average swimming speeds in management schemes, particularly in relation to barriers, is dangerous because ‘one size does not fit all’ in freshwater fishes.⁷

1. Cooke SJ, Cramp RL, Madiger CL, et al. 2021. Conservation physiology and the COVID-19 pandemic. Conserv Physiol 9: coaa139.

2. Charapata P, Horstmann L, Misarti N. 2021. Steroid hormones in Pacific walrus bones collected over three millennia indicate physiological responses to changes in estimated population size and the environment. Conserv Physiol 9: coaa135.

3. Græsli AR, Le Grand L, Thiel A, et al. 2020. Physiological and behavioural responses of moose to hunting with dogs. Conserv Physiol 8: coaa122.

4. Steell SC, Cooke SJ, Eliason EJ. 2020. Artificial light at night does not alter heart rate or locomotor behaviour in Caribbean spiny lobster (Panulirus argus): insights into light pollution and physiological disturbance using biologgers. Conserv Physiol 8: coaa097.

5. Mottola G, Kristensen T, Anttila K. 2020. Compromised thermal tolerance of cardiovascular capacity in upstream migrating Arctic char and brown trout—are hot summers threatening migrating salmonids? Conserv Physiol 8: coaa101.

6. Shuert CR, Marcoux M, Hussey NE, et al. 2021. Assessing the post-release effects of capture, handling and placement of satellite telemetry devices on narwhal (Monodon monoceros) movement behaviour. Conserv Physiol 9: coaa128.